SYSTEMS AND METHODS FOR DETERMINING WHEN TO MEASURE A PHYSIOLOGICAL PARAMETER

• US 20120143067A1
• Filed: 12/01/2010
• Published: 06/07/2012
• Est. Priority Date: 12/01/2010
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Watson, James N., Addison, Paul Stanley, Sethi, Rakesh, Manning, Keith
• Granted Patent: US 9,259,160 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

Systems and methods are provided for determining when to update a blood pressure measurement. The value of a physiological metric may be monitored and compared to a reference value. A patient monitoring system may compute a difference between a monitored metric and a reference value, and compare the difference to a threshold value to determine whether to update a blood pressure measurement. The threshold value may be constant or variable, and may depend on the monitored metric.

Claims

1. A method for monitoring blood pressure (BP), the method comprising:

(a) determining using an electronic processor a current BP measurement using a non-invasive blood pressure (NIBP) device;

(b) associating a reference metric value with the current BP measurement;

(c) monitoring a metric value based at least in part on a continuous noninvasive technique;

(d) computing a difference based at least in part on a monitored metric value and the reference metric value; and

(e) updating the current BP measurement using the NIBP device when the difference exceeds a threshold.

2. The method of claim 1, wherein the metric value comprises a combination of differential pulse transit time (DPTT), pulse rate, pulse wave area, pulse statistical moment, pulse wave centroid, rotational moments, pulse wave fiducial positions, and/or DC offset.

3. The method of claim 1, wherein the threshold is based at least in part on the current blood pressure measurement.

4. The method of claim 1, wherein the threshold is directly proportional to the monitored metric value.

5. The method of claim 1, wherein the threshold value is based at least in part on the relative magnitudes of the monitored metric value and the reference metric value.

6. The method of claim 1, wherein the threshold is based at least in part on user input.

7. The method of claim 1, wherein the monitored metric value is based at least in part on a photoplethysmograph (PPG) signal.

8. The method of claim 1, wherein computing the difference further comprises computing a difference in parameters comprising DPTT, pulse rate, signal derivative, pulse wave area, notch position, pulse moment, and/or baseline offset, and/or a combination thereof.

9. The method of claim 1, further comprising measuring a change in the monitored metric value, wherein computing the difference based at least in part on the monitored metric value and the reference metric value is further based at least in part on the change in the monitored metric value.

10. The method of claim 1, further comprising repeating steps (a) through (e) at least once upon completing step (e).

11. A system for monitoring blood pressure (BP), the system comprising:

at least one sensing device;

a signal input configured to receive at least one physiological signal of a subject from the at least one sensing device;

a non-invasive blood pressure (NIBP) device; and

processing equipment coupled to the signal input and to the NIBP device and configured to;

(a) determine a current BP measurement using the NIBP device;

(b) associate a reference metric value with the current BP measurement based at least in part on the at least one physiological signal;

(c) monitor a metric value based at least in part on a continuous noninvasive technique and on the at least one physiological signal;

(d) compute a difference based at least in part on a monitored metric value and the reference metric value; and

(e) update the current BP measurement using the NIBP device when the difference exceeds a threshold.

12. The system of claim 11, wherein the processing equipment is further configured to compute the threshold value.

13. The system of claim 11, wherein the processing equipment is further configured to receive user input, wherein the threshold value is determined based at least in part on user input.

14. The method of claim 11, wherein the threshold is directly proportional to the monitored metric value.

15. The method of claim 11, wherein the threshold value is based at least in part on the relative magnitudes of the monitored metric value and the reference metric value.

16. The system of claim 11, wherein the processing equipment is further configured to compute the difference based at least in part on pulse rate, signal derivative, pulse wave area, notch position, pulse moment, and/or baseline offset, and/or a combination thereof.

17. The system of claim 11, wherein the processing equipment is further configured to measure a change in the monitored metric value, wherein the difference is further based at least in part on the change in the monitored metric value.

18. The system of claim 11, wherein the at least one sensing device comprises a photoplethysmograph (PPG) sensor.

19. The system of claim 11, wherein the processing equipment is further configured to repeat steps (a) through (e) at least once upon completing step (e).

20. The system of claim 11, wherein the at least one sensing device comprises two PPG sensors, and wherein the monitored metric value is a differential pulse transit time (DPTT).