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Medical Patent Abstract
A care system and associated methods are provided for alleviating
patient pain, anxiety and discomfort associated with medical or
surgical procedures. The system comprises: at least one patient
health monitor device coupled to a patient and generating a signal
reflecting at least one physiological condition of the patient;
a drug delivery controller supplying one or more drugs to the patient;
a memory device storing a safety data set reflecting parameters
of at least one patient physiological condition; and an electronic
controller interconnected between the patient health monitor, the
drug delivery controller and the safety data set. The electronic
controller is capable of effecting a change in the drug supply delivered
to the patient and the generation of current signals by the patient
health monitor device depending on a comparison between at least
one patient physiological condition at its corresponding value reflected
in the safety data set.
Medical Patent Claims
I claim:
1. A system for alleviating patient pain, anxiety and discomfort
associated with medical or surgical procedures, the system comprising:
one or more patient health monitor devices coupled to a patient
and generating at least one first signal reflecting at least one
physiological condition of the patient during a medical or surgical
procedure; a drug delivery controller supplying one or more drugs
to the patient based upon the at least one first signal; and an
electronic controller accessing safety parameters for said at least
one physiological conditions, said parameters correlating to safe
and effective sedation, said electronic controller operatively connected
to the patient health monitor, and the drug delivery controller;
wherein said electronic controller receives the at least one first
signal and in response manages the application of the drugs by the
drug delivery controller in accord with the safety parameters; and
wherein the electronic controller, in response to the at least one
first signal, manages the generation of at least one second signal
by a second patient health monitor device in accord with the safety
parameters.
2. The system according to claim 1, wherein the at least one first
signal reflects one or more of the following physiological conditions
of the patient: heart rate, SpO.sub.2, respiratory rate, blood pressure,
and responsiveness.
3. The system according to claim 1, wherein the at least one second
signal reflects one or more of the following physiological conditions
of the patient: blood pressure and responsiveness.
4. The system according to claim 1, wherein the management of the
generation of the at least one second signal includes an assignment
of an event condition to the at least one first signal in accord
with the parameters, and wherein the event condition triggers the
one or more patient health monitor devices to generate the at least
one second signal.
5. The system according to claim 4, wherein the electronic controller
assigns an event condition in accord with the parameters when the
at least one first signal reflects a physiological condition of
the patient that is outside of predetermined safe levels.
6. The system according to claim 5, wherein the event condition
is high when the at least one first signal reflects a physiological
condition of the patient that is above predetermined safe levels.
7. The system according to claim 5, wherein the event condition
is low when the at least one first signal reflects a physiological
condition of the patient that is below predetermined safe levels.
8. The system according to claim 4, wherein the electronic controller
assigns an event condition in accord with the parameters when said
at least one first signal reflects a trend in the physiological
condition of the patient over time that suggests the condition will
be outside of predetermined safe levels within a predetermined time
period.
9. The system according to claim 4, the system further comprising
a user interface, wherein notice of the event condition is communicated
to a user of the system via the user interface.
10. The system according to claim 1, wherein the management of
the application of the drugs by the electronic controller includes
at least one of reducing or halting the flow of drugs.
11. A method for alleviating pain and anxiety in connection with
medical and surgical procedures, the method comprising the steps
of: a) connecting to a patient a drug delivery device having a drug
delivery controller supplying one or more drugs, said drug delivery
controller being coupled to an electronic controller which controls
the delivery of the drugs to the patient; b) attaching at least
one patient health monitor device to a patient, the health monitor
devices generating a first value reflecting at least one physiological
condition of a patient, the at least one patient health monitor
device coupled to the electronic controller; c) accessing stored
parameters of at least one patient physiological condition; d) delivering
the drugs to the patient based upon the generated first value and
in accord with stored parameters; and e) the at least one patient
health monitor device generating a second value reflecting a second
current physiological condition of the patient, the second value
generated for comparison with the stored parameters.
12. The method according to claim 11, wherein said first value
reflects at least one of the following physiological conditions
of the patient: heart rate, SpO.sub.2, respiratory rate, blood pressure,
and responsiveness.
13. The method according to claim 11, wherein the second value
reflects at least one of the following physiological conditions
of the patient: blood pressure and responsiveness.
14. The method according to claim 11, said method further including
the step of assigning an event condition to the first value in accord
with the stored parameters, wherein the event condition triggers
the at least one patient health monitor device to generate the second
value.
15. The method according to claim 14, wherein the electronic controller
assigns an event condition in accord with the stored parameters
when said first value reflects a physiological condition of the
patient that is outside of predetermined safe levels.
16. The method according to claim 15, wherein the event condition
is high when said first value reflects a physiological condition
of the patient that is above predetermined safe levels.
17. The method according to claim 15, wherein the event condition
is low when said first value reflects a physiological condition
of the patient that is below predetermined safe levels.
18. The method according to claim 14, wherein the electronic controller
assigns an event condition in accord with the stored parameters
when said first value reflects a trend in the physiological condition
of the patient over time that suggests the condition will be outside
of predetermined safe levels within a predetermined time period.
19. The method according to claim 14, said method further comprising
the step of communicating an event condition to a user of the system
via a user interface.
20. The method according to claim 14, wherein the step of delivering
the drugs to the patient comprises at least one of the step of reducing
and the step of halting the flow of drugs.
21. A method for alleviating pain and anxiety in connection with
medical and surgical procedures, the method comprising the steps
of: a) measuring at least one physiological condition; b) generating
a first value based upon the at least one physiological condition;
c) correlating the generated first value with predetermined safety
data; d) delivering at least one medication based upon the correlating
step; and e) providing an updated measurement of the at least one
physiological condition based upon the correlating step.
22. The method according to claim 21, wherein the at least one
physiological condition is at least one of heart rate, SpO.sub.2,
respiratory rate, blood pressure, and responsiveness.
23. The method according to claim 21, wherein the physiological
condition provided as an updated measurement is one of the same
physiological condition used to generate the first value and is
a different physiological condition.
24. The method according to claim 21, wherein the physiological
condition provided as an updated measurement is one of blood pressure
or responsiveness.
Medical Patent Description
FIELD OF THE INVENTION
This invention relates generally to an apparatus and method for
relieving patient pain and/or anxiety. More particularly, this invention
relates to a system and method for providing sedation, analgesia
and/or amnesia to a conscious patient undergoing a painful or anxiety-producing
medical or surgical procedure, or suffering from post-procedural
or other pain or discomfort. The invention electronically integrates
through conservative software management the delivery of one or
more sedative, analgesic or amnestic drugs with the electronic monitoring
of one or more patient physiological conditions. In one form, the
invention includes the use of one or more sets of stored data-defining
parameters reflecting patient and system states, the parameters
being accessed through software to conservatively manage and correlate
drug delivery to safe, cost effective, optimized values related
to the conscious patient's vital signs and other physiological conditions.
BACKGROUND OF THE INVENTION
This invention is directed to providing a conscious patient who
is undergoing a painful, uncomfortable or otherwise frightening
(anxiety-inspiring) medical or surgical procedure, or who is suffering
from post-procedural or other pain or discomfort, with safe, effective
and cost-effective relief from such pain and/or anxiety. Focuses
of the invention include, but are not limited to, enabling the provision
of sedation (inducement of a state of calm), analgesia (insensitivity
to pain) and/or amnesia to a conscious patient (sometimes referred
to collectively as "conscious sedation") by a nonanesthetist
practitioner, i.e., a physician or other clinician who is not an
anesthesiologist (M.D.A.) or certified nurse anesthetist (C.R.N.A.),
in a manner that is safe, effective and cost-effective; the provision
of same to patients in ambulatory settings such as hospital laboratories,
ambulatory surgical centers, and physician's offices; and the provision
of patient post-operative or other pain relief in remote medical
care locations or in home care environments. To those ends, the
invention mechanically integrates through physical proximity and
incorporation into an overall structural system and electronically
integrates through conservative, decision-making software management,
the delivery of one or more sedative, analgesic or amnestic drugs
to the patient with the electronic monitoring of one or more patient
physiological conditions.
In traditional operating rooms, anesthesiologists provide patients
relief from pain, fear and physiological stress by providing general
anesthesia. "Anesthesia" is typically used (and is so
used herein) interchangeably with the state of "unconsciousness."
Over a billion painful and anxiety-inspiring medical and surgical
procedures, however, are performed worldwide each year without anesthesia.
Thus, outside the practice of anesthesiology there are currently
a large number of patients who, while conscious, undergo medical
or surgical procedures that produce considerable pain, profound
anxiety, and/or physiological stress. Such medical or surgical procedures
are often performed by procedural physicians (nonanesthetists) in
hospital laboratories, in physicians' offices, and in ambulatory
surgical centers. For example, physician specialists perform painful
procedures on conscious patients such as pacemaker placement, colonoscopies,
various radiological procedures, microlaparoscopy, fracture reduction,
wound dressing changes in burn units, and central and arterial catheter
insertion in pediatric patients, in hospital laboratory settings.
Primary care physicians perform such procedures as flexible sigmoidoscopies,
laceration repairs, bone marrow biopsies and other procedures in
physicians' offices. Many surgical specialists perform painful procedures
such as anterior segment repairs by ophthalmologists, plastic procedures
by cosmetic surgeons, foreign body removal, transurethral procedures,
incisions of neck and axilla nodes, and breast biopsies in their
offices or in ambulatory surgical centers. The needs of patients
for safe and effective pain and anxiety relief during and after
such procedures are currently unmet.
Conscious sedation techniques currently available for use by procedural
physicians (nonanesthetists) during medical or surgical procedures
such as those described above include sedatives and opioids given
orally, rectally or intra-muscularly; sedatives and analgesics administered
intravenously; and local anesthetics. Often, however, such techniques
are less than satisfactory.
In the case of oral, rectal or intramuscular administration of
sedatives and opioids by procedural physicians during the provision
of conscious sedation, there are currently no effective means available
to assure that the effects of those drugs can be readily controlled
to meet patient need. This is due in part to the variable interval
between administration and the onset and dissipation of drug effect.
Unreliable sedation and analgesia can result because of mismatches
between the dosage administered and the patient's needs which can
vary depending on the condition of the patient and the type of procedure
performed. Such administration of sedation can also produce an unconscious
patient at risk for developing airway obstruction, emesis with pulmonary
aspiration or cardiovascular instability. To attempt to avoid these
complications, procedural physicians often administer sedatives
and analgesics sparingly. This may reduce the risk of major complications,
but may also mean that few patients receive adequate relief from
pain and/or anxiety during medical and surgical procedures outside
the practice of anesthesiology.
The use of intravenous administration of sedatives and analgesics
to conscious patients by procedural physicians in settings such
as hospital laboratories, physicians' offices and other ambulatory
settings is also less than satisfactory. With respect to intravenous
bolus administration, plasma concentrations vary considerably when
drugs are injected directly into the blood stream. This can result
in initially excessive (potentially toxic) levels followed by sub-therapeutic
concentrations. Although intravenously administered drugs can be
titrated to the patient's need, doing so safely and effectively
usually requires the full-time attention of a trained care giver,
e.g., an anesthesiologist. Costs and scheduling difficulties among
other things typically preclude this option.
Due to the difficulties described above involving administration
of sedatives and opioids, many procedural physicians rely on local
anesthetics for pain relief. However, local anesthetics alone usually
provide inadequate analgesia (insensitivity to pain) for most medical
and surgical procedures and the injections themselves are often
relatively painful.
In short, current methods commonly available to procedural physicians
for providing effective pain relief to conscious patients outside
the practice of anesthesiology typically fall short of the objective.
Moreover, there are currently no clear standards of practice for
nonanesthetists to guide the relief of pain and anxiety for conscious
patients. There is not adequate training for such practitioners
in the diagnosis and treatment of complications that may arise or
result from the provision of sedation and analgesia to conscious
patients. Procedures or mechanisms for ongoing quality management
of the care of conscious patients undergoing painful and anxiety-inspiring
medical or surgical procedures and the devices and methods employed
in that care are inadequate.
An additional focus of this invention is the electronic monitoring
of a conscious patient's physiological condition during drug delivery,
and the electronic management of drug delivery by conservative decision-making
software that integrates and correlates drug delivery with electronic
feedback values representing the patient's physiological condition,
thereby ensuring safe, cost-effective, optimized care. Significantly,
in many cases involving conscious sedation, the patient's physiological
condition is inadequately monitored or not electronically monitored
at all during drug delivery and recovery therefrom. That is, there
is often no electronic monitoring of basic patient vital signs such
as blood pressure, blood oxygen saturation (oximetry) nor of carbon
dioxide levels in a patient's inhaled and exhaled gases (capnometry).
For example, patients undergoing painful procedures in dentists'
offices may receive nitrous oxide (N.sub.2O) gas to relieve pain,
but that drug delivery is often not accompanied by electronic monitoring
of a patient's physiological condition, and currently there are
no devices available to nonanesthetists which safely and effectively
integrate electronic patient monitoring with such drug delivery
mechanisms.
In other circumstances involving the provision of conscious sedation
and analgesia by the procedural physician, such as a cardiologist's
performing a catheterization procedure in a hospital laboratory,
electronic patient monitors are sometimes used, but again, there
are no devices currently available to the nonanesthetist which safely
and effectively integrate both mechanically (through close, physical
proximity and incorporation into a structural system), and electronically
(through conservative software management), electronic patient monitors
with mechanisms for drug delivery.
One aspect of the invention of this application is directed to
the simplification of drug delivery machines for relieving patient
pain and anxiety by eliminating features of those machines that
complicate the provision of patient pain and anxiety relief, and
by including those features that enable nonanesthetists to provide
safe, cost-effective, optimized conscious sedation and analgesia.
More specifically, current anesthesia machines used by anesthesiologists
to provide general anesthesia and a form of conscious sedation administered
by the anesthesiologist known as "monitored anesthesia care"
(MAC) include various complex features such as oxygen (O.sub.2)
flush valves which are capable of providing large amounts of oxygen
to the patient at excessive pressures, and carbon dioxide (CO.sub.2)
absorbent material which absorbs CO.sub.2 from a patient's exhaled
gases. In addition, anesthesia machines typically deliver halogenated
anesthetic gases which can trigger malignant hyperthermia. Malignant
hyperthermia is a rare, but highly critical condition requiring
the advanced training and skills of an anesthesiologist for rapid
diagnosis and therapy. The airway circuit in current anesthesia
machines is circular in nature and self-contained in that the patient
inhales an oxygen/anesthetic gas mixture, exhales that mixture which
is then passed through CO.sub.2 absorbent material, re-inhales the
filtered gas mixture (supplemented by additional anesthetic and
oxygen), and repeats the process.
