The detection of gas bubbles in guinea‐pigs after decompression from air saturation dives using ultrasonic imaging.

Abstract

Bubble formation in the hind limb of anesthetized guinea-pigs after decompression from 2 different saturation exposures to air, 0.69 and 0.83 MPa [Pascal] gauge, was studied using an ultrasonic pulse-echo imaging technique. Bubble formation was qualitatively analyzed over 30 min after decompression. Profuse, largely stationary bubble formation occurred within 3 min of the decompression from 0.83 MPa gauge; extensive stationary bubble formation was not observed until 17 min after decompression from 0.69 MPa gauge. Electrocardiogram changes appeared coincidently with the appearance of major bubble formation after the 0.83 MPa decompression. After the 0.69 MPa decompression changes were not observed until the end of the 30 min surveillance period, considerably after a large number of bubbles occurred. The echo patterns recorded during the 60 s decompression and for 60 s after the decompression were quantitively analyzed. The increase in severity of the decompression corresponded to an increase of 152% in the number of bubbles. The echoes during this period were transient or persistent. Their distribution of size, location and appearance and duration were described. The contribution by mobile, intravascular gas bubbles to the elimination of the excess gas was estimated. These estimates ranged from 0.01-0.9% after the 0.69 MPa decompression and from 0.06-6% after 0.83 MPa decompression. The pulse-echo ultrasonic imaging technique apparently provides a powerful means of analyzing the distributions of bubble formation qualitatively and quantitatively after decompression. It is able to monitor moving and stationary bubbles simultaneously in a variety of tissue types.