Continuous transdermal monitoring system and method

• US 9,107,644 B2
• Filed: 07/07/2014
• Issued: 08/18/2015
• Est. Priority Date: 07/05/2013
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Andrew Johnson, James Mitchell Frix, James Tyler Frix, Robert Andrew Taylor
• Inventors: FRIX, JAMES MITCHELL, Johnson, Andrew, FRIX, JAMES TYLER, TAYLOR, ROBERT ANDREW
• Primary Examiner(s): Natnithithadha, Navin
• Assistant Examiner(s): MESSERSMITH, ERIC J
• Application Number:
  US14/324,963
• Publication Number:
  US 20150011854A1
• Time in Patent Office: 407 Days
• Field of Search: 600/323, 600500-509
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/0242 adapted to measure environmental factors, e.g. temperature, pollution
• CPC Class Codes: A61B 2560/0475 Special features of memory means, e.g. removable memory cards
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0004 characterised by the type of physiological signal transmitted
• 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 5/01 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 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02433 for infrared radiation
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/1112 Global tracking of patients, e.g. by using GPS
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/1126 using a particular sensing technique
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/4809 Sleep detection, i.e. determining whether a subject is asleep or not
• 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 5/74 Details of notification to user or communication with user or patient indicating measured values G01D7/00; user input means input or output arrangements for computers G06F3/00
• CPC Class Codes: A61B 5/742 : using visual displays A61B5/339 takes precedence

Abstract

Various embodiments of methods and systems for continuous transdermal monitoring (“CTM”) are disclosed. One exemplary method for CTM begins by monitoring an output signal from an accelerometer. The accelerometer output signal may indicate acceleration and deceleration of a body part of a user, such as the user'"'"'s wrist. Based on the accelerometer output signal, it may be determined that the body part of the user has decelerated to a minimum, e.g., substantially zero. With a determination that the body part has decelerated to the minimum, e.g., substantially zero, or has not accelerated beyond the minimum, e.g., substantially zero, the method may determine a reading from a pulse oximeter associated with the accelerometer. Advantageously, the pulse oximetry reading, or a reading from other sensors associated with the accelerometer, may be optimally accurate as motion artifact may be minimized. The pulse oximetry reading may be recorded for later query and/or rendered for the benefit of the user.

Claims

1. A method for minimizing the effects of motion artifact on sensor readings taken during continuous transdermal monitoring of a body part in motion, the method comprising:

monitoring, with a processor, an output signal from an accelerometer, wherein the output signal indicates acceleration and deceleration of the body part of a user as the body part is in motion translating continuously between a rearward most point and a forward most point relative to the user;

determining, with the processor, from the output signal that the body part of the user has decelerated to a predetermined minimum before becoming momentarily stationary to begin acceleration;

based on the determination that the body part of the user has decelerated to the predetermined minimum, determining, with the processor, a reading from a pulse oximeter, wherein determining the reading from the pulse oximeter occurs over a time window that includes the body part of the user becoming momentarily stationary and comprises;

pulsing a red light source for approximately 50 microseconds; and

delaying approximately 450 microseconds before pulsing an infrared light source approximately 50 microseconds; and

recording in a memory device the determined reading from the pulse oximeter.

2. The method of claim 1, further comprising rendering the determined reading from the pulse oximeter to the user via a display.

3. The method of claim 1, wherein the reading from the pulse oximeter indicates a blood oxygen saturation level of the user.

4. The method of claim 1, wherein the pulse oximeter is a reflective pulse oximeter.

5. The method of claim 1, wherein the accelerometer is a 3-axis accelerometer.

6. The method of claim 1, wherein the body part of the user is a wrist.

7. A system for minimizing the effects of motion artifact on sensor readings taken during continuous transdermal monitoring of a body part in motion, the system comprising:

a sensor package comprising a processor, an accelerometer, a pulse oximeter and a memory device, the sensor package configured to;

monitor an output signal from the accelerometer, wherein the output signal indicates acceleration and deceleration of the body part of a user as the body part is in motion translating continuously between a rearward most point and a forward most point relative to the user;

determine from the output signal that the body part of the user has decelerated to a predetermined minimum before becoming momentarily stationary to begin acceleration;

based on the determination that the body part of the user has decelerated to the predetermined minimum, determine a reading from the pulse oximeter, wherein the determined reading from the pulse oximeter occurs over a time window that includes the body part of the user becoming momentarily stationary and comprises;

pulsing a red light source for approximately 50 microseconds; and

delaying approximately 450 microseconds before pulsing an infrared light source approximately 50 microseconds; and

record the determined reading from the pulse oximeter in the memory device.

8. The system of claim 7, further comprising a hub device configured to render the determined reading from the pulse oximeter to the user via a display.

9. The system of claim 7, wherein the reading from the pulse oximeter indicates a blood oxygen saturation level of the user.

10. The system of claim 7, wherein the pulse oximeter is a reflective pulse oximeter.

11. The system of claim 7, wherein the accelerometer is a 3-axis accelerometer.

12. The system of claim 7, wherein the body part of the user is a wrist.

13. A computer program product comprising a non-transitory computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed by a processor to implement a method for minimizing the effects of motion artifact on sensor readings taken during continuous transdermal monitoring of a body part in motion, said method comprising:

monitoring an output signal from an accelerometer, wherein the output signal indicates acceleration and deceleration of the body part of a user as the body part is in motion translating continuously between a rearward most point and a forward most point relative to the user;

determining from the output signal that the body part of the user has decelerated to a predetermined minimum before becoming momentarily stationary to begin acceleration;

based on the determination that the body part of the user has decelerated to the predetermined minimum, determining a reading from a pulse oximeter, wherein determining the reading from the pulse oximeter occurs over a time window that includes the body part of the user becoming momentarily stationary and comprises;

pulsing a red light source for approximately 50 microseconds; and

delaying approximately 450 microseconds before pulsing an infrared light source approximately 50 microseconds; and

recording in a memory device the determined reading from the pulse oximeter.

14. The computer program product of claim 13, further comprising rendering the determined reading from the pulse oximeter to the user via a display.

15. The computer program product of claim 13, wherein the reading from the pulse oximeter indicates a blood oxygen saturation level of the user.

16. The computer program product of claim 13, wherein the pulse oximeter is a reflective pulse oximeter.

17. The computer program product of claim 13, wherein the accelerometer is a 3-axis accelerometer.