INTRAOPERATIVE ECHOCARDIOGRAPHIC STUDY OF AIR-EMBOLISM DURING CARDIACOPERATIONS

Background. Central nervous system damage remains a feared complicatio n after heart operations. Air embolism (AE) is one of several possible causes of central nervous system damage. In previous studies, intraop erative transesophageal echocardiography (ITEE) has been used to detec t AE, but identification of the periods of risk and the origin of AE i s lacking. Methods. Two groups of patients undergoing elective heart o perations were studied with ITEE. Group I consisted of 15 patients und ergoing true ''open heart'' operations, either aortic or mitral valve. Group II consisted of 15 patients undergoing coronary artery bypass g rafting. Results. In group I (valve operation), ITEE detected AE in al l patients, particularly in the period between the release of the aort ic cross-clamp and the termination of cardiopulmonary bypass. Furtherm ore, 12 of the 15 patients had new episodes of AE up to 28 minutes aft er termination of cardiopulmonary bypass. In the majority of cases, IT EE clearly demonstrated that the air originated in the lung veins and was not air retained in the heart. In group II (coronary artery bypass grafting) episodes of AE were only seen in the period between cross-c lamp removal and the termination of cardiopulmonary bypass, and only i n half of the patients. Conclusions. Careful standard cardiac deairing did not prevent AE caused by the delayed release of air trapped in th e lung vessels. Routine use of ITEE is recommended to assess the thoro ughness of deairing procedures. This will help eliminate AE or at leas t lead to an increased awareness of the problem of retained air. Minim izing AE during open heart operations should contribute to a reduction in central nervous system damage and improvement of intellectual func tion after heart operations.