Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD AND SYSTEM FOR MONITORING A HEALTH CONDITION
CLAIM OF PRIORITY
This application claims priority from U.S. Pat. Appl. No. 12/119,315, entitled
"OPTICAL
SENSOR APPARATUS AND METHOD OF USING SAME," U.S. Pat. Appl. No. 12/119,339,
entitled "DOPPLER MOTION SENSOR APPARATUS AND METHOD OF USING SAME," U.S.
Pat. Appl. No. 12/119,325, entitled "INTEGRATED HEART MONITORING DEVICE AND
METHOD OF USING SAME," U.S. Pat. Appl. No. 12/119,462, entitled "METHOD AND
SYSTEM FOR MONITORING A HEALTH CONDITION," all filed on May 12, 2008, and U.S.
Pat. Appl. No. 12/206,885, entitled "DOPPLER MOTION SENSOR APPARATUS AND
METHOD OF USING SAME," filed on September 9, 2008, all by the same inventor
hereto, and
all applications incorporated herein by reference in their entirety.
FIELD OF THE INVENTION
The present invention relates to health monitoring systems and methods and,
more
specifically, to systems and methods including devices for monitoring cardiac
behaviour.
BACKGROUND AND SUMMARY OF THE INVENTION
Cardiovascular disease is a large, growing health problem world wide. Some
studies
indicate that approximately 15% of the Western World suffers from one or more
cardiovascular
disease. In the United States, nearly 25% of the population is affected,
resulting in more than
six million hospitalizations every year.
Various devices exist for monitoring certain parameters relating to cardiac
performance.
In some instances, in vivo parameters of a patient may need to be monitored
over a period of
time. Heart arrhythmias are changes in the normal sequence of electrical
impulses that cause
the heart to pump blood through the body. Continuous monitoring may be
required to detect
arrhythmias because abnormal heart impulse changes might only occur
sporadically. With
continuous monitoring, medical personnel can characterize cardiac conditions
and establish a
proper course of treatment.
One prior art device that measures heart rate is the "Reveal" monitor by
Medtronic
(Minneapolis, MN, USA). This device comprises an implantable heart monitor
used, for
example, in determining if syncope (fainting) in a patient is related to a
heart rhythm problem.
The Reveal monitor continuously monitors the rate and rhythm of the heart for
up to 14 months.
After waking from a fainting episode, the patient places a recording device
external to the skin
over the implanted Reveal monitor and presses a button to transfer data from
the monitor to the
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recording device. The recording device is provided to a physician who analyzes
the information
stored therein to determine whether abnormal heart rhythm has been recorded.
The use of the
recording device is neither automatic nor autonomic, and therefore requires
either the patient to
be conscious or another person's intervention to transfer the information from
the monitor to the
recording device.
Another known type of implantable sensing device is a transponder-type device,
in which
a transponder is implanted in a patient and is subsequently accessed with a
hand-held
electromagnetic reader in a non-invasive manner. An example of the latter type
of device is
described in U.S. Pat. No. 5,833,603.
In many circumstances, medical personnel are interested in collecting a
variety of
different types of data relating to the behaviour of the heart and the
condition of the patient.
Moreover, as mentioned above, it is desirable to obtain as much relevant data
as possible
without requiring the patient to visit a health care provider (HCP). Relevant
information may
include the oxygen saturation level of blood flowing through the aorta, blood
pressure, heart
rate, blood flow, stroke volume, cardiac output, the electrical activity of
the heart (for generating
electrocardiogram (ECG) data), and body temperature.
A method and system for monitoring a health condition are disclosed herein. In
one
embodiment of the system according to the invention, the system includes a
monitoring device,
a patient monitoring application, and a data store. The monitoring device
includes a Doppler
sensor, an optical sensor, and a computing device. The sensors and the
computing device are
enclosed in a housing. The patient monitoring application receives parameter
values from the
monitoring application and stores them in the data store.
In one embodiment, a method for monitoring a health condition is provided. The
method
includes the steps of providing a monitoring device as described in the
paragraph immediately
above and computing one or more hemodynamic parameters with the monitoring
device. The
method further includes the steps of diagnosing a health condition based on
the hemodynamic
parameters and performing a function responsive to the health condition.
In another embodiment, the method for monitoring a health condition includes
the steps
of providing a monitoring device as described above and further including a
communication
device. The method further includes the steps of transmitting a command to the
monitoring
device and performing a function responsive to the command.
The features of this invention, and the manner of attaining them, will become
more
apparent and the invention itself will be better understood by reference to
the following
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description of embodiments of the invention taken in conjunction with the
accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS:
Figures 1 and 2 are schematic views of a system according to one embodiment of
the
present invention.
Figure 3 is a schematic side view of a monitoring device according to one
embodiment
of the present invention.
Figure 4 is a conceptual view of a computing device according to one
embodiment of the
present invention.
Figures 5 and 6 are a conceptual representations of protocols for performing
embodiments of a method according to the invention.
