Patent ID: 6712768
Filing Date: 2004-03-30
Classification: A61B

Abstract:
An apparatus for determining, based on a pulse wave detected from a living subject, an augmentation index indicating a proportion of a reflected-wave component of the pulse wave to an incident-wave component thereof, the apparatus comprising:an inflatable cuff which is adapted to be worn on a portion of the subject and inflated to apply a pressing pressure to said portion; a cuff-pressure changing device which changes the pressing pressure of the cuff; a pulse-wave extracting device which extracts a pulse wave from a pressure oscillation which is transmitted from said portion of the subject to the cuff; a peak-occurrence-time determining means for determining, based on a high-cuff-pressure pulse wave which is extracted by the pulse-wave extracting device when the cuff-pressure changing device makes the pressing pressure of the cuff higher than a systolic blood pressure of said portion of the subject, a time of occurrence of a peak point of an incident-wave component of the high-cuff-pressure pulse and a time of occurrence of a peak point of a reflected-wave component of the high-cuff-pressure pulse wave; and an augmentation-index determining means for determining, based on the respective times of occurrence of the respective peak points of the incident-wave and reflected-wave components of the high-cuff-pressure pulse, determined by the peak-occurrence-time determining means, respective times of occurrence of respective peak points of incident-wave and reflected-wave components of a low-cuff-pressure pulse which is extracted by the pulse-wave extracting device when the cuff-pressure changing device makes the pressing pressure of the cuff lower than a mean blood pressure of said portion of the subject, and determining an augmentation index based on respective magnitudes of the low-cuff-pressure pulse wave at the respective times of occurrence of the respective peak points of the incident-wave and reflected-wave components of the low-cuff-pressure pulse.