Method and system for classification of photo-plethysmographically detected respiratory effort

• US 8,365,730 B2
• Filed: 03/24/2009
• Issued: 02/05/2013
• Est. Priority Date: 03/24/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Baker, Clark R. Jr., O'Neil, Michael, Campbell, Shannon, Hausmann, Gilbert
• Primary Examiner(s): Anderson, Lynne
• Assistant Examiner(s): PHILIPS, BRADLEY H
• Application Number:
  US12/409,685
• Publication Number:
  US 20090240126A1
• Time in Patent Office: 1,414 Days
• Field of Search: 128/200.24, 128/204.18, 128/204.23, 128/204.22
• US Class Current: 128/204.23
• 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 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0057 Pumps therefor
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/33 Controlling, regulating or measuring
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2230/20 Blood composition characteristics
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/40 Respiratory characteristics

Abstract

Embodiments disclosed herein may include systems and methods for determining a patient'"'"'s respiratory effort and blood oxygen saturation based on data acquired from a pulse oximetry sensor and analyzing the parameters in conjunction with each other. For example, the respiratory effort may be determined based on a photo-plethysmographic waveform generated from light attenuation detected by the sensor, and the blood oxygen saturation may be a pulse -based estimate of arterial blood oxygen saturation determined from the detected attenuation. Analysis of the parameters may enable detection and classification of apnea (e.g., obstructive or central) or another underlying cause for respiratory instability. Furthermore, the measured respiratory effort may be compared to respiratory effort supplied by a ventilator to ensure proper sensor placement before enabling automatic adjustment of ventilator settings.

Claims

1. A method performed by a photo-plethysmographic monitor, the method comprising:

determining a respiratory effort of a patient based at least in part on a photo-plethysmographic signal;

calculating a value of a physiological parameter of the patient based at least in part on the photo-plethysmographic signal;

determining whether the patient is experiencing an apneic event based at least in part on the respiratory effort and the value of the physiological parameter; and

distinguishing the apneic event from a measurement artifact based at least in part on analysis of the respiratory effort and the value of the physiological parameter in conjunction with heart rate patterns of the patient.

2. The method of claim 1, wherein determining the respiratory effort and calculating the value of the physiological parameter comprise analyzing light attenuation data from a non-invasive pulse oximetry sensor.

3. The method of claim 1, comprising characterizing the apneic event based at least in part on the respiratory effort and the value of the physiological parameter.

4. The method of claim 3, wherein characterizing the apneic event comprises analyzing a history of repetitive changes in the respiratory effort and/or changes in the value of the physiological parameter, and/or combinations thereof.

5. The method of claim 1, wherein calculating the value of the physiological parameter comprises determining a pulse-based estimate of arterial blood oxygen saturation.

6. The method of claim 1, wherein determining the respiratory effort comprises determining an indication of a respiratory minute volume, a respiratory rate, a tidal volume, a diaphragmatic or intrathoracic pressure variation, and/or a combination thereof.

7. A system, comprising:

a sensor configured to emit light into tissue and to measure attenuation of the light from the tissue;

a monitor configured to;

generate a photo-plethysmographic waveform based at least in part upon the measured attenuation;

determine a respiratory effort of a patient based at least in part on the photo-plethysmographic waveform;

estimate a value of a physiological parameter of the patient based at least in part on the photo-plethysmographic waveform;

determine whether the patient is experiencing an apneic event based at least in part on the respiratory effort and the value of the physiological parameter; and

distinguish the apneic event from a measurement artifact based at least in part on analysis of the respiratory effort and the value of the physiological parameter in conjunction with heart rate patterns of the patient.

8. The system of claim 7, wherein the monitor is configured to characterize the apneic event based at least in part on the respiratory effort and the value of the physiological parameter.

9. The system of claim 8, wherein the monitor is further configured to analyze a history of repetitive changes in the respiratory effort and/or changes in the value of the physiological parameter, and/or combinations thereof.

10. The system of claim 7, wherein the monitor is further configured to analyze light attenuation data from a non-invasive pulse oximetry sensor.

11. The system of claim 7, wherein the monitor is further configured to determine a pulse-based estimate of arterial blood oxygen saturation.

12. The system of claim 7, wherein the monitor is further configured to determine an indication of a respiratory minute volume, a respiratory rate, a tidal volume, a diaphragmatic or intrathoracic pressure variation, and/or a combination thereof.