These aspects of anesthesia machines, among others, carry attendant
risks for the patient such that anesthesia machines require operation
by a professional trained through a multi-year apprenticeship (e.g.,
an anesthesiologist or C.R.N.A.) in detecting and correcting failure
modes in the technology. For example, an oxygen flush valve can
cause oxygen to enter a patient's stomach thereby causing vomiting;
and carbon dioxide absorbent material can fail in which case the
patient could receive too much carbon dioxide if the failure was
not promptly detected and corrected. Moreover, the use of the self-contained,
circular airway circuit could result in a circumstance whereby if
the supply of O.sub.2 suddenly ceased, a patient would only be breathing
the finite supply of oxygen with no provision for administration
of additional requirements for O.sub.2 or atmospheric air. Such
features, among others, make anesthesia machines unusable by nonanesthetists.
Therefore, a focal point of this aspect of the invention is the
simplification of a drug delivery apparatus by selecting and incorporating
the appropriate features to facilitate the rendition of safe and
effective conscious sedation by nonanesthetists.
Certain aspects of this invention also focus on ensuring maintenance
of patient consciousness to prevent airway difficulties, including
monitoring the level of patient consciousness during the delivery
of one or more sedative, analgesic and/or amnestic drugs to a conscious,
non-intubated, spontaneously-ventilating patient to prevent airway
difficulties. For patients not intubated on a ventilator, monitoring
the level of patient consciousness is important to provide information
about the likelihood of depressed airway reflexes and respiratory
drive to breathe, the ability to maintain a patent airway, and the
likelihood of cardiovascular instability. Despite the importance
of monitoring and maintaining adequate levels of consciousness in
certain medical settings, there is no currently available device
for ensuring maintenance of patient consciousness by integrating
mechanically and electronically such monitoring of a patient's level
of consciousness with a drug delivery system. The invention of this
application is directed to this unmet need, as well.
Further aspects of this invention focus on the electronic monitoring
of a patient's physiological conditions during a physician administered
medical procedure, the electronic monitoring of the state of the
drug delivery system, automated events triggered upon certain states
of or changes in the patient's conditions or the states of the system,
and automated heuristic responses to such automated events. The
purpose of these aspects is to provide, among other things, a means
for safe sedation and analgesia, particularly when administered
by a physician and nurse team that is multi-tasking during the performance
of a medical procedure that may be painful to the patient. The present
invention accomplishes this purpose by, first, automatically gathering
information about the conditions triggering an event in order to
better understand what the event conditions mean and, second, automatically
responding to the event conditions based upon clinically appropriate
heuristics.
This invention is also directed to providing conscious patients
relief from pain and/or anxiety in a manner that is cost-effective
and time efficient. Current solutions for relieving patient pain
and anxiety by drug delivery and electronic monitoring of a patient's
physiological condition are expensive and require a great deal of
time to set-up and take down. Also, the current requirement or desire
for the presence of an anesthesiologist during some medical or surgical
procedures increases costs, especially if that desire requires in-patient
care as opposed to care in an ambulatory setting. To the extent
medical procedures are performed on conscious patients without adequate
sedation and analgesia due to the current unavailability of appropriate
methods and devices for providing such care (e.g., wound dressing
changes in burn wards), such procedures may need to be conducted
on numerous occasions, but over short periods of time (due to a
patient's inability to tolerate the level of pain), as opposed to
conducting a fewer number of more definitive procedures. The requirement
of multiple sessions of care also typically involves increased costs.
This invention addresses such cost-effectiveness concerns and provides
solutions to problems such as those described.
The invention is further directed to the provision of relief from
post-operative or other post-procedural pain and discomfort in remote
medical care locations and home care type settings. Current devices
may permit certain patients in, for example, a home care type setting,
to provide themselves with an increased dosage of analgesic through
the use of a patient-controlled drug delivery device, e.g., a device
that permits a patient to press a button or toggle a switch and
receive more analgesic (often intravenously or transdermally). This
practice is sometimes called "PCA" or patient-controlled
analgesia. Known commercially available PCA-type devices do not
electronically integrate and conservatively manage delivery of analgesics
in accord with the electronic monitoring of a patient's physiological
condition. This invention focuses on this unmet need, as well.
An additional aspect of this invention is directed to the integration
of a billing/information system for use with an apparatus providing
sedation, analgesia and/or amnesia to conscious patients in physician's
offices, hospital laboratory or other ambulatory settings or remote
medical care locations. Current techniques for automated billing
and invoice generating provide inadequate and inefficient methods
for tracking recurring revenues derived from repeated use of medical
devices such as the apparatus of this invention.
Other focuses of the invention are apparent from the below detailed
description of preferred embodiments.
DESCRIPTION OF RELATED ART
Known machines or methods administered by the nonanesthetist for
providing conscious, non-intubated, spontaneously-ventilating patients
with sedation and analgesia are unreliable, not cost-effective or
are otherwise unsatisfactory. No commercially available devices
reliably provide such patients with safe and cost-effective sedation,
analgesia and amnesia to conscious patients by integrating and correlating
the delivery of sedative, analgesic and/or amnestic drugs with electronic
monitoring of a patient's physiological condition. Available drug
delivery systems do not incorporate a safety set of defined data
parameters so as to permit drug delivery to be conservatively managed
electronically in correlation with the patient's physiological conditions,
including vital signs, to effectuate safe, cost-effective and optimized
drug delivery to a patient. Available drug delivery systems do not
incorporate alarm alerts that safely and reliably free the nonanesthetist
practitioner from continued concern of drug delivery effects and
dangers to permit the nonanesthetist to focus on the intended medical
examination and procedure. Moreover, there are no known patient-controlled
analgesia devices that mechanically and electronically integrate
and correlate (through conservative software management) patient
requests for adjustments to drug dosage and electronic monitoring
of patient physiological conditions.
Known techniques have focused on the delivery of sedation and analgesia
to conscious patients with inadequate or no electronic monitoring
of patient physiological conditions, including vital signs, and
no electronic integration or correlation of such patient monitoring
with drug delivery. Other techniques have focused on the provision
of anesthesia to unconscious patients with the requirement of an
anesthesiologist to operate a complicated, failure-intensive anesthesia
machine.
Presently known nitrous oxide delivery systems such as those manufactured
by Matrx Medical, Inc., Accutron, Inc., and others are used primarily
in dental offices for providing conscious sedation only. Such devices
contain sources of nitrous oxide and oxygen, a gas mixing device
and system monitors, but no mechanical or electrical integration
of patient physiological condition monitors with drug delivery mechanisms.
Similarly, other known drug delivery systems (e.g., intravenous
infusion or intramuscular delivery mechanisms) for providing sedatives
and analgesics to conscious patients used, for example, in hospital
laboratories, do not include mechanical or electronic integration
of patient physiological condition monitors with drug delivery mechanisms.
Anesthesia machines used by anesthesiologists to provide general
anesthesia or MAC, such as, by way of example, the NARKOMED line
of machines manufactured by North American Drager and EXCEL SE ANESTHESIA
SYSTEMS manufactured by Ohmeda Inc., mechanically integrate electronic
patient monitors in physical proximity to drug delivery mechanisms.
These machines, however, employ features such as O.sub.2 flush valves,
malignant hyperthermia triggering agents, CO.sub.2 absorbent material,
as well as circular airway circuits, among others, thereby requiring
operation by an M.D.A. (or C.R.N.A.) to avoid the occurrence of
life-threatening incidents. These devices do not provide for the
electronic integration or management of drug delivery in correlation
with the monitoring of a patient's physiological condition, much
less such electronic management through conservative, decision-making
software or logic incorporating established safe data-defining parameters.
U.S. Pat. No. 2,888,922 (Bellville) discloses a servo-controlled
drug delivery device for automatic and continuous maintenance of
the level of unconsciousness in a patient based on voltages representative
of the patient's cortical activity obtained by means of an electroencephalograph
(EEG). The device continuously and automatically increases or decreases
in robotic fashion the flow of anesthetic gas (or I.V. infusion)
in response to selected frequencies of brain potential to maintain
a constant level of unconsciousness.
U.S. Pat. No. 4,681,121 (Kobal) discloses a device for measuring
a patient's sensitivity to pain during the provision of anesthesia,
by applying a continuous, painful stimulus to the nasal mucosa and
regulating the level of anesthesia in response to EEG signals indicating
the patient's response to the nasal pain stimulus, with the goal
of maintaining a sufficient level of unconsciousness.
Among other things, none of the above-described known devices manages
drug delivery to conscious patients employing conservative decision-making
software or logic which correlates the drug delivery to electronic
patient feedback signals and an established set of safety data parameters.
Further, there are no known devices which integrate a clinically
appropriate heuristic approach to managing the automated checking
of a patient's health parameters with automated drug delivery or
patient responsiveness testing. U.S. Pat. Nos. 6,196,974 and 6,421,680
disclose devices that heuristically trigger a blood pressure measurement
cycle upon receiving certain pulse wave data. U.S. Pat. Nos. 5,876,348
and 6,083,171 disclose devices which cross-correlate data received
from an ECG and a pulse oximeter in order to control a blood pressure
measurement cycle. These devices do not, however, heuristically
manage either drug delivery or patient responsiveness testing based
on the patient health data they receive.
SUMMARY OF THE INVENTION
The invention provides apparatuses and methods to safely and effectively
deliver a sedative, analgesic, amnestic or other pharmaceutical
agent (drug) to a conscious, non-intubated, spontaneously-ventilating
patient. The invention is directed to apparatuses and methods for
alleviating a patient's pain and anxiety before and/or during a
medical or surgical procedure and for alleviating a patient's post-operative
or other post-procedural pain or discomfort while simultaneously
enabling a physician to safely control or manage such pain and/or
anxiety. The costs and time loss often associated with traditional
operating room settings or other requirements or desires for the
presence of anesthetists may thus be avoided.
A care system in accordance with the invention includes at least
one patient health monitor which monitors a patient's physiological
condition integrated with a drug delivery controller supplying an
analgesic or other drug to the patient. A programmable, microprocessor-based
electronic controller compares the electronic feedback signals generated
from the patient health monitor and representing the patient's actual
physiological condition with a stored safety data set reflecting
safe and undesirable parameters of at least one patient physiological
condition and manages the application or delivery of the drug to
the patient in accord with that comparison. In a preferred embodiment,
the management of drug delivery is effected by the electronic controller
via conservative, decision-making software accessing the stored
safety data set.
In another aspect the invention also includes at least one system
state monitor which monitors at least one operating condition of
the care system, the system state monitor being integrated with
a drug delivery controller supplying drugs to the patient. In this
aspect, an electronic controller receives instruction signals generated
from the system monitor and conservatively controls (i.e., curtails
or ceases) drug delivery in response thereto. In a preferred embodiment,
this is accomplished through software control of the electronic
controller whereby the software accesses a stored data set reflecting
safe and undesirable parameters of at least one operating condition
of the care system, effects a comparison of the signal generated
by the system state monitor with the stored data set of parameters
and controls drug delivery in accord with same, curtailing or ceasing
drug delivery if the monitored system state is outside of a safe
range. The electronic controller may also activate attention-commanding
devices such as visual or audible alarms in response to the signal
generated by the system state monitor to alert the physician to
any abnormal or unsafe operating state of the care system apparatus.
The invention is further directed to an apparatus which includes
a drug delivery controller, which delivers drugs to the patient,
electronically integrated with an automated consciousness monitoring
system which ensures the consciousness of the patient and generates
signal values reflecting patient consciousness. An electronic controller
is also included which is interconnected to the drug delivery controller
and the automated consciousness monitor and manages the delivery
of the drugs in accord with the signal values reflecting patient
consciousness.
In another aspect, the invention includes one or more patient health
monitors such as a pulse oximeter or capnometer and an automated
consciousness monitoring system, wherein the patient health monitors
and consciousness monitoring system are integrated with a drug delivery
controller supplying an analgesic or other drug to the patient.
A microprocessor-based electronic controller compares electronic
feedback signals representing the patient's actual physiological
condition including level of consciousness, with a stored safety
data set of parameters reflecting patient physiological conditions
(including consciousness level), and manages the delivery of the
drug in accord with that comparison while ensuring the patient's
consciousness. In additional aspects of the invention the automated
consciousness monitoring system includes a patient stimulus or query
device and a patient initiate response device.
The invention also provides apparatuses and methods for alleviating
post-operative or other post-procedural pain or discomfort in a
home care-type setting or remote medical care location. Here the
care system includes at least one patient health monitor integrated
with patient-controlled drug delivery. An electronic controller
manages the patient-controlled drug delivery in accord with electronic
feedback signals from the patient health monitors. In a preferred
embodiment the electronic controller is responsive to software effecting
conservative management of drug delivery in accord with a stored
safety data set.
DESCRIPTION OF THE DRAWINGS
Other objects and many of the intended advantages of the invention
will be readily appreciated as they become better understood by
reference to the following detailed description of preferred embodiments
of the invention considered in connection with the accompanying
drawings, wherein:
FIG. 1 is a perspective view of a preferred embodiment of a care
system apparatus constructed in accordance with this invention,
depicting the provision of sedation, analgesia and/or amnesia to
a conscious patient by a nonanesthetist.
FIG. 2 is a perspective view of a preferred embodiment of a care
system apparatus constructed in accordance with this invention depicting
user interface and patient interface devices.
FIGS. 3A and 3B are side-elevational views of a preferred embodiment
of an apparatus constructed in accordance with this invention.
FIG. 4A is a block diagram overview of the invention.
FIG. 4B is an overview data-flow diagram depicting the drug delivery
management aspect of the invention.
FIG. 5 depicts a preferred embodiment of the invention.
FIG. 6 depicts a preferred embodiment of a drug delivery system
in accordance with the invention.
FIGS. 7A-7C depict the details of a preferred embodiment of the
drug source system in accordance with the invention.
FIG. 8 depicts a preferred embodiment of an electronic mixer system
in accordance with the invention.
FIG. 9A depicts one embodiment of a manifold system in accordance
with the invention.
FIG. 9B depicts a second embodiment of a manifold system in accordance
with the invention.
FIG. 10A depicts a preferred embodiment of a manual bypass system
in accordance with the invention.
FIG. 10B depicts a preferred embodiment of a scavenger system in
accordance with the invention.
FIG. 11 depicts a preferred embodiment of a patient interface system
in accordance with the invention.
FIGS. 12A and 12B are a front perspective view and a side-elevational
view, respectively, of a preferred embodiment of hand cradle device
constructed in accordance with the invention.
