Alarm system that processes both motion and vital signs using specific heuristic rules and thresholds

• US 9,566,007 B2
• Filed: 06/14/2015
• Issued: 02/14/2017
• Est. Priority Date: 05/20/2009
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: McCombie, Devin, Banet, Matt, Dhillon, Marshal, Moon, Jim
• Primary Examiner(s): Schaetzle, Kennedy
• Application Number:
  US14/738,910
• Publication Number:
  US 20150282717A1
• Time in Patent Office: 611 Days
• US Class Current: 1/1
• 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 continuously monitoring a patient, comprising the following steps:

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 an arm of the patient;

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;

detecting sets of time-dependent motion waveforms with at least three motion-detecting sensors, a first of which is positioned on the arm of the patient at the forearm, a second of which is positioned on the arm of the patient at the upper arm, and a third of which is located on the patient'"'"'s chest, wherein each set of motion waveforms is indicative of motion of the location on the patient'"'"'s body to which it is affixed;

analyzing at least a portion of the sets of time-dependent motion waveforms obtained from the first and second motion-detecting sensors to determine a time-dependent arm height for the patient;

processing the first and second time-dependent physiological waveforms and a correction value determined from the time-dependent arm height to determine a time-dependent blood pressure for the patient;

analyzing at least a portion of the sets of time-dependent motion waveforms obtained from the third motion-detecting sensor with a motion-determining algorithm to determine a time-dependent posture state for the patient;

determining an alarm condition by comparing the blood pressure to a predetermined alarm criterion that is regulated according to the patient'"'"'s time-dependent posture state, wherein if the patient has undergone a change in posture state that would result in an expected drop in blood pressure, the alarm criterion is altered to reflect the expected drop in blood pressure; and

continuously displaying an icon indicative of the patient'"'"'s time-dependent posture state and alarm condition and the time-dependent blood pressure on a display monitor.

2. The method of claim 1, wherein the first time-dependent physiological waveform is an ECG waveform.

3. The method of claim 1, wherein the second time-dependent physiological waveform is a plethysmogram waveform.

4. The method of claim 1, wherein the first time-dependent physiological waveform is an ECG waveform and the second time-dependent physiological waveform is a plethysmogram waveform.