VITAL SIGN MONITORING SYSTEM FEATURING 3 ACCELEROMETERS

• US 20100298650A1
• Filed: 05/20/2009
• Published: 11/25/2010
• Est. Priority Date: 05/20/2009
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Triage Wireless, Inc.
• Inventors: Dhillon, Marshal, McCombie, Devin, Moon, Jim, Banet, Matt
• Granted Patent: US 10,973,414 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 2560/0261 using hydrostatic pressure
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/0024 for multiple sensor units attached to the patient, e.g. using a body or personal area network
• CPC Class Codes: A61B 5/0082 adapted for particular medical purposes
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1117 Fall detection
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/1122 of movement trajectories
• CPC Class Codes: A61B 5/1123 : Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/14551 : for measuring blood gases
• CPC Class Codes: A61B 5/25 : Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/282 : Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/30 : Input circuits therefor
• CPC Class Codes: A61B 5/316 : Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/318 : Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/339 : Displays specially adapted therefor
• CPC Class Codes: A61B 5/349 : Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/447 : specially adapted for aiding the prevention of ulcer or pressure sore development, i.e. before the ulcer or sore has developed
• CPC Class Codes: A61B 5/681 : Wristwatch-type devices
• CPC Class Codes: A61B 5/6823 : Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6824 : Arm or wrist
• CPC Class Codes: A61B 5/6826 : Finger
• CPC Class Codes: A61B 5/7207 : of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7239 : using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7257 : using Fourier transforms
• CPC Class Codes: A61B 5/746 : Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B

Abstract

The invention provides a system and method for measuring vital signs (e.g. SYS, DIA, SpO2, heart rate, and respiratory rate) and motion (e.g. activity level, posture, degree of motion, and arm height) from a patient. The system features: (i) first and second sensors configured to independently generate time-dependent waveforms indicative of one or more contractile properties of the patient'"'"'s heart; and (ii) at least three motion-detecting sensors positioned on the forearm, upper arm, and a body location other than the forearm or upper arm of the patient. Each motion-detecting sensor generates at least one time-dependent motion waveform indicative of motion of the location on the patient'"'"'s body to which it is affixed. A processing component, typically worn on the patient'"'"'s body and featuring a microprocessor, receives the time-dependent waveforms generated by the different sensors and processes them to determine: (i) a pulse transit time calculated using a time difference between features in two separate time-dependent waveforms, (ii) a blood pressure value calculated from the time difference, and (iii) a motion parameter calculated from at least one motion waveform.

Claims

1. A system for measuring vital signs from a patient, comprising:

(a) a first sensor configured to generate a first time-dependent waveform indicative of one or more contractile properties of the patient'"'"'s heart;

(b) a second sensor configured to generate a second time-dependent waveform indicative of one or more contractile properties of the patient'"'"'s heart;

(c) at least three motion-detecting sensors positioned on the forearm, upper arm, and a body location other than the forearm or upper arm of the patient, each of said motion-detecting sensors generating at least one time-dependent motion waveform indicative of motion of the location on the patient'"'"'s body to which the motion-detecting sensor is affixed;

(d) a processing component configured to be worn on the patient'"'"'s body and comprising a microprocessor, said processing component configured to receive the first time-dependent waveform, the second time-dependent waveform, and the at least one time-dependent motion waveform generated by each motion-detecting sensor and determine therefrom;

(i) a pulse transit time calculated using a time difference between a time-dependent feature in each of the first and second time-dependent waveforms, (ii) a blood pressure value calculated using said time difference, and (iii) at least one motion parameter selected from the patient'"'"'s posture, activity level, and degree of motion calculated using at least one motion waveform generated by each of said motion-detecting sensors; and

(e) a wireless communication system configured to be worn on the patient'"'"'s body and operably connect to the processing component, the wireless system configured to wirelessly transmit the blood pressure value and at least one motion parameter determined by the processing component to a remote receiver.

2. A system according to claim 1, wherein:

said first sensor is an optical sensor comprising;

a source of electromagnetic radiation configured to irradiate tissue of the patient with radiation emitted therefrom, and a detector configured to detect one or more properties of the electromagnetic radiation after it irradiates said tissue, wherein the first time-dependent waveform is an optical waveform indicative of volumetric changes in the irradiated tissue caused by ventricular contraction of the patient'"'"'s heart; and

,

said second sensor is an electrical sensor comprising;

at least two electrodes configured to detect electrical signals from the patient'"'"'s body, and an electrical circuit operably connected to the electrodes and configured to process the detected electrical signals to generate the second time-dependent waveform, wherein said second time-dependent waveform is an electrical waveform indicative of ventricular depolarization of the patient'"'"'s heart.

3. A system according to claim 2, wherein the optical waveform represents a time-dependent change in optical absorption of an underlying vessel resulting from the ejection of blood from the left ventricle.

4. A system according to claim 3, wherein the pulse transit time is a time difference between a peak of a QRS complex of an ECG waveform and an inflection point in said optical waveform.