FIGS. 13A and 13B are rear perspective views of a preferred embodiment
of hand cradle device constructed in accordance with the invention.
FIGS. 14A and 14B are, respectively, a front perspective view of
an alternative embodiment of a hand cradle device constructed in
accordance with this invention and a top plan view of a patient
drug dosage request device in accordance with the invention.
FIG. 15 shows a perspective view of a preferred embodiment of the
invention, including a hand cradle device and an ear piece combination
oximeter/auditory query device.
FIG. 16 is a side-elevational view of an ear piece placed within
a patient's ear containing a pulse oximetry sensor and an auditory
query in accordance with the present invention.
FIG. 17 depicts an alternative preferred embodiment of a care system
apparatus constructed in accordance with the invention.
FIG. 18 depicts a user interface system in accordance with a preferred
embodiment of the invention.
FIGS. 19A and 19B depict the various peripheral devices included
in a preferred embodiment of the invention.
FIG. 20 depicts a preferred embodiment of a patient information/billing
system in accordance with the invention.
FIG. 21A depicts examples of drug delivery management protocols
for 3-stage alarm states reflecting monitored patient parameters
in accordance with the invention.
FIG. 21B depicts examples of drug delivery management protocols
for 2-stage alarm states reflecting monitored system state parameters
in accordance with the invention.
FIG. 22A depicts a first embodiment of a user interface screen
display in accordance with the invention.
FIG. 22B depicts a second embodiment of a user interface screen
display in accordance with the invention.
FIG. 23A is a data-flow diagram depicting an example of the steps
performed by the drug delivery management software or logic responsive
to patient health monitors in accordance with the invention.
FIG. 23B is a data-flow diagram depicting an example of the steps
performed by the drug delivery management software or logic responsive
to system state monitors in accordance with the invention.
FIG. 24 is a data-flow diagram depicting examples of clinically
appropriate responses that the system can perform depending upon
certain patient health parameters.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The embodiments illustrated below are not intended to be exhaustive
or to limit the invention to the precise forms disclosed. The embodiments
are chosen and described in order to explain the principles of the
invention and its applications and uses, and thereby enable others
skilled in the art to make and utilize the invention.
FIG. 1 shows a care system 10 constructed in accordance with this
invention, providing sedative, analgesic and/or amnestic drugs to
a conscious, non-intubated, spontaneously-ventilating patient undergoing
a medical or surgical procedure by a procedural physician. The system
10 has a generally columnar housing 15 with various storage compartments
16 therein for storage of user and patient interface devices, and
a base 17 supported on castor wheels 18. A drug delivery system
40 delivers a mixture of one or more gaseous sedative, analgesic
or amnestic drugs in combination with oxygen (O.sub.2) gas to a
patient, and includes a one-way airway circuit 20 connected at one
end to a face mask 30 and at the other end to a manifold valving
system contained within housing 15. FIGS. 3A and 3B show from a
side-elevation perspective, airway circuit 20, face mask 30, and
exhaust hose 32 through which scavenged patient exhaled gases are
exhausted to a safe location.
Referring to FIG. 2, lead 50 connects one or more patient interface
devices (e.g., 55) to a microprocessor-based electronic controller
or computer (sometimes also referred to herein as main logic board,
MLB) located within housing 15. The electronic controller or main
logic board may be comprised of combinations of available programmable-type
microprocessors and other "chips," memory devices and
logic devices on various board(s) such as those manufactured by
Texas Instruments (e.g., XK21E) and National Semiconductor (e.g.,
HKL 72, among others. Patient interface devices 55 can include one
or more patient health monitors that monitor a patient's physiological
condition, such as known pulse oximeter, capnometer (not shown),
non-invasive blood pressure monitors; EKG, EEG, acoustical monitors
(not shown), and others; an automated consciousness monitoring system,
including query initiate and response devices in accordance with
the invention (described below); and patient drug dosage request
devices (also described below). The main logic board electronically
manages operation of the apparatus 10 by means of conservative,
decision-making software that integrates and correlates patient
feedback signals received from the one or more patient health monitors
with drug delivery.
Also shown in FIGS. 1 and 2 are various user interface devices,
including a display device 35 integrated into the top surface of
apparatus 10 which displays patient and system parameters and operation
status of the apparatus, a printer 37 which prints, for example,
a hard copy of patient parameters indicating the patient's physiological
condition and the status of various system alarms with time stamps,
and a remote control device 45 which permits a physician to interact
with apparatus 10. The various patient and user interface devices
are described in more detail below.
It should be recognized that although certain embodiments of the
invention show the analgesic delivery system 40 in a form for delivering
one or more sedative, analgesic or amnestic drugs in gaseous form,
the invention also specifically includes embodiments where such
drugs are delivered intravenously, in nebulized, vaporized or other
inhaled form, and/or transdermally such as by using known ion-transfer
principles. Drugs that may be delivered by the care system include,
but are not limited to, nitrous oxide, propofol, remifentanil, dexmedetamidine,
epibatadine and sevoflurane. Alternative embodiments are described
in more detail herein.
FIG. 4A is a block diagram overview of a preferred embodiment of
the invention. FIG. 4B is an overview data flow diagram depicting
the drug delivery management steps performed by the software/logic
control of microprocessor controller 14 in a preferred embodiment
of the invention. In FIG. 4A, one or more patient health monitors
12a (which may include one or more known patient physiological condition
monitors such as pulse oximeters, capnometers, other ventilatory
monitors, non-invasive blood pressure monitors, EKG, EEG and others,
as well as a patient consciousness monitoring system, are electronically
coupled, through suitable A-D converters where appropriate, to electronic
controller 14, described above. Patient health monitors 12a generate
electronic feedback signals representing actual patient physiological
data which are converted to electronic signals and then provided
to controller 14. Now referring to FIG. 4B, electronic controller
14, e.g., through appropriate software and/or logic, compares the
received electronic patient feedback signals 13b with the safety
data set 15b stored in a memory device (such as an EPROM device).
The stored safety data set 14a (FIG. 4A) contains at least one
set of data parameters representing safe and undesirable patient
physiological conditions. Based on the comparison of the actual
monitored patient physiological data 13b with the safety data set
14a, controller 14 determines whether the monitored patient physiological
data is outside of a safe range (FIG. 4B, 16b). If the monitored
patient data is outside of a safe range, electronic controller 14
sends instruction commands (signals) to drug delivery controller
2a (FIG. 4A) instructing drug delivery controller 2a to conservatively
manage (e.g., reduce or cease) drug delivery (FIG. 4B, 18b). Drug
delivery controller 2a may be a standard solenoid valve-type electronic
flow controller known to those skilled in the art.
As is described below, additional embodiments of the invention
also contemplate provision of electronic feedback signals representing
patient-controlled drug dosage increase or decrease requests to
controller 14 and electronic management of drug delivery in consideration
of such patient requests vis-a-vis the patient's physiological parameters
and/or the state of the care system.
A block diagram of a preferred embodiment of a care system in accordance
with the invention is depicted in FIG. 5. Analgesic delivery system
2 of FIG. 5 delivers a mixture of gaseous sedative, analgesic and/or
amnestic drugs (such as nitrous oxide, sevoflurane or nebulized
narcotics) and oxygen gas to the patient. Manual bypass circuit
4 (shown in further detail in FIG. 6 and FIG. 10A) is coupled to
the manifold system portion of analgesic delivery system 2 and bypasses
the source of analgesia enabling the manual control of delivery
of atmospheric air to the patient. An auxiliary inlet 6 is provided
to analgesic delivery system 2 and enables the provision of in-house
supply of gaseous drug or oxygen to the delivery system 2. Scavenger
system 8 (shown in detail in FIG. 10B) is coupled to analgesic delivery
system 2 and collects exhaled gases from the patient and exhausts
them to a safe location through exhaust hose 32 (FIG. 3B).
Patient interface system 12 includes one or more patient health
monitors (these can be known vital sign monitors, such as non-invasive
blood pressure monitors, or known pulse oximeters, capnometers,
EKGs, etc.); means for monitoring the level of a patient's consciousness;
and/or means for the patient to communicate with system 10 (FIG.
1), such as by requesting an increase or decrease in the dosage
of drugs. One or more of these patient monitoring and request devices
are electronically coupled to and, through A-D converters, provide
feedback signals representing the patient's actual physiological
condition and drug dosage requests to electronic controller 14.
Controller 14 compares this electronic feedback received with data
stored in a memory device, said data representing sets of one or
more safe and undesirable patient physiological condition parameters
(e.g., safe and undesirable O.sub.2 saturation conditions, end tidal
CO.sub.2 levels and/or levels of patient consciousness). These sets
of parameters are collectively referred to as a safety data set.
Based on the comparison, controller 14 commands conservative application
of drug delivery in accord with said parameters at safe, cost-effective
optimized values.
Still referring to FIG. 5, user interface system 16 (described
in more detail in FIGS. 18 and 22) displays electronic signal values
stored in or provided to electronic controller 14, such values reflecting
the status of one or more of the patient's physiological state,
the patient's level of consciousness, and/or the status of various
care system parameters. User interface system 16 includes devices
that permit the nonanesthetist to interact with the care system
via controller 14 (e.g., input patient information, pre-set drug
dosages, silence alarms) such as keyboard 230 (FIG. 2) and/or remote
control unit 45 (FIG. 1). Patient and care system information is
displayed by means of graphical and numeric display devices, e.g.,
35 (FIG. 1), LEDs incorporated into housing 15 (FIG. 1) and/or on
remote control unit 45.
External communication devices 18 (also described in FIGS. 19A
and 19B) enable the sending and/or receiving of electronic information
signals to and from electronic controller 14 and external computers
at remote locations or on local networks. Peripheral devices 22
such as door and temperature sensors, among others, communicate
electronically with controller 14 to ensure the proper, safe and
secure operation of care system 10.
The above systems overviewed in FIG. 5 are now described in more
detail.
FIG. 6 shows in further detail an overview of a preferred drug
delivery system 2 (FIG. 5) which provides a mixture of one or more
sedative, analgesic and/or amnestic drugs in gaseous form; oxygen;
and atmospheric air to a patient, the provision of each being independently
adjustable (manually and via electronic controller 14) by the physician.
The drug delivery system is comprised of a drug source system 42,
an electronic mixer system 44 and a manifold system 46.
Drug source system 42 contains sources of one or more gaseous drugs
and oxygen and is coupled through pneumatic lines to electronic
mixer system 42. Drug source system 42 is also electronically coupled
to electronic controller 14, and as is described below, contains
sensors monitoring one or more operating states of drug source system
42 (e.g., whether the drug is flowing). Such monitored system information
is converted to appropriate electronic signals and fed back to electronic
controller 14 via the electronic coupling.
Electronic mixer 44 receives the one or more gaseous drugs, O.sub.2
and atmospheric air through the pneumatic lines and electronically
mixes same. Electronic mixer 44 is also electronically coupled to
electronic controller 14 and also contains sensors that provide
electronic feedback signals reflecting system operation parameters
of mixer 44 to electronic controller 14. Mixer 44 includes electronic
flow controllers with solenoid valves which receive flow control
instruction signals from controller 14.
Manifold system 46 is coupled through pneumatic lines to and receives
the one or more gaseous drugs, O.sub.2 and air mixture from electronic
mixer 44 and delivers the mixture to the patient via airway circuit
20 (FIG. 1) and face mask 30 (FIG. 1). Manifold system 46 is also
electronically coupled to electronic controller 14 and includes
sensors that provide electronic feedback signals reflecting manifold
system 46 operation parameters to controller 14. Manifold 46 delivers
patient exhaled gases to a scavenging system 48 for exhaust to a
safe location via exhaust hose 32 (FIG. 3B).
Drug source system 42 is shown in further detail in FIGS. 7A-7C.
Referring to FIG. 7A, analgesic source system includes drug source
system 142 which provides a source of one or more sedative, analgesic
and/or amnestic drugs; and an oxygen source system 144 which provides
a source of oxygen. In aspects of this invention where the drugs
are in gaseous form, the sources of drugs and oxygen provide the
gases at low pressure, and can be tanks contained within housing
15 (FIG. 1) such as those shown at numeral 54 in FIG. 2 or an in-house
source. The ability to use alternative sources increases the useability
of the care system of the invention because the system can function
as a source-dependent unit within rooms with access to in-house
gas supplies or as a self-contained unit within rooms that do not
have in-house gas connections.
In additional aspects of the invention, drug source system 42 can
include one or more of the following: known nebulizers 143 which
enable the delivery of aerosolized drugs, such as morphine, meperidine,
fentanyl and others; known vaporizers 145 which enable the delivery
of halogenated agents, such as sevoflurane; known infusion pump-type
drug delivery devices 147 or known transdermal-type drug delivery
devices 149 (including ion transfer based devices) to enable the
delivery of drugs such as propofol, remifentanil, and other infusible
drugs by continuous or bolus administration.
FIG. 7B details the oxygen source system and shows an oxygen tank
or other source of oxygen 104 and a pneumatic line 109 for delivering
oxygen gas to electronic mixer system 44 (FIG. 7A). Filter 106a
in oxygen line 109 removes contaminants within the oxygen stream
from oxygen source 104. Pressure sensor 106 (which may be of a type
known and currently available) in oxygen line 109 monitors the pressure
in oxygen source 104 generating a signal reflecting same and thereby
indirectly measuring the amount of oxygen remaining. Pressure sensor
106 is electronically coupled to electronic controller 14 and forwards
signals reflecting the measure of pressure in the oxygen source
to controller 14. In a preferred embodiment, electronic controller
14 receives the signal from pressure sensor 106 and through software
accesses data parameters stored in a memory device. The parameters
reflect one or more setpoints establishing safe and undesirable
operating conditions of O.sub.2 operating pressure. Controller 14
compares the actual O.sub.2 pressure to the stored parameter set
point data. If the comparison reveals that the O.sub.2 pressure
is outside of an established safe range as established by the stored
data, an alarm or other attention-commanding device activates and
if same is not manually deactivated, electronic controller 14 instructs
the flow of drug delivery to reduce to a pre-set safe amount (or
cease). The operation of the software control vis-a-vis system state
monitors is described in more detail in connection with FIGS. 21B
and 23B.
