Systems and methods for assessing measurements in physiological monitoring devices

• US 8,290,730 B2
• Filed: 06/30/2009
• Issued: 10/16/2012
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Watson, James N., Baker, Clark R. Jr., Addison, Paul Stanley
• Primary Examiner(s): WACHSMAN, HAL D
• Application Number:
  US12/494,971
• Publication Number:
  US 20100332173A1
• Time in Patent Office: 1,204 Days
• Field of Search: 702/85, 702/19, 702/50, 702/98, 702/100, 702/139
• US Class Current: 702/85
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• 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 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

Methods and systems are provided for deriving and analyzing shape metrics, including skewness metrics, from physiological signals and their derivatives to determine measurement quality, patient status and operating conditions of a physiological measurement device. Such determinations may be used for any number of functions, including indicating to a patient or care provider that the measurement quality is low or unacceptable, alerting a patient or care provider to a change in patient status, triggering or delaying a recalibration of a monitoring device, and adjusting the operating parameters of a monitoring system.

Claims

1. A method for initiating a recalibration of a measurement device, comprising:

receiving a first sensor signal representative of a physiological process;

calculating a skewness value representative of a skewness of the received first signal;

generating, an electronic recalibration signal based at least in part on a comparison of the skewness value and at least one reference skewness value; and

transmitting the electronic recalibration signal to a measurement device to initiate a recalibration of the measurement device.

2. The method of claim 1, wherein the received first signal is a photoplethysmograph signal.

3. The method of claim 1, wherein the measurement device is a part of a continuous, non-invasive blood pressure monitoring system.

4. The method of claim 1, wherein calculating a skewness value comprises calculating at least one of a skewness of a time derivative of the received first signal and a ratio of characteristics of the received first signal.

5. The method of claim 1, wherein the at least one reference skewness value is based at least in part on at least one past portion of the received first signal.

6. The method of claim 1, wherein the received first signal is based at least in part on a comparison of an electronic signal generated by a sensor located at a first site on a patient'"'"'s body and an electronic signal generated by a sensor located at a second site on the patient'"'"'s body.

7. The method of claim 1, further comprising:

generating an electronic measurement quality signal based at least in part on a comparison of the skewness value and the at least one reference skewness value.

8. The method of claim 7, wherein the electronic recalibration signal is further based at least in part on the electronic measurement quality signal.

9. The method of claim 7, further comprising determining, with the measurement device, a physiological measurement based at least in part on the received first signal and the electronic measurement quality signal.

10. A system for initiating a recalibration of a measurement device, comprising:

at least one memory device, storing at least one reference skewness value;

a calibration device, configured to initiate a recalibration of the measurement device in response to a recalibration signal;

a processor, communicably coupled to the at least one memory device and to the calibration device configured to receive a first sensor signal representative of a physiological process, the processor further configured to;

calculate a skewness value representative of a skewness of the received first signal;

retrieve the at least one reference skewness value from the at least one memory device;

generate a recalibration signal based at least in part on a comparison of the skewness value and the at least one reference skewness value; and

transmit the recalibration signal to the calibration device.

11. The system of claim 10, wherein the received first signal is a photoplethysmograph signal.

12. The system of claim 10, wherein the measurement device is a part of a continuous, non-invasive blood pressure monitoring system.

13. The system of claim 10, wherein calculating a skewness value comprises calculating at least one of a skewness of a time derivative of the received first signal and a ratio of characteristics of the received first signal.

14. The system of claim 10, wherein the at least one reference skewness value is based at least in part on at least one past portion of the received first signal.

15. The system of claim 10, wherein the received first signal is based at least in part on a comparison of a signal generated by a sensor located at a first site on a patient'"'"'s body and a signal generated by a sensor located at a second site on the patient'"'"'s body.

16. The system of claim 10, wherein the processor is further configured to:

generate a measurement quality signal based at least in part on a comparison of the skewness value and at least one reference skewness value.

17. The system of claim 16, wherein generating a recalibration signal is further based at least in part on the measurement quality signal.

18. The system of claim 16, wherein the processor is further configured to:

generate a physiological measurement based at least in part on the received first signal and the measurement quality signal.

19. A non-transitory computer-readable medium for use in initiating a recalibration of a physiological measurement, the computer-readable medium having computer program instructions recorded thereon for causing processing equipment to:

receive a first sensor signal representative of a physiological process;

calculate a skewness value representative of a skewness of the received first signal;

generate, an electronic recalibration signal based at least in part on a comparison of the skewness value and at least one reference skewness value; and

transmit the electronic recalibration signal to a measurement device to initiate a recalibration of the measurement device.

20. The non-transitory computer-readable medium of claim 19, wherein the received first signal is a photoplethysmograph signal.