U.S. patent application number 11/160912 was filed with the patent office on 2005-11-03 for patch sensor for measuring blood pressure without a cuff.
This patent application is currently assigned to TRIAGE WIRELESS, INC.. Invention is credited to Banet, Matthew John.
Application Number | 20050245831 11/160912 |
Document ID | / |
Family ID | 35061470 |
Filed Date | 2005-11-03 |
United States Patent
Application |
20050245831 |
Kind Code |
A1 |
Banet, Matthew John |
November 3, 2005 |
PATCH SENSOR FOR MEASURING BLOOD PRESSURE WITHOUT A CUFF
Abstract
A monitoring device, method and system for monitoring vital
signs of a patient over a wireless network are disclosed herein.
The monitoring device includes an adhesive patch sensor, typically
mounted on a patient's head, and a processing component. The
adhesive patch sensor typically includes an optical system that
generates an optical waveform, and an electrode that generates an
electrical waveform. The processing component processes the optical
and electrical waveforms, along with a calibration table, to
determine the patient's vital signs.
Inventors: |
Banet, Matthew John; (Del
Mar, CA) |
Correspondence
Address: |
MATTHEW J. BANET
6540 LUSK BLVD., C200
SAN DIEGO
CA
92121
US
|
Assignee: |
TRIAGE WIRELESS, INC.
6540 Lusk Blvd. C200
San Diego
CA
|
Family ID: |
35061470 |
Appl. No.: |
11/160912 |
Filed: |
July 14, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11160912 |
Jul 14, 2005 |
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10906315 |
Feb 14, 2005 |
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10906315 |
Feb 14, 2005 |
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10709014 |
Apr 7, 2004 |
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Current U.S.
Class: |
600/485 ;
600/323; 600/500 |
Current CPC
Class: |
A61B 2562/06 20130101;
A61B 5/25 20210101; A61B 5/0022 20130101; A61B 5/14552 20130101;
A61B 5/14532 20130101; A61B 5/6814 20130101; A61B 5/021 20130101;
A61B 5/002 20130101; A61B 5/1455 20130101; A61B 5/1112 20130101;
A61B 5/02125 20130101; A61B 5/02438 20130101; A61B 5/0205 20130101;
A61B 2560/0412 20130101 |
Class at
Publication: |
600/485 ;
600/323; 600/500 |
International
Class: |
A61B 005/02; A61B
005/00 |
Claims
What is claimed is:
1. A system for measuring vital signs from a patient, the system
comprising: an adhesive patch sensor comprising 1) an optical
system comprising a first LED which emits a first optical
wavelength, a second LED which emits a second optical wavelength,
and a photodetector that detects reflected radiation from at least
one of the first LED and the second LED to generate at least one
radiation-induced photocurrent, 2) an electrical system comprising
an electrode that generates an electrical impulse, and 3) an
adhesive component for adhering the adhesive patch sensor to the
patient's skin; and a controller in electrical communication with
the adhesive patch sensor, the controller comprising 1) means to
convert the at least one radiation-induced photocurrent into an
optical waveform, 2) a microcontroller comprising means to generate
an electrical waveform from the electrical impulse, the
microcontroller configured to operate a computer algorithm that
determines a blood pressure value and at least one other vital sign
by processing i) a time-dependent property of the optical waveform,
ii) a time-dependent property of the electrical waveform, iii) a
time delay between the optical waveform and the electrical
waveform, and iv) at least one calibration parameter.
2. The system of claim 1, wherein the computer algorithm of the
microcontroller further comprises: a first step for measuring a
first amplitude of the optical waveform; a second step for
measuring a second amplitude of the electrical waveform; and a
third step for measuring a time delay between the first amplitude
of the optical waveform and the second amplitude of the electrical
waveform.
3. The system of claim 2, wherein the computer algorithm of the
microcontroller processes the time delay and the at least one
calibration parameter to determine a blood pressure value for the
patient.
