Doppler analysis of the left venting line: an effective and simple technique to control heart de-airing

Air embolism is still a major risk of open-heart surgery. Different techniques of air removal have been established, even though none is completely effective. Since 1989 the authors have used a new technique to avoid air passage into the left vent line when the left heart cavities are open. A specially designed probe attached to a vascular Doppler analyser is fixed to the left vent tubing. Air passage is detected by a characteristic acoustic signal. Air removal procedures are continued until no audible signals are detected. This technique was carried out in 150 open left heart operations in which there were no clinical signs of air embolism. To validate this procedure, simultaneous assessment of air removal was made using transoesophageal echocardiography (TEE) and carotid Doppler (CD) in six patients. When Doppler signs of air in the left vent disappeared, TEE revealed that a small amount of air was still present in two patients; carotid Doppler showed only minimal passage of air bubbles in three patients after left vent removal while the heart was freely ejecting. These results demonstrate that this technique is a reliable method of assessing air removal, which is especially useful when de-airing is difficult during reoperation.