Calibrated systems, devices and methods for preventing, detecting, and treating pressure-induced ischemia, pressure ulcers, and other conditions

• US 10,588,565 B2
• Filed: 06/15/2016
• Issued: 03/17/2020
• Est. Priority Date: 04/22/2010
• Status: Active Grant

• Current Assignee: Leaf Healthcare, Inc. (Smith & Nephew PLC)
• Original Assignee: Leaf Healthcare, Inc. (Smith & Nephew PLC)
• Inventors: Larson, Barrett J, Shen, Daniel Z., Weckwerth, Mark V., Hammond, Charles Matthew Peterson
• Primary Examiner(s): Zhong, Xin Y
• Application Number:
  US15/183,739
• Publication Number:
  US 20160296159A1
• Time in Patent Office: 1,371 Days
• CPC Class Codes: A41B 9/00 Undergarments corsets A41C1/00; brassières A41C3/00
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 2562/0214 Capacitive electrodes
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/0223 Magnetic field sensors
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/0261 Strain gauges
• CPC Class Codes: A61B 2562/029 Humidity sensors
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes 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 5/0205 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 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1113 : Local tracking of patients, e.g. in a hospital or private home
• CPC Class Codes: A61B 5/1114 : Tracking parts of the body
• CPC Class Codes: A61B 5/1115 : Monitoring leaving of a patient support, e.g. a bed or a wheelchair
• CPC Class Codes: A61B 5/1116 : Determining posture transitions
• CPC Class Codes: A61B 5/1118 : Determining activity level
• CPC Class Codes: A61B 5/1121 : Determining geometric values, e.g. centre of rotation or angular range of movement
• CPC Class Codes: A61B 5/113 : occurring during breathing
• CPC Class Codes: A61B 5/14542 : for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14551 : for measuring blood gases
• CPC Class Codes: A61B 5/363 : Detecting tachycardia or bradycardia
• 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 5/4833 : Assessment of subject's compliance to treatment
• CPC Class Codes: A61B 5/4866 : Evaluating metabolism A61B5/083 takes precedence
• CPC Class Codes: A61B 5/4884 : inducing physiological or psychological stress, e.g. applications for stress testing
• CPC Class Codes: A61B 5/6801 : specially adapted to be attached to or worn on the body surface
• CPC Class Codes: A61B 5/6804 : Garments; Clothes
• CPC Class Codes: A61B 5/6823 : Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6843 : Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/6891 : Furniture
• CPC Class Codes: A61B 5/6892 : Mats
• 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 5/7275 : Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7282 : Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take 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: A61B 7/00 : Instruments for auscultation
• CPC Class Codes: A61G 2203/42 : for inclination
• CPC Class Codes: A61G 2203/46 : for temperature
• CPC Class Codes: A61G 7/057 : Arrangements for preventing bed-sores or for supporting patients with burns, e.g. mattresses specially adapted therefor ventilation openings in mattresses A47C21/042; pneumatic or hydraulic mattresses A47C27/08
• CPC Class Codes: A61G 7/05769 : with inflatable chambers
• CPC Class Codes: A61G 7/05776 : with at least two groups of alternately inflated chambers
• CPC Class Codes: G01P 15/18 : in two or more dimensions
• CPC Class Codes: G01P 21/00 : Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: G16H 20/00 : ICT specially adapted for therapies or health-improving plans, e.g. for handling prescriptions, for steering therapy or for monitoring patient compliance
• CPC Class Codes: G16H 20/30 : relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising
• CPC Class Codes: G16H 20/40 : relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture
• CPC Class Codes: G16H 40/63 : for local operation
• CPC Class Codes: G16H 40/67 : for remote operation
• CPC Class Codes: G16H 50/20 : for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/70 : for mining of medical data, e.g. analysing previous cases of other patients
• CPC Class Codes: G16H 80/00 : ICT specially adapted for facilitating communication between medical practitioners or patients, e.g. for collaborative diagnosis, therapy or health monitoring

