CALIBRATION FOR BLOOD PRESSURE MEASUREMENTS

• US 20140364749A1
• Filed: 10/21/2011
• Published: 12/11/2014
• Est. Priority Date: 10/21/2010
• Status: Abandoned Application

• Current Assignee: Drexel University
• Original Assignee: Drexel University
• Inventors: Swoboda, Marek, Lec, Ryszard M., Varma, Kushal, Pourshoghi, Ahmadreza, Magee, Nathaniel, Shah, Atman, Shah, Sagar
• Application Number:
  US13/880,382
• Publication Number:
  US 20140364749A1
• Time in Patent Office: Days
• US Class Current: 600/494
• CPC Class Codes: A61B 2560/0228 using calibration standards
• 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 5/02233 Occluders specially adapted therefor tourniquets A61B17/132
• CPC Class Codes: A61B 5/22 Ergometry; Measuring muscular strength or the force of a muscular blow exercising apparatus A63B21/00 ; measuring of work or force in general G01L
• CPC Class Codes: A61B 5/489 Blood vessels
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

Blood pressure measurement devices comprising a transducer may have error introduced when the transducer is placed in mechanical communication with a vein or artery. This error may be based on alignment, applanation, calibration, and the contact based stress required to obtain a signal from pressure in a vein or artery. The present invention teaches isolating and removing this error from the blood pressure system which may increase the accuracy of the measurement. Calibration is also provided.

Claims

1. A blood pressure measurement system comprising:

a reference;

a suspended member coupled to the reference by a resilient member having a spring constant, wherein displacement of the suspended member gives rise to a load on the resilient member having a spring constant;

a load sensor configured to determine the load on the resilient member having a spring constant; and

a processor comprising a computer readable storage medium having stored thereon logic configured to correlate the load on the resilient member having a spring constant to a contact based stress causing the displacement of the suspended member.

2. The system of claim 1 further comprising a sensor area coupled to a transducer and wherein the sensor area and transducer comprise the suspended member.

3. The system of claim 2 wherein the transducer is configured to output a signal correlated with a pulse incident on the sensor area.

6. The system of claim 1 further comprising an actuator in communication with the resilient member having a spring constant, the actuator configured to place a second load on the resilient member having a spring constant in a direction substantially perpendicular to the surface contact of the sensor area.

16. The system of claim 1 wherein the computer readable medium comprises logic to determine systolic and diastolic blood pressure based on the peak to peak values of the transducer and mean values of the load sensor at a plurality of surface contact pressures.

4-5. -5. (canceled)

7-15. -15. (canceled)

17. A method for calibrating a blood pressure sensor comprising:

receiving a first signal from a transducer coupled to a sensor area of a suspended member, which is suspended with respect to a reference by reason of a resilient member having a spring constant;

receiving a second signal from a load sensor configured to measure the load on the resilient member having a spring constant;

determining a first stress from the first signal;

determining a second stress from the second signal; and

adding the second stress to the first stress.

18. The method of claim 17 wherein the load on the resilient member having a spring constant is correlated with a displacement of the suspended member.

21. The method of claim 17 wherein the suspended member comprises the sensor area.

23. The method of claim 17 wherein the first signal is correlated with a pulse incident on the sensor area.

25. The method of claim 17 wherein determining further comprising determining an applanation value comprises by:

determining a first pressure value with said sensor area;

receiving a indication that an actuatort has actuated the suspended member;

determining a second pressure value with said sensor area; and

comparing the first pressure value with the second pressure value.

19-20. -20. (canceled)

22. (canceled)

24. (canceled)

26. (canceled)

27. A blood pressure measurement system comprising:

a reference;

a suspended member coupled to the reference by a resilient member having a spring constant, wherein displacement of the suspended member gives rise to a load on the resilient member having a spring constant; and

a load sensor configured to determine the load on the resilient member having a spring constant.

28. The system of claim 27 further comprising a sensor area coupled to a transducer and wherein the sensor area and transducer comprise the suspended member.

29. The system of claim 28 wherein the transducer is configured to output a signal correlated with a pulse incident on the sensor area.

32. The system of claim 27 further comprising an actuator in communication with the resilient member having a spring constant, the actuator configured to place a second load on the resilient member having a spring constant in a direction substantially perpendicular to the surface contact of the sensor area.

41. The system of claim 27 wherein the computer readable medium has logic to determine peak to peak values of the transducer and mean values of the load sensor at a plurality of surface contact pressures.

42. The system of claim 41 wherein the computer readable medium comprises logic to determine systolic and diastolic blood pressure based on the peak to peak values of the transducer and mean values of the load sensor at the plurality of surface contact pressures.

30-31. -31. (canceled)

33-34. -34. (canceled)

38-39. -39. (canceled)

43-49. -49. (canceled)