Figure 7 is a flow-chart of a further embodiment of a method according to the
invention.
Corresponding reference characters indicate corresponding parts throughout the
several
views. Although the drawings represent embodiments of the present invention,
the drawings
are not necessarily to scale and certain features may be exaggerated in order
to better illustrate
and explain the present invention. The exemplifications set out herein
illustrate embodiments of
the invention in several forms and such exemplification is not to be construed
as limiting the
scope of the invention in any manner.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
The embodiments discussed below are not intended to be exhaustive or limit the
invention to the precise forms disclosed in the following detailed
description. Rather, the
embodiments are chosen and described so that others skilled in the art may
utilize their
teachings.
Figs. 1 and 2 illustrate a system according to one embodiment of the
invention. System
100 comprises a monitoring device 1 positioned on a patient 102, and an
external
communication device 120, exemplified as a personal digital assistant or
Blackberry device.
External communication devices may be any devices capable of receiving
wireless or internet
communications, such as communication devices 110, 132, and 142, exemplified
as a relay
unit, phone, and computer, respectively. Communication devices 120 and 132
and, optionally,
110, transfer information wirelessly through telecommunication network 130.
Communication
device 110 may also include a Bluetooth adapter or another adapter for
communicating
wirelessly with monitoring device 1 without using telecommunication network
130.
Telecommunication network 130 is operably connected to the internet,
represented by numeral
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140, which transfers information from the telecommunication network to
communication device
142. In one embodiment, system 100 further includes a website (not shown)
containing
webpages and residing in a server 144. In another embodiment, system 100 also
includes a
cardiac device 150 adapted to provide a treatment to the heart of patient 102.
System 100 includes a patient management application 200 and a data store 210.
Patient management application 200 is a program configured to receive data
from monitoring
device 1 and other computing devices and to store data in data store 210.
Patient management
application 200 may reside in server 144. Patient management application 200
may be a
client/server application with client programs residing in communication
devices accessible
through the internet. Data store 210 stores data pertaining to patients 102.
Data may include a
patient profile 212 including patient information such as, for example,
address, insurance
information, contact information, and device identification information for
associating patient 102
with a specific monitoring device 1 and for enabling access to the sensing
device. Data may
also include values 214 comprising reference, measurement and parameter values
retrieved
from an associated monitoring device 1. Patient management application 200 may
display
values in a variety of ways to assist the HCP in managing the patient's
health. Data may also
include protocols 216.
Patient management application 200 has many functions. It retrieves data from
monitoring device 1. It also updates reference values and protocols. It also
transmits
commands to monitoring device 1. In one embodiment, patient management
application 200
sends commands to monitoring device 1 and monitoring device 1 performs
functions responsive
to the commands. In another embodiment, an HCP uses an external communication
device to
communicate with client management application 200 and client management
application 200
communicates with monitoring device 1 responsive to the HCP communications. In
another
embodiment, an HCP accesses patient management application 200 through a
website
accessible via the internet.
Fig. 3 depicts monitoring device 1 including, generally, a plurality of
components. One
or more of the components may be incorporated in monitoring device 1 to suit
the application of
a method according to the invention. Monitoring device 1 may include a
computing device 20, a
communication device 30, an energy storage device 40, an optical sensor
assembly 2, an ECG
sensor including probes 50A and 50B (hereinafter collectively referred to as
ECG sensor 50), a
Doppler sensor 60, and a temperature sensor 70, each of the components mounted
on a board
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80 and being in electronic communication with computing device 20. The
components are
enclosed in a housing 90.
System 100 operably connects monitoring device 1 with one or more
communication
devices adapted to exchange data with monitoring device 1. Data includes
commands,
5 measurement, parameter and reference values, and protocols. Monitoring
device 1 acquires
measurement values, processes them according to a protocol, which in many
cases involves
comparing them to reference values and diagnostic profiles to diagnose
abnormal conditions,
and then performs a function according to a response profile based on the
diagnosis.
Commands are instructions provided from an external communication device to
computing device 20. Generally, commands are instructions for performing a
function.
Functions include transmitting data, performing a treatment, updating
reference values, and
updating protocols.
Reference values represent a normal or stable condition of a patient.
Monitoring device
1 may be programmed with reference values or may be programmed to collect
measurements
upon placement of the device on patient 102 and to store the initial
measurements or
parameters as reference values. As explained in more detail below with
reference to computing
device 20, parameter values include hemodynamic parameters such as pulse rate,
oxygen
saturation, cardiac output, and blood pressure, and also temperature.
Reference values may include target values and acceptable variation ranges or
limits.
Parameter values may indicate an abnormality when they fall outside reference
target values or
ranges. In some embodiments, parameter values may produce a statistic such as,
for example,
a moving average, and an abnormality would be detected when the parametric
statistic differs
from a reference statistic by more than an expected amount.
One abnormal medical condition is cardiac arrhythmia. Computing device 20 may
be
configured to perform an analysis of the measurement values to determine, for
example,
whether the cardiac rhythm is irregular indicating arrhythmia. Other abnormal
conditions include
low oxygen saturation, low cardiac output, and high or low blood pressure.
