SYSTEMS AND METHODS FOR DETERMINING WHETHER REGIONAL OXIMETRY SENSORS ARE PROPERLY POSITIONED

• US 20150208962A1
• Filed: 01/26/2015
• Published: 07/30/2015
• Est. Priority Date: 01/27/2014
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Baker, Clark R. Jr.
• Granted Patent: US 9,867,561 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/684 Indicating the position of the sensor on the body
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence

Abstract

Methods and systems are presented for determining whether a regional oximetry sensor is properly positioned on a subject. First and second metric values may be determined based on respective first and second light signals. The first and second metric values and a relationship between the first and second metrics are used to determine whether the sensor is properly positioned on the subject. The first and second metrics may form a pair of metrics, and whether the sensor is properly positioned on the subject may be determined based on whether the pair of metrics falls within a sensor-on region. In some embodiments, a plurality of metrics may be determined based on a plurality of received physiological signals. The plurality of metrics may be combined, using, for example, a neural network, to determine whether the regional oximetry sensor is properly positioned on a subject.

Claims

1. A system for determining whether a regional oximetry sensor is properly positioned on a subject, the system comprising:

one or more inputs configured for;

receiving a first signal representative of an intensity of light at a first detector of the regional oximetry sensor; and

receiving a second signal representative of an intensity of light at a second detector of the regional oximetry sensor; and

one or more processors configured for;

determining a first metric value based on the first signal;

determining a second metric value based on the second signal; and

determining, based on the first metric value, the second metric value, and a relationship between the first metric and the second metric, whether the regional oximetry sensor is properly positioned on the subject.

2. The system of claim 1, wherein the one or more processors are further configured for using a neural network to determine, based on the first metric value, the second metric value, and the relationship, whether the regional oximetry sensor is properly positioned on the subject.

3. The system of claim 1, wherein the one or more processors are further configured for determining the regional oxygen saturation (rSO₂) of the subject when it is determined that the regional oximetry sensor is properly positioned on the subject.

4. The system of claim 1, wherein the one or more processors are further configured for:

normalizing the first signal based on a first calibration coefficient;

normalizing the second signal based on a second calibration coefficient; and

wherein;

determining the first metric value based on the first signal comprises determining the first metric value based on the normalized first signal, and

determining the second metric value based on the second signal comprises determining the second metric value based on the normalized second signal.

5. The system of claim 4, wherein the regional oximetry sensor comprises a light source for emitting a plurality of wavelengths of light, wherein the first and second detectors receive the plurality of wavelengths of light, and wherein:

the first calibration coefficient is based on the brightness of the light source and the sensitivity of the first detector, and

the second calibration coefficient is based on the brightness of the light source and the sensitivity of the second detector.

6. The system of claim 4, wherein:

the first metric value is based on a near-infrared light component of the first signal;

the second metric value is based on a near-infrared light component of the second signal; and

wherein the one or more processors are further configured for;

comparing the first metric value and the second metric value to a distribution threshold, wherein the distribution threshold is a function of the first metric and the second metric, and

determining, based on the comparison, whether the regional oximetry sensor is properly positioned on the subject.

7. The system of claim 1, wherein the one or more processors are further configured for:

considering the first metric value and the second metric value as a pair of metrics, wherein the pair of metrics is associated with the first and second signals; and

determining whether the pair of metrics falls within a sensor-on region, wherein determining, based on the first metric value, the second metric value, and the relationship, whether the regional oximetry sensor is properly positioned comprises determining, based on whether the pair of metrics falls within a sensor-on region, whether the regional oximetry sensor is properly positioned on the subject.

8. The system of claim 1, wherein the one or more processors are further configured for:

determining a first morphology metric value associated with morphology of the first signal; and

determining a second morphology metric value associated with morphology of the second signal.

9. The system of claim 8, wherein the first signal is associated with a first mean path length and the second signal is associated with a second mean path length such that the second mean path length is longer than the first mean path length, and wherein determining the first morphology metric value is based on the shape of the pulsatile modulation of the first signal.

10. The system of claim 9, wherein determining the first morphology metric is based on skewness of a first derivative of the first signal.

11. The system of claim 9, wherein determining the second morphology metric value is based on the peak-to-peak modulation of the second signal.

12. The system of claim 8, wherein the one or more processors are further configured for:

considering the first morphology metric and the second morphology metric as a pair of metrics, wherein the pair of metrics is associated with the morphologies of the first and second signals; and

determining whether the pair of metrics falls within a sensor-on region, wherein determining, based on the first metric value, the second metric value, and the relationship, whether the regional oximetry sensor is properly positioned comprises determining, based on whether the pair of metrics falls within a sensor-on region, whether the regional oximetry sensor is properly positioned on the subject.

13. The system of claim 1, wherein the second metric value is based on an ambient light component of the second signal.

14. The system of claim 1, wherein the one or more processors are further configured for:

determining a first trend parameter based on the values of the first metric over time; and

determining a second trend parameter based on values of the second metric over time, wherein determining, based on the first metric value, the second metric value, and the relationship, whether the regional oximetry sensor is properly positioned comprises determining, based on the first and second trend parameters, whether the regional oximetry sensor is properly positioned.

15. The system of claim 1, wherein the one or more processors are further configured for:

receiving an impedance signal; and

determining a third metric value based on the impedance signal, wherein determining whether the regional oximetry sensor is properly positioned on the subject is further based on the third metric value.

16. The system of claim 1, wherein the one or more processors are further configured for detecting variations in the levels of the first and second signals, and wherein the first metric value and the second metric value are based on the detected variations in the levels of the respective first and second signals.

17. The system of claim 1, wherein the one or more processors are further configured for receiving sensor information, wherein the sensor information comprises a sensor type, and wherein determining whether the regional oximetry sensor is properly positioned on the subject is further based on the sensor information.

18. The system of claim 17, wherein the sensor type comprises an identification of whether the regional oximetry sensor is an infant sensor or an adult sensor.

19. The system of claim 17, wherein the sensor information is indicative of where, on the subject, the regional oximetry sensor is configured for positioning.

20. A method for determining whether a regional oximetry sensor is properly positioned on a subject, the method comprising:

receiving a first signal representative of an intensity of light at a first detector of the regional oximetry sensor;

receiving a second signal representative of an intensity of light at a second detector of the regional oximetry sensor;

determining, using one or more processors, a first metric value based on the first signal;

determining, using one or more processors, a second metric value based on the second signal; and

determining, using one or more processors, based on the first metric value, the second metric value, and a relationship between the first metric and the second metric, whether the regional oximetry sensor is properly positioned on the subject.