The signal obtained from oxygen source pressure sensor 106 can
be related to the user via display devices (e.g., 35, FIG. 2) in
terms of the time remaining under present use so that the user can
ascertain if the procedure can be completed. The user is immediately
notified if the pressure falls out of the normal operating conditions
by an alarm, display device or other suitable attention-commanding
device. Pressure gauges 108 visually display to the user the oxygen
source pressure obtained by sensor 106. Pressure regulator 110,
which may be of a known solenoid type currently available or other
suitable regulator, enables the reduction of pressure in oxygen
source 104 to a reasonable operating pressure to provide flow of
O.sub.2 to the patient. Check valve 112 (check valves may be of
a standard one-way type), in oxygen line 109 downstream of regulator
110 prohibits backward flow of the patient's exhalations and ensures
that such back-flow does not damage or contaminate regulator 110
and oxygen source 104. In systems where an in-house oxygen source
105 is used, remote check valve 114 ensures that back-flow from
the patient's exhalations does not damage or contaminate in-house
oxygen source 105. Pressure relief valve 116 exhausts oxygen to
the atmosphere if the pressure in oxygen line 109 exceeds safe operating
values pre-programmed into electronic controller 14.
FIG. 7C details the drug source system and in a preferred embodiment
includes a tank or other source of drug 204 and a pneumatic line
209 for delivering gaseous drugs to electronic mixer 44. Filter
206a in drug line 209 removes contaminants within the drug stream
from drug source 204. Pressure sensor 206 (which may be of a type
known and currently available) in drug line 209 monitors the pressure
in drug source 204 generating a signal reflecting same and thereby
indirectly measuring the amount of drug. Pressure sensor 206 is
electronically coupled to electronic controller 14 and forwards
signals reflecting the measure of pressure in the drug source to
controller 14. As is described above in connection with oxygen source
pressure sensor 106 and in FIGS. 21B and 23B, in a preferred embodiment
controller 14 receives the signal from sensor 206 and through software
accesses stored data parameters reflecting safe and undesirable
operating conditions of drug source pressure and conservatively
controls drug delivery in accord with said stored parameters.
The signal obtained from the drug source pressure sensor 206 can
be related to the user via display devices (e.g., 35, FIG. 2) in
terms of the time remaining under present use so that the user can
ascertain if the procedure can be completed. The user is immediately
notified via an alarm, display device or other suitable attention-commanding
device if the pressure falls out of the normal operating conditions.
Pressure gauges 208 visually display to the user the drug source
pressure obtained by sensor 206. Pressure regulator 210, which may
be of a known solenoid type currently available, enables the reduction
of pressure in drug source 204 to a reasonable operating pressure
to provide flow of drug to the patient. Check valve 212 in drug
line 209 downstream of regulator 210 prohibits backward flow of
the patient's exhalations and ensures that back-flow from the patient's
exhalations does not damage or contaminate regulator 210 and drug
source 204. In systems where an in-house drug source 205 is used,
remote check valve 214 ensures that back-flow from the patient's
exhalations does not damage or contaminate in-house drug source
205. Pressure relief valve 216 exhausts the drug to the atmosphere
if the pressure in drug line 209 exceeds safe operating values pre-programmed
into electronic controller 14.
To increase safety, the known pin indexed safety system (P.I.S.S.)
and/or diameter indexed safety system (D.I.S.S.) may be used for
all O.sub.2 source and line fittings where appropriate for tank
and/or in-house sources. This ensures, for example, that oxygen
source 104 is not mistakenly attached to the drug line 209 and vice
versa.
FIG. 8 details a preferred electronic gas mixer system which electronically
mixes gaseous drugs and oxygen so that the precise flow rate of
gaseous drug and oxygen is delivered to the patient. The use of
the electronic mixer system of this invention increases the operational
safety of the apparatus of the invention because, as described below,
the volume of drug delivery can be electronically controlled in
closed-loop fashion by currently available electronic flow controllers
which include solenoid type valves which, in response to command
signals from electronic controller 14, halt or reduce the flow of
drugs to the patient in the event of an occurrence of unsafe patient
or system conditions. Specifically, pneumatic oxygen line 109 and
drug line 209 from analgesic source system 42 deliver gaseous drugs
and oxygen to filters 125 and 127 in lines 109 and 209, respectively,
which filter contaminants from lines 109 and 209. System state monitors,
namely, pressure sensors 129, 131, monitor the oxygen and gaseous
drug line pressures, respectively, and transmit signals reflecting
said pressures to electronic controller 14, which conservatively
controls drug delivery in accord with a stored data set containing
parameters reflecting one or more safe and undesirable system operation
states as described above and in FIGS. 21B. and 23B. Also, if any
of the pressures fall out of the norm, electronic controller 14
immediately alerts the user, for example, by means of signaling
an alarm device.
Electronic flow controllers 133, 135, which may be of a known type
currently available including solenoid valves, are electronically
coupled to and receive instruction signals from electronic controller
14 which has been programmed with and/or calculates a desired flow
rate of oxygen and drug. Programmed flow rates may be those input
by the physician user employing traditional choices regarding drug
administration amounts and rates, including in IV embodiments, target
controlled infusion principles, among others. Calculated flow rates
may be arrived at through conservative decision-making software
protocols including comparison of actual patient physiological condition
feedback values with stored data representing safe and undesirable
patient physiological conditions. Drug delivery is effected at the
rates calculated in a closed, control-loop fashion (described in
more detail below) by flow controllers 133, 135. Drug administration
may be a combination of one or more physician inputs and/or electronic
flow rate calculations based on patient and system state parameters;
flow controllers may respond to instruction signals initiated by
electronic controller 14 or by the physician.
Flow controllers 133, 135 receive instruction signals from controller
14 reflecting the electronic output of both system state monitors
(such as pressure sensors 106, 206 described above) and patient
state monitors. Flow controllers 133, 135, in response to instruction
signals from controller 14, may curtail or cease flow of drug delivery
when system state and/or patient health monitors indicate to controller
14 that failures in the operation of care system 10 have occurred,
that system 10 is otherwise operating outside of an established
safe state, or that a patient's physiological state (e.g., vital
signs or consciousness level) has deteriorated to an unsafe condition.
As the invention includes both intravenous and gaseous, among other
forms of drug delivery, such embodiments may also include known
electronic flow controllers coupled to electronic controller 14
and responsive to instruction signals from controller 14 reflecting
both patient and system states.
Referring again to FIG. 8, solenoid valve 132 is electronically
coupled to electronic controller 14 and must be activated by same
before drug will flow through line 209. In the event of system power
failure, drug delivery will be halted due to the fail-closed nature
of solenoid valve 132. This is described, for example, in FIG. 21B
which shows that if a system state monitor indicates power failure,
alarm type "2" sounds to alert the nonanesthetist and
drug delivery is halted (i.e., reduced to 0%).
Moreover, pressure actuated valve 134 in drug line 209 responds
to the amount of pressure in O.sub.2 line 109 and permits flow of
gaseous drug only if sufficient oxygen flows through oxygen line
109. Check valve 136a in drug line 209 ensures that the flow of
gaseous drug to manifold system 46 is one-way and that there is
no back-flow. Check valve 136b in oxygen line 109 ensures one-way
flow of O.sub.2 to manifold system 46 with no back-flow.
In atmospheric air line 139, air inlet solenoid valve 137 is electronically
coupled to and activated by electronic controller 14 and if activated
permits atmospheric air to be mixed with the oxygen gas by means
of air ejector 138. Air ejector 138 injects a fixed ratio of atmospheric
air into oxygen line 109. Filter 128 removes contaminants from air
line 139 and check valve 136c ensures one-way flow of air from solenoid
valve 137 to ejector 138 with no back-flow.
Referring to FIG. 9A which details one embodiment of manifold system
46 (FIG. 6), the drug/O.sub.2 gas mixture from electronic mixer
system 44 (FIG. 6) enters manifold system 46 and flows into inspiratory
plenum 150 from which it proceeds through inspiratory line 151 to
primary inspiratory valve (PIV) 152 and eventually to airway circuit
20 and mask 30 (FIG. 1). Primary inspiratory valve 152 permits one-way
flow of said gas mixture and ensures that exhaled gases from the
patient do not enter the inspiratory side of manifold system 46
(FIG. 6), thereby guarding against possible contamination. Atmospheric
air may be permitted to enter inspiratory line 151 through an inspiratory
negative pressure relief valve (INPRV) 154 which allows one-way
flow of atmospheric air to reach the patient if a significant negative
vacuum is drawn on the inspiratory side of manifold system 46 (e.g.,
the patient inhales and receives no or insufficient oxygen). INPRV
154 thereby essentially permits air on demand by the patient. INPRV
filter 153 removes particulates which may be in air line 155 or
present in the atmosphere. INPRV status sensor 156 (which may be
of a known pressure, temperature, infra-red or other suitable type)
monitors the extent of open/close status of INPRV 154 and generates
a signal which is converted to an appropriate electronic (digital)
signal and communicates the status of INPRV 154 to electronic controller
14. During the exhalation phase of the patient's breathing cycle,
inspiratory reservoir bag 149 collects the drug/O.sub.2/air mixture
which the patient will draw on the next inhalation phase.
Still referring to FIG. 9A, pressure sensor 166 measures pressure
in airway circuit 20 (FIG. 1) and is used to indicate airway flow,
i.e., if the primary inspiratory valve (PIV) 152 or the primary
expiratory valve (PEV) 168 is occluded. For example, if sensor 166
reads a high pressure that indicates that PEV 168 is blocked, whereas
a low pressure indicates PIV 152 is blocked. Airway circuit 20 (FIG.
1) also contains a fraction of inspired oxygen (FIO.sub.2) sensor
167 (which may be of a known type currently available) which measures
the oxygen percentage of gas contained in the mixture delivered
to the patient, and thus guards against the possibility of delivering
a hypoxic mixture to the patient (i.e., a drug/O.sub.2 mixture that
does not provide enough O.sub.2 to the patient). INPRV status sensor
156, pressure/airway flow sensor 166, and FIO.sub.2 sensor 167 are
electronically coupled to and provide electronic feedback signals
reflecting system state parameters to electronic controller 14.
As described in FIGS. 21B and 23B, controller 14, through software
and/or logic, effects a comparison of the signals generated by these
system monitors with a stored data set of system parameters established
by setpoints and/or logic-type data reflecting safe and undesirable
system operating states, and conservatively controls (e.g., reduces
or halts) drug delivery if the comparison determines that care system
10 is operating outside of a safe range.
Airway circuit and mask (20, FIG. 9) interface with the patient
to provide a closed circuit for the delivery of drug/O.sub.2 gas
mixture to the patient. It should be recognized that embodiments
of the subject invention in which the drugs are delivered in a form
other than compressed gas, such as intravenously or transdermally,
may not include face masks, airway circuit features and other aspects
associated with delivery of drugs in gaseous form. Where the drug
is delivered in gaseous form and an airway circuit and face mask
are employed, such face mask and attendant airway circuitry and
other features such as the scavenging system maybe in the form of
that described in U.S. Pat. No. 5,676,133 issued to Hickle et al.
and entitled Expiratory Scavenging Method and Apparatus and Oxygen
Control System for Post-Anesthesia Care Patients. (With respect
to such embodiments, the specification of Hickle et al. is incorporated
herein by reference.)
In preferred embodiments the mask is disposable and contains means
for sampling the CO.sub.2 content of the patient's respiratory airstream
and, optionally, means for also measuring the flow of the patient's
airstream and/or means for acoustical monitoring. The sampling of
the CO.sub.2 in the patient's airstream may be done by means of
a capnometer or a lumen mounted within the mask through a port in
the mask, and placed close to the patient's airway. A second lumen
similarly mounted within the mask could be used to measure the airflow
in the patient's airstream. This airflow measurement could be accomplished
by a variety of currently available devices, including for example,
devices that measure the pressure drop in the airstream over a known
resistance element and thereby calculate the airflow by known formula.
The means for acoustical monitoring may be a lumen placed within
the mask with a microphone affixed within that lumen. The microphone
would permit recording, transducing and playing out through an amplifier
the audible sound of the patient's breathing. It is noted that the
lumen for acoustical monitoring could be a separate lumen or could
be combined with the lumen for calculating the flow of the patient's
airstream. It is further noted that it is important to place the
lumens, especially the CO.sub.2 sampling lumen, close to the patient's
open airway and to ensure such lumens remain close to the patient's
airway.
Referring again to FIG. 9A, primary expiratory valve (PEV) 168
in expiratory line 172 ensures one-way flow of a patient's exhaled
gases to scavenger pump system 48, thus, prohibiting any back-flow
from gases exhaled to the scavenger system from reaching the patient.
Importantly, PEV 168 guards against the re-breathing of exhaled
carbon dioxide. As is easily seen, the manifold 46 and airway circuit
20 of a preferred embodiment of this invention permit one-way airway
flow only. That is, unlike prior devices that employ circular airway
circuits (which require CO.sub.2 absorbent material to permit re-breathing
of exhaled air), there is no re-breathing of exhaled gases in this
embodiment of the invention.
In the embodiment of the invention shown in FIG. 9A, expiratory
positive pressure relief valve (EPPRV) 164 in expiratory line 172
allows exhaled gases to escape to the atmosphere if sufficient positive
pressure develops on the expiratory side of the manifold system.
This could happen, for example, if the patient is exhaling, but
scavenger system 48 (FIG. 6) is occluded or otherwise not working
properly. EPPRV filter 175 downstream of EPPRV 164 filters contaminants
from the expiratory stream flowing through EPPRV 164 prior to the
stream entering the atmosphere. Expiratory negative pressure relief
valve (ENPRV) 178 is a one-way valve that allows atmospheric air
to be drawn into expiratory plenum 180 and then on to scavenger
system 48 if sufficient vacuum pressure is drawn on the expiratory
side of manifold system 46. This could happen, for example, if the
vacuum pump of scavenger system 48 is set too high or PEV 168 is
blocked. Expiratory reservoir bag 177 collects exhaled gases from
the patient during exhalation via expiratory plenum 180. These gases
will be exhausted by scavenger system 48 during the next patient
inhalation phase. As is described in detail below, patient vital
sign monitor, such as a capnometer 184, monitors the amount of CO.sub.2
in the patient's exhaled gases and provides electronic feedback
signals reflecting the level of CO.sub.2 in the patient's exhalations
to controller 14. Other types of ventilatory monitors such as an
airflow measure, IPG device or an acoustical monitor could also
be used to provide electronic feedback signals reflecting patient
health parameters to controller 14.
In an alternative preferred embodiment shown in FIG. 9B, ENPRV
164, filter 175 and ENPRV 178 are eliminated. A long pipe or similar
conduit 175a, interconnected with reservoir bag 177 and opening
to atmospheric air, is substituted therefor. The elimination of
the valves 164 and 175 provides for a more cost efficient and simple
system, while the substituting of the pipe 175a still ensures that
if the scavenger system 48 is occluded, is set too high, is otherwise
not working or if PEV 168 is blocked, that there is still access
to atmospheric air, and the patient may breath into the room or
air may come into the system. A highly compliant reservoir bag 179
also assists in catching excess flow of exhaled air. In this simplified
embodiment, there are essentially only three valves, PIV 152, PEV
168 and INPRV 154.