Other abnormal
conditions may depend on combinations of various hemodynamic parameter values.
Protocols include diagnostic and response profiles. Diagnostic profiles
provide
computing device 20 decision criteria for diagnosing abnormal conditions.
Response profiles
provide computing device 20 instructions for performing functions responsive
to diagnosis.
Initially, one or more protocols may be programmed into monitoring device 1. A
response
profile in a first protocol may instruct computing device 20 to switch to a
second protocol in
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response to an abnormal condition. In one embodiment, protocols may be
downloaded to
computing device 20 through communication device 30.
1. MONITORING DEVICE
Throughout this application, references made to monitoring device 1 refer to
the
monitoring device 1 described in the Integrated Device application
incorporated herein by
reference above. Also, references made to optical sensor assembly 2 refer to
the optical sensor
assembly 2 described in the Optical Sensor Apparatus application incorporated
herein by
reference above. Furthermore, references to the Doppler sensor 60 refer to the
Doppler sensor
60 described in the Doppler Motion Sensor application incorporated by
reference above. The
full description of the monitoring device 1, optical sensor assembly 2 and
Doppler sensor 60 will
not be repeated in this application.
By communication signal is meant a signal that has one or more of its
characteristics set
or changed to encode information in the signal. By way of example, and not
limitation,
communication signals include acoustic, RF, infrared, other wireless media,
and combinations
of any of the above. Relay unit 110 is located externally of the patient's
body, e.g. clipped to
the patient's belt. Relay unit 110 may include a receiver for receiving the
transmissions from
communication device 30, and a transmitter for re-transmitting the
communication signal to
another external communication device. Relay unit 110 may also be stationary
and hardwired
for connection to the internet or direct connection to a healthcare provider's
computer.
Likewise, relay unit 110 may receive a communication signal from a healthcare
provider and
transmit the signal to communication device 30.
Optical sensor assembly 2 includes a plurality of photon emitters and a
plurality of
photon detectors for detecting a plurality of optical signals. The emitters
and detectors face the
aorta. Computing device 20 operates the plurality of emitters and detectors
and processes the
plurality of optical signals to obtain optical measurement values representing
the location and
size of the aorta and the oxygen saturation of the blood flowing through the
aorta.
Doppler sensor 60 emits and detects a plurality of ultrasonic waves. Computing
device
20 also operates Doppler sensor 60 and, with the aid of the optical
measurement values
obtained using optical sensor assembly 2, processes the plurality of
ultrasonic waves to obtain
Doppler measurement values representing heart rate, blood flow, stroke volume,
blood
pressure, and cardiac output.
ECG sensor 50 detects the electrical signals which cause the heart to pump.
Temperature sensor 70 measures the temperature of the patient. Energy storage
device 40
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powers computing device 20, the various sensors, and communication device 30
which is
configured to transmit the collected data, or information relating to the
collected data, according
to various embodiments of a method disclosed herein. The sensors, computing
device 20,
communication device 30, and energy storage device 40 are enclosed in a
housing 90.
Integrating the plurality of sensors and other components mentioned above in
monitoring
device 1 permits a single device, mounted at one location on the patient's
body, to accurately
measure a comprehensive set of parameters relating to the behaviour of the
heart, including
cardiac output. Moreover, monitoring device 1 may perform analyses of the
parameters and
perform functions in response to the "on-board" analyses, as opposed to other
sensing devices
that export raw data for analysis by another device. As indicated above,
monitoring device 1
also communicates with other devices, wirelessly or otherwise, providing
information and
receiving commands and data. As such, monitoring device 1 collects, analyzes,
and
communicates data without any human intervention.
By "patient" it is meant a person or animal. In one embodiment according to
the
invention, monitoring device 1 is implanted subcutaneously in the patient's
body. It should be
understood, however, that monitoring device 1 may be implanted at different
locations using
various implantation techniques. For example, monitoring device 1 may be
implanted within the
chest cavity beneath the rib cage. Housing 90 may be formed in the shape of a
circular or oval
disc, with dimensions roughly the same as two stacked quarter dollar coins.
More specifically,
housing 90 may be approximately three centimetres in diameter and
approximately one
centimetre thick. Of course, housing 90 may be configured in a variety of
other shapes and
sizes, depending upon the application. Optical sensor assembly 2, Doppler
sensor 60, ECG
sensor 50, and temperature sensor 70 are positioned facing inwardly while an
energy coupler
component of energy storage device 40 faces outwardly.
Monitoring device 1 may be integrated with an implanted cardiac device 150
such as a
pacemaker, a Cardiac Resynchronization Therapy (CRT) device, an implantable
cardioverter
defibrillator (ICD), etc. In such an embodiment, monitoring device 1 may
communicate with the
implanted cardiac device and provide information from the implanted cardiac
device as well as
from its own sensors to external devices. As many implanted cardiac devices
are currently well-
understood and routinely prescribed, integration of monitoring device 1 into
such other devices
may provide an effective means for achieving market acceptance.
