Automatic blood pressure measurement device

An automatic blood pressure measuring apparatus comprising:

• a compression band wrapped around a compressed site of a living body, the automatic blood pressure measuring apparatus sequentially extracting a pulse wave that is pressure oscillation in the compression band in a process of changing a compression pressure value of the compression band to determine a blood pressure value of the living body based on a change in the pulse wave,
• the compression band having a plurality of expansion bags having independent air chambers aligned in a width direction to respectively compress the compressed site of the living body,
• the automatic blood pressure measuring apparatus having a processor configured to:
• sequentially calculate within one pulse period, amplitude ratios of an amplitude value of a downstream pulse wave from a predetermined expansion bag positioned on a downstream side of an upstream expansion bag positioned on an upstream side of an artery in the compressed site out of the plurality of the expansion bags to an amplitude value of an upstream pulse wave from the upstream expansion bag, the automatic blood pressure measuring apparatus determining a maximum blood pressure value of the living body based on whether the amplitude ratios exceed a preset amplitude ratio change judgment value that is defined in advance for judging a rise of the amplitude ratios at a start of a blood flow,
• wherein the amplitude value of the upstream pulse wave from the upstream expansion bag and the amplitude value of the downstream pulse wave from the downstream expansion bag are sequentially acquired in periods within one pulse of the living body and shorter than a period of a pulse,
• wherein the amplitude ratios are sequentially calculated in periods shorter than the period of the pulse from the amplitude value of the upstream pulse wave from the upstream expansion bag and the amplitude value of the downstream pulse wave from the downstream expansion bag sequentially acquired in periods shorter than the period of the pulse;
• and
• determining, for each pulse wave, whether the amplitude ratios sequentially calculated within the one pulse period from the amplitude value of the upstream pulse wave from the upstream expansion bag and the amplitude value of the downstream pulse wave from the downstream expansion bag sequentially acquired within the each pulse wave exceeds the preset amplitude ratio change judgment value, and using the determination to thereby estimate the maximum blood pressure value of the living body.