DEVICE FOR MEASURING BLOOD FLOW VELOCITY AND QUANTITY IN AORTA

摘要

The blood flow in the upper arm is obstructed by a blood flow obstruction bag (220) in a cuff (200) applied to the upper arm. The flow obstruction bag is provided with a front detecting bag (210) and rear one (230) on the up- and down-stream sides thereof, respectively, and a front sensor (110) and rear one (120) are provided for detecting pressure in respective detecting bags. Each sensor detects front pulse waves (Wf) and rear ones (Wb) respectively. Standard internal pressure in the cuff is controlled by a pneumatic pump (140) and a leak valve (150) controlled by the CPU (130). With every pulse wave monitored, the internal standard pressure in the cuff can be maintained at systolic phase pressure SP or diastolic phase pressure DP. A propagation speed of the pulse wave passing beneath the cuff whose internal pressure is maintained at the systolic phase pressure SP can be found from the time of delay SPdt of the rear pulse wave from the front pulse wave and is approximate to a blood flow velocity VH when the aorta is at high pressure. A blood flow velocity VL when the aorta is at low pressure is found when dividing the blood flow velocity VH by a given coefficient R. The rear pulse wave obtained when the standard internal pressure is maintained at the diastolic phase pressure DP becomes an approximate aortic wave. On the basis of the waveform of this approximate aortic wave, effective cross-sectional areas SH and SL of the blood flow are found and a blood flow quantity per unit pulse is calculated by multiplying the cross-sectional area by the blood flow velocity.