The above-described integration may be achieved by combining the components of
monitoring device 1 and the cardiac device. If the cardiac device includes a
computing device,
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for example, the algorithms that carry out the functions according to the
invention may be
incorporated with the computing device of the cardiac device instead of adding
a second
computing device. In a similar manner, energy storage and communication
devices may be
combined to avoid duplication and lower cost.
Monitoring device 1 may be positioned externally to the patient's body. A
support
member is provided to support monitoring device 1 externally to the body. The
support
member may be permanently or temporarily coupled to monitoring device 1. The
support
member may comprise an adhesive layer for adhesively coupling the support
member to the
patient's body or may comprise a belt, which may be elastic, for holding
monitoring device 1
against the patient's body.
Monitoring device 1 may be implanted or positioned on the patient with the aid
of an
external mapping system such as an ultrasound machine. Proper placement
ensures that a
vessel of interest, e.g. the aorta, is located within the sensing range of the
various sensors of
monitoring device 1. For example, monitoring device 1 may be positioned on the
chest or back
of the patient in a location that reduces interference by the ribs of the
measurements acquired in
the manner described herein.
Computing device 20 comprises a plurality of components. While components are
described herein as if they were independent components, the components may be
combined in
a single device such as an application specific integrated circuit. As shown
in Fig. 4, computing
device 20 includes an A/D converter 22 (which also converts optical signals to
digital signals), a
processor 24, a memory 26, a program 28, a data 29, inputs 23, and outputs 25.
Memory 26
may include, but is not limited to, RAM, ROM, EEPROM, flash memory or other
memory
technology. A/D converter 22, processor 24 and memory 26 may be constructed in
an
integrated circuit. The integrated circuit may further include emitter array
100, detector array
200, and communication device 30.
Program 28 represents computer instructions directing processor 24 to perform
tasks
responsive to data 29. Program 28 resides in memory 26. Data 29 includes
values and
protocols and also resides in memory 26. Reference data may be stored in ROM
or it may be
stored in RAM so that it may be modified over time, either in response to
external inputs or in
response to characteristics of measurement data collected over time. Protocols
for responding
to measurement values may also be provided. Protocols may be stored in
permanent memory
or may be stored in non-permanent memory such as RAM.
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Computing device 20 may be configured to cause communication device 30 to
transmit
an alert if an abnormal condition is detected, particularly a condition
determined to be a serious
or dangerous condition. A diagnosis profile in an active protocol provides
criteria to determine
whether a condition is normal or abnormal, and if abnormal, the degree of
severity. A response
profile in the protocol provides criteria to respond to the diagnosis.
Transmission of an alert is
one example of a response. The alert may be used to actuate an alarm or to
alert the patient to
take remedial action. A remedial action may be terminating or reducing
physical activity. The
alert may also provide global positioning (GPS) information to an emergency
service. Referring
to Fig. 1, the abnormal condition, when found to be present, may also be
displayed on external
communication devices 110, 120, 132 and or 142. The alert may comprise a text
message or a
code corresponding to the condition. According to a protocol, computing device
20 may also
initiate a new measurement cycle and measure on a continuous basis in response
to the
detection of an abnormal condition.
Computing device 20 may also initiate a treatment according to a response
profile or
responsive to a command. Monitoring device 1 may receive, through
communication device 30,
an external command to perform a treatment in response to the alert.
Optionally, based on the
protocol, an abnormal condition may also be used to direct a device adapted to
provide
treatment to deliver such treatment. Treatment may include, for example, an
electric shock or a
drug delivery.
Parameter values and/or other information may be communicated to an external
device.
The parameter values may be stored in memory 26 and transmitted wirelessly by
communication device 30. The communication signal from communication device 30
may be
activated on a periodic basis (e.g., once per day, once per week, etc.), in
response to an
abnormal condition, in response to an externally received command, whenever
memory usage
exceeds a predetermined amount, or whenever the energy storage level is
determined to be
low, the latter two conditions established to prevent data loss as a result of
memory overflow or
energy loss. It should also be understood that monitoring device 1 may include
communication
devices in addition to communication device 30. For example, where
communication device 30
is a cellular modem, monitoring device 1 may also include a backup Bluetooth
or RF
communication device. Such a backup device may be desirable in situations
where, after one
or more attempts, it becomes apparent that the cellular modem is unable to
transmit information
(e.g., due to low available power, poor network coverage, etc.). In such a
situation, computing
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device 20 may activate the backup communication device to transmit information
or an alert to
an alternate external communication device.
Alternatively or in addition to the above-described transmissions, computing
device 20
may be programmed to respond to requests for data received by communication
device 30
5 (e.g., from a health care provider) by causing communication device 30 to
transmit the
requested data or information representing the requested data.
The communication signal may be received by equipment near the patient to
alert the
patient to the condition, or received remotely (such as over a network) by a
healthcare provider,
relative, or other predetermined recipient.
