Monitor for number of bubbles in heart blood vessels - uses doppler ultrasonic detection and electronically counts bubbles over settable period to indicate necessity manual heart manipulation

摘要

The presence of bubbles in the blood after a surgical operation on the heart is detected by an ultrasonic transducer (1) placed near the root of the aorta. The ultrasonic transducer uses Doppler techniques to detect the motion of the bubbles during manual manipulation of the heart to dispel air bubbles in the blood. The transducer signals are amplified (3) and compared to an adjustable (6) threshold (5) to reduce noise transmission. Pulses exceeding the threshold operate a counter (8) which has connected an electronic display (10). A clock generator (14) displays (16) the time as the count progresses and stops the pulse counter (8) when a preset (19,20) time is reached. The preset time interval is adjustable (20) from 15 to 120 seconds and manual manipulation of the heart continues till the number of bubbles counted, in the preset interval, falls below the medically desirable count.