4. The system of claim 3, wherein the computer algorithm of the
microcontroller processes: the electrical waveform to determine a
heart rate of the patient; the optical waveform and a second
optical waveform generated from a second radiation-induced
photocurrent from the photodetector to determine a pulse oximetry
value for the patient; and the optical waveform and the electrical
waveform to determine a blood pressure value of the patient.
5. The system of claim 1, further comprising a cable to connect the
adhesive patch sensor to the controller.
6. The system of claim 1, wherein both the controller and adhesive
patch sensor each comprise a wireless component.
7. The system of claim 6, further comprising a wireless interface
between the separate wireless components.
8. The system of claim 1, further comprising a component configured
to connect to the Internet.
9. The system of claim 1, further comprising an Internet-accessible
website configured to display the blood pressure of the patient and
the at least one other vital sign.
10. The system of claim 1, wherein the adhesive component is
further configured to attach on or near the patient's head.
11. A method for measuring vital signs from a patient, the method
comprising the following steps: attaching an adhesive patch sensor
on or near a patient's head, the adhesive patch sensor comprising
1) an optical system comprising a first LED which emits a first
optical wavelength, a second LED which emits a second optical
wavelength, and a photodetector that detects reflected radiation
from at least one of the first LED and the second LED to generate
at least one radiation-induced photocurrent, 2) an electrical
system comprising an electrode that generates an electrical
impulse, and 3) an adhesive component for adhering the adhesive
patch sensor to the patient's skin; generating an optical waveform
from the at least one radiation-induced photocurrent; generating an
electrical waveform from the electrical impulse; processing the
optical waveform and electrical waveform with a controller in
communication with the adhesive patch sensor, the controller
comprising a microcontroller configured to operate a computer
algorithm that determines a blood pressure value and at least one
other vital sign by processing i) a time-dependent property of the
optical waveform, ii) a time delay between the optical waveform and
the electrical waveform, and iii) at least one calibration
parameter.
12. The method of claim 11, further comprising: a step for
measuring a first amplitude of the optical waveform; a step for
measuring a second amplitude of the electrical waveform; and a step
for measuring a time delay between the first amplitude of the
optical waveform and the second amplitude of the electrical
waveform.
13. The method of claim 12, further comprising a step for
processing the time delay and the at least one calibration
parameter to determine a blood pressure value for the patient.
14. The method of claim 13, further comprising: a step for
processing the electrical waveform to determine a heart rate for
the patient; a step for processing the optical waveform and a
second optical waveform generated from a second radiation-induced
photocurrent from the photodetector to determine a pulse oximetry
value for the patient; and a step for processing the optical
waveform and the electrical waveform to determine a blood pressure
value for the patient.
15. The method of claim 11, further comprising a step of
transmitting the blood pressure value of the patient and the at
least one vital sign value of the patient to an Internet-accessible
website.
16. The method of claim 15, further comprising a step of displaying
the blood pressure value of the patient and the at least one vital
sign value of the patient on the Internet-accessible website.
17. A method for measuring vital signs from a patient, the method
comprising the following steps: attaching a vital sign-measuring
system on or near a patient's head, the system comprising: an
adhesive patch sensor comprising 1) an optical system comprising a
first LED which emits a first optical wavelength, a second LED
which emits a second optical wavelength, and a photodetector that
detects reflected radiation from at least one of the first LED and
the second LED to generate at least one radiation-induced
photocurrent, 2) an electrical system comprising an electrode that
generates an electrical impulse, and 3) an adhesive component for
adhering the adhesive patch sensor to the patient's skin;
generating an optical waveform from the at least one
radiation-induced photocurrent; generating an electrical waveform
from the electrical impulse; processing the optical waveform and
the electrical waveform with a controller in communication with the
adhesive patch sensor, the controller comprising a microcontroller
configured to operate an algorithm that determines a blood pressure
value of the patient and at least one other vital sign using the
following steps, i) determining a time-dependent property of the
optical waveform using a first numerical fitting algorithm, ii)
determining a time-dependent property of the electrical waveform
using a second numerical fitting algorithm, iii) comparing the
time-dependent properties of the optical and electrical waveform to
determine a time delay, and iv) comparing the time delay to at
least one calibration parameter to determine the blood pressure
value of the patient.
