Many self-measurement devices of the blood pressure inflate the cuff up to 180 millimetres of mercury and then deflate it gradually. If this pressure is lower than the systolic blood pressure, then the device inflates the cuff again until the pressure is above the systolic blood pressure.

Many self-measurement devices of the blood pressure have a possibility of presetting the maximal level of the pressure, such as 140, 170, 200 and 240 millimetres of mercury. Thus, when the cuff inflates with 140 millimetres of mercury and that the systolic blood pressure is 190 millimetres of mercury, the cuff inflates again with 170 and then 200 millimetres of mercury.

The very sophisticated devices inflate their cuff gradually, hears the noises at the level of the artery at the same time and stop the inflation as soon as the blood pressure measured by the device exceeds the systolic blood pressure.

10.3.2 - The deflating of the cuff

The deflating must be very meticulous in order not to make an error of measurement of the blood pressure. If the deflating is too fast, the systolic blood pressure may be underestimated whereas the diastolic blood pressure may be over-estimated.

The best self-measurement devices use a deflating programmed at a speed of 2 millimetres of mercury per second. Other devices use a deflating programmed on the heart pulsations, but they are valid only when the patient heart rate is between 60 and 80 per minute.

10.3.3- Automatic measurement

Very often, the self-measurement devices for blood pressure are automatic, i.e. the patient just has to press on a button to begin the inflation. Many devices are even equipped with a special program that can measure the blood pressure 3 times in a row.