Abstract

A system for monitoring medical conditions including pressure ulcers, pressure-induced ischemia and related medical conditions comprises at least one sensor adapted to detect one or more patient characteristic including at least position, orientation, temperature, acceleration, moisture, resistance, stress, heart rate, respiration rate, and blood oxygenation, a host for processing the data received from the sensors together with historical patient data to develop an assessment of patient condition and suggested course of treatment. In some embodiments, the system can further include a support surface having one or more sensors incorporated therein either in addition to sensors affixed to the patient or as an alternative thereof. The sensor can include bi-axial or tri-axial accelerometers, as well as resistive, inductive, capactive, magnetic and other sensing devices, depending on whether the sensor is located on the patient or the support surface, and for what purpose. Compensation for errors introduced because of chest angle or slope can be automatically performed.

Claims

1. A method for calibrating a wearable sensor device including at least one accelerometer for monitoring a user based on the calibrated acceleration data, the method comprising:

securing the wearable sensor device to the user in an aligned orientation relative to a first rotational axis of the user based on visual alignment indicia provided on the wearable sensor device,

receiving or determining, by the processor, a correction factor to adjust for an offset angle of the at least one accelerometer provided in the wearable sensor device relative to a second rotational axis of the user orthogonal to the first rotational axis of the user, the offset angle representing an angle of offset between (a) an orientation of the at least one accelerometer provided in the wearable sensor device and (b) the second rotational axis of the user,

receiving, by the processor, acceleration data generated by the at least one accelerometer, the generated acceleration data including at least (a) first axis acceleration data indicating accelerations relative to the first rotational axis of the user and (b) second axis acceleration data indicating accelerations relative to the second rotational axis of the user,

applying, by the processor, the correction factor to the received second axis acceleration data to generate corrected second axis acceleration data indicating accelerations relative to the second rotational axis of the user, and

determining, by the processor, an orientation of the user based at least on (a) the first axis acceleration data and (b) the corrected second axis acceleration data.

2. The method of claim 1, wherein the second rotational axis of the user is a longitudinal axis and the offset angle of the at least one accelerometer relative to the second rotational axis of the user is an angle of pitch.

3. The method of claim 1, wherein the second rotational axis of the user is a lateral axis and the offset angle of the at least one accelerometer relative to the second rotational axis of the user is an angle of roll.

4. The method of claim 2, wherein the acceleration data generated by the at least one accelerometer represents acceleration along three axes.

5. The method of claim 1, further comprising determining a user-specific offset angle specific to the user based on second axis acceleration data generated by the at least one accelerometer during a calibration period, and

wherein receiving or determining a correction factor to adjust for the offset angle of the at least one accelerometer comprises determining a user-specific correction factor based on the user-specific offset angle.

6. The method of claim 5, wherein the user-specific offset angle comprises a user-specific chest angle representing an angle of offset between an angle defined by the user'"'"'s chest and a longitudinal axis of rotation of the user.

7. The method of claim 5, wherein the user-specific offset angle comprises a user-specific chest angle representing an angle of offset between an angle defined by the user'"'"'s chest and a lateral axis of rotation of the user.

8. The method of claim 1, wherein receiving or determining a correction factor to adjust for the offset angle of the at least one accelerometer comprises accessing a predetermined correction factor associated with an angle of slope of the chest.

9. The method of claim 8, where the correction factor is predetermined based on a range of known patient measurements.

10. The method of claim 2, wherein applying the correction factor to the received second axis acceleration data to generate corrected second axis acceleration data comprises applying the correction factor to the received second axis acceleration data in a rotation matrix, wherein the rotation matrix is applied along the Y axis.

11. The method of claim 3, wherein applying the correction factor to the received second axis acceleration data to generate corrected second axis acceleration data comprises applying the correction factor to the received second axis acceleration data in a rotation matrix, wherein the rotation matrix is applied along the X axis.

