Monitoring physiological parameters based on variations in a photoplethysmographic signal

• US 7,001,337 B2
• Filed: 03/02/2004
• Issued: 02/21/2006
• Est. Priority Date: 02/22/2002
• Status: Expired due to Term

• Current Assignee: Datex-Ohmeda Incorporated (GE Healthcare Technologies, Inc.)
• Original Assignee: Datex-Ohmeda Incorporated (GE Healthcare Technologies, Inc.)
• Inventors: Dekker, Andreas Lubbertus Aloysius Johannes
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US10/790,950
• Publication Number:
  US 20040260186A1
• Time in Patent Office: 721 Days
• Field of Search: 600529-543, 600500-505, 600/507, 600/481, 600483-485
• US Class Current: 600/484
• 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 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1073 Measuring volume, e.g. of limbs
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

A method and apparatus are disclosed for using photoplethysmography to obtain physiological parameter information related to respiration rate, heart rate, heart rate variability, blood volume variability and/or the autonomic nervous system. In one implementation, the process involves obtaining (2502) a pleth, filtering (2504) the pleth to remove unwanted components, identifying (2506) a signal component of interest, monitoring (2508) blood pressure changes, monitoring (2510) heart rate, and performing (2512) an analysis of the blood pressure signal to the heart rate signal to identify a relationship associated with the component of interest. Based on this relationship, the component of interest may be identified (2514) as relating to the respiration or Mayer Wave. If it is related to the respiration wave (2516), a respiratory parameter such as breathing rate may be determined (2520). Otherwise, a Mayer Wave analysis (2518) may be performed to obtain parameter information related to the autonomic nervous system.

Claims

1. A method for use in non-invasively monitoring a physiological parameter of a patient, comprising the steps of:

obtaining a time-based photoplethysmographic (“

pleth”

) signal that is modulated based on interaction of a transmitted optical signal with blood of said patient, wherein said pleth signal includes at least a first component associated with the operation of the patient'"'"'s respiratory system and a second Mayer wave component associated with the patient'"'"'s autonomic nervous system;

transforming said time-based pleth signal into a frecquency domain to obtain spectral information including information associated with said first component and said second Mayer wave components;

processing said spectral information to distinguish an effect associated with one of said first component and second Mayer wave component from an effect associated with the other of said components; and

using said distinguished effect to monitor said physiological parameter.

2. A method as set forth in claim 1, further comprising:

providing an output related to said Mayer wave.

3. A method as set forth in claim 2, wherein said step of providing an output comprises providing a graphical output that shows at least one of an amplitude and a frequency of the Mayer Wave.

4. A method as set forth in claim 1, further comprising monitoring one of said amplitude and said frequency over time to detect a variation of interest.

5. A method as set forth in claim 1, wherein said step of processing comprises extracting information regarding at least one of an amplitude and a frequency of a Mayer Wave.

6. A method as set forth in claim 5, wherein said step of processing comprises filtering the spectral information to extract information regarding the Mayer Wave.

7. A method as set forth in claim 6, wherein said step of filtering comprises band pass filtering the spectral information using a frequency band that passes a spectral peak of said spectral information located between about 0.05 Hz and 0.5 Hz.

8. A method as set forth in claim 1, further comprising:

processing said spectral information to identify a variation in blood volume.

9. A method as set forth in claim 1, wherein said step of processing comprises first analyzing said spectral information to obtain heart rate information.

10. A method as set forth in claim 9, wherein said step of processing further comprises monitoring said heart rate information over time to obtain a time series of heart rate values.

11. A method as set forth in claim 9, wherein said step of processing further comprises second analyzing said heart rate information to obtain information regarding heart rate variability.

12. A method as set forth in claim 9, wherein said heart rate information comprises a time series of heart rate values and said step of processing further comprises filtering said time series of heart rate values to identify a low frequency variability therein.

13. A method as set forth in claim 12, wherein said low frequency variability is in the range between about 0.05 Hz and 0.5 Hz.