Adjusting parameters used in pulse oximetry analysis

• US 9,131,878 B2
• Filed: 07/12/2012
• Issued: 09/15/2015
• Est. Priority Date: 10/28/2005
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Baker, Clark R. Jr.
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US13/548,008
• Publication Number:
  US 20120277595A1
• Time in Patent Office: 1,160 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence

Abstract

Adjusting a pulse qualification criterion includes receiving a signal representing a plurality of pulses, where the signal is generated in response to detecting light scattered from blood perfused tissue. A characteristic is determined. A pulse qualification criterion used for qualifying a pulse is adjusted in accordance with the characteristic. The pulses are evaluated according to the pulse qualification criterion.

Claims

1. A method for calculating a physiological parameter, comprising:

receiving, via a processor, a signal representing a plurality of pulses, the signal generated in response to detecting light scattered from blood perfused tissue;

determining, via the processor, an ensemble averaging weight for an ensemble averaging filter;

adjusting, via the processor, a pulse qualification criterion in accordance with the ensemble averaging weight, the pulse qualification criterion for qualifying a pulse;

evaluating, via the processor, the plurality of pulses according to the pulse qualification criterion to determine one or more qualified pulses of the plurality of pulses;

ensemble averaging, via the ensemble averaging filter, the one or more qualified pulses of the plurality of pulses using the ensemble averaging weight;

calculating, via the processor, a physiological parameter based at least in part upon one or more ensemble averaged pulses; and

outputting, via the processor, the physiological parameter for display.

2. The method of claim 1, wherein adjusting the pulse qualification criterion comprises reducing a noise gate level when the ensemble averaging weight is below a threshold.

3. The method of claim 1, wherein:

adjusting a pulse qualification criterion in accordance with the ensemble averaging weight comprises adjusting, via the processor, a pulse period threshold to disqualify a pulse having a pulse period that is substantially shorter than an average pulse period.

4. The method of claim 1, wherein evaluating the plurality of pulses in accordance with the pulse qualification criterion comprises applying a trained neural net to the plurality of pulses to determine the one or more qualified pulses.

5. The method of claim 1, wherein the pulse qualification criterion comprises a threshold for a signal metric of the signal.

6. The method of claim 5, wherein the signal metric comprises amplitude, period, pulse shape, ratio-of-ratios, or rise time.

7. A system configured to calculate a physiological parameter, comprising:

an interface configured to;

receive a signal representing a plurality of pulses, the signal generated in response to detecting light scattered from blood perfused tissue;

an ensemble averaging filter configured to filter the signal; and

a processor configured to;

determine an ensemble averaging weight for the ensemble averaging filter;

adjust a pulse qualification criterion in accordance with the ensemble averaging weight, the pulse qualification criterion for qualifying a pulse; and

evaluate the plurality of pulses according to the pulse qualification criterion to determine one or more qualified pulses of the plurality of pulses;

wherein the ensemble averaging filter is configured to ensemble average the one or more qualified pulses of the plurality of pulses using the ensemble averaging weight, and the processor is configured to calculate a physiological parameter based at least in part upon one or more ensemble averaged pulses and output the physiological parameter for display.

8. The system of claim 7, wherein the processor is configured to adjust the pulse qualification criterion by reducing a noise gate level when the ensemble averaging weight is below a threshold.

9. The system of claim 7, the processor further configured to:

adjust a pulse qualification criterion in accordance with the ensemble averaging weight by adjusting a pulse period threshold to disqualify a pulse having a pulse period that is substantially shorter than an average pulse period.

10. The system of claim 7, wherein the processor is configured to apply a trained neural net to the plurality of pulses to determine the one or more qualified pulses.

11. The system of claim 7, wherein the pulse qualification criterion comprises a threshold for a signal metric of the signal.

12. The system of claim 11, wherein the signal metric comprises amplitude, period, pulse shape, ratio-of-ratios, or rise time.

13. A system for calculating a physiological parameter, comprising:

means for receiving a signal representing a plurality of pulses, the signal generated in response to detecting light scattered from blood perfused tissue;

means for determining an ensemble averaging weight for an ensemble averaging filter;

means for adjusting a pulse qualification criterion in accordance with the ensemble averaging weight, the pulse qualification criterion for qualifying a pulse;

means for evaluating the plurality of pulses according to the pulse qualification criterion to determine one or more qualified pulses of the plurality of pulses;

means for ensemble averaging the one or more qualified pulses of the plurality of pulses using the ensemble averaging weight;

means for calculating a physiological parameter based on one or more ensemble averaged pulses; and

means for outputting the physiological parameter for display.

14. The system of claim 13, wherein the means for adjusting a pulse qualification criterion comprises means for reducing a noise gate level when the ensemble averaging weight is below a threshold.

15. The system of claim 13, wherein the pulse qualification criterion comprises a threshold for a signal metric of the signal.

16. The system of claim 15, wherein the signal metric comprises amplitude, period, pulse shape, ratio-of-ratios, or rise time.

17. A system configured to calculate a physiological parameter, comprising:

an interface configured to;

receive a signal representing a plurality of pulses, the signal generated in response to detecting light scattered from blood perfused tissue;

an ensemble averaging filter configured to filter the signal; and

a processor configured to;

determine an ensemble averaging weight for the ensemble averaging filter;

adjust one or more pulse qualification criteria in accordance with the ensemble averaging weight, a pulse qualification criterion for qualifying a pulse, the one or more pulse qualification criteria adjusted by;

reducing a noise gate level of a noise gate criterion based at least in part on the ensemble averaging weight; and

adjusting a pulse period criterion to disqualify a pulse having a pulse period that is substantially shorter than an average pulse period; and

evaluate the plurality of pulses according to the one or more pulse qualification criteria to determine one or more qualified pulses of the plurality of pulses, wherein the ensemble averaging filter is configured to ensemble average the one or more qualified pulses using the ensemble averaging weight, and the processor is configured to calculate a physiological parameter based at least in part on one or more ensemble averaged pulses and to output the physiological parameter for display.

18. The system of claim 17, wherein the signal metric comprises amplitude, period, pulse shape, ratio-of-ratios, or rise time.

19. The system of claim 18, wherein the one or more pulse qualification criteria comprise a threshold for a signal metric of the signal.

20. The system of claim 19, wherein the signal metric comprises amplitude, period, pulse shape, ratio-of-ratios, or rise time.