As is described above, system valves PIV 152 and PEV 168 ensure
one-way flow of inspired and expired gases. The patient cannot re-breathe
exhaled gases and no contaminants are allowed to enter the source
system. The valve system INPRV 154, EPPRV 164, and ENPRV 178 (or
the alternate INPRV 154 and pipe) provides a system fail-safe. If
analgesic source system 42 (FIG. 6) or scavenging system 48 (FIG.
6) is functioning improperly, the valves will open and allow the
patient to breath without significant effort. The system state sensors
156, 166 and 167 monitor system operation such as INPRV valve status,
gas pressure and fraction of inspired oxygen, and electronically
feed back signals reflecting the operating status of those operations
to microprocessor controller 14 to ensure safe operation of the
apparatus.
It is noted that the valves and sensors between INPRV 154 and ENPRV
178 in a preferred embodiment of manifold system 46 can be considered
a system state monitoring system because there are no valves controlled
by the software of electronic controller 14. At this point in the
care system 10, the gas has already been mixed and the volume determined
by the flow controllers 133, 135 (FIG. 8). Manifold system 46 (FIG.
6) provides at least two basic services, sensor inputs for FiO.sub.2
and CO.sub.2 (167, 184 of FIG. 9) and flow status derived from flow
sensor 166 (FIG. 9).
The determination of appropriate drug delivery/flow percentages
by controller 14 can be accomplished through a variety of methods.
Initial drug administration amounts and rates may be selected and
input by the physician employing traditional methods. Physicians
may also employ pharmacokinetic/pharmacodynamic modeling to predict
resulting drug concentrations and their effect based on physician
choices, but not permit automatic changes to drug concentrations
without instructions from the physician. In intravenous embodiments
known target-controlled infusion techniques may be employed where
the physician selects a desired (targeted) blood serum or brain
effective site concentration based on such patient parameters as
height, weight, gender and/or age.
During operation of the system when an internal or external event
occurs, such as the activation of a system or patient health monitor
alarm or a physician or patient request for increased drug, electronic
controller 14 determines the desired amount of intravenous drug
(or fractional amount of O.sub.2, gaseous drug and air in the total
gas flow) as the function of such event. The actual IV drug concentrations
(or gaseous drug/O.sub.2/air fractions) are then calculated. These
actual calculated amounts will not always be the same as those requested
(e.g., by the user, patient or system) because of the often complex
relationship between drug or drug and gas mixtures. In sum, drug
mix fractions are typically calculated when, for example, an alarm
levels change, alarm time-outs occur (e.g., there is no silencing
of an initial alarm by the user), a user requests a change, the
patient requests a change, when a procedure begins (system resorts
to default values) and when a controller clock triggers.
In a preferred embodiment of the invention delivering gaseous drugs,
flow controllers in mixer 44 (detailed in FIG. 8) determine the
total fresh gas flow (FGF) which is the sum of the volumes of each
gas being controlled, namely, the gaseous drug, oxygen and atmospheric
air. Solenoid valves are opened proportionally to achieve the desired
FGF and fractional amount of each gas. Flow controllers 133, 135
close the feedback loop on the gas fractions by measuring the FiO.sub.2
and fraction of inspired gaseous drug in the manifold system 46
and adjusting the mixer solenoid valves accordingly.
In one aspect of the invention, the flow controllers 133, 135 match
the FGF with patient minute ventilation rates. The minute ventilation
rate is the volume of breath one inhales and then exhales (e.g.,
in cubic centimeters or milliliters) in one minute. A patient's
respiratory physiology is balanced at this minute ventilation. The
care system optimizes FGF rates by matching gas delivery to patient
minute ventilation rates. This conserves gas supplies, minimizes
the release of anesthesia gases into the operating environment,
and helps balance respiratory function. For example, if the FGF
is less than the minute ventilation, INPRV 154 will open to supplement
the air flow (INPRV 154 being a mechanical system not under electronic
control).
In an additional aspect of the invention, the care system will
not only measure and monitor minute ventilation as described above,
but also "effective minute ventilation" and thereby improve
the quantitative information about patient physiology considered
by the system. "Effective minute ventilation" is a term
used herein to mean the amount of gas that is actually involved
in respiratory gas exchange between the alveolar sacs of the lungs
and the capillary blood surrounding those sacs (as opposed to simply
the volume of gas one inhales and then exhales, "tidal volume").
This measure may be arrived at by subtracting the volume of anatomical
space imposed between the air source (e.g., mouth) and the transfer
of gas at the alveolar sacs (estimated from the patient's height
and weight), from the tidal volume of gas to arrive at "effective
tidal volume." The effective tidal volume is then multiplied
by respiratory rate to arrive at "effective minute ventilation."
FIG. 10A details manual bypass system 4 (FIG. 5) which is coupled
to manifold system 46. The bypass system 4 includes a self-inflating
resuscitation bag (SIRB) 19a (also shown in FIG. 3B) which is a
manual pump with which the user can provide air intermittently to
the patient through a bypass air line 90. A quick disconnect type
fitting 91 (such as that disclosed in Hickle above) couples SIRB
19a with manifold system 46 and provides rapid attachment thereto.
A manual flow control valve 92 opens or closes bypass air line 90.
When line 90 is open, manual flow control valve 92 can be adjusted
to provide the necessary air flow. A flow meter 94 placed in bypass
air line 90 provides a visual display to the user of the status
of air flowing through the bypass air line 90. The above-described
manual bypass system 4 provides the patient with manually-controlled
flow of air and thus enables air delivery in the case of an oxygen
source system 144 (FIG. 7A) failure.
FIG. 10B details scavenger pump system 48 (FIG. 6) which is integrated
into the care system and vacuums exhaled gases from manifold system
46 through a scavenging line 85. A filter 86 in scavenging line
85 removes contaminants from the gases which have been exhaled from
the patient and which are flowing through the scavenger line 85.
Pressure regulator 87 receives the filtered gases and ensures that
the vacuum pressure is maintained in vacuum pump 95 downstream at
a reasonable working level. Flow restrictor 88 sets the flow rate
through the vacuum 95 for a given vacuum pressure. Check valve 89
downstream of flow restrictor 88 provides one-way flow of scavenged
gases, and thus ensures that back-flow does not inadvertently flow
into scavenger system 48 from the vacuum pump 95 downstream. Vacuum
pump 95 provides the vacuum pressure necessary for scavenging of
exhaled gases from the patient. The pump may be of an electrical
type that can be powered by office standard AC current. As the vacuum
pump is integrated into the care system, a wall vacuum source (such
as that typically in an OR) is not required. Once the gases are
vacuumed off, they are exhausted via exhaust hose 32 (FIG. 3B) to
an appropriate area. The benefit of scavenging system 48 is at least
two-fold in that the system helps assist the patient in the work
of breathing and work environment safety is increased.
In a preferred embodiment, an emesis aspirator 19 (FIG. 3B) is
integrated into system 10 and may be stored within housing 15. Emesis
aspirator 19 is a manually operated device used to suction a patient's
airway in the event of vomiting. Emesis aspirator 19 does not require
an external vacuum source (e.g., wall suctioning) or electrical
power for operation.
To enhance the safety of the invention, housing 15 may include
structure integrated adjacent or otherwise near where emesis aspirator
19 is stored within housing 15 (FIG. 3B) to hold and prominently
display containers of drugs capable of reversing the effects of
various sedatives/analgesics. These "reversal drugs,"
such as naloxone, remazicon and others may be immediately administered
to the patient in the event of an overdose of sedative, analgesic
and/or amnestic.
Referring to FIG. 11, a preferred embodiment of the invention includes
an integrated patient interface system which combines one or more
patient health monitors 252 (additional health monitors to those
shown are also contemplated by the invention) with additional automated
patient feedback devices including a patient drug dosage increase
or decrease request device 254 and an automated consciousness query
system 256 for monitoring a patient's level of consciousness. These
health monitors 252 and automated patient feedback devices 254,
256 are electronically coupled to electronic controller 14 via leads
(e.g., 50, FIG. 2) and provide electronic feedback values (signals)
representing the patient's physiological condition to controller
14. Generally, if any monitored patient parameter falls outside
a normal range (which may be preset by the user or otherwise preprogrammed
and stored in memory device as described above), the nonanesthetist
is immediately alerted, for example, by an alarm, display or other
attention-commanding device. The information obtained from patient
health monitors 252 is displayed on a display device 35 (FIG. 2),
in, for example, continuous wave form or numerics on LEDs, thus
allowing the procedural physician to immediately gain useful information
by reviewing the display device. Preferred embodiments of displays
contemplated by the invention are described in more detail below.
A preferred embodiment of one aspect of the invention integrates
drug delivery with one or more basic patient monitoring systems.
These systems interface with the patient and obtain electronic feedback
information regarding the patient's physiological condition. Referring
to FIG. 11, a first patient monitoring system includes one or more
patient health monitors 252 which monitor a patient's physiological
conditions. Such monitors can include a known pulse oximeter 258
(e.g, an Ohmeda 724) which measures a patient's arterial oxygen
saturation and heart rate via an infra-red diffusion sensor; a known
capnometer 184 (e.g., a Nihon Kohden Sj5i2) which measures the carbon
dioxide levels in a patient's inhalation/exhalation stream via a
carbon dioxide sensor and also measures respiration rate; and a
known non-invasive blood pressure monitor 262 (e.g., a Criticon
First BP) which measures a patient's systolic, diastolic and mean
arterial blood pressure and heart rate by means of an inflatable
cuff and air pump. A care system constructed in accordance with
this invention may include one or more of such patient health monitors.
Additional integrated patient health monitors may also be included,
such as, for example, a measure of the flow in a patient's airstream,
IPG ventilatory monitoring, a standard electrocardiogram (EKG) which
monitors the electrical activity in a patient's cardiac cycle, an
electroencephalograph (EEG) which measures the electrical activity
of a patient's brain, and an acoustical monitor whose audio signals
may be processed and provided to controller 14 and amplified and
played audibly.
A second patient monitoring system monitors a patient's level of
consciousness by means of an automated consciousness query (ACQ)
system 256 in accordance with the invention. ACQ system 256 comprises
a query initiate device 264 and a query response device 266. ACQ
system 256 operates by obtaining the patient's attention with query
initiate device 264 and commanding the patient to activate query
response device 266. Query initiate device 264 may be any type of
a stimulus such as a speaker which provides an auditory command
to the patient to activate query response device 266 and/or a vibrating
mechanism which cues the patient to activate query response device
266. The automated pressurization of the blood pressure cuff employed
in the patient health monitoring system may also be used as a stimulus.
Query response device 266 can take the form of, for example, a toggle
or rocker switch or a depressible button or other moveable member
hand held or otherwise accessible to the patient so that the member
can be moved or depressed by the patient upon the patient's receiving
the auditory or other instruction to respond. In a preferred embodiment,
the query system has multiple levels of auditory stimulation and/or
vibratory or other sensory stimulation to command the patient to
respond to the query. For example, an auditory stimulus would increase
in loudness or urgency if a patient does not respond immediately
or a vibratory stimulus may be increased in intensity.
After the query is initiated, ACQ system 256 generates signals
to reflect the amount of time it took for the patient to activate
response device 266 in response to query initiate device 264 (i.e.,
this amount of time is sometimes referred to as the "latency
period"). ACQ system 256 is electronically coupled to electronic
controller 14 and the signals generated by ACQ system 256 are suitably
converted (e.g., employing an A-D converter) and thereby provided
to controller 14. If the latency period is determined by controller
14, which employs software to compare the actual latency period
with stored safety data set parameters reflecting safe and undesirable
latency period parameters, to be outside of a safe range, the physician
is notified, for example, by means of an alarm or other attention-commanding
device. If no action is taken by the physician within a pre-set
time period, controller 14 commands the decrease in level of sedation/analgesia/amnesia
by control and operation on electronic flow controllers 133, 135
of FIG. 8. The values of the signals reflecting the latency period
are displayed on display device 35 (or on LED devices located on
housing 15 or on remote control device 45, FIG. 1) and the physician
may thus increase or decrease drug delivery based on the latency
period.
The patient interface system of FIG. 11 also includes a drug dosage
request device 254 which allows the patient direct control of drug
dosage. This is accomplished by the patient activating a switch
or button to request electronic controller 14 to command the increase
or decrease in the amount of drug he or she is receiving. For example,
if a patient experiences increased pain he or she may activate the
increase portion of the switch 254, whereas, if a patient begins
to feel nauseous, disoriented or otherwise uncomfortable, he or
she may request a decrease in drug dosage. In embodiments where
drug delivery is intravenous, such delivery can be by continuous
infusion or bolus. A feedback signal from analgesic request 254
representing the patient's increase or decrease in drug dosage request
is electronically communicated to controller 14 which employs conservative,
decision-making software, including comparison of monitored patient
conditions with stored safety parameters reflecting patient physiological
conditions, to effect safe, optimized drug delivery in response
to patient requests. The amount of increase or decrease administered
by controller 14 can be pre-set by the physician through user access
devices such as keyboard 230, FIG. 2. For example, where the drug
being delivered is nitrous oxide, the approved increase or decrease
may be in increments of .+-.10%. When not activated by the patient,
drug request device 254 remains in a neutral position. The invention
thus integrates and correlates patient-controlled drug delivery
with electronic monitoring of patient physiological conditions.
In an alternative embodiment, the physician is notified via user
interface system 16 (display device 30 or LEDs remote control device
45), FIG. 1 of the patient request to increase or decrease drug
dosage and can approve the requested increase or decrease taking
into account the patient's present vital signs and other monitored
physiological conditions, including consciousness level status as
obtained from the various patient interface system monitors 252,
256 (FIG. 11).
In a preferred embodiment of the invention, the patient controlled
drug dosage request system 254 has lock-out capabilities that prevent
patient self-administration of drugs under certain circumstances.
For example, access to self-administration will be prevented by
electronic controller 14 under circumstances where patient physiology
parameters or machine state parameters are or are predicted to be
outside of the stored safety data set parameters. Access to self-administration
of drugs could also be inhibited at certain target levels or predicted
target levels of drugs or combined levels of drugs. For example,
if it were predicted that the combined effect of requested drugs
would be too great, drug delivery in response to patient requests
would be prohibited. It is noted that such predictive effects of
drugs could be determined through the use of various mathematical
modeling, expert system type analysis or neural networks, among
other applications. In short, the invention is designed to dynamically
change drug administration and amount variables as a function of
patient physiology, care system state and predictive elements of
patient physiology.
