BACKGROUNDAwareness under general anesthesia is a serious complication which leads to psychiatric disorders. The incidence of awareness in patients undergoing cardiac surgery has been reported in as many as 1.5% - 23% in foreign countries. But so far, medical literature about awareness during cardiac surgery is still rare in China. Therefore, we investigated the incidence of awareness in patients undergoing different kinds of cardiac surgery, the phases when awareness occurred and the effect of cardiopulmonary bypass on the incidence of awareness in coronary artery bypass grafting in Beijing.

METHODