Electronic blood pressure monitor

An electronic blood pressure monitor comprising:

• a cuff configured to be mounted on a predetermined portion of a subject for pressurizing an artery of the subject;
• a cuff pressure controller for controlling a cuff pressure inside the cuff;
• a pressure detector for detecting the cuff pressure;
• a pulse wave detector for detecting a pulse wave of the artery that is pressurized by the cuff;
• and
• a first blood pressure measuring portion and a second blood pressure measuring portion, the electronic blood pressure monitor selectively using the first or second blood pressure measuring portion at a time, wherein
• the first blood pressure measuring portion comprises a first calculating unit that calculates a blood pressure of the subject based on a set of the cuff pressures chronologically detected by the pressure detector during a period in which the cuff pressure is gradually changed by the cuff pressure controller and on amplitudes of the pulse waves detected by the pulse wave detector at the timings of the corresponding cuff pressure detection by the pressure detector, and a calibration unit that calibrates the second blood pressure measuring portion based on a result of the blood pressure calculation by the first calculating unit, and
• the second blood pressure measuring portion comprises a parameter measuring unit that provides a measured value of a pulse wave parameter based on at least one of the pulse waves detected by the pulse wave detector, the pulse wave parameter being indicative of a waveform of the pulse wave that represents a relative cuff pressure corresponding to a pressure difference between the detected cuff pressure and the blood pressure of the subject, a function memory that stores a function of the relative cuff pressure comprising a set of sub-functions, a function selection unit that selects one of the sub-functions that corresponds to a level of the measured value of the pulse wave parameter, and a second calculating unit that identifies the relative cuff pressure based on the selected sub-function and calculates the blood pressure of the subject by subtracting the identified relative cuff pressure from the cuff pressure detected by the pressure detector at the time of the pulse wave detection, wherein
• the calibration unit comprises a data gathering unit that gathers, for each of the pulse waves detected during an operation of the first blood pressure measuring portion at the timings of the corresponding cuff pressure detection, the corresponding relative cuff pressure and the corresponding measured value of the pulse wave parameter, and a data updating unit that modifies the function based on the relative cuff pressures and the corresponding measured values of the pulse wave parameter that are gathered by data gathering unit.