Ultrasonic detection of bloodstream emboli

Quantitative assessment of decompression-induced emboli in the blood flow may provide important information relating to physiological changes associated with decompression. A CW transmitter-receiver unit and a chest-mounted transducer probe have been developed for non-invasive ultrasonic monitoring of pulmonary blood flow using Doppler shift techniques. Preliminary spectral analysis of signals obtained during simulated dives in a hyperbaric test facility indicates that the spectrum of abnormal emboli signals is significantly different from that of normal blood flow. A preliminary theory explaining the observed spectra is offered.