| 摘要 |
The sphygmomanometer comprises an arm band having an inflatable cuff and a microphone, and an instrument connected to the arm band, which contains the necessary pneumatic and electronic elements. By means of the microphone and an amplifier, electrical signals corresponding to the Korotkoff sounds are generated during the decompression phase, and are applied to a discriminator. At the appearance of the first and the last signals, corresponding to the Korotkoff sounds, and each having an amplitude at least equal to a threshold value UR, the pressure in the cuff is measured and stored in memory as the systolic pressure and diastolic pressure respectively. During the decompression phase, the threshold value UR is first decreasing like a value proportional to the pressure in the cuff; then it increases at appearance of each signal corresponding to a Korotkoff sound and exceeding the instananeous value of the threshold level UR, after which it decreases again. This variation of the threshold value allows an exact determination of the blood pressure, eliminating in the optimum manner the parasitic signals over a large range of pressure values and in a large domain of Korotkoff sound intensities.
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