Additionally, it is contemplated that patient self-administration
of drugs could be prohibited at times when drug levels are changing
rapidly. For example, if a patient is experiencing pain and that
is apparent to the physician, the physician may increase the target
level of drug while at the same time the patient requests additional
drug. The subject invention will sequentially address the physician
and patient requests for drug increases and will lock out any patient-requested
increases that are beyond programmed parameters.
In an additional aspect of the invention, a patient may be stimulated
or reminded to administer drugs based on electronic feedback from
the patient physiology monitoring systems. For example, if there
is an underdosing of analgesics and the patient is suffering pain
evidenced by a high respiratory rate or high blood pressure reflected
in electronic feedbacks to the electronic controller, the controller
can prompt the patient to self-administer an increase in drugs.
This could be accomplished by, for example, an audio suggestion
in the patient's ear. Thus, it is contemplated that the invention
will have an anticipatory function where it will anticipate the
patient's needs for increased drugs.
In a preferred embodiment of the invention, one or more patient
vital sign monitoring devices 252, ACQ system devices 256, and a
drug dosage request device 254 are mechanically integrated in a
cradle or gauntlet device 55 (FIG. 2) constructed to accommodate
and otherwise fit around a patient's hand and wrist. FIG. 2 shows
generally hand cradle device 55 electronically coupled by lead 50
to care system 10. One embodiment of a hand cradle device in accordance
with this invention is shown in more detail in FIGS. 12A and 12B.
FIG. 12A shows blood pressure cuff 301 capable of being wrapped
around a patient's wrist and affixed to itself such that it can
be held in place. Cuff 301 is affixed to palm support portion 303.
Alternatively, the cuff may be separated from palm support portion
303 and placed on the upper arm at the physician's discretion. A
recessed, generally elliptical or rounded portion 305 is supported
by the top edge of palm support portion 303 and is capable of receiving
and supporting the bottom surface of a patient's thumb. Depressible
query response switch 307 is located within thumb support portion
305 such that switch 307 is capable of being depressed by the patient's
thumb. The thumb support portion 305 may be constructed so as to
have a housing, frame, raised walls or other guide so that a patient's
thumb may more easily be guided to depress or move buttons or switches
within portion 305 (here, switch 307), or so that any significant
patient thumb movement toward the switch will activate same. Supporting
thumb support portion 305 and abutting palm portion 303 is finger
support portion 309 for receiving in a wrapable fashion the patient's
fingers. Drug dosage request switch 311 is integrated into finger
support portion 309 and is in the form of a rocker switch whereby
depressing the top portion 310a of said switch will effect an increase
in the delivery of sedative, analgesic and/or amnestic whereas depressing
the bottom portion 310b of said rocker switch will effect a decrease
in drug delivery at an appropriate set percentage (e.g., .+-.10%,
FIG. 12B). Rocker switch 311 is constructed so as to remain in a
neutral position when not being actuated by the patient.
FIGS. 13A and 13B show an additional embodiment of the hand cradle
device of this invention. Specifically, a pulse oximetry sensor
314 is mechanically affixed to and electronically coupled to hand
cradle device 55 abutting the upper end of finger support portion
309, and being generally planar vis-a-vis the outer edge of thumb
support portion 305. Pulse oximeter 314 is constructed as a clip
which can be placed on a patient's finger. The transmitter and receiver
portions of sensor 314 are contained in the opposite sides 315a,
315b (FIG. 13B) of the finger clip 314 such that when placed on
a finger, infra-red radiation travels through the finger; through
spectral analysis the percentage of oxygenated hemoglobin molecules
is determined. In this embodiment of hand cradle device 55 the query
initiate device 313 is in the form of a small vibrator located in
palm support portion 303. Alternatively, to enhance patient attentativeness
to the query initiate device and to increase patient accuracy in
depressing the response switch, the vibrator may be located adjacent
the query response switch 307 or, in the embodiment of FIG. 14A,
adjacent response switch 407.
In an alternative embodiment of hand cradle device 55, now referring
to FIGS. 14A and 14B, drug dosage request device 409 is located
within thumb portion 405 and is in the form of a slidable member
409 wherein sliding member 409 forward effects an increase in analgesic
dosage and sliding portion 409 backward effects a decrease in analgesic
dosage (FIG. 14B). In this embodiment of the invention, query response
device 407 is a depressible portion integrated within finger support
portion 409.
All embodiments of hand cradle device 55 are constructed so as
to be ambidextrous in nature, namely, they accommodate and are workable
by a patient's right or left hand. For example, in FIGS. 12A and
13A, a second query response switch 307b is located within a symmetrically
opposed thumb portion 305b affixed to the opposite end of finger
portion 309. Similarly the device of FIG. 14A is also constructed
with a symmetrically opposed thumb portion 405b and drug dosage
request device 409b. The pulse oximeter clip 314 is affixed to finger
support portion 309 so as to be mechanically and electronically
quick releasable to permit reversibility when used on the opposite
hand. It should also be recognized that the pulse oximeter clip
314 may be tethered to hand cradle device 55 rather than mechanically
affixed thereto, or blood pressure cuff 301 and oximeter clip 314
may be mechanically separate from cradle device 55 and electronically
coupled to controller 14 with flexible leads.
Referring to FIG. 15, an additional alternative embodiment of the
invention is shown in which hand cradle device 55 includes mechanically
integrated blood pressure cuff 301, query response device 307 and
analgesic request device 309 similar to that described above. This
embodiment, however, includes an ear clip device 450 capable of
being clipped to the lobe of a patient's ear and being electronically
coupled to electronic controller 14 via lead 456. Referring additionally
to FIG. 16, ear clip 450 comprises a query initiate device 452 in
the form of a speaker which provides an audible command to patient
to activate the response switch. Such speaker may also command a
patient to self-administer drugs or play music to a patient during
a procedure. Pulse oximeter 454 is a clip capable of being affixed
to a patient's ear lobe. One side of the clip being a transmitter
and the other side of the clip being a receiver to effect the infra-red
spectral analysis of the level of oxygen saturation in the patient's
blood.
In an additional aspect of the invention, the care system's automated
monitoring of one or more of the patient's health conditions is
synchronized with the re-monitoring of those one or more conditions
and/or the monitoring of one or more other health conditions of
the patient. For example, in one embodiment, controller 14 receives
parameters such as blood pressure, heart rate, respiratory rate,
and blood O.sub.2 saturation from patient health monitors 412 and
can automatically inflate the blood pressure cuff and check the
patient's blood pressure whenever those parameters exist outside
of a desirable range (i.e., outside of the stored safety data set
for those parameters.) In a further preferred embodiment, controller
14 immediately initiates ACQ system 256 to query consciousness by
triggering an automated responsiveness test (ART) upon receiving
certain patient health parameters that are outside of the safety
data set.
If controller 14 receives a value for a patient health parameter
that falls outside of the safety data set for that parameter, it
will trigger an event. Preferably, the safety data set for each
health parameter includes values or a range of values that correspond
to high and low event conditions and values or a range of values
for each of the high and low event conditions that correspond to
warning and caution event conditions. Therefore, some sets of patient
health data (e.g. heart rate) may constitute conditions that trigger
high warning, high caution, low warning, and low caution events.
These sets of patient health data may be dependent on such patient
parameters as age or gender. Data within the safety data set for
a parameter, i.e., data not triggering one of the four above events,
may still trigger an event where the trend of such data over time
suggests that it will eventually constitute a condition that would
trigger a high warning, a high caution, a low warning, or a low
caution event if no clinically appropriate preemptive action is
taken.
Once an event is triggered, notice of it may be displayed to the
user via the user interface system. The event may prompt the system
to gather more information about the patient health parameters which
resulted in the event condition and/or the event may prompt the
system to effect a clinically appropriate response to the event
condition.
For example, in one embodiment, controller 14 will call for an
immediate blood pressure check (STAT BP) upon its receipt of heart
rate or blood O.sub.2 saturation data that falls within either low
warning or low caution event conditions for those parameters. Low
blood pressure may be associated with a low heart rate or low blood
O.sub.2 saturation, but it may also be caused by too much drug being
administered to the patient. Therefore, upon being informed that
the patient's heart rate or blood O.sub.2 saturation data falls
within the low event conditions for those parameters, the user may
want to also have up-to-date blood pressure data for the patient.
Therefore, the aforementioned automated response may be clinically
appropriate.
Blood pressure measurements themselves may be in error if the patient
flexes a muscle, such as a bicep or tricep, beneath the blood pressure
cuff during a measurement cycle. Ordinarily, the care system will
only measure the patient's blood pressure intermittently (every
five minutes, for example) resulting in blood pressure data that
is only infrequently presented to the system's user. Therefore,
in a further embodiment, controller 14 triggers an immediate re-check
of the blood pressure (STAT BP) whenever it receives blood pressure
data that constitutes either high or low alarm conditions in order
to provide the user with the most recent blood pressure data between
the intermittent blood pressure checks.
A high heart rate is often associated with a high blood pressure
because the same stress hormones (e.g. epinephrine and norepinephrine)
cause both conditions. Therefore, when a patient's heart rate constitutes
a high event condition, it is probable that the patient's blood
pressure is too high as well. Conversely, a high heart rate event
may indicate that the patient's blood pressure is low since a high
heart rate is occasionally due to arrhythmias which depress blood
pressure. So, in another embodiment, when controller 14 receives
a heart rate that constitutes a high event condition, it triggers
a STAT BP. Therefore, this automated response is clinically appropriate
because it automatically provides the care system's user with up-to-date
blood pressure data so the user can assess whether a patient's high
heart rate is a symptom or a cause of a further condition.
The above embodiments in which a STAT BP is triggered because of
certain events are summarized in Table 1 below:
TABLE-US-00001 TABLE 1 Events Which Trigger a STAT BP Parameter
Event Heart Rate LOW WARNING SpO.sub.2 LOW WARNING Systolic BP LOW
WARNING Diastolic BP LOW WARNING Mean BP LOW WARNING Heart Rate
HIGH WARNING Systolic BP HIGH WARNING Diastolic BP HIGH WARNING
Mean BP HIGH WARNING Heart Rate LOW CAUTION SpO.sub.2 LOW CAUTION
Systolic BP LOW CAUTION Diastolic BP LOW CAUTION Mean BP LOW CAUTION
Heart Rate HIGH CAUTION Systolic BP HIGH CAUTION Diastolic BP HIGH
CAUTION Mean BP HIGH CAUTION
In another example, the electronic checking of blood pressure may
be synchronized with the automated responsiveness query because
the activation of the cuff may arouse a patient and affect query
response times. Thus the invention contemplates an "orthogonal
redundancy" among patient health monitors to ensure maximum
safety and effectiveness.
In an additional aspect of the invention, the care system's automated
monitoring of one or more of the patient's health conditions is
synchronized with the automated checking of the patient's responsiveness
by an ART. Low event conditions of certain health parameters, including
heart rate, blood O.sub.2 saturation, respiratory rate, and blood
pressure, may be caused by a state of drug overdose. If, however,
the patient is responsive to the ART, then it is unlikely that any
low event conditions of the above health parameters were caused
by a sedative drug overdose. Therefore, in a preferred embodiment,
whenever the controller 14 receives heart rate, blood O.sub.2 saturation,
respiratory rate, and/or blood pressure data that constitute low
event conditions for the respective health parameter, it triggers
an immediate check of the patient's responsiveness (STAT ART). The
user is thus freed from having to routinely initiate an ART measurement
cycle or manually evaluate the patient's responsiveness each time
the above event conditions are present before being able to assess
whether those conditions represent possible drug overdose.
The above embodiment in which a STAT ART is triggered because of
certain events is summarized in Table 2 below:
TABLE-US-00002 TABLE 2 EVENTS WHICH TRIGGER A STAT ART Parameter
Event Heart Rate LOW WARNING SpO.sub.2 LOW WARNING Respiratory Rate
LOW WARNING Systolic BP LOW WARNING Diastolic BP LOW WARNING Mean
BP LOW WARNING Heart Rate LOW CAUTION SpO.sub.2 LOW CAUTION Respiratory
Rate LOW CAUTION Systolic BP LOW CAUTION Diastolic BP LOW CAUTION
Mean BP LOW CAUTION
As described above, one aspect of a preferred embodiment of the
invention includes the electronic management of drug delivery via
software/logic controlled electronic controller 14 to integrate
and correlate drug delivery with electronic feedback signals from
system monitors, one or more patient monitor/interface devices and/or
user interface devices. Specifically, electronic signal values are
obtained from care system state monitors; from patient monitor/interface
devices (which can include one or more vital sign or other patient
health monitors 252, ACQ system 256, and/or patient drug dosage
request device 254, FIG. 11); and in some instances from one or
more user interface devices. All are electronically coupled to,
through standard A-D converters where appropriate, electronic controller
14. The controller 14 receives the feedback signal values and, via
software and programmed logic, effects a comparison of these values
representing the patient's monitored physiological conditions with
known stored data parameters representing safe and undesirable patient
physiological conditions (a safety data set). Controller 14 then
generates an instruction in response thereto to maintain or decrease
the level of sedation, analgesia, and/or amnesia being provided
to the conscious patient thereby managing and correlating drug delivery
to safe, cost-effective and optimized values (FIG. 2B. Controller
14 is operatively, electronically coupled to electronic flow controllers
133, 135 (FIG. 8) of electronic mixer 44 which (via solenoid valves)
adjust flow of gaseous drug and O.sub.2 in a closed-loop fashion
as described above. In intravenous embodiments such flow controllers
would adjust the flow of one or more combination of IV drugs. It
should be recognized that the electronic values provided to microprocessor
controller 14 to effect management and correlation of drug delivery,
could include one or more signals representing patient vital signs
and other health conditions such as pulse oximetry, without necessarily
including signal(s) representing level of patient consciousness,
and vice versa.
For example, in one embodiment, when either the patient's blood
O.sub.2 saturation or respiratory rate data received by controller
14 constitutes low event conditions, as described above, the controller
effects management and correlation of drug delivery. Preferably,
when the low event conditions for either of the patient's blood
O.sub.2 saturation or respiratory rate data further constitute caution
event conditions, controller 14 effects a transition to a reduction
in drug (REDUCE) where the drug level being administered to the
patient is reduced to achieve a drug level that is a fraction (80%,
for example) of the level that was present when the event condition
was first detected. Preferably also, when the low event conditions
for either of the patient's blood O.sub.2 saturation or respiratory
rate data further constitute warning event conditions, controller
14 effects a transition to a complete halt of drug (OFF) where the
drug administration is automatically turned off.