18. A method for measuring vital signs from a patient, the method
comprising the following steps: attaching a vital sign-measuring
system on or near a patient's head, the vital-sign measuring system
comprising 1) an optical system comprising a first LED which emits
a first optical wavelength, a second LED which emits a second
optical wavelength, and a photodetector that detects reflected
radiation from at least one of the first LED and the second LED to
generate at least one radiation-induced photocurrent, 2) an
electrical system comprising an electrode that generates an
electrical impulse, and 3) an adhesive component for adhering the
adhesive patch sensor to the patient's skin; generating an optical
waveform from the at least one radiation-induced photocurrent;
generating an electrical waveform from the electrical impulse; and
processing the optical waveform and the electrical waveform with a
controller in communication with the vital sign measuring system,
the controller comprising a microcontroller configured to operate
an algorithm that determines a blood pressure value for the patient
and at least one other vital sign of the patient using the
following steps i) determining a local maximum value of the optical
waveform, ii) determining a local maximum value of the electrical
waveform, iii) comparing the local maximum value of the optical
waveform and the local maximum value of the electrical waveform to
determine a time delay between the optical waveform and the
electrical waveform, and iv) comparing the time delay to at least
one calibration parameter to determine the blood pressure value of
the patient.
Description
CROSS REFERENCES TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/906,315, filed on Feb. 14, 2005, which is a
continuation-in-part application of U.S. patent application Ser.
No. 10/709,014, filed on Apr. 7, 2004.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
DESCRIPTION
[0002] 1. Background of the Invention
[0003] The present invention relates to a device, method and system
for measuring vital signs, particularly blood pressure.
[0004] 2. Description of Related Art
[0005] Pulse oximeters are medical devices featuring an optical
module, typically worn on a patient's finger or ear lobe, and a
processing module that analyzes data generated by the optical
module. The optical module typically includes first and second
light sources (e.g., light-emitting diodes, or LEDs) that transmit
optical radiation at, respectively, red (.DELTA..about.630-670 nm)
and infrared (.DELTA..about.800-1200 nm) wavelengths. The optical
module also features a photodetector that detects radiation
transmitted or reflected by an underlying artery. Typically the red
and infrared LEDs sequentially emit radiation that is partially
absorbed by blood flowing in the artery. The photodetector is
synchronized with the LEDs to detect transmitted or reflected
radiation. In response, the photodetector generates a separate
radiation-induced signal for each wavelength. The signal, called a
plethysmograph, varies in a time-dependent manner as each heartbeat
varies the volume of arterial blood and hence the amount of
transmitted or reflected radiation. A microprocessor in the pulse
oximeter processes the relative absorption of red and infrared
radiation to determine the oxygen saturation in the patient's
blood. A number between 94%-100% is considered normal, while a
value below 85% typically indicates the patient requires
hospitalization. In addition, the microprocessor analyzes
time-dependent features in the plethysmograph to determine the
patient's heart rate.
[0006] Pulse oximeters work best when the appendage they attach to
(e.g., a finger) is at rest. If the finger is moving, for example,
the light source and photodetector within the optical module
typically move relative to the underlying artery. This generates
`noise` in the plethysmograph, which in turn can lead to
motion-related artifacts in data describing pulse oximetry and
heart rate. Ultimately this reduces the accuracy of the
measurement. Another medical device, called a sphygmomanometer,
measures a patient's blood pressure using an inflatable cuff and a
sensor (e.g., a stethoscope) that detects blood flow by listening
for sounds called the Korotkoff sounds. During a measurement, a
medical professional typically places the cuff around the patient's
arm and inflates it to a pressure that exceeds the systolic blood
pressure. The medical professional then incrementally reduces
pressure in the cuff while listening for flowing blood with the
stethoscope. The pressure value at which blood first begins to flow
past the deflating cuff, indicated by a Korotkoff sound, is the
systolic pressure. The stethoscope monitors this pressure by
detecting strong, periodic acoustic `beats` or `taps` indicating
that the blood is flowing past the cuff (i.e., the systolic
pressure barely exceeds the cuff pressure). The minimum pressure in
the cuff that restricts blood flow, as detected by the stethoscope,
is the diastolic pressure. The stethoscope monitors this pressure
by detecting another Korotkoff sound, in this case a `leveling off`
or disappearance in the acoustic magnitude of the periodic beats,
indicating that the cuff no longer restricts blood flow (i.e., the
diastolic pressure barely exceeds the cuff pressure).
