Ultrasonic identification of sources of gaseous microemboli during open heart surgery.

An ultrasonic transducer was used to detect gaseous microemboli during open heart surgery. When placed over the carotid artery of patients during surgery it was recognized that gaseous emboli were released into the systemic circulation following recognizable surgical procedures and from the oxygenator during bypass. Fixation of the transducer on the arterial return from the oxygenator demonstrated that the two types of disposable bubble oxygenators and disc oxygenators tested delivered microbubbles in the arterial blood. Some factors affecting the number of bubbles released were recognized and are discussed. Case reports of two patients who received large volumes of gaseous microemboli from different sources are presented.