Recall of intraoperative events after general anaesthesia and cardiopulmonary bypass

We wished to identify patients able to recall intraoperative events after general anaesthesia involving cardiopulmonary bypass (CPB). A balanced anaesthetic technique consisting of benzodiazepines, low dose fentanyl (15.9 +/- 8.5 micrograms.kg-1) and a volatile agent was employed. Perioperative recall was sought utilizing a structured interview on the fourth or fifth postoperative day. During 20 mo 837 patients underwent CPB. Seven hundred patients (84%) were able to respond to a structured postoperative interview. A detailed chart review was performed in patients with recall and in 60 randomly selected patients without recall. Eight patients (1.14%) reported recall of intraoperative events. We were unable to identify any differences between the two groups with respect to narcotic, benzodiazepine dosage or usage of inhalational agents. The incidence of recall in patients undergoing cardiac surgery was less in our group than previously reported. It is, however, higher than the 0.2% incidence recently reported in patients undergoing non-cardiac surgery. This is probably due to patient characteristics and intraoperative factors which make it difficult to avoid periods of relatively light anaesthesia during cardiac surgery.