[0007] Low-cost, automated devices measure blood pressure using an
inflatable cuff and an automated acoustic or pressure sensor that
measures blood flow. These devices typically feature cuffs fitted
to measure blood pressure in a patient's wrist, arm or finger.
During a measurement, the cuff automatically inflates and then
incrementally deflates while the automated sensor monitors blood
flow. A microcontroller in the automated device then calculates
blood pressure. Cuff-based blood-pressure measurements such as
these typically only determine the systolic and diastolic blood
pressures; they do not measure dynamic, time-dependent blood
pressure.
[0008] Data indicating blood pressure are most accurately measured
during a patient's appointment with a medical professional, such as
a doctor or a nurse. Once measured, the medical professional can
manually record these data in either a written or electronic file.
Appointments typically take place a few times each year.
Unfortunately, in some cases, patients experience `white coat
syndrome` where anxiety during the appointment affects the blood
pressure that is measured. For example, white coat syndrome can
elevate a patient's heart rate and blood pressure; this, in turn,
can lead to an inaccurate diagnoses.
[0009] Various methods have been disclosed for using pulse
oximeters to obtain arterial blood pressure. One such method is
disclosed in U.S. Pat. No. 5,140,990 to Jones et al., for a `Method
Of Measuring Blood Pressure With a Photoplethysmograph`. The '990
patent discloses using a pulse oximeter with a calibrated auxiliary
blood pressure to generate a constant that is specific to a
patient's blood pressure.
[0010] Another method for using a pulse oximeter to measure blood
pressure is disclosed in U.S. Pat. No. 6,616,613 to Goodman for a
`Physiological Signal Monitoring System`. The '613 patent discloses
processing a pulse oximetry signal in combination with information
from a calibrating device to determine a patient's blood
pressure.
[0011] Chen et al, U.S. Pat. No. 6,599,251, discloses a system and
method for monitoring blood pressure by detecting pulse signals at
two different locations on a subject's body, preferably on the
subject's finger and earlobe. The pulse signals are preferably
detected using pulse oximetry devices, and then processed to
determine blood pressure.
[0012] Schulze et al., U.S. Pat. No. 6,556,852, discloses an
earpiece having an embedded pulse oximetry device and thermopile to
monitor and measure physiological variables of a user.
[0013] Jobsis et al., U.S. Pat. No. 4,380,240, discloses an optical
probe featuring a light source and a light detector incorporated
into channels within a deformable mounting structure which is
adhered to a strap. The light source and the light detector are
secured to the patient's body by adhesive tapes and pressure
induced by closing the strap around a portion of the body.
[0014] Tan et al., U.S. Pat. No. 4,825,879, discloses an optical
probe with a T-shaped wrap having a vertical stem and a horizontal
cross bar, which is utilized to secure a light source and an
optical sensor in optical contact with a finger. A metallic
material is utilized to reflect heat back to the patient's body and
to provide opacity to interfering ambient light. The sensor is
secured to the patient's body using an adhesive or hook-and-loop
material.
[0015] Modgil et al., U.S. Pat. No. 6,681,454, discloses a strap
composed of an elastic material that wraps around the outside of a
pulse oximeter probe and is secured to the oximeter probe by
attachment mechanisms such as Velcro.
[0016] Diab et al., U.S. Pat. Nos. 6,813,511 and 6,678,543,
discloses a disposable optical probe that reduces noise during a
measurement. The probe is adhesively secured to a patient's finger,
toe, forehead, earlobe or lip, and can include reusable and
disposable portions.
