Biological information monitor

A biological information monitor comprising:

• a first measuring unit which measures a pulse wave propagation time of a patient;
• a second measuring unit which measures a blood pressure of the patient;
• a calculating unit which calculates an estimated blood pressure value of the patient based on the pulse wave propagation time of the patient;
• a setting unit which sets a threshold;
• and
• a determining unit which compares the estimated blood pressure value with a first upper limit, a second upper limit, a first lower limit, and a second lower limit,
• wherein when the estimated blood pressure exceeds the second upper limit, the second measuring unit is not activated,
• wherein when the estimated blood pressure exceeds the first upper limit, the second measuring unit is activated to measure the blood pressure of the patient, and after the estimated blood pressure value exceeds the first upper limit, the second measuring unit is not activated unless the estimated blood pressure value falls below the second upper limit and then exceeds the first upper limit again,
• wherein the first and second upper limits are different from each other and the first upper limit is greater than the second upper limit;
• wherein when the estimated blood pressure falls below the second lower limit, the second measuring unit is not activated,
• wherein when the estimated blood pressure falls below the first lower limit, the second measuring unit is activated to measure the blood pressure of the patient and after the estimated blood pressure value falls below the first lower limit, the second measuring unit is not activated unless the estimated blood pressure value exceeds the second lower limit and then falls below the first lower limit again, and
• wherein the first and second lower limits are different from each other and the first lower limit is less than the second lower limit.