Blood pressure information measuring device

A blood pressure information measurement device comprising:

• a cuff comprising
• a first fluid bag configured to expand and contract by a fluid entering and exiting a first nipple of the first fluid bag, and
• a second fluid bag accommodated in the first fluid bag and configured to expand and contract by a fluid entering and exiting a second nipple of the second fluid bag, wherein the first nipple is disposed at a position corresponding to an outer edge section of the second fluid bag or a position further outward than the outer edge section;
• a pressure increase/reduction mechanism configured to increase and decrease an internal pressure in an internal space of the first fluid bag and an internal pressure in an internal space of the second fluid bag;
• a control unit configured to control operation of the pressure increase/reduction mechanism;
• a pressure detection device configured to detect the internal pressure of the first fluid bag and the internal pressure of the second fluid bag;
• and
• a calculation unit configured to calculate blood pressure on the basis of pressure information detected by the pressure detection device with the cuff being worn at a measurement site;
• wherein
• the control unit controls the operation of the pressure increase/reduction mechanism such that, in a first stage, the internal space of the first fluid bag is pressurized and expanded until the internal pressure of the first fluid bag reaches a predetermined pressure, and, in a second stage which begins immediately after the first stage, the internal space of the second fluid bag is pressurized and expanded while the first fluid bag is kept sealed, so that in the second stage the internal pressure of the internal space of the first fluid bag and the internal pressure of the internal space of the second fluid bag are increased, wherein the control unit begins the second stage upon determining that the internal pressure of the first fluid bag reaches the predetermined pressure,
• the calculation unit calculates the blood pressure using the internal pressure of the first fluid bag as detected by the pressure detection device during the second stage, the first fluid bag being kept sealed during the entire second stage, and
• the blood pressure is calculated during the expansion of the second fluid bag.