BRIEF SUMMARY OF THE INVENTION
[0017] The present invention provides a cuffless, blood-pressure
monitor, featuring an adhesive patch. The patch is disposable and
is typically used for 24-72 hours. The blood pressure monitor makes
a transdermal, optical measurement of the time-dependent dynamics
of blood flowing in an underlying artery. A processor analyzes this
information, typically with a calibration table, to determine blood
pressure. Once determined, the processor sends it to a hand-held
wireless component (e.g., a cellular phone or wireless PDA). The
processing component preferably features an embedded, short-range
wireless transceiver and a software platform that displays,
analyzes, and then transmits the information through a wireless
network to an Internet-based system. With this system a medical
professional can continuously monitor a patient's blood pressure
during their day-to-day activities. Monitoring patients in this
manner minimizes erroneous measurements due to `white coat
syndrome` and increases the accuracy of a blood-pressure
measurement. The invention has many advantages. In particular, one
aspect of the invention provides a system that continuously
monitors a patient's blood pressure using a cuffless blood pressure
monitor and an off-the-shelf mobile communication device.
Information describing the blood pressure can be viewed using an
Internet-based website, using a personal computer, or simply by
viewing a display on the mobile device. Blood-pressure information
measured continuously throughout the day provides a relatively
comprehensive data set compared to that measured during isolated
medical appointments. This approach identifies trends in a
patient's blood pressure, such as a gradual increase or decrease,
which may indicate a medical condition that requires treatment. The
invention also minimizes effects of `white coat syndrome` since the
monitor automatically and continuously makes measurements away from
a medical office with basically no discomfort to the patient.
Real-time, automatic blood pressure measurements, followed by
wireless transmission of the data, are only practical with a
non-invasive, cuffless monitor like that of the present invention.
Measurements can be made completely unobtrusive to the patient.
[0018] The monitor can also characterize the patient's heart rate
and blood oxygen saturation using the same optical system for the
blood-pressure measurement. This information can be wirelessly
transmitted along with blood-pressure information and used to
further diagnose the patient's cardiac condition.
[0019] The monitor is small, easily worn by the patient during
periods of exercise or day-to-day activities, and makes a
non-invasive blood-pressure measurement in a matter of seconds. The
resulting information has many uses for patients, medical
professional, insurance companies, pharmaceutical agencies
conducting clinical trials, and organizations for home-health
monitoring.
[0020] Having briefly described the present invention, the above
and further objects, features and advantages thereof will be
recognized by those skilled in the pertinent art from the following
detailed description of the invention when taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0021] FIG. 1A is a schematic top view of an adhesive patch sensor
that measures blood pressure according to the invention;
[0022] FIG. 1B is a schematic, cross-sectional view of the patch
sensor of FIG. 1A;
[0023] FIG. 2 is a graph of time-dependent optical and electrical
waveforms generated by the patch sensor of FIG. 1A;
[0024] FIG. 3 is a schematic diagram of the electrical components
of a processing module connected to the patch sensor of FIG.
1A;
[0025] FIGS. 4A and 4B are schematic diagrams of the patch sensor
of FIG. 1A attached to, respectively, a patient's forehead and
ear;
[0026] FIG. 5 is a schematic diagram of a head-mounted sensor
similar to that shown in FIG. 4A connected to a belt-mounted
processing module using a wireless link;
[0027] FIG. 6 is a schematic view of an Internet-based system used
to send vital-sign information from a patient to an
Internet-accessible website.
