Method And System For Classification of Photo-Plethysmographically Detected Respiratory Effort

• US 20090240126A1
• Filed: 03/24/2009
• Published: 09/24/2009
• Est. Priority Date: 03/24/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: O'Neil, Michael, Baker, Clark R. JR., Hausmann, Gilbert, Campbell, Shannon
• Granted Patent: US 8,365,730 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• 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, comprising:

quantifying 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; and

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.

2. The method of claim 1, wherein quantifying 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 determining whether the patient is experiencing an apneic event comprises distinguishing the apneic event from a measurement artifact based at least in part on analysis of the respiratory effort and/or the value of the physiological parameter in conjunction with heart rate patterns of the patient.

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

7. The method of claim 1, wherein quantifying 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.

8. A method, comprising:

detecting a respiratory-induced effect on a photo-plethysmographic signal;

comparing the respiratory-induced effect to a respiratory effort of a ventilator; and

providing an indication to a caregiver and/or disabling automatic adjustment of ventilator settings if the respiratory-induced effect does not correspond to the respiratory effort.

9. The method of claim 8, comprising:

calculating a value of a physiological parameter of the patient; and

adjusting one or more of the ventilator settings based on the value of the physiological parameter based at least in part upon if the respiratory-induced effect corresponds to the respiratory effort.

10. The method of claim 9, wherein detecting the respiratory-induced effect and calculating the value of the physiological parameter comprise analyzing light attenuation data from a non-invasive pulse oximetry sensor.

11. The method of claim 9, wherein calculating the value of the physiological parameter comprises determining a pulse-based estimate of arterial blood oxygen saturation.

12. The method of claim 8, comprising:

detecting a pattern in the photo-plethysmographic signal indicative of a delay between a patient effort to trigger a breath and a ventilator trigger; and

adjusting ventilator triggering settings based on the delay if the respiratory-induced effect corresponds to the respiratory effort.

13. 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 an indication of respiratory effort of a patient;

estimate a value of a physiological parameter of the patient based at least in part on the measured attenuation; and

determine whether the patient is experiencing an apneic event based at least in part on the respiratory effort and/or the value of the physiological parameter, and/or combinations thereof.

14. The system of claim 13, 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.