By automating these responses, the present invention improves the
safety of sedation and analgesia by timely gathering information
and effecting a clinically appropriate response thereby relieving
a multi-tasked physician and nurse team from such routine. By automatically
effecting a change of the drug administered, REDUCE for example,
the care system prevents mild patient abnormalities, such as a respiratory
rate constituting a low caution event condition, from progressing
to severe pathophysiology.
The above embodiments in which REDUCE or OFF is triggered because
of certain events is summarized in Table 3 below:
TABLE-US-00003 TABLE 3 Events Which Trigger REDUCE or OFF Parameter
Event Effect SpO.sub.2 LOW WARNING OFF Respiratory Rate LOW WARNING
OFF SpO.sub.2 LOW CAUTION REDUCE Respiratory Rate LOW CAUTION REDUCE
FIG. 24 shows three data-flow diagrams depicting examples of the
clinical heuristics that the care system provides. Event conditions
LOW Heart Rate 241, LOW SpO.sub.2 242, LOW Respiratory Rate 243,
and LOW Blood Pressure 244 are shown triggering STAT ART 245. Event
conditions LOW Heart Rate 241, LOW SpO.sub.2 242, and LOW Blood
Pressure 244, HIGH Heart Rate 246, and HIGH BP 247 are shown triggering
STAT BP 248. Event conditions LOW SPO.sub.2 242 and LOW Respiratory
Rate 243 in Caution and Warning status are shown triggering REDUCE
249a and OFF 249b, respectively.
As also indicated above, the software effecting electronic management
of drug delivery by controller 14 employs "conservative decision-making"
or "negative feedback" principles. This means, for example,
that the electronic management of drug delivery essentially only
effects an overall maintenance or decrease in drug delivery (and
does not increase drugs to achieve overall increased sedation/analgesia).
For example, if ACQ system 256 (FIG. 11) indicates a latency period
outside of an acceptable range, controller 14 may instruct electronic
flow controller 133 (FIG. 8) to increase the flow of oxygen and/or
instruct flow controller 135 to decrease the flow of gaseous drug
to manifold system 48.
In another example of such electronic management of drug delivery
by conservative decision-making principles, if ACQ system 256 (FIG.
11) indicates a latency period in response to a patient query given
every 3 minutes outside of an acceptable range, electronic controller
14 may immediately cease drug delivery, but at the same time, increase
the frequency of times that the patient is queried, e.g., to every
15 seconds. When the patient does respond to the query, the drug
delivery is reinitiated, but at a lower overall dose such as 20%
less than the original concentration of drug that had been provided.
A further example of the invention's electronic management of drug
delivery through conservative, decision-making software instruction
employs known target-controlled infusion software routines to calculate
an appropriate dosage of IV drug based on patient physical parameters
such as age, gender, body weight, height, etc. Here, a practitioner
provides the patient physiological parameters through the user interface
system, the electronic controller 14 calculates the appropriate
drug dosage based on those parameters, and drug delivery begins,
for example, as a bolus and is then brought to the pre-calculated
target level of infusion. If later there is a significant change
in a patient monitored parameter, e.g., pulse oximetry or latency
period falls outside of a desired range, controller 14 effects a
decrease in overall drug delivery as described above.
One concern that the invention addresses with respect to the target
controlled infusion of IV drugs is the nature and speed at which
the care system reaches the steady state target level of drug. For
example, an important consideration for the physician is, once drug
administration begins, when is the patient sufficiently medicated
(e.g., sedated or anesthetized), so that the physician can begin
the procedure. It is frequently desirable that the patient reach
the steady state target level of drug as rapidly as possible so
that the procedure can begin as soon as possible. It has been determined
that one way of reaching a suitable level of drug effectiveness
quickly is to initially overshoot the ultimate steady state target
drug level. This shortens the time between the beginning of drug
delivery and the onset of clinical drug effectiveness so that the
procedure may begin. Typically, predicted target levels have an
error of plus or minus 20%, therefore, one approach of reaching
the clinical effectiveness state quickly is to attempt to reach
at least 80% of the ultimate target level, but initially overshoot
that 80% level by giving a 15% additional increase of drug infusion
beyond the 80% target. One method of accomplishing this is to use
currently available PDI controllers which employ an error state
(here the difference between predicted drug levels in the blood
stream and the target level) to arrive at an infusion rate. Other
control systems, however, that allow some initial overshoot of the
target blood level of the drug to get to a clinical effectiveness
level quicker would also be appropriate.
FIG. 17 is a schematic of an alternative embodiment of an apparatus
constructed in accordance with the invention which is particularly
suitable for remote medical care locations and home care-type settings
for indications such as post-operative or other post-procedural
pain and/or discomfort, including, for example, nausea secondary
to oncology chemotherapy. In this embodiment, drug source system
442 delivers drugs to the patient (which may be drugs such as propofol,
morphine, remifentanil and others) intravenously by, for example,
use of a known syringe pump-type device capable of being worn or
otherwise affixed to the patient, or delivers such drugs transdermally
by, for example, use of known ion transfer-type devices, among others.
The drug delivery may be continuous or by drug bolus and without
an integrated supply of O.sub.2. If necessary, oxygen may be supplied
to the patient from separate tanks or an in-house, on-site oxygen
source. The resulting apparatus is simplified--there is no requirement
for an integrated O.sub.2 source, electronic mixer, manifold, or
the airway circuit and face mask devices described above.
One or more patient health monitors 412 such as known pulse oximeters,
blood pressure cuffs, CO.sub.2 end tidal monitors, EKG, and/or consciousness
monitors, or other monitors such as those indicated herein, monitor
the patient's physiological condition. Drug dosage may be pre-set
by a physician prior to or during application of drug delivery and/or
also patient controlled thereafter by means of a patient drug dosage
increase or decrease request devices generally of the type of that
described above. It should also be understood that the intravenous
delivery of drugs may be by continuous infusion, target-controlled
infusion, pure bolus, patient-elected bolus or combinations thereof.
Still referring to FIG. 17, electronic management of drug delivery
in this embodiment of the invention is provided by electronic controller
414 which may be of a type described above. Controller 414 employs
conservative decision-making software and/or logic devices to integrate
and correlate drug delivery by drug source system 442 (which may
include known solenoid type or other electronic flow controllers)
with electronic feedback values from one or more patient health
monitors 412. The values (signals) from patient health monitors
412 represent one or more actual patient monitored physiological
conditions. Controller 414, through software employing comparison
protocols such as those described herein, accesses stored safety
data set 410 which contains data reflecting safe and undesirable
patient physiological conditions, and compares the signals reflecting
actual patient monitored conditions with same. As described above,
safety data set 410 may be stored in a memory device such as an
EPROM. Based on the result of the comparison, controller 414 either
instructs no change in drug delivery or generates a signal instructing
the drug flow controllers of drug source system 442 to manage application
of the drug to safe, optimized levels.
In certain aspects of the invention, controller 414 may also access,
through software, pre-set parameters stored in a memory device representing
initial or target drug dosages and lock-outs of patient drug administration
requests as described above. In these circumstances, instruction
signals generated by controller 414 would also account for and control
drug delivery in accord with these pre-set parameters.
This embodiment of the invention would also typically include system
state monitors, such as electronic sensors which indicate whether
power is being supplied to the system or which measure the flow
of drugs being delivered. Such system state monitors are electronically
coupled to controller 414 and provide feedback signals to same--the
control of drug delivery by controller 414 electronically coupled
to drug source system 442 in response to said feedback signals is
similar to that as described herein with respect to other embodiments.
In another aspect of the invention, electronic controller 414 is
located on a remote computer system and electronically manages on-site
drug delivery integrating and correlating same with on-site monitoring
of patient physiological conditions and care system states as described
above, but here with instructions signals generated from a remote
location. It is contemplated that controller 414 may, in some embodiments,
effect transmission via modem or electronic pager or cellular-type
or other wired or wireless technologies of electronic alarm alerts
to remote locations if a monitored patient parameter such as the
percentage of oxygen absorbed into the blood (S.sub.pO.sub.2) falls
outside of a safe established value or range of values as established
by the stored safety data set. Such remote locations could thereby
summon an ambulance or other trained caregiver to respond to the
alarm alert.
FIG. 18 details the user interface system of a preferred embodiment
of the invention. This system enables the physician to safely and
efficaciously deliver one or more of sedation, analgesia or amnesia
to a patient while concurrently performing multiple tasks. The user
interface permits the physician to interact with the care system
and informs the user of the patient's and system's status in passive
display devices and a variety of active audio/visual alarms thereby
enhancing the safety and enabling immediate response time (including
the "conservative" responses, e.g., detailed drug delivery
discussed above) to abnormal situations.
Specifically, a keypad and/or touch screen 230 (FIGS. 2 and 18)
allows the physician to interact with electronic controller 14,
inputting patient background and setting drug delivery and oxygen
levels. A remote control device 45 (FIGS. 1 and 18) provides the
physician with remote interaction with the care system 10 allowing
him or her to remotely control the functions of the system. Remote
control device 45 may be removably integrated into the top surface
of housing 15 and capable of being clipped onto material close to
the physician and/or patient. In one aspect of the invention, the
remote control device 45 itself contains display devices such as
LEDs to advise the physician of patient and system parameters. A
panic switch 232 (FIG. 18), which may be on-board housing 15 (FIG.
1) or contained in remote control device 45 and electronically coupled
to controller 14 allows the physician to shut down care system 10
and maintains it in a safe state pre-programmed into controller
14.
Visual display devices 234 (FIG. 2, 35) display actual and predictive
or target patient and system parameters and the overall operation
status of the care system.
One version of a preferred embodiment of visual display 234 is
shown in FIG. 22A. The display 2230 includes a first portion of
the display 2234 which is devoted to displaying to the user the
current status of the system operation and monitored patient conditions,
including the status of any alarm caused by a change in monitored
system or patient condition. For example, if a patient's timed response
to a consciousness query (latency period) is outside an established
range and an alarm is thus activated, that query latency period
is displayed in this first portion 2234 of the visual display, thereby
enabling the physician to immediately understand the cause of the
alarm.
The visual display device 2230 of this embodiment also includes
a second portion of the display 2236 which is devoted to displaying
the actions taken or soon to be taken by the care system. For example,
if in response to an alarm indicating a latency period outside of
an established safe range the apparatus will decrease the flow of
drug to the patient, this second portion 2236 displays the percentage
decrease in drug dosage to be effected.
Visual display 2230 facilitates the physician's interaction with
the apparatus by walking the physician through various system operation
software subprograms. Such subprograms may include system start-up
where a variety of system self-checks are run to ensure that the
system is fully functional; and a patient set-up. To begin the procedure,
the care system monitors are placed on the patient and the physician
activates the system by turning it on and entering a user ID (it
is contemplated that such user ID would only be issued to physicians
who are trained and credentialed). Next, the visual display would
prompt the physician to begin a pre-op assessment, including inputting
patient ID information and taking a patient history and/or physical.
In the pre-op assessment, the physician poses to the patient a series
of questions aimed at determining appropriate drug dosage amounts
(such as age, weight, height and gender), including factors indicative
of illness or high sensitivity to drugs. The responses to such questions
would be inputted into the care system and employed by the system
to assist the physician in selecting the appropriate dose amount.
For example, the care system may make available to the physician
one range of dosage units for a healthy person and a narrower range
of dosage units for a sick or older person. The physician would
have to make an explicit decision to go above the recommended range.
In addition to the pre-op assessment performed by the physician
described above, it is also contemplated that the care system is
capable of performing an automated pre-op assessment of the patient's
physiology. For example, with the monitors in place, the care system
will assess such parameters as the oxygenation function of the patient's
lungs and/or the ventilatory function of the patient's lungs. The
oxygenation function could be determined, for example, by considering
the A-a gradient, namely, the alveolar or lung level of oxygen compared
to the arteriolar or blood level of oxygen. The ventilatory function
of the lungs could be determined from pulmonary function tests (PFTs),
among other things, which are measurements of the amount of air
and the pressure at which that air is moved in and out of the lungs
with each breath or on a minute basis. (It is contemplated that
these assessments are performed before the procedure begins and
during the procedure as a dynamic intra-operative assessment as
well.) Also during the pre-op (or as a continuous intra-operative)
assessment, heart function may be assessed by viewing the output
of an EKG to determine whether there is evidence of ischemia or
arrhythmias. Alternatively, automated algorhythms could be applied
to the EKG signals to diagnose ischemia or arrhythmias. Additional
automated patient health assessments could also be made.
During patient set-up, current patient and system parameters may
also be assessed and displayed, and the consciousness-query system
and patient drug increase/decrease system tested and baselined.
A set drug subprogram allow for the selection of drugs and/or mixture
of drugs (or drug, oxygen and air), allows for picking target levels
of drugs, and/or permits enabling of the patient's self-administration
of drugs within certain ranges. The invention also contemplates
during the pre-op assessment determining a sedation threshold limit
for the given patient in the unstimulated state. This could be done
as a manual check, i.e., by simply turning up the drug levels and
watching the patient manually or the procedure could be automated
where the drugs are increased and the safety set parameters such
as those for latency (consciousness queries) are tested as the concentration
at the drug effect site is increased.
The system and patient status and system action may be displayed
during, for example, a sedation subprogram. Visual display device
2230 may include graphical and numeric representations of patient
monitored conditions such as patient respiratory and ventilatory
status, consciousness, blood O.sub.2 saturation, heart rate and
blood pressure (2238); an indication of elapsed time from the start
of drug delivery (2239); drug and/or O.sub.2 concentrations (2241);
and indications of patient requests for increases or decreases in
drug (2243). The actual fraction of inspired oxygen calculated may
also be displayed. Command "buttons" are included to mute
alarms (2240), change concentration of drug delivered (2242), turn
on or off the mixing of an oxygen stream with atmospheric air (2244),
and to turn on or off or make other changes to the automated consciousness
query system (2246). Command buttons may also be included to place
the apparatus in a "recovery" mode once the procedure
is completed (patient parameters are monitored, but drug delivery
is disabled) (2248), and to end the case and start a new case (2250)
or shut-down the system.