DETAILED DESCRIPTION OF THE INVENTION
[0028] FIGS. 1A and 1B show an adhesive patch sensor 20 according
to the invention that features a pair of LEDs 10, 12 and
photodetector 14 that, when attached to a patient, generate an
optical waveform (31 in FIG. 2). A horseshoe-shaped metal electrode
17 surrounds these optical components and generates an electrical
waveform (32 in FIG. 2). The electrical and optical waveforms, once
generated, pass through a cable 18 to a processing module, which
analyzes them as described in detail below to measure a patient's
systolic and diastolic blood pressure, heart rate, and pulse
oximetry. The patch sensor 20 features an adhesive component 19
that adheres to the patient's skin and secures the LEDs 10, 12,
photodetector 14, and electrode 17 in place to minimize the effects
of motion. During operation, the cable 18 snaps into a plastic
header 16 disposed on a top portion of the patch sensor 20. Both
the cable 18 and header 16 include matched electrical leads that
supply power and ground to the LEDs 10, 12, photodetector 14, and
electrode 19. The cable 18 and header 16 additionally supply a
high-frequency electrical signal to the electrode that helps
generate the electrical waveform. When the patch sensor 20 is not
measuring optical and electrical waveforms (e.g., when the patient
is sleeping), the cable 18 unsnaps from the header 16, while the
sensor 20 remains adhered to the patient's skin. In this way a
single sensor can be used for several days. After use, the patient
removes and then discards the sensor 20.
[0029] To measure blood pressure, heart rate, and pulse oximetry,
the LEDs 10, 12 generate, respectively, red and infrared radiation
that irradiates an underlying artery. Blood volume increases and
then decreases as the heart pumps blood through the patient's
artery. Blood cells within the blood absorb and transmit varying
amounts of the red and infrared radiation depending the on the
blood volume and how much oxygen binds to the cells' hemoglobin.
The photodetector 14 detects a portion of the radiation that
reflects off an underlying artery, and in response sends a
radiation-induced photocurrent to an analog-to-digital converter
embedded within the processing module. The analog-to-digital
converter digitizes the photocurrent to generate a time-dependent
optical waveform for each wavelength. In addition, the
microprocessor analyzes waveforms generated at both red and
infrared wavelengths, and compares a ratio of the relative
absorption to a calibration table coded in its firmware to
determine pulse oximetry. The microprocessor additionally analyzes
the time-dependent properties of one of the optical waveforms to
determine the patient's heart rate.
[0030] Concurrent with measurement of the optical waveform, the
electrode 19 detects an electrical impulse from the patient's skin
that the microprocessor processes to generate an electrical
waveform. The electrical impulse is generated each time the
patient's heart beats.
[0031] The patch sensor 20 preferably has a diameter, `D`, ranging
from 0.5 centimeter (`cm`) to 10 cm, more preferably from 1.5 cm to
3.0 cm, and most preferably 2.5 cm. The patch sensor 20 preferably
has a thickness, `T`, ranging from 1.0 millimeter ("mm") to 3 mm,
more preferably from 1.0 mm to 1.5 mm, and most preferably 1.25 mm.
The patch sensor 20 preferably includes a body composed of a
polymeric material such as a neoprene rubber. The body is
preferably colored to match a patient's skin color, and is
preferably opaque to reduce the affects of ambient light. The body
is preferably circular in shape, but can also be non-circular, e.g.
an oval, square, rectangular, triangular or other shape.
[0032] FIG. 2 shows both optical 31 and electrical 32 waveforms
generated by the patch sensor of FIGS. 1A and 1B. Following a
heartbeat, the electrical impulse travels essentially
instantaneously from the patient's heart to the patch sensor, where
the electrode detects it to generate the electrical waveform 32. At
a later time, a pressure wave induced by the same heartbeat
propagates through the patient's arteries and arrives at the
sensor, where the LEDs and photodetector detect it as described
above to generate the optical waveform 31. The propagation time of
the electrical impulse is independent of blood pressure pressure,
whereas the propagation time of the pressure wave depends strongly
on pressure, as well as mechanical properties of the patient's
arteries (e.g., arterial size, stiffness). The microprocessor runs
an algorithm that analyzes the time difference .DELTA.T between the
arrivals of these signals, i.e. the relative occurrence of the
optical 31 and electrical 32 waveforms as measured by the patch
sensor. Calibrating the measurement (e.g., with a conventional
blood pressure cuff) accounts for patient-to-patient variations in
arterial properties, and correlates .DELTA.T to both systolic and
diastolic blood pressure. This results in a calibration table.