5. A system according to claim 1, wherein:

said first sensor is an optical sensor comprising;

a source of electromagnetic radiation configured to irradiate tissue of the patient with radiation emitted therefrom at a first location on an extremity, and a detector configured to detect one or more properties of the electromagnetic radiation after it irradiates said tissue, wherein the first time-dependent waveform is an optical waveform indicative of volumetric changes in the irradiated tissue at said first location caused by ventricular contraction of the patient'"'"'s heart; and

said second sensor is an optical sensor comprising;

a source of electromagnetic radiation configured to irradiate tissue of the patient with radiation emitted therefrom at a second position, and a detector configured to detect one or more properties of the electromagnetic radiation after it irradiates said tissue, wherein the second time-dependent waveform is an optical waveform indicative of volumetric changes in the irradiated tissue at said second location caused by ventricular contraction of the patient'"'"'s heart.

6. A system according to claim 1, wherein the remote receiver is configured to generate an alarm condition based on the blood pressure value, wherein the alarm condition is optionally modified based on the at least one motion parameter.

7. A system according to claim 6, wherein an alarm condition indicating a need for medical intervention is modified by a motion parameter indicating said patient is ambulatory.

8. A system according to claim 1, wherein each of said three motion-detecting sensors are accelerometers.

9. A system according to claim 1, wherein the motion-detecting sensor positioned on the forearm is positioned on the wrist.

10. A system according to claim 9, wherein the processing component is positioned on the wrist proximate to the motion-detecting sensor.

11. A system according to claim 10, wherein the motion-detecting sensor positioned on the upper arm is electrically connected to the processing component through a cable.

12. A system according to claim 11, wherein the motion-detecting sensor positioned at a body location other than the forearm or upper arm is positioned on the chest and is electrically connected to the processing component through said cable.

13. A system according to claim 12, wherein the motion waveform generated by the motion-detecting sensor positioned on the upper arm is transmitted to the processing component through said cable as a first digital data stream, and the motion waveform generated by the motion-detecting sensor positioned at a body location other than the forearm or upper arm is transmitted to the processing component through said cable as a second digital data stream, wherein the first digital data stream is separately resolvable from the second digital data stream by the processing component.

14. A system according to claim 13, wherein the second time-dependent waveform is an ECG waveform that is transmitted to the processing component through said cable as a third digital data stream separately resolvable from each of the first and second digital data streams.

15. A system according to claim 14, wherein said cable comprises a terminal portion, said terminal portion comprising:

a connector configured for reversible attachment of one or more ECG electrodes;

an ECG circuit configured to receive electrical signals from said one or more ECG electrodes and process them to determine one or more ECG waveforms therefrom; and

an analog-to-digital converter configured to convert said one or more ECG waveforms to said third digital data stream.

16. A system according to claim 15, wherein the terminal portion comprises the motion-detecting sensor positioned at a body location other than the forearm or upper arm of the patient.

17. A method of measuring blood pressure from a patient, comprising:

attaching a system according to one of claims 1-16 to a patient;

determining a pulse transit time, blood pressure value, and at least one motion parameter using said processing component; and

,

transmitting said blood pressure value, and at least one motion parameter to said remote receiver using said wireless communication system,

wherein said method optionally comprises generating an alarm condition based on the blood pressure value and the at least one motion parameter.

18. A system for measuring vital signs from a patient, comprising:

(a) a sensor configured to detect a first time-dependent physiological waveform indicative of one or more contractile properties of the patient'"'"'s heart;

(b) a cable system comprising;

an electrical sensor comprising;

at least two electrodes configured to detect electrical signals from the patient'"'"'s body and operably connect to an electrical circuit configured to process the detected electrical signals, the electrical sensor generating a time-dependent electrical waveform indicative of one or more contractile properties of the patient'"'"'s heart, and,

at least two motion-detecting sensors, each of said motion-detecting sensors generating at least one time-dependent motion waveform indicative of motion of the location on the patient'"'"'s body to which the motion-detecting sensor is affixed; and

,

(c) a processing component configured to be worn on the patient'"'"'s body and comprising a microprocessor and one or more electrical connectors for operably connecting the microprocessor to the sensor and the cable system, said processing component configured to receive the time-dependent electrical waveform, the time-dependent physiological waveform, and the at least one time-dependent motion waveform generated by each motion-detecting sensor and determine therefrom;

(i) at least one vital sign calculated using at least one of the time-dependent physiological waveform and the time-dependent electrical waveform, and (ii) at least one motion parameter selected from the patient'"'"'s posture, activity level, arm height, and degree of motion calculated using at least one time-dependent motion waveform generated by each of said motion-detecting sensors.