An alternate version of a preferred embodiment of the visual display
portion of the invention is shown in FIG. 22B. Portions 2202, 2204,
2206 and 2208 of display device 2200 show current patient O.sub.2
saturation, blood pressure, heart rate, and end tidal CO.sub.2 levels,
respectively. These portions displaying patient physiological state
are uniquely color coded. Smart alarm box portion 2212 which may
be coded in an attention getting color such as red, displays to
the physician the particular alarm that has sounded. For example,
if the patient O.sub.2 blood saturation level falls below safe levels,
the O.sub.2 saturation alarm will sound and the O.sub.2 saturation
level will appear in smart alarm box portion 2212 where it can be
easily seen by the physician. In short, whatever parameter has alarmed
is moved to the smart alarm box portion; the specific alarm indicator
is moved to the same place every time an alarm sounds. Also, the
level of criticality of the alarm which, as described below, in
a preferred embodiment may be indicated by either yellow or red
color, is displayed in the patient physiological parameter portion
of the display. For example, if a red level O.sub.2 saturation alarm
sounds, the background portion of the O.sub.2 saturation portion
2202 will appear in red.
Portion 2214 of display 2200 shows the past, present and predicted
levels (2215) of drug administration (the drug levels shown in FIG.
22B are the levels of nitrous oxide remifentanil and propofol).
In a preferred embodiment target controlled infusion past, present
and predicted levels are shown graphically beginning with the past
thirty minutes and going thirty minutes into the future. The invention
also contemplates bracketing a range of accuracy of target controlled
infusion levels (not shown).
Display portions 2220 and 2224 depict graphical representations
of patient health parameters such as the A-a gradient (oxygenation
function) for the lungs, the results of pulmonary function tests,
electrocardiogram, blood O.sub.2 saturation, among others.
In another aspect of the invention, visual display 35 (FIG. 1)
may be removably integrated into the top surface of housing 15 and
capable of being removed from housing 15 and affixed to a frame
near the patient, such as a gurney rail or examination table. Alternatively,
or in addition thereto, a heads-up type visual display device is
provided to facilitate a nonanesthetist's involvement in the medical
or surgical procedure while simultaneously being able to view the
status of system and patient monitored values and the details of
alarm states. In this case, the display device is miniaturized and
mounted onto a wearable headset or eyeglass-type mount or mounted
on an easily viewed wall display.
Referring again to FIG. 18, in a preferred embodiment, audible
alarms 236 alert the physician when patient or system parameters
are outside of the normal range. In preferred embodiments, the alarms
may be two or three stages with different tones to indicate different
levels of concern or criticality. As is described above, when an
alarm sounds, the user is able to immediately view the cause of
the alarm because the smart alarm box portion 2212 of the visual
display 2200 shows the value of the monitored system or patient
parameter that caused the alarm to activate.
FIG. 21 A shows examples of drug delivery management protocols
for three-stage alarms responsive to patient monitors, namely, alarms
"1," "2" and "3," in accordance with
a preferred embodiment of one aspect of the invention. These alarms
may have different tones or other indicators to denote different
levels of concern or criticality. The dataflow diagram of FIG. 23A
depicts one example of the steps performed by the drug delivery
managing software or logic for one such protocol, namely, one where
electronic controller 14 described above receives an electronic
feedback signal from a pulse oximeter monitoring the actual amount
of oxygen saturation in a patient's blood (the value indicated by
"SpO.sub.2"). As is shown, the SpO.sub.2 value is compared
with stored safety data set 220 containing a parameter value or
range of parameters values reflecting safe and undesirable patient
blood oxygen saturation conditions. If the SpO.sub.2 value is greater
than or equal to stored parameter 90%, no alarm sounds and no adjustment
to drug delivery is effected (221a). If the SpO.sub.2 value is less
than 90%, but greater than 85% (221b), alarm 1 sounds for 15 seconds
(222). If alarm 1 is silenced manually (222a), no further action
is taken by the system. If alarm 1 is not silenced, the amount of
drug being delivered (in this example gaseous N.sub.2O) is reduced
to the lesser of a concentration of 45% or the current concentration
minus 10% (223). The software/logic procedure would operate in a
similar fashion for intravenous and nebulized forms of drugs and
the instructions provided (e.g., as in 223) would be specified for
safe dosages of such drugs.
Further, if the value of oxygen saturation (SpO.sub.2) is less
than 85%, but greater than or equal to 80% (221c), alarm 2 sounds
and the amount of N.sub.2O being delivered is immediately reduced
to the lesser of a concentration of 45% or the current concentration
minus 10% (224). If the feedback value SpO.sub.2 from the pulse
oximeter indicates that the oxygen saturation in the blood is less
than 80%, alarm 3 sounds and the amount of N.sub.2O being delivered
would be immediately reduced to 0% (225).
Similar protocols are described in FIG. 21A for electronic feedback
signals from patient health monitors indicating pulse rate, amount
of carbon dioxide in a patient's end tidal exhalations, respiration
rate, systolic blood pressure, and feedback from the automated consciousness
monitoring system constructed in accordance with the invention.
These protocols are effected with software (and/or logic) operating
in similar fashion to that described in the dataflow diagram of
FIG. 23A. That is, the protocol shown in FIG. 23A is one example
employing one patient monitored parameter, but the operation of
the invention would be similar to effect the remaining protocols
of FIG. 21A.
It should be understood that the system responses to alarms (described
above in terms of decreases or cessation of drug concentration)
could also include institution and/or increases in administration
of oxygen in accord with patient and system state parameters as
described above. In circumstances where drugs are halted and pure
oxygen (or an O.sub.2 atmospheric mix) is provided, e.g., where
feedback signals indicate the patient has a low blood O.sub.2 saturation,
a preferred system is designed to operate in a LIFO ("last-in-first-out")
manner. This means that when controller 14 receives feedback signaling
an adverse patient or machine state and instructs flow controllers
to turn on the oxygen, the very next breath the patient takes will
be of pure O.sub.2 (and/or atmospheric air) rather than of a drug/air
mixture. This may be accomplished, for example, by supplying O.sub.2
for air directly to PIV 152 (FIG. 9A) and bypassing reservoir bag
149.
FIG. 21B shows examples of drug delivery management protocols for
two-stage alarms responsive to system state monitors, namely, alarms
"1" and "2," in accordance with a preferred
embodiment of one aspect of the invention. The alarms may have different
tones or other indicators to note different levels of concern or
criticality. The dataflow diagram of FIG. 23B depicts one example
of the steps performed by the drug delivery managing software and/or
logic for one such protocol, namely, one where electronic controller
14 (e.g., FIG. 2A) receives an electronic feedback value from an
O.sub.2 tank pressure sensor (519) indirectly measuring the amount
of oxygen remaining in an on-board oxygen tank (the value indicated
by "O.sub.2 remaining"). As is shown, the O.sub.2 remaining
value is compared with an established data set of safe system parameters
stored in a memory device as described above, said data set containing
a "setpoint" reflecting known safe and undesirable oxygen
tank pressure conditions (520). If the oxygen pressure is greater
than the setpoint, no alarm sounds and no adjustment to drug delivery
is effected (521). If the O.sub.2% value is less than the setpoint,
alarm "1" sounds (522). If alarm "1" is silenced
manually within 15 seconds, no further action is taken by the system
(523). If alarm "1" is not silenced within 15 seconds,
the amount of drug being delivered (in this example gaseous N.sub.2O)
is reduced to the lesser of the concentration of 45% or the current
concentration minus 10% (524). The software or logic procedure would
operate in a similar fashion for intravenous and nebulized forms
of drugs and the instructions provided (e.g., as in 524), would
be specified for safe dosages of such drugs.
In another example of FIG. 21B involving a system state monitor
which indicates whether power is being supplied to apparatus 10,
a logic operation determines whether power has been interrupted.
If the system state monitor for power signals that power has been
interrupted, alarm "2" sounds and the delivery of drug
is reduced to 0%.
Similar protocols are described in FIG. 21B for system state monitors
indicating O.sub.2 interruption fail safe, total gas flow, drug
tank pressure, fraction of inspired oxygen (FIO.sub.2), and operation
of the vacuum pump for scavenging system 48 (FIG. 6). These protocols
are effected with software (and/or logic) operating in similar fashion
to that described in the dataflow diagram of FIG. 23B. That is,
the protocol shown in FIG. 23B is one example employing one system
state monitor stored parameters, but the operation would be similar
to effect the remaining protocols of FIG. 21B.
In the above examples, involving response to patient physiological
state, there is a time lapse between the alarm's sounding and any
decrease in drug delivery to the patient. In alternate protocols
contemplated by the invention, electronic controller 14 will immediately
cease or curtail drug administration upon the sounding of an alarm.
For less critical ("yellow") alarms, drug delivery may
be decreased to 80% levels upon the sounding of the alarm; for more
critical ("red") alarms, drug delivery would cease upon
the sounding of the alarm. In either case, the physician will then
be given time, for example, thirty seconds, to instruct controller
14 to restart the drug delivery (e.g., the physician will need to
override the curtailing of drug delivery). If the physician does
override controller 14, drugs are reinitiated, for example, by a
bolus amount. This method prevents against a patient's deteriorating
while a physician waits to respond to an alarm at current drug levels,
and also avoids underdosing by permitting the physician sufficient
time to reinitiate drug delivery.
Referring again to FIGS. 2 and 18, a printer 238 (FIG. 2, 37) provides
an on-site hard copy of monitored patient health parameters (e.g.,
the feedback values from the one or more patient health monitors),
as well as alarm states with time stamps indicating which type of
alarms sounded, why and when. Diagnostic LEDs 240 affixed to the
exterior of apparatus 10 (e.g., FIG. 1) and electronically coupled
to controller 14 permit the physician typically involved in the
procedure to ascertain system states at a glance; LEDs coupled to
microprocessor controller 14 also permit service technicians to
assess fault states.
A preferred embodiment of the invention includes a variety of peripheral
electronic devices, one group internal to or integrated within housing
15 of apparatus 10 (e.g., FIG. 1) and a second group on-board electronic
controller 14. These electronic devices ensure proper operation
of various aspects of system 10, including providing hardware status
feedback through sensors to ensure that the apparatus is operating
within its desired parameters. FIGS. 19A and 19B describe various
peripheral devices in accordance with the invention, such devices
may be of a known, off-the-shelf types currently available. Specifically,
internal solenoid-type activated door locks 190 restrict access
to the interior of apparatus 10. Door locks 190 are located within
housing 15 (FIG. 1) and are electronically coupled to and controlled
by controller 14 by means of software that includes protocols for
password protection. Access to the interior of apparatus 10 is thus
restricted to authorized personnel with passwords. This is intended
to, among other things, minimize chances of "recreational"
abuse of the pharmaceuticals (e.g., N.sub.2O) contained therein.
Internal door status sensors 191 located within housing 15 and electronically
coupled to controller 14 generate signals indicating if an access
door to the interior of apparatus 10 is open or closed. Real-time
clock 192 on-board controller 14 enables said controller 14 to provide
time stamps for overall system and patient activities and thereby
enables creation of an accurate log of the operation of care system
10. On-board ambient temperature sensor 193 monitors the exterior
temperature signaling same to controller 14 which through software
comparison type protocols confirms that apparatus 10 is being operated
under desired conditions with respect to surrounding temperature.
Internal battery temperature sensor 194 located within housing 15
and electronically coupled to controller 14 generates signals to
same indicating whether the back-up battery power system is functioning
correctly and not overcharging. Tilt sensor 195 located on-board
controller 14 signals same if the apparatus 10 is being operated
at an angle beyond its designed conditions.
In a preferred embodiment, the software control processes of electronic
controller 14 are stored in a standard flash memory 196 and SRAM
type battery-backed memory 197 stores system, patient and other
status information in the event of an AC power loss. On-board fault
detection processor (FDP) 198 signals failures to controller 14
and is a secondary microprocessor based computing system which relieves
controller 14 of its control duties if a fault is detected in operation.
On-board watch dog timer 199 indicates to controller 14 that the
apparatus 10 is functioning and resets controller 14 if system 10
fails to respond.
A preferred embodiment of the invention also includes a standard
serial port interface, such as an RS-232C serial port, for data
transfer to and from electronic controller 14. The port enables,
for example, downloading software upgrades to and transfer of system
and patient log data from controller 14. An interface such as a
PC Type III slot is also provided to enable the addition of computer
support devices to system 10, such as modems or a LAN, to be used,
for example, to transfer billing information to a remote site; or
to permit diagnosis of problems remotely thereby minimizing the
time required for trouble-shooting and accounting.
It should be understood that the care system of the invention may
be modular in nature with its functions divided into separable,
portable, plug-in type units. For example, electronic controller
14, display devices (FIG. 2, 35) and one or more patient health
monitors would be contained in one module, the pneumatic systems
(flow controllers, pressure regulators, manifold) in a second module,
and the base (FIG. 3B, 17), oxygen and drug tanks (FIG. 2, 54),
scavenger system and vacuum pump (FIG. 3B, 32) in a third module.
Additionally, the patient health monitors or drug delivery aspects
of the system may each be their own plug-in type modules. The system,
for example, may provide for a pluggable ventilator type module.
This modularity enables the system not only to be more easily portable,
but also enables use of certain features of the system (such as
certain patient health monitors), while not requiring use of others.
FIG. 20 depicts a preferred embodiment of a patient information
and billing system capable of being interfaced with care system
10 (FIG. 1) to allow billing or other gathering of patient information
to take place locally at the place of use or remotely at a billing
office. Specifically, information/billing storage system 280, which
may be of a known type microprocessor-based computing system controlled
by software, collects and stores patient data 281 such as the patient's
name, address and other account information, as well as metered
system operation data 282 generated during operation of apparatus
10 and stored in controller 14 such as start time, time of use,
frequency of use, duration of patient monitoring, amount of gases
expended, and other such parameters. User access device 283 which
may be of a standard keyboard type permits the physician to interact
with information/billing storage system 280 to input additional
data such as pre-determined treatment or billing parameters or to
read the status of same (e.g., to read the status of metered system
operation parameters 282). Preferably, a password is provided to
permit access to information/billing system 280.
At the termination of a medical or surgical procedure or at some
other desired period, information/billing storage system 280 processes
the received data and transmits same to revenue/billing processing
center 286 at a remote location. Revenue/billing processing center
286 may be of a known, mainframe-type computing system such as that
manufactured by International Business Machines (IBM) or a known
client-server type computer network system. At the remote location
a patient invoice is generated by printer 287 as may be other revenue
records used for payment to vendors, etc.
The invention also contemplates that an automated record of the
system operation details will be printed at the user site on printer
285 which is preferably located on-board apparatus 10 (FIG. 1).
Such system operation details may include, for example, all alarm
and actual system operation states, drug flow rates and/or monitored
actual patient physiological conditions as supplied by electronic
controller 14. A modem or LAN may be used to send and receive billing
and other information remotely and to communicate with remote client/server
or other networks 288 as described above. |