Patent ID: 8202225
Filing Date: 2012-06-19
Classification: A61B

Abstract:
1. A method for noninvasively estimating a blood pressure, the method comprising: a) applying a bandpass filter to a second heart sound (S2) component to generate a filtered S2 component, the bandpass filter having a lower cutoff frequency greater than a maximum frequency of the S2 component; b) estimating the maximum frequency of the S2 component using the filtered S2 component; c) applying a predetermined relationship between the estimated maximum frequency and blood pressure to generate a blood pressure estimate; and d) displaying the blood pressure estimate, wherein step (b) includes: (b1) calculating a ratio between the S2 component and the filtered S2 component; (b2) decreasing the lower cutoff frequency and repeating steps (a) and (b1) with the decreased lower cutoff frequency to calculate the ratio, the lower cutoff frequency being decreased until the calculated ratio is less than or equal to a predetermined threshold, and wherein the decreased lower cutoff frequency is used to define the estimated maximum frequency.