Method for generating alarms/alerts based on a patient's posture and vital signs

• US 10,555,676 B2
• Filed: 05/20/2009
• Issued: 02/11/2020
• Est. Priority Date: 05/20/2009
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated (Foxconn Technology Co., Ltd.)
• Original Assignee: Sotera Wireless Incorporated (Foxconn Technology Co., Ltd.)
• Inventors: McCombie, Devin, Dhillon, Marshal, Banet, Matt
• Primary Examiner(s): Weare, Meredith
• Application Number:
  US12/469,236
• Publication Number:
  US 20100298661A1
• Time in Patent Office: 3,919 Days
• Field of Search: 600301, 600483, 600595
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• 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 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• 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 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/1114 Tracking parts of the body
• 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 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/145 : Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• 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 5/322 : Physical templates or devices for measuring ECG waveforms, e.g. electrocardiograph rulers or calipers by template matching A61B5/35
• CPC Class Codes: A61B 5/332 : Portable devices specially adapted therefor
• CPC Class Codes: A61B 5/349 : Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 : Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/6824 : Arm or wrist
• CPC Class Codes: A61B 5/721 : using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7246 : using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7257 : using Fourier transforms
• CPC Class Codes: A61B 5/7278 : Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/742 : using visual displays A61B5/339 takes precedence
• 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
• CPC Class Codes: G08B 21/0446 : worn on the body to detect changes of posture, e.g. a fall, inclination, acceleration, gait
• CPC Class Codes: G08B 21/0453 : worn on the body to detect health condition by physiological monitoring, e.g. electrocardiogram, temperature, breathing detecting, measuring or recording for diagnostic purposes A61B5/00
• CPC Class Codes: G16H 15/00 : ICT specially adapted for medical reports, e.g. generation or transmission thereof
• CPC Class Codes: G16H 50/20 : for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/50 : for simulation or modelling of medical disorders

Abstract

The invention provides a body-worn monitor that measures a patient'"'"'s vital signs (e.g. blood pressure, SpO2, heart rate, respiratory rate, and temperature) while simultaneously characterizing their activity state (e.g. resting, walking, convulsing, falling). The body-worn monitor processes this information to minimize corruption of the vital signs by motion-related artifacts. A software framework generates alarms/alerts based on threshold values that are either preset or determined in real time. The framework additionally includes a series of ‘heuristic’ rules that take the patient'"'"'s activity state and motion into account, and process the vital signs accordingly. These rules, for example, indicate that a walking patient is likely breathing and has a regular heart rate, even if their motion-corrupted vital signs suggest otherwise.

Claims

1. A method for generating an alarm while 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 set of time-dependent motion waveforms are indicative of motion of the patient'"'"'s torso;

(d) receiving and processing the first and second time-dependent physiological waveforms and the set of time-dependent motion waveforms, and generating an alarm therefrom indicative of a need for medical attention, using one or more processing components comprising a microprocessor, the one or more processing components configured to

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

(ii) analyze 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;

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

(iv) compare the posture parameter to a threshold value to estimate the patient'"'"'s posture;

(v) compare the at least one vital sign from the patient to a predetermined alarm criteria, wherein an alarm is indicated by a variance of the vital sign relative to the predetermined alarm criteria to determine an alarm parameter; and

(vi) generate the alarm by collectively processing the patient'"'"'s posture and the alarm parameter, wherein the alarm indicated by a variance of the vital sign relative to the predetermined alarm criteria is regulated according to the patient'"'"'s posture.

2. The method of claim 1, wherein the set of time-dependent motion waveforms comprises three time-dependent motion waveforms, each corresponding to a unique axis, and wherein the vector corresponding to motion of the patient'"'"'s torso is determined from the three time-dependent motion waveforms.

3. The method of claim 2, wherein the coordinate space representative of how the motion-detecting sensor is oriented on the patient is defined by three positional vectors, each indicating an orientation of the motion-detecting sensor on the patient.

4. The method of claim 3, wherein a first positional vector of the three positional vectors corresponds to a vertical axis in the coordinate space, a second positional vector of the three positional vectors corresponds to a horizontal axis in the coordinate space, and a third positional vector of the three positional vectors corresponds to a normal axis extending normal to the patient'"'"'s chest.

5. The method of claim 3, wherein the posture parameter is an angle.

6. The method of claim 5, wherein step (f) further comprises comparing the vector to the coordinate space to determine the angle between the vector and at least one of the three positional vectors.

7. The method of claim 6, wherein step (d)(iii) further comprises comparing the vector to the coordinate space to determine the angle between the vector and the first positional vector.

8. The method of claim 7, wherein step (d)(iv) further comprises estimating the patient'"'"'s posture to be upright if the angle between the vector and the first positional vector is less than 45 degrees.

9. The method of claim 7, wherein step (d)(iv) further comprises estimating the patient'"'"'s posture to be lying down if the angle between the vector and the first positional vector is greater than 45 degrees.

10. The method of claim 9, wherein step (d)(iii) further comprises comparing the vector to the coordinate space to determine the angle between the vector and the third positional vector.

11. The method of claim 10, wherein step (d)(iv) further comprises estimating the patient'"'"'s posture to be supine if the angle between the vector and the third positional vector is less than 35 degrees.

12. The method of claim 10, wherein step (d)(iv) further comprises estimating the patient'"'"'s posture to be prone if the angle between the vector and the third positional vector is greater than 135 degrees.

13. The method of claim 9, wherein step (d)(iii) further comprises comparing the vector to the coordinate space to determine the angle between the vector and the second positional vector.

14. The method of claim 13, wherein step (d)(iv) further comprises estimating the patient'"'"'s posture to be lying on a first side if the angle between the vector and the third positional vector is less than 90 degrees.

15. The method of claim 13, wherein step (d)(iv) further comprises estimating the patient'"'"'s posture to be lying on a side opposite the first side if the angle between the vector and the second positional vector is greater than 90 degrees.

16. The method of claim 1, wherein at least one motion-detecting sensor positioned on the patient'"'"'s torso is positioned on the patient'"'"'s chest.

17. The method of claim 1, where the at least one motion-detecting sensor positioned on the patient'"'"'s torso is an accelerometer.

18. The method of claim 1, wherein step (d) further comprises processing the first and second time-dependent physiological waveforms to calculate a time difference between a feature in the first time-dependent physiological waveform and a feature in the second time-dependent physiological waveform.

19. The method of claim 18, wherein step (d) further comprises calculating a blood pressure from the time difference.

20. The method of claim 18, wherein the first time-dependent physiological waveform is an electrical waveform, and step (a) further comprises detecting the electrical waveform with at least two electrodes attached to the patient and operably connected to an electrical circuit.

21. The method of claim 20, wherein the second time-dependent physiological waveform is an optical waveform, and step (b) further comprises detecting the optical waveform with an optical sensor comprising a light source and a photodiode.

22. The method of claim 18, wherein each of the first and second time-dependent physiological waveforms are selected from a group consisting of an optical waveform, an electrical waveform, an acoustic waveform, and a pressure waveform.

23. The method of claim 22, wherein steps (a) and (b) each further comprise detecting a time-dependent physiological waveform with a sensor selected from a group consisting of:

(i) an optical sensor comprising a light source and a photodiode;

(ii) an electrical sensor comprising at least two electrodes operably connected to an electrical circuit;

(iii) an acoustic sensor comprising a microphone; and

(iv) a pressure sensor comprising a transducer.