Hills B A, Grulke D C
Ultrasonics. 1975 Jul;13(4):181-4. doi: 10.1016/0041-624x(75)90088-8.
Two standard Doppler ultrasonic devices, currently used for detecting bubbles in vivo, have been evaluated and compared in vitro using carefully calibrated uniform micro-bubbles rising at terminal velocity through a static aqueous medium. Two unexpected findings were observed: (a) the focal length of the transducer apparently decreases for smaller bubble sizes, and (b) a significant horizontal convection current was produced by one of the instruments. When the medium was in motion, it was found that the sensitivity varied markedly with bubble velocity, varying from a minimum detectable diameter of 40 mum at 55 cm/sec to 170 mum at 20 cm/sec. These findings are discussed with regard to the limitations of the Doppler technique for monitoring gas emboli in vivo and as an early warning for decompression sickness in divers.
目前用于体内气泡检测的两种标准多普勒超声设备，已通过精心校准的均匀微泡在静态水性介质中以终端速度上升的方式进行了体外评估和比较。观察到两个意外发现：(a) 对于较小的气泡尺寸，换能器的焦距明显减小；(b) 其中一台仪器产生了显著的水平对流。当介质运动时，发现灵敏度随气泡速度显著变化，从 55 厘米/秒时的最小可检测直径 40 微米变化到 20 厘米/秒时的 170 微米。针对多普勒技术在体内监测气体栓子以及作为潜水员减压病早期预警方面的局限性，对这些发现进行了讨论。