12. The method of claim 1, wherein the correction factor comprises a value of or otherwise represents the offset angle.

13. A method for calibrating accelerometer data generated by at least one accelerometer provided in a wearable sensor device for monitoring a user based on the calibrated acceleration data, the method comprising:

securing the wearable sensor device to the user in an aligned orientation relative to a first rotational axis of the user based on visual alignment indicia provided on the wearable sensor device,

orienting the user in a supine position,

while the user is in the supine position, determining, by the processor, both (a) a pitch correction factor to adjust for a pitch angle offset between an orientation of the at least one accelerometer relative to a second rotational axis of the user and (a) a roll correction factor to adjust for a roll angle offset between the orientation of the at least one accelerometer relative to a third rotational axis of the user, wherein each of the second rotational axis and the third rotational axis is orthogonal to the first rotational axis,

receiving, by the processor, multi-axis acceleration data generated by the at least one accelerometer, the multi-axis acceleration data indicating accelerations relative to the orientation of the at least one accelerometer,

applying, by the processor, the at least one correction factor to the received acceleration data to generate corrected acceleration data indicating accelerations relative to the second rotational axis of the user and the third rotational axis of the user, and

determining, by the processor, an orientation of the user based on the corrected acceleration data indicating accelerations relative to the second rotational axis of the user and the third rotational axis of the user.

14. The method of claim 13, further comprising determining a user-specific pitch angle offset and a user-specific roll angle offset, and

wherein receiving or determining the pitch correction factor and the roll correction factor comprises determining a user-specific pitch correction factor and a user-specific roll correction factor based on the user-specific pitch angle offset and the user-specific roll angle offset.

15. The method of claim 13, wherein:

the pitch correction factor comprises a value of or otherwise represents the pitch angle offset; and

the roll correction factor comprises a value of or otherwise represents the roll angle offset.

16. A method for calibrating a wearable sensor device secured to a user and including an accelerometer configured to generate acceleration data for monitoring the user and a calibration sensor for calibrating the acceleration data, the method comprising:

receiving, by a processor, calibration data generated by the calibration sensor provided in the wearable sensor device secured to the user,

using, by the processor, the calibration data generated by the calibration sensor to determine an acceleration correction factor as an offset for an angle between (a) an orientation of the accelerometer provided in the wearable sensor device and (b) a defined rotational axis of the user,

receiving, by the processor, acceleration data generated by the accelerometer, the generated acceleration data indicating accelerations relative to the defined rotational axis of the user,

applying, by the processor, the acceleration correction factor to the received acceleration data to generate corrected acceleration data indicating accelerations relative to the defined rotational axis of the user,

determining, by the processor, an orientation of the user based on the corrected acceleration data indicating accelerations relative to the defined rotational axis of the user,

identifying, by the processor, acceleration data that falls outside a defined range of acceleration values corresponding with normal movements of the human body, and

in response to identifying the acceleration data that falls outside the defined range of acceleration values, (a) generating, by the processor, an alert notification regarding attachment of the wearable sensor or (b) automatically recalibrating, by the processor, the acceleration data generated by the accelerometer.

17. The method of claim 16, wherein the acceleration correction factor comprises a value of or otherwise represents the offset angle.

18. The method of claim 16, further comprising:

receiving, by the processor, acceleration data generated by the at least one accelerometer provided in the wearable sensor device while the user is in the supine position, and

determining, by the processor, both a pitch correction factor and a roll correction factor based on the acceleration data generated by the at least one accelerometer while the user is in the supine position.

19. The method of claim 16, wherein:

the wearable sensor device includes a magnetometer; and

the method further comprises;

receiving, by the processor, magnetometer data generated by the magnetometer while the user is in the supine position, and

determining, by the processor, a yaw correction factor based on the magnetometer data generated by the magnetometer while the user is in the supine position.

20. The method of claim 16, wherein the calibration sensor provided in the wearable sensor device comprises a magnetometer.