Systems and Methods for Maintaining Blood Pressure Monitor Calibration

• US 20100081945A1
• Filed: 09/30/2008
• Published: 04/01/2010
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Campbell, Shannon, Sethi, Rakesh
• Granted Patent: US 9,687,161 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• 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 5/7257 using Fourier transforms

Abstract

Systems and methods are disclosed herein for maintaining the calibration of non-invasive blood pressure monitoring devices. Phase components of pulse signals detected by the blood pressure monitoring device are compared to stored baseline phase component values. If the difference exceeds a threshold, the blood pressure monitoring device is recalibrated.

Claims

1. A method for monitoring blood pressure comprising:

storing a baseline pulse signal phase component associated with a pulse signal obtained at a calibration time;

monitoring a current phase component of the pulse signal over a period of time subsequent to the calibration time;

calculating a difference between the current phase component with the stored baseline phase component;

triggering a recalibration of a pulse signal-based blood pressure monitor in response to the calculated difference exceeding a threshold.

2. The method of claim 1, wherein the pulse signal comprises a pleth signal.

3. The method of claim 1, comprising receiving a calibration blood pressure measurement derived at about the calibration time wherein the calibration blood pressure measurement is determined independent of the pulse signal data.

4. The method of claim 3, comprising calibrating a blood pressure monitor based on the calibration blood pressure measurement and the pulse signal obtained at the calibration time.

5. The method of claim 4, comprising calculating a monitored blood pressure value using a pulse signal at a time subsequent to the calibration time in response to the calculated difference falling below the threshold.

6. The method of claim 1, wherein recalibration comprises:

obtaining a second calibration blood pressure measurement independent of pulse signal data at a second calibration time;

calculating blood pressure calibration values based on a pulse signal obtained at about the second calibration time and the second calibration blood pressure measurement; and

storing an updated baseline pulse signal phase component.

7. The method of claim 1, wherein calculating the difference between the current phase component with the stored baseline phase component comprises calculating the difference between the phase components at a signal frequency of less than about 10 Hz.

8. The method of claim 1, wherein calculating the difference between the current phase component with the stored baseline phase component comprises calculating the difference between the phase components at a signal frequency of less than about 5 Hz.

9. The method of claim 1, wherein calculating the difference between the current phase component with the stored baseline phase component comprises calculating the Fourier phase component of the pulse signal.

10. A blood pressure monitor comprising:

a sensor for detecting a pulse signal from a patient;

a memory for storing baseline pulse signal phase components;

a processor capable of,

storing a baseline pulse signal phase component derived from a pulse signal obtained at about a calibration time;

monitoring a current phase component of the pulse signal over a period of time subsequent to the calibration time;

calculating a difference between the current phase component and the stored baseline phase component; and

triggering a recalibration of a pulse signal-based blood pressure monitor in response to the calculated difference exceeding a threshold.

11. The blood pressure monitor of claim 10, wherein the sensor comprises a pulse oximeter.

12. The blood pressure monitor of claim 10, comprising an input for receiving the calibration blood pressure measurement at about the calibration time from an external blood pressure sensor.

13. The blood pressure monitor of claim 10, wherein the processor is capable of calibrating the blood pressure monitor based on the calibration blood pressure measurement and the pulse signal obtained at the calibration time.

14. The blood pressure monitor of claim 10, wherein the processor is capable of:

obtaining a second calibration blood pressure measurement at a second calibration time;

calculating blood pressure calibration values based on a pulse signal obtained at about the second calibration time and the second calibration blood pressure measurement; and

storing an updated baseline pulse signal phase component.

15. The blood pressure monitor of claim 10, wherein calculating the difference between the current phase component with the stored baseline phase component comprises calculating the difference between the phase components at a signal frequency of less than about 10 Hz.

16. The blood pressure monitor of claim 10, wherein calculating the difference between the current phase component with the stored baseline phase component comprises calculating the difference between the phase components at a signal frequency of less than about 5 Hz.

17. The blood pressure monitor of claim 10, wherein calculating the difference between the current phase component with the stored baseline phase component comprises calculating the Fourier phase component of the pulse signal.

18. A computer readable medium storing computer readable instructions, which, when executed by a processor, cause the processor to a carry out a method comprising:

storing a baseline pulse signal phase component associated with a pleth signal obtained at a calibration time;

monitoring a current phase component of the pleth signal over a period of time subsequent to the calibration time;

calculating a difference between the current phase component with the stored baseline phase component;

triggering a recalibration of a pleth signal-based blood pressure monitor in response to the calculated difference exceeding a threshold.

19. The computer readable medium of claim 18, wherein calculating the difference between the current phase component with the stored baseline phase component comprises calculating the difference between the phase components at a signal frequency of less than about 10 Hz.

20. The computer readable medium of claim 18, wherein calculating the difference between the current phase component with the stored baseline phase component comprises calculating the Fourier phase component of the pulse signal.