Detection of gas bubbles in the pulmonary artery and aorta of dogs by ultrasonic echography after intravenous infusion of air

The transducer and receiving amplifier of a standard ultrasonic echocardiograph were modified to develop a device for detecting unmasked echocardiographic images of gas bubbles in blood vessels. This device was employed to detect gas bubbles passing from the venous to the arterial bed via lungs in anesthesized and thoracotomized dogs during air intravenous infusion. Gas bubbles entered the aorta when the dose of infused airw as 12-15 ml. It is postulated that gas bubbles formed in the animal and human body during decompression may pass from the venous into the arterial bed not only through shunts but also through lung capillaries.