METHOD AND APPARATUS FOR PROCESSING PHOTOPLETHYMOGRAPH SIGNALS

• US 20120253156A1
• Filed: 11/24/2010
• Published: 10/04/2012
• Est. Priority Date: 12/21/2009
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Muhlsteff, Jens
• Application Number:
  US13/513,912
• Publication Number:
  US 20120253156A1
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence

Abstract

The disclosure relates to the field a method of and apparatus for processing a photoplethysmograph signal to support the analysis of photoplethysmograph signals in clinical scenarios. A derivative of a photoplethysmograph signal acquired over a time period is calculated. The derivative of the acquired photoplethysmograph signal with respect to time is analyzed and displayed in an x-y diagram as a function of the acquired photoplethysmograph signal or vice versa.

Claims

1. A method of processing a photoplethysmograph signal retrieved from a subject, said method comprising the steps of:

acquiring the photoplethysmograph signal over a time period;

calculating a derivative with respect to time of the acquired photoplethysmograph signal; and

analyzing the derivative of the acquired photoplethysmograph signal as a function of the acquired photoplethysmograph signal or vice versa.

2. The method according to claim 1, wherein the derivative of the photoplethysmograph signal is a first derivative of the acquired photoplethysmograph signal with respect to time.

3. The method according to claim 1, wherein the step of analyzing comprises a step of comparing the derivative of the acquired photoplethysmograph signal as a function of the acquired photoplethysmograph signal with the derivative of a second photoplethysmograph signal as a function of a second photoplethysmograph signal, which second photoplethysmograph signal represents a specific physiological condition.

4. The method according to claim 1, wherein the acquired photoplethysmograph signal is displayed in an x-y diagram, wherein a first axis of the x-y diagram represents the derivative of the acquired photoplethysmograph signal, and a second axis of the x-y diagram represents the acquired photoplethysmograph signal.

5. The method according to claim 4, wherein photoplethysmograph signals acquired during different time periods are displayed in one x-y diagram.

6. The method according to claim 4, wherein at least two photoplethysmograph signals, which are acquired at different time periods, are displayed in the x-y diagram with an offset on the first axis with respect to each other.

7. The method according to claim 6, further comprising the step of monitoring a posture of the subject and wherein the offset is induced by a change of the posture of the subject.

14. A computer program for instructing a computer to perform the method according to claim 1.

15. A computer-readable medium such as a storage device, such as a floppy disk, CD, DVD, Blue Ray disk, or a random access memory (RAM), containing a set of instructions that causes a computer to perform a method according to claim 1.

8. A photoplethysmograph measurement apparatus comprising:

a sensor for acquiring a photoplethysmograph signal over a time period corresponding to a property of blood in the subject tissue, and

a processor connected to the sensor and adapted to receive and process the photoplethysmograph signal from the sensor,

wherein the processor is adapted to calculate a derivative with respect to time of the photoplethysmograph signal received from the sensor, and to analyze the derivative of the photoplethysmograph signal as a function of the photoplethysmograph signal or vice versa.

9. The photoplethysmograph measurement apparatus according to claim 8, wherein the processor is adapted to extract a parameter that characterizes at least a part of the x-y diagram.

10. The photoplethysmograph measurement apparatus according to claim 8, further comprising a display unit connected to the processor for displaying an x-y diagram, wherein a first axis of the x-y diagram on the display unit represents the derivative of the acquired photoplethysmograph signal, and a second axis of the x-y diagram represents the photoplethysmograph signal.

11. The photoplethysmograph measurement apparatus according to claim 8, wherein the processor calculates the first derivative with respect to the time of the photoplethysmograph signal received from the sensor.

12. The photoplethysmograph measurement apparatus according to claim 8, further comprising a posture sensor indicating the posture of the subject monitored by the photoplethysmograph measurement apparatus and wherein the processor is adapted to receive and process signals from the posture sensor.

13. A patient monitoring system comprising the photoplethysmograph measurement apparatus according to claim 8.