10 It should be understood that each of or some of optical sensor assembly 2,
Doppler
sensor 60, ECG sensor 50, and temperature sensor 70 may be modular in design.
As such, a
plurality of different Doppler sensors 60, for example, may be produced to
have different
performance characteristics (e.g., different output frequencies). Depending
upon the
application, any of the plurality of the sensors may be installed in
monitoring device 1 to achieve
the desired performance. Once monitoring device 1 is equipped with the
selected sensors,
computing device 20 may be programmed to adapt the various algorithms to
accommodate the
selected sensors. In this manner, a basic monitoring device 1 including
computing device 20,
communication device 30, etc., may be "custom" built with any of a variety of
sensors and
programmed to operate with the selected sensors.
It should be understood that while optical sensor assembly 2, Doppler sensor
60, and
temperature sensor 70 are described herein as being activated to obtain
measurements
relatively infrequently (at least under normal conditions) to conserve power,
as battery
technology improves, the frequency of activation of these sensors may be
increased. Also,
where monitoring device 1 is worn externally, connector 85 may be used to
supply power to
sensing device 85, thereby eliminating the power consumption concern and
permitting frequent,
or even continuous, operation of these sensors. Furthermore, connector 85 may
be utilized to
operably connect other sensors to monitoring device 1.
In one embodiment of the invention, communication device 30 is a two-way
communication device, e.g. via the cellular telephone system and/or the GPS
satellite system,
such as NOKIA model number KNL1 147-V. In an alternate embodiment,
communication device
30 is capable of transmitting information, but does not receive information or
commands.
A system for recharging energy storage device 40 may be provided in one
embodiment
according to the invention. Computing device 20 receives energy from energy
storage device
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40. Energy storage device 40 includes an energy storage component such as a
battery.
Optionally, monitoring device 1 may also include an energy coupler for
receiving energy from an
external source to charge energy storage device 40.
One example of an energy coupler is an electromagnetic device, such as
induction coils,
for receiving external electromagnetic signals and converting them into
electrical energy for
recharging the energy storage component. An external electromagnetic device
generates
electromagnetic signals which are received and converted into electrical
energy by energy
storage device 40. Energy storage device 40 may provide a charge signal to
computing device
20. Computing device 20 may compare the charge signal to a reference charge
signal and
initiate a low charge communication signal for alerting the patient and/or
healthcare providers.
Alternatively, a detector, such as a voltage sensor, may be used to monitor
the charge of energy
storage device 40 and provide a signal to computing device 20 when the charge
falls below a
threshold. The electromagnetic device may be placed near monitoring device 1
to charge
energy storage device 40.
Energy may instead, or additionally, be provided in the form of ultrasonic
vibrations. For
example, a piezoelectric transducer may be included in monitoring device 1. An
ultrasonic
vibration may be provided externally. The transducer generates electricity
when driven by
ultrasonic vibrations. As indicated herein, energy or power may also be
provided to monitoring
device 1 through connector 85.
2. DIAGNOSIS AND OPERATION
It is important to diagnose heart conditions properly. Improper diagnosis may
lead to
improper treatment which may result in the death or severe permanent
disability of the patient.
Due to the potential harm, it is natural to employ abundant caution. However,
abundant caution
raises treatment costs which, in aggregate, impose a cost on society. Proper
diagnosis may
reduce treatment costs while also likely improving the condition of the
patient.
Heart failure can result from any structural or functional cardiac disorder
that impairs the
ability of the heart to pump a sufficient amount of blood through the body.
Heart failure is
caused by any condition which reduces the efficiency of the myocardium through
damage or
overloading, including myocardial infarction (in which the heart muscle is
starved of oxygen and
becomes damaged) and hypertension (which increases the force of contraction
needed to pump
blood and often causes the heart muscle to become thicker, resulting in
altered function of the
muscle).
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In addition to monitoring and responding instantaneously to abnormalities, it
is important
to develop a physiological history of a patient with chronic heart failure to
prevent potentially
fatal incidents. Heart failure can be chronic and congestive, or
decompensated.
Decompensated heart failure occurs when a patient with chronic heart failure
develops acute
symptoms. Symptoms may be based on the side of the heart, right or left, that
is involved, the
type of failure, either diastolic or systolic, whether the abnormality is due
to low cardiac output,
and the degree of functional impairment conferred by the abnormality (based on
functional
classification).
There is no universally accepted diagnostic standard for heart failure.
Various standards
include the Framingham, Boston and Duke criteria (named after related
studies). The New York
Heart Association Functional Classification classifies the severity of
symptoms and can be used
to assess response to treatment. Patients in Class I experience no limitations
in any activities
and experience no symptoms from ordinary activities. Patients in Class II
experience slight,
mild limitation of activity but are comfortable at rest or with mild exertion.
Patients in Class III
experience marked limitations of any activity and are comfortable only at
rest. Patients in Class
IV experience discomfort with any physical activity and experience symptoms at
rest. A
patient's classification may be programmed and used to identify a protocol to
respond to a
diagnosis.
