Background and aims of the study: Air embolism during open heart surgery seems to be a common occurrence and may be responsible for neuropsychological deficit or myocardial damage.
Material and methods: Forty-two consecutive patients undergoing valvular surgery were studied using the long axis view of the heart by two dimensional transesophageal echocardiography (TEE). The patients were randomized into two groups of 21 each. In group 1, the routine air evacuation method was used. In group 2, the same air evacuation method was used and controlled with a Doppler ultrasonic probe adjusted around the root of the aorta. At the end of air evacuation, intracardiac microbubbles and retained air were analyzed with TEE and when air was founded, its location was communicated to the surgeons who tried to remove it by shaking the heart and tilting the operating table for 15 minutes. The patients were assessed for detection of cardiac or neurological postoperative complications.
Results: The incidences of microbubbles and retained air were 57% and 43% in group 1, and 62% and 38% in group 2 respectively (ns). The mean grade of microbubbles was lower in group 2: 1.4 +/- 0.8 vs. 2.2 +/- 0.9, p < 0.05. TEE allowed to significantly decrease (p < 0.05) retained air and mean grade of microbubbles to 14% and 1.3 +/- 0.8 in group 1, and to 10% and 0.8 +/- 0.8 in group 2, without statistical difference between the two groups. Despite the help of TEE, manual attempts to eradicate retained air were unsuccessful in five patients (three in group 1, two in group 2).
Conclusions: The use of aortic ultrasonic probe allowed to reduce the amount of microbubbles. TEE was a useful tool not only for the detection of retained air but also for locating it, and guiding the procedure to eliminate it.