VITAL SIGN MONITOR FOR CUFFLESSLY MEASURING BLOOD PRESSURE USING A PULSE TRANSIT TIME CORRECTED FOR VASCULAR INDEX

• US 20140142445A1
• Filed: 11/05/2013
• Published: 05/22/2014
• Est. Priority Date: 06/12/2007
• Status: Abandoned Application

• Current Assignee: Sotera Wireless Incorporated (Foxconn Technology Co., Ltd.)
• Original Assignee: Sotera Wireless Incorporated (Foxconn Technology Co., Ltd.)
• Inventors: Banet, Matthew J., Dhillon, Marshal Singh, Terry, Andrew Stanley, Zhou, Zhou, Visser, Henk II, Kopotic, Robert J.
• Application Number:
  US14/072,305
• Publication Number:
  US 20140142445A1
• Time in Patent Office: Days
• US Class Current: 600/493
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• 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 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/7475 User input or interface means, e.g. keyboard, pointing device, joystick

Abstract

A method and apparatus for measuring a patient'"'"'s blood pressure featuring the following steps: 1) measuring a time-dependent optical waveform with an optical sensor; 2) measuring a time-dependent electrical signal with an electrical sensor; 3) estimating the patient'"'"'s arterial properties using the optical waveform; 4) determining a pulse transit time (PTT) from the time-dependent electrical signal and the time-dependent optical waveform; and 5) calculating a blood pressure value using a mathematical model that includes the PTT and the patient'"'"'s arterial properties.

Claims

1-20. -20. (canceled)

21. A method for measuring a patient'"'"'s blood pressure with a blood pressure monitor, the method, comprising:

determining a vascular index (VI) according to the equation VI=(A1+[(b-c-d-e)/a])/A2, where A1 is 1.515, A2 is 0.023, and a, b, c, d, and e are fiduciary features obtained from a time-dependent plethysmography signal measured using an optical sensor disposed on the patient'"'"'s finger;

determining a first systolic blood pressure using a pulse transit time (PTT) obtained from the first time-dependent plethysmography signal and a time dependent electrical waveform measured using an ECG sensor disposed on the patient'"'"'s chest;

determining a second systolic blood pressure using the PTT, the VI, and the patient'"'"'s age.

22. The method of claim 21, wherein a, b, c, d, and e are obtained from the time-dependent plethysmography signal by calculating a second derivative of the time-dependent plethysmography signal and identifying a, b, c, d, and e in the second derivative waveform.

23. The method of claim 21, further comprising determining arterial stiffness for the patient.

24. The method of claim 21, wherein the PTT is obtained by analyzing a first time-dependent feature from the time dependent electrical waveform or a derivative thereof, and a second time-dependent feature from the time-dependent plethysmography signal or a derivative thereof.

25. The method of claim 21, wherein the first time-dependent feature comprises a peak corresponding to a QRS complex.

26. The method of claim 25, wherein the second time-dependent feature comprises a foot in the time-dependent plethysmography signal or a derivative thereof.