Methods and systems for determining physiological information based on distortion information

• US 10,098,575 B2
• Filed: 01/23/2015
• Issued: 10/16/2018
• Est. Priority Date: 01/23/2014
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Wilmering, Tom
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US14/604,601
• Publication Number:
  US 20150201873A1
• Time in Patent Office: 1,362 Days
• 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 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal

Abstract

Methods and systems are provided for determining physiological information based on distortion factors and physiological signals. Physiological signals are received by a system. The system may receive or determine a value indicative of oxygen saturation. The distortion factors may be calculated based on the value indicative of oxygen saturation and the physiological signals. The distortion factors may be used to determine physiological information.

Claims

1. A system for operating a physiological monitor, the system comprising:

an input configured for receiving physiological signals, the physiological signals comprising a first physiological signal and a second, subsequent physiological signal, the first physiological signal and the second, subsequent physiological signal each comprising a first component corresponding to a first wavelength of light and a second component corresponding to a second wavelength of light; and

one or more processors configured to perform operations comprising;

receiving a value indicative of oxygen saturation;

determining a distortion factor corresponding to one of the first and second wavelengths of light based on the first component of the received first physiological signal, the second component of the received first physiological signal, and the value indicative of oxygen saturation; and

determining physiological information using the distortion factor and the second, subsequent physiological signal.

2. The system of claim 1, wherein determining the physiological information comprises:

determining an AC component of the second, subsequent physiological signal;

determining a baseline component of the second, subsequent physiological signal; and

determining a value indicative of perfusion using the AC component, the baseline component, and the distortion factor.

3. The system of claim 2, wherein determining the value indicative of perfusion comprises determining the value indicative of perfusion using the following expression:

4. The system of claim 1, wherein the first component and the second component correspond to tissue at a first depth, wherein the second, subsequent physiological signal further comprises a third component corresponding to the first wavelength of light and a fourth component corresponding to the second wavelength of light, wherein the third component and the fourth component correspond to tissue at a second depth;

wherein determining the physiological information comprises determining regional oxygen saturation using the first component, the second component, the third component, the fourth component, and the distortion factor.

5. The system of claim 4, wherein determining regional oxygen saturation comprise determining the regional oxygen saturation using an equation of the form:

6. The system of claim 1, wherein the one or more processors are further configured to perform operations comprising determining a value indicative of changes in the distortion factor over time, wherein the physiological information comprises confidence information associated with the physiological signal.

7. The system of claim 1, wherein the one or more processors are further configured to perform operations comprising:

determining a value indicative of changes in the distortion factor over time;

comparing the value indicative of changes to a threshold; and

generating an alert based on the comparison.

8. The system of claim 1, wherein the distortion factor comprises a first distortion factor corresponding to the first wavelength of light, wherein the one or more processors are further configured to perform operations comprising:

determining a second distortion factor corresponding to the second wavelength of light based on the first component of the received first physiological signal, the second component of the received first physiological signal, and the value indicative of oxygen saturation, wherein determining the physiological information comprises determining the physiological information using the first distortion factor and the second distortion factor.

9. The system of claim 8, wherein the first physiological signal comprises a third component corresponding to a third wavelength of light, wherein the one or more processors are further configured to perform operations comprising:

determining a third distortion factor corresponding to the third wavelength of light based on the first component of the received first physiological signal, the second component of the received first physiological signal, the third component of the received first physiological signal, and the value indicative of oxygen saturation, wherein determining the physiological information comprises determining the physiological information using the first distortion factor, the second distortion factor, and the third distortion factor.

10. The system of claim 1, wherein the physiological information comprises cardiac output information.

11. The system of claim 1, wherein the physiological information comprises stroke volume information.

12. The system of claim 1, wherein the value indicative of oxygen saturation comprises a ratio of oxygenated hemoglobin and total hemoglobin.