Does the use of carbon dioxide field flooding during heart valve surgery prevent postoperative cerebrovascular complications?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was whether there is any benefit with the use of carbon dioxide (CO(2)) field flooding techniques in heart valve surgery, in order to reduce postoperative neurological complications. Altogether 202 articles were found using the reported search, and six of them were used to answer the clinical question. All but one trial, were prospective, randomised. Four studies reported a significantly lower intracardiac bubble count in the CO(2) group. A significant reduction of p300 peak latencies in the CO(2) group was observed in one study. Otherwise, neurocognitive test batteries did not reveal any advantages of CO(2) field flooding in two studies. Three studies reported on postoperative cerebrovascular complications and the overall rate of stroke, transient ischemic attack (TIA) or prolonged reversible ischemic neurological deficit was 1.2% in the CO(2) group and 2.5% in the control group (P=ns). Although the use of CO(2) field flooding has been observed to be associated with a significantly lower count of intracardiac air bubbles, and improved survival in two small studies, so far there is no evidence of a sustained reduction of cerebrovascular complications with the use of this method.