During an actual measurement, the calibration source is removed,
and the microprocessor analyzes .DELTA.T along with other
properties of the optical and electrical waveforms and the
calibration table to calculate the patient's real-time blood
pressure.
[0033] The microprocessor can analyze other properties of the
optical waveform 31 to augment the above-mentioned measurement of
blood pressure. For example, the waveform can be `fit` using a
mathematical function that accurately describes the waveform's
features, and an algorithm (e.g., the Marquardt-Levenberg
algorithm) that iteratively varies the parameters of the function
until it best matches the time-dependent features of the waveform.
In this way, blood pressure-dependent properties of the waveform,
such as its width, rise time, fall time, and area, can be
calibrated as described above. After the calibration source is
removed, the patch sensor measures these properties along with
.DELTA.T to determine the patient's blood pressure.
[0034] Methods for processing the optical and electrical waveform
to determine blood pressure are described in the following
co-pending patent applications, the entire contents of which are
incorporated by reference: 1) CUFFLESS BLOOD-PRESSURE MONITOR AND
ACCOMPANYING WIRELESS, INTERNET-BASED SYSTEM (U.S. Ser. No.
10/709,015; filed Apr. 7, 2004); 2) CUFFLESS SYSTEM FOR MEASURING
BLOOD PRESSURE (U.S. Ser. No. 10/709,014; filed Apr. 7, 2004); 3)
CUFFLESS BLOOD PRESSURE MONITOR AND ACCOMPANYING WEB SERVICES
INTERFACE (U.S. Ser. No. 10/810,237; filed Mar. 26, 2004); 4)
VITAL-SIGN MONITOR FOR ATHLETIC APPLICATIONS (U.S. Ser. No. ______;
filed Sep. 13, 2004); 5) CUFFLESS BLOOD PRESSURE MONITOR AND
ACCOMPANYING WIRELESS MOBILE DEVICE (U.S. Ser. No. 10/967,511;
filed Oct. 18, 2004); and 6) BLOOD PRESSURE MONITORING DEVICE
FEATURING A CALIBRATION-BASED ANALYSIS (U.S. Ser. No. 10/967,610;
filed Oct. 18, 2004); and 7) PERSONAL COMPUTER-BASED VITAL SIGN
MONITOR (U.S. Ser. No. 10/906,342; filed Apr. 7, 2004).
[0035] FIG. 3 shows a preferred configuration of electronic
components featured within the processing module 50. A
data-processing circuit 17 connects to an optical signal processing
circuit 35 that powers both the LEDs and the photodetector, and
additionally processes radiation-induced photocurrent generated by
the photodetector. The data-processing circuit 17 typically
includes a microprocessor 45, which in turn includes an embedded
analog-to-digital converter 46 that digitizes signals to generate
both the electrical and optical waveforms. In a similar manner, the
data-processing circuit 17 controls an RF source 18 for the
electrode. To receive inputs from wireless devices, the processing
module 50 includes a Bluetooth.TM. wireless transceiver 38 that
receives information through an antenna 26 from a matched
transceiver embedded within an external component. The processing
module 50 can also include a liquid crystal display (`LCD`) 42 that
displays blood-pressure information for the user or patient. In
another embodiment, the data-processing circuit 17 avails
calculated information through a serial port 40 to an external
personal computer, which then displays and analyzes the information
using a client-side software application. A battery 37 powers all
the electrical components within the processing module, and is
preferably a metal hydride battery (generating 3-7V) that can be
recharged through a battery-recharge interface 44.
[0036] Referring to FIGS. 4A and 4B, in embodiments the patch
sensor 20 is head-mounted and attaches through a cable 18 to a
processing module 50 worn on the patient's belt. Preferably the
sensor attaches to the patent's forehead 52, underneath the
patient's ear, on the back of the patient's neck, or to any other
location on the patient's head that is on or near an artery.