Over time, conditions that increase the heart's workload will produce changes
to the
heart itself so it is important to monitor heart performance for changes that
may lead to re-
classification of a patient with corresponding changes in treatment. Heart
changes include
reduced contractility, or force of contraction, due to overloading of the
ventricle; reduced stroke
volume; increased end systolic volume (usually caused by reduced
contractility); decreased end
diastolic volume (usually caused by impaired ventricular filling); reduced
spare capacity; and
increased heart rate stimulated by increased sympathetic activity in order to
maintain cardiac
output.
The predominant respiratory symptom of left side failure is shortness of
breath on
exertion (dyspnea) or at rest, and easy fatigueability. Other symptoms include
increasing
breathlessness on reclining and severe breathlessness during sleep, usually
several hours after
going to sleep. Poor circulation to the body leads to dizziness and confusion.
The right side of
the heart pumps deoxygenated blood and right side failure leads to congestion
of peripheral
tissues. Heart failure may decompensate easily as a result of intercurrent
illness, myocardial
infarction, arrhythmias, and uncontrolled hypertension, among other causes.
General signs
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indicating possible heart failure include a laterally displaced apex beat (as
the heart is
enlarged), a gallop rhythm (additional heart sounds) in case of
decompensation, and heart
murmurs which may indicate valvular heart disease, either as a cause (e.g.
aortic stenosis) or
as a result of the heart failure. An echocardiogram may be used to identify
these general signs
of possible heart failure.
Heart failure caused by systolic dysfunction is the failure of the pump
function of the
heart. It is characterized by a decreased ejection fraction (less than 50%,
and often significantly
lower). Normally, the ejection fraction should be between 50% and 70%. The
strength of
ventricular contraction is attenuated and inadequate for creating an adequate
stroke volume,
resulting in inadequate cardiac output. Because the ventricle is inadequately
emptied,
ventricular end-diastolic pressure and volumes increase. On the left side of
the heart, the
increased pressure causes pulmonary edema. On the right side of the heart, the
increased
pressure results in dependent peripheral edema. Doppler sensor 60 may be used
to determine
the stroke volume (SV), an important determinant of cardiac function.
Heart failure caused by diastolic dysfunction is the failure of the ventricle
to adequately
relax and typically denotes a stiffer ventricular wall. This causes inadequate
filling of the
ventricle which results in an inadequate stroke volume. The failure of
ventricular relaxation also
results in elevated end-diastolic pressures which results in edemas. Diastolic
dysfunction may
not manifest itself except in physiologic extremes if systolic function is
preserved, thus, a patient
may be completely asymptomatic at rest. However, diastolic dysfunction is
hypersensitive to
increases in heart rate and blood pressure. Sudden bouts of tachycardia can be
caused by
exertion, fever, or dehydration. ECG sensor 50 may track increases in heart
rate by comparing
heart rate to reference values. Elevated blood pressures may be identified
with Doppler sensor
60 in a similar manner. The parameters may be correlated in time to
potentially diagnose
diastolic dysfunction.
Hypothetical scenarios will now be described to exemplify protocols responsive
to a
cardiac failure event. The scenarios are based on hypothetical symptoms.
In the first case, the patient is 65 years old and suffered an anterior
myocardial infarction
two years prior to the event. During the year prior to the event, he suffered
from congestive
heart failure, characterized by dyspnoea on mild effort, fatigue and rare
events of shortness of
breadth at rest. His New York Heart Association functional class was defined
as II-III. He
received medications including ACE inhibitors, beta blockers and
spironolactone which resulted
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in some functional improvement. After experiencing general weakness and some
shortness of
breath, the patient called his HCP and communicated his symptoms.
In a base scenario, the patient does not benefit from using monitoring device
1. Under
normal conditions, the symptoms would almost certainly lead the HCP to suspect
decompensated heart failure. A typical response would be to send a mobile
intensive care unit
to collect the patient. If decompensated heart failure did not exist,
collecting the patient would
be unnecessary. However, if decompensated heart failure did exist, and the
patient arrived at
the healthcare facility more than two or three hours after the event, late
treatment may be
dangerous and, occasionally, life threatening.
In the following alternative scenarios exemplifying different embodiments of a
method
according to the invention, the patient does benefit from using monitoring
device 1. Prior to the
event, the HCP programs monitoring device 1 with protocols corresponding to
the patient's
history and New York Heart Association functional class or another
classification. The protocols
may be updated from time to time.
In a first scenario, upon receiving the phone call the HCP accesses an
external
communication device to retrieve pulse rate data, through communication device
30, to
determine whether any arrhythmia is present. Then, the HCP retrieves 02
saturation
measurements. A normal saturation (>98%) would almost certainly exclude a
serious event.
To complete the examination, the HCP instructs the patient, by telephone, to
sit still for two to
three minutes after which time the HCP commands monitoring device 1 to compute
cardiac
output and blood pressure. This information would be sufficient to determine
whether the
patient indeed suffers from decompensation. If he does not, an unnecessary
trip to the
healthcare facility may be avoided.
