METHODS AND SYSTEMS FOR QUALIFYING CALCULATED VALUES BASED ON A STATISTICAL METRIC

• US 20140073865A1
• Filed: 09/11/2012
• Published: 03/13/2014
• Est. Priority Date: 09/11/2012
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Rodriguez-Llorente, Fernando, Engelbrecht, Pirow, Wooder, Nicholas James
• Granted Patent: US 9,186,110 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G06F 2218/10 by analysing the shape of a waveform, e.g. extracting parameters relating to peaks
• CPC Class Codes: G06F 2218/14 by matching peak patterns
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may receive a calculated value indicative of a physiological rate. The system may generate value pairs from a first collection of values of the physiological signal and another collection of corresponding value of the physiological signal spaced from the first collection based on the calculated value. The system may determine a best fit linear relationship based on the value pairs and determine at least one statistical metric based on the linear relationship and the value pairs. The system may qualify or disqualify the calculated value based on the at least one statistical metric.

Claims

1. A subject monitoring system for processing physiological information of a subject, comprising:

a sensor configured to generate a physiological signal, wherein the sensor detects light attenuated by the subject; and

processing equipment coupled to the sensor, wherein the processing equipment is configured to;

receive a calculated value that may be indicative of a physiological rate of the subject;

generate a plurality of value pairs each comprising a first sample point of the physiological signal and a second point of the physiological signal spaced apart by a particular spacing, wherein the particular spacing is based on the calculated value;

determine a best fit linear relationship based on the plurality of value pairs;

determining at least one statistical metric based on the linear relationship and the plurality of value pairs; and

qualify or disqualifying the calculated value based on the at least one statistical metric.

2. The system of claim 1, wherein the processing equipment is further configured to determine a standard error between the plurality of value pairs and the linear relationship, and a slope of the linear relationship.

3. The system of claim 1, wherein the processing equipment is further configured to determine a value indicative of the probability, relative to a predetermined probability distribution function, of the at least one statistical metric being outside of a set of bounding values.

4. The system of claim 3, wherein the processing equipment is further configured to:

determine at least one additional spacing other than the particular spacing, and for each of the at least one additional spacing;

generate a plurality of value pairs each comprising a first sample point of the physiological signal and a second point of the physiological signal spaced apart by the respective spacing,

determine a best fit linear relationship based on the respective plurality of value pairs, and

determine at least one statistical metric based on the respective linear relationship and the respective plurality of value pairs; and

determine a value indicative of the probability, relative to a predetermined probability distribution function, of the respective at least one statistical metric being outside of the set of bounding values;

calculate a sum based on the values indicative of the probability of the respective at least one statistical metric being outside of the set of bounding values for the at least one additional lag value and the value indicative of the probability of the at least one statistical metric being outside of the set of bounding values for the particular spacing; and

qualify or disqualify the calculated value based on the sum.

5. The system of claim 3, wherein the processing equipment is further configured to use a reference look-up table comprising a plurality of probability values.

6. A processing module for processing physiological information of a subject, wherein the processing module is configured to:

receive a physiological signal derived from a detector output, wherein the detector detects light attenuated by the subject;

receive a calculated value that may be indicative of a physiological rate of the subject;

generate a plurality of value pairs each comprising a first sample point of the physiological signal and a second point of the physiological signal spaced apart by a particular spacing, wherein the particular spacing is based on the calculated value;

determine a best fit linear relationship based on the plurality of value pairs;

determining at least one statistical metric based on the linear relationship and the plurality of value pairs; and

qualify or disqualifying the calculated value based on the at least one statistical metric.

7. The processing module of claim 6, further configured to determine a standard error between the plurality of value pairs and the linear relationship, and a slope of the linear relationship.

8. The processing module of claim 6, further configured to determine a value indicative of the probability, relative to a predetermined probability distribution function, of the at least one statistical metric being outside of a set of bounding values.

9. The processing module of claim 8, further configured to:

determine at least one additional spacing other than the particular spacing, and for each of the at least one additional spacing;

generate a plurality of value pairs each comprising a first sample point of the physiological signal and a second point of the physiological signal spaced apart by the respective spacing,

determine a best fit linear relationship based on the respective plurality of value pairs, and

determine at least one statistical metric based on the respective linear relationship and the respective plurality of value pairs; and

determine a value indicative of the probability, relative to a predetermined probability distribution function, of the respective at least one statistical metric being outside of the set of bounding values;

calculate a sum based on the values indicative of the probability of the respective at least one statistical metric being outside of the set of bounding values for the at least one additional lag value and the value indicative of the probability of the at least one statistical metric being outside of the set of bounding values for the particular spacing; and

qualify or disqualify the calculated value based on the sum.

10. The processing module of claim 8, further configured to use a reference look-up table comprising a plurality of probability values.

11. A method for processing physiological information of a subject, comprising:

receiving, using processing equipment, a physiological signal derived from a detector output, wherein the detector detects light attenuated by the subject;

receiving, using the processing equipment, a calculated value that may be indicative of a physiological rate of the subject;

generating, using the processing equipment, a plurality of value pairs each comprising a first sample point of the physiological signal and a second point of the physiological signal spaced apart by a particular spacing, wherein the particular spacing is based on the calculated value;

determining, using the processing equipment, a best fit linear relationship based on the plurality of value pairs;

determining, using the processing equipment, at least one statistical metric based on the linear relationship and the plurality of value pairs; and

qualifying or disqualifying, using the processing equipment, the calculated value based on the at least one statistical metric.

12. The method of claim 11, wherein determining the at least one statistical metric comprises determining a standard error between the plurality of value pairs and the linear relationship, and a slope of the linear relationship.

13. The method of claim 11, wherein qualifying or disqualifying the calculated value comprises determining a value indicative of the probability, relative to a predetermined probability distribution function, of the at least one statistical metric being outside of a set of bounding values.

14. The method of claim 13, further comprising:

determining at least one additional spacing other than the particular spacing, and for each of the at least one additional spacing;

generating a plurality of value pairs each comprising a first sample point of the physiological signal and a second point of the physiological signal spaced apart by the respective spacing,

determining a best fit linear relationship based on the respective plurality of value pairs, and

determining at least one statistical metric based on the respective linear relationship and the respective plurality of value pairs; and

determining a value indicative of the probability, relative to a predetermined probability distribution function, of the respective at least one statistical metric being outside of the set of bounding values; and

calculating a sum based on the values indicative of the probability of the respective at least one statistical metric being outside of the set of bounding values for the at least one additional lag value and the value indicative of the probability of the at least one statistical metric being outside of the set of bounding values for the particular spacing, wherein qualifying or disqualifying the calculated value is based on the sum.

15. The method of claim 13, wherein determining the value indicative of the probability of the respective at least one statistical metric being outside of the set of bounding values comprises using a reference look-up table comprising a plurality of probability values.

16. A computer-readable medium for use in processing physiological information of a subject, the computer-readable medium having computer program instructions recorded thereon for:

receiving a physiological signal derived from a detector output, wherein the detector detects light attenuated by the subject;

receiving a calculated value that may be indicative of a physiological rate of the subject;

generating a plurality of value pairs each comprising a first sample point of the physiological signal and a second point of the physiological signal spaced apart by a particular spacing, wherein the particular spacing is based on the calculated value;

determining a best fit linear relationship based on the plurality of value pairs;

determining at least one statistical metric based on the linear relationship and the plurality of value pairs; and

qualifying or disqualifying the calculated value based on the at least one statistical metric.

17. The computer-readable medium of claim 16, having further computer program instructions recorded thereon for determining a standard error between the plurality of value pairs and the linear relationship, and a slope of the linear relationship.

18. The computer-readable medium of claim 16, having further computer program instructions recorded thereon for determining a value indicative of the probability, relative to a predetermined probability distribution function, of the at least one statistical metric being outside of a set of bounding values.

19. The computer-readable medium of claim 18, having further computer program instructions recorded thereon for:

determining at least one additional spacing other than the particular spacing, and for each of the at least one additional spacing;

generating a plurality of value pairs each comprising a first sample point of the physiological signal and a second point of the physiological signal spaced apart by the respective spacing,

determining a best fit linear relationship based on the respective plurality of value pairs, and

determining at least one statistical metric based on the respective linear relationship and the respective plurality of value pairs; and

determining a value indicative of the probability, relative to a predetermined probability distribution function, of the respective at least one statistical metric being outside of the set of bounding values;

calculating a sum based on the values indicative of the probability of the respective at least one statistical metric being outside of the set of bounding values for the at least one additional lag value and the value indicative of the probability of the at least one statistical metric being outside of the set of bounding values for the particular spacing; and

qualifying or disqualifying the calculated value based on the sum.

20. The computer-readable medium of claim 18, having further computer program instructions recorded thereon for using a reference look-up table comprising a plurality of probability values.