Typically the patient's head undergoes relatively little motion
compared to other parts of the patient's body (e.g., the hands),
and thus attaching the sensor to this region reduces the negative
affects of motion-related artifacts.
[0037] In another embodiment, shown in FIG. 5, the sensor 20
includes a wireless transceiver 70 (e.g., a Bluetooth transceiver)
that communicates with a matched wireless transceiver 71 in the
processing module 50 through a wireless link 24. In this embodiment
the sensor 20 additionally includes a battery 73 that powers the
wireless transceiver 70 and all the sensing components therein.
During operation, the battery-powered sensor 20 collects the
optical and electrical waveforms as described above, and transmits
these with the wireless transceiver 70 to the transceiver 71 in the
processing component 50. The processing module 50 then processes
the waveforms as described above to determine the patient's vital
signs.
[0038] FIG. 6 shows a preferred embodiment of an Internet-based
system 53 that operates in concert with the adhesive patch sensor
20 and processing module 50 to send information from a patient to a
hand-held wireless device 15. The wireless device 15 then sends the
information through a wireless network 54 to a web site 66 hosted
on an Internet-based host computer system 57. A secondary computer
system 69 accesses the website 66 through the Internet 67. The
system 53 functions in a bi-directional manner, i.e. the processing
module 50 can both send and receive data. Most data flows from the
processing module 20 to the website 66; using the same network,
however, the device can also receive data (e.g., `requests` to
measure data or text messages) and software upgrades. A wireless
gateway 55 connects to the wireless network 54 and receives data
from one or more wireless devices 15, as discussed below. The
wireless gateway 55 additionally connects to a host computer system
57 that includes a database 63 and a data-processing component 68
for, respectively, storing and analyzing the data. The host
computer system 57, for example, may include multiple computers,
software pieces, and other signal-processing and switching
equipment, such as routers and digital signal processors. The
wireless gateway 55 preferably connects to the wireless network 54
using a TCP/IP-based connection, or with a dedicated, digital
leased line (e.g., a frame-relay circuit or a digital line running
an X.25 or other protocols). The host computer system 57 also hosts
the web site 66 using conventional computer hardware (e.g. computer
servers for both a database and the web site) and software (e.g.,
web server and database software).
[0039] During typical operation, the patient continuously wears the
patch sensor 20 for a period of time ranging from a 1-2 days to
weeks. Alternatively, the patient may wear the sensor 20 for
shorter periods of time, e.g. just a few hours. For example, the
patient may wear the sensor during a brief hospital stay, or during
a medical checkup. To view information sent from the processing
module, the patient or medical professional accesses a user
interface hosted on the web site 66 through the Internet 67 from
the secondary computer system 69. The system 53 may also include a
call center, typically staffed with medical professionals such as
doctors, nurses, or nurse practioners, whom access a care-provider
interface hosted on the same website 66.
[0040] In an alternate embodiment, the host computer system 57
includes a web services interface 70 that sends information using
an XML-based web services link to a secondary, web-based computer
application 71. This application 71, for example, could be a
data-management system operating at a hospital.
[0041] The processing module 50 can optionally be used to determine
the patient's location using embedded position-location technology
(e.g., GPS, network-assisted GPS, or 802.11-based location system).
In situations requiring immediate medical assistance, the patient's
location, along with relevant medical data collected by the blood
pressure monitoring system, can be relayed to emergency response
personnel.
[0042] In a related embodiment, the processing module 50 and
wireless device may use a `store and forward` protocol wherein the
processing module 50 stores information when the wireless device is
out of wireless coverage, and then sends this information to the
wireless device when it roams back into wireless coverage.
[0043] In an alternate embodiment of the invention, the processing
module and patch sensor are used within a hospital, and the
processing module includes a short-range wireless link (e.g., a
module operating Bluetooth.TM., 802.11a, 802.11b, 802.1g, or
802.15.4 wireless protocols) that sends vital-sign information to
an in-hospital network. In this embodiment, a nurse working at a
central nursing station can quickly view the vital signs of the
patient using a simple computer interface.
[0044] Still other embodiments are within the scope of the
following claims.
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