19. A system for measuring a blood pressure from a patient, comprising:

(a) a first sensor configured to generate a first time-dependent waveform indicative of one or more contractile properties of the patient'"'"'s heart;

(b) an electrical sensor comprising;

at least two electrodes configured to detect electrical signals from the patient'"'"'s body, and an electrical circuit operably connected to the electrodes and configured to process the detected electrical signals, the electrical sensor generating a time-dependent electrical waveform indicative of one or more contractile properties of the patient'"'"'s heart;

(c) at least two motion-detecting sensors positioned on separate locations on the patient'"'"'s body, each of said motion-detecting sensors generating at least one time-dependent motion waveform indicative of motion of the location on the patient'"'"'s body to which the motion-detecting sensor is affixed; and

,

(d) a processing component configured to be worn on the patient'"'"'s body and comprising a microprocessor, said processing component configured to receive the first time-dependent waveform, the time-dependent electrical waveform, and the at least one time-dependent motion waveform generated by each motion-detecting sensor, and to determine;

(i) a first arm position from one or more of the time-dependent motion waveforms acquired in a first arm position;

(ii) a first time difference between a feature present in each of a first time-dependent waveform and a first time-dependent electrical waveform acquired in the first arm position;

(iii) a second arm position from one or more of the time-dependent motion waveforms acquired in a second arm position;

(iv) a second time difference between a feature present in each of a second time-dependent waveform and a second time-dependent electrical waveform acquired in the second arm position;

(v) a first blood pressure value calculated at the first arm position;

(vi) a second blood pressure value calculated at the second arm position;

(vii) a blood pressure factor calculated using the first blood pressure value and the first time difference or a property derived therefrom, together with the second blood pressure value and the second time difference or a property derived therefrom.

20. A method for monitoring a patient, comprising the following steps:

(a) detecting a first time-dependent physiological waveform indicative of one or more contractile properties of the patient'"'"'s heart with a first sensor comprising a first detector configured to be worn on the patient'"'"'s body;

(b) detecting a second time-dependent physiological waveform indicative of one or more contractile properties of the patient'"'"'s heart with a second sensor comprising a second detector configured to be worn on the patient'"'"'s body;

(c) detecting sets of time-dependent motion waveforms with at least two motion-detecting sensors positioned on different locations on the patient'"'"'s body, wherein each motion-detecting sensor detects a set of motion waveforms indicative of motion of the location on the patient'"'"'s body to which the motion-detecting sensor is affixed;

(d) processing the first and second time-dependent physiological waveforms to determine at least one vital sign from the patient;

(e) analyzing at least a portion of each set of time-dependent motion waveforms, or a mathematical derivative thereof, to determine a motion parameter;

(f) processing the motion parameter to determine a probability that the patient is undergoing a specific activity state; and

(g) estimating the patient'"'"'s activity state based on the probability.

21. A system for measuring vital signs from a patient, comprising:

(a) a first sensor configured to generate a first time-dependent waveform indicative of one or more contractile properties of the patient'"'"'s heart;

(b) a second sensor configured to generate a second time-dependent waveform indicative of one or more contractile properties of the patient'"'"'s heart;

(c) at least two motion-detecting sensors positioned on a location selected from a forearm, upper arm, and a body location other than the forearm or upper arm of the patient, each of said motion-detecting sensors generating at least one time-dependent motion waveform indicative of motion of the location on the patient'"'"'s body to which the motion-detecting sensor is affixed; and

,

(d) a processing component configured to be worn on the patient'"'"'s body and comprising a microprocessor, said processing component configured to receive the first time-dependent waveform, the second time-dependent waveform, and the at least one time-dependent motion waveform generated by each motion-detecting sensor and determine therefrom;

(i) one or more vital signs calculated using the first and second time-dependent waveforms;

(ii) at least one motion parameter selected from the patient'"'"'s posture, activity level, arm height, and degree of motion and calculated using at least one motion waveform generated by each of said motion-detecting sensors; and

(iii) at least one alarm condition calculated using one or more of the vital signs and at least one motion parameter, wherein an alarm condition indicated by a variance in one or more of the vital signs is regulated according to one or more motion parameters.

22. A method for monitoring vital signs and posture of a patient, the method comprising the following steps:

(a) detecting a first time-dependent physiological waveform indicative of one or more contractile properties of the patient'"'"'s heart with a first sensor comprising a first detector configured to be worn on the patient'"'"'s body;

(b) detecting a second time-dependent physiological waveform indicative of one or more contractile properties of the patient'"'"'s heart with a second sensor comprising a second detector configured to be worn on the patient'"'"'s body;

(c) detecting a set of time-dependent motion waveforms with at least one motion-detecting sensor positioned on the patient'"'"'s torso, wherein the one motion-detecting sensor detects a set of motion waveforms indicative of motion of the patient'"'"'s torso;

(d) processing the first and second time-dependent physiological waveforms to determine at least one vital sign from the patient;

(e) analyzing at least a portion of the set of time-dependent motion waveforms, or a mathematical derivative thereof, to determine a vector corresponding to motion of the patient'"'"'s torso;

(f) comparing the vector to a coordinate space representative of how the motion-detecting sensor is oriented on the patient to determine a posture parameter; and

(g) comparing the posture parameter to a threshold value to estimate the patient'"'"'s posture.