In this scenario, the HCP sends commands to monitoring device 1 using the
external
communication device. The HCP may select commands from patient management
application
200 which may include a website dedicated to support such communications.
Alternatively, the
external communication device may be phone 132 and the commands may comprise
dialing a
phone number for accessing communication device 30, in this case a telephone
modem,
entering a numeric access code for accessing data on monitoring device 1, and
subsequently
entering a numeric code corresponding to a protocol for retrieving data. A
protocol may refer to
a single parameter or to more than one parameter. Monitoring device 1 responds
to each
command by transmitting a string of data.
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Referring to Fig. 5, an exemplary group of protocols are illustrated. The HCP
activates a
protocol A to retrieve pulse and oxygen saturation data. Because these
parameters are
obtained with ECG sensor 50 and optical sensor assembly 2, which are low power
devices,
obtaining these values does not consume much energy. If the patient has relay
unit 110
5 including a display screen, a protocol B may also be activated instructing
the patient to rest for
two or three minutes. Finally, the HCP activates a protocol C to retrieve
cardiac output and
blood pressure values. These are obtained with the Doppler sensor 60 which
consumes more
energy than optical sensor assembly 2. Alternatively, the patient may have
been resting already
and the HCP might not need to wait before activating protocol C.
10 In a second scenario, exhibiting some automation, upon receiving the phone
call the
HCP accesses an external communication device to activate a diagnosis protocol
D. Protocol D
may then cause computing device 20 to (a) transmit pulse and oxygen saturation
data, (b) wait
and send a "wait" message to relay unit 110, and (c) transmit cardiac output
and blood pressure
data. In other words, protocol D automates activation of protocols A-C. The
HCP may remain
15 on the phone with the patient while transmitting the command to activate
protocol D and
receiving information on the external communication device. If the patient
does not have a relay
unit, the HCP may instruct the patient to rest.
In a third scenario, exhibiting more automation, the patient executes a
command on the
relay unit. Relay unit 110 may be a communication device capable of
transmitting wireless
commands to monitoring device 1. For example, relay unit 110 may include a
button
designated as a "panic" button which a patient or another person may press in
case of concern.
Upon experiencing the general weakness and shortness of breath, patient 102
presses the
panic button which commands monitoring device 1 to activate a protocol E.
Protocol E directs
computing device 20 to activate protocol D and to also protocol F to inform
the HCP that the
panic button was pushed. The HCP may text-message relay unit 110 from a
communication
device with additional instructions for the patient or may take other
discretionary actions.
Protocol E saves the time required for the patient to call the HCP and for the
HCP to activate
protocol D.
Referring to Fig. 6, in a fourth scenario exhibiting full automation,
monitoring device 1
diagnoses an abnormality and performs a function according to a protocol F. A
diagnosis profile
in monitoring device 1 directs the device to monitor, at predetermined time
intervals, changes in
cardiac pulse rate, cardiac output, oxygen saturation, or combinations of
changes in these
parameters. The profile also directs the device to compare the changes to
reference values and
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to signal an abnormal condition if the changes exceed a predefined amounts. A
response
profile directs the device to perform a function responsive to the
abnormality. In one
embodiment, monitoring device 1 sends a message or data to the HCP if values
differ from
reference values within a range. In another embodiment, monitoring device 1
sends an alarm to
the HCP if values differ by more than a range, signifying an emergency. The
alarm may also be
sent to designated caretakers of the patient, or may even send an alarm to a
healthcare facility,
ambulance service or fire department. Additionally, monitoring device 1 may
send a message
to relay unit 110 which patient 102 may read. For example, the relay unit may
display a
message instructing the patient to sit, rest, drink water, etc.
In a second case, a 60 year old patient experiences an event 2 weeks after
coronary
bypass surgery. He has been well, already walking 45 minutes/day and starting
to do some
office work from home. He experiences palpitation, some shortness of breath
and dizziness.
The symptoms may be due to atrial flutter/fibrillation which is a common
condition during the
first several weeks after bypass surgery. Diagnosis in this case requires
pulse, blood
saturation, blood pressure and cardiac output data. If the data appears normal
compared to
reference values, the patient is instructed to rest and the heart parameters
are checked again in
one to two hours. The second check may be performed by the HCP without
requiring a phone
call to contact the patient. If all parameters are stable and the patient
feels better - he can stay
home.
In a third case, a patient has an implanted ICD (defibrillator). After waking
up from an
afternoon nap, the patient is somewhat confused and has some chest discomfort.
He is worried
that the ICD may have charged and that he may have had a serious arrhythmia.
In one scenario, monitoring device 1 is incorporated, either integrated or
operably
connected, into the ICD. If the ICD determines that defibrillation is
appropriate, the ICD
communicates the determination to monitoring device 1. Monitoring device 1
checks
hemodynamic parameters (pulse, oxygen saturation, blood pressure, cardiac
output) and
verifies an abnormality indicating that defibrillation is appropriate or
determines that it is not. If
the latter, monitoring device 1 instructs the ICD to not charge. Monitoring
device 1 might also
transmit the event information to the HCP. The HCP could interrogate the
device to collect the
hemodynamic parameters and to determine whether an arrhythmia had indeed
occurred. If no
arrhythmia was detected and hemodynamic parameters are normal, no further
investigation is
necessary.
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In another scenario, monitoring device 1 is not incorporated into the ICD.
Monitoring
device 1 may be programmed to detect when the ICD charges. The patient may
initiate
communication with the HCP by telephone, panic button, or any other means
described above
to determine whether the ICD charged. In another embodiment, the charge event
is displayed
in relay unit 110 for the patient to read. In other embodiments, other cardiac
devices are
operationally integrated with monitoring device 1 to improve their joint
performance by
combining features.
Fig. 7 illustrates an embodiment of a patient management method according to
one
embodiment of the invention. Initially, an HCP sets up monitoring device 1 for
use with patient
102. The HCP populates data store 210 with information relating to patient 102
including
patient history, monitoring device identification, and other information. The
HCP also selects
protocols to download to monitoring device 1. Protocols may be downloaded
using connector
85 while monitoring device 1 is docked in a docking station. Monitoring device
1 is positioned
on the patient with the aid of an ultrasound machine. During the initial
setup, the HCP may
obtain baseline measurements and may store the measurements as reference
values in
computing device 20.
At step 700, monitoring device 1 monitors patient 102. Monitoring may be
performed
according to protocol F as described above or according to another protocol.
Monitoring
includes activating sensors to obtain measurement values, computing parameter
values,
comparing the values to reference values according to a protocol, and
diagnosing a normal or
abnormal condition. If values are outside a reference range, monitoring device
1 may proceed
to step 712 or may initiate a new measurement cycle to verify the parametric
data before
diagnosing an abnormality. Otherwise, monitoring device 1 proceeds to step 720
and then
returns to step 700.
At step 710, monitoring device 1 receives a command from an external
communication
device. A command may direct monitoring device 1 to transmit parameter values
according to a
protocol, or update a protocol, or update a program.
At step 712, monitoring device activates a protocol. The protocol may indicate
which
parameters to sense, how much data (minutes, hours, days) to acquire, and how
frequently to
continue measuring. The protocol is determined by the command received or
responsive to the
monitoring protocol from step 700. The external communication device may be
computer 142.
Computer 142 may include patient management application 200 or may access
patient
management application 200 through the internet. Patient management
application 200 may
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provide an option menu showing available protocols and may also include
security features for
the protection of the patient's privacy as well as well-being. The external
communication device
may also be communication device 110, 120 and 132. In this step, monitoring
device 1
activates the sensors which generate signals that are received by computing
device 20.
Computing device 20 conditions the signals and converts them to measurements,
then analyzes
the measurements and computes parameter values. Finally, computing device 20
performs
additional instructions provided in the protocol.
In another embodiment, the communication device accesses monitoring device 1
directly
without using a patient management application. The communication device may
dial
monitoring device 1 and provide commands via a keypad.
At step 714, monitoring device 1 executes a command for updating a protocol.
Updating
may involve changing the reference values that determine an abnormal condition
or changing
reference values that distinguish the severity of an abnormal condition, e.g.
an emergency.
Other updates include changing the sequence of steps or the responses in the
response profile.
In this step, additional protocols may be added. Protocols may be updated to
reflect changing
patient conditions, history or other factors.
At step 716, monitoring device 1 executes a command to update a program. A
program
may comprise modules including algorithms for processing signals from sensors.
Modules may
be updated to reflect newer modules with improved features. Additionally,
modules may be
updated to reflect the addition of external or additional sensors.
At step 718, monitoring device 1 performs a function. A function may include
transmitting a communication signal, performing a treatment, or other
functions specified in the
response profile of the protocol. The response profile may indicate which
parameters to
transmit, how much data (minutes, hours, days) to transmit, and how frequently
to continue
measuring.
At step 720, monitoring device 1 stores measurement values. Values may be
stored as
a result of a protocol activated at step 712 or as a result of normal
conditions. Step 720 may be
performed, for example, once an abnormal condition has been detected so as to
update a
caregiver on a substantially real-time basis. Step 720 may also be performed
at regular
intervals, such as once a day, once a week, once a month, etc. Alternatively
or in addition to
these transmissions, computing device 20 may be programmed to respond to
requests for data
received by communication device 30 (e.g., from a health care provider) by
causing
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communication device 30 to transmit the requested data or information
representing the
requested data.
While this invention has been described as having an exemplary design, the
present
invention may be further modified within the spirit and scope of this
disclosure. This application
is therefore intended to cover any variations, uses, or adaptations of the
invention using its
general principles. Further, this application is intended to cover such
departures from the
present disclosure as come within known or customary practice in the art to
which this invention
pertains.
