CONTINUOUS NON-INVASIVE BLOOD PRESSURE MEASUREMENT APPARATUS AND METHODS PROVIDING AUTOMATIC RECALIBRATION

• US 20140012147A1
• Filed: 09/09/2013
• Published: 01/09/2014
• Est. Priority Date: 07/07/2003
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Li, Luya, Sethi, Rakesh Kumar, Sun, Ming, Sit, Alexander Yuk, Liu, Yong
• Granted Patent: US 9,949,648 B2
• Time in Patent Office: Days
• US Class Current: 600/494
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/0225 the pressure being controlled by electric signals, e.g. derived from Korotkoff sounds
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

A blood pressure measurement system is configured to perform a calibration automatically when a calibration condition is satisfied. The calibration condition is based upon one or more parameters of pulse waves of a subject. The parameters may include pulse wave area; a time difference between systolic peak and reflected wave peak or dichrotic notch in the pulse wave and a shape of at least a portion of the pulse wave.

Claims

1. (canceled)

2. A method for operating a blood pressure measurement system, comprising:

activating a blood pressure detector to obtain a first blood pressure measurement of a subject;

detecting, by a pulse oximetry sensor, a pulse wave signal from the subject comprising a plurality of individual pulses;

determining a morphology metric of one or more the individual pulses of the pulse wave signal;

quantifying a difference between the morphology metric and a template; and

triggering the blood pressure detector to obtain a second blood pressure measurement of the subject when the difference passes a threshold.

3. The method of claim 2, further comprising tracking a time duration since the first blood pressure measurement, and triggering the blood pressure detector to obtain the second blood pressure measurement when the difference passes a threshold or when the time duration exceeds a limit.

4. The method of claim 2, wherein the morphology metric comprises one of an area of the one or more individual pulses, an amplitude of the one or more individual pulses, a shape of the one or more individual pulses, and a time difference of the one or more individual pulses.

5. The method of claim 2, wherein the morphology metric is determined from a current group of individual pulses.

6. The method of claim 2, further comprising determining a reference parameter of the pulse wave signal proximate the time of the first blood pressure measurement, and storing the reference parameter as the template.

7. The method of claim 2, further comprising calculating a continuous blood pressure measurement after the first blood pressure measurement and before the second blood pressure measurement.

8. The method of claim 7, wherein calculating the continuous blood pressure measurement comprises calculating blood pressure from a differential pulse transit time.

9. The method of claim 8, further comprising re-calibrating the continuous blood pressure measurement by adjusting the calculation of the differential pulse transit time, based on the morphology metric of the pulse wave signal.

10. The method of claim 2, further comprising adjusting the threshold or the difference based on a sensitivity factor.

11. The method of claim 2, further comprising periodically updating the template.

12. The method of claim 2, wherein the template comprises a reference pulse wave.

13. A method for operating a blood pressure measurement system, comprising:

activating a blood pressure detector to obtain a first blood pressure measurement of a subject;

detecting, by a pulse oximetry sensor, a pulsatile signal from the subject, the pulsatile signal comprising a plurality of pulses;

determining first and second morphology parameters of the plurality of pulses;

comparing the first morphology parameter to a first reference, and the second morphology parameter to a second reference;

evaluating a new measurement condition based on the comparisons; and

when the new measurement condition is satisfied, triggering the blood pressure detector to obtain a second blood pressure measurement of the subject.

14. The method of claim 13, wherein evaluating the new measurement condition comprises performing a logical OR operation of the first and second comparisons.

15. The method of claim 13, further comprising determining a time duration since the first blood pressure measurement, and satisfying the new measurement condition when the time duration passes a limit.

16. The method of claim 13, further comprising calculating a continuous blood pressure measurement after the first blood pressure measurement, based at least in part on the pulsatile signal.

17. The method of claim 13, further comprising applying a sensitivity factor to one or more of the comparisons.

18. The method of claim 13, further comprising monitoring the pulsatile signal for an indication of motion, and wherein evaluating the new measurement condition comprises finding the new measurement condition to be unsatisfied when the indication of motion is present.

19. The method of claim 13, wherein comparing the first and second morphology parameters to the first and second references, respectively, comprises quantifying a difference between the respective morphology parameter and the respective reference.

20. A method for operating a blood pressure measurement system, comprising:

detecting a pulse wave signal of a subject;

monitoring a morphology characteristic of the pulse wave signal over time;

storing a reference characteristic;

comparing the monitored characteristic to the reference characteristic;

evaluating a new measurement condition based on the comparison; and

triggering a blood pressure measurement when the new measurement condition is satisfied.

21. The method of claim 20, wherein the morphology characteristic of the pulse wave signal comprises an area of a pulse.

22. The method of claim 20, wherein the morphology characteristic of the pulse wave signal comprises a pulse amplitude of a pulse.

23. The method of claim 20, wherein the morphology characteristic of the pulse wave signal comprises a shape of a portion of a pulse.

24. The method of claim 20, wherein the morphology characteristic of the pulse wave signal comprises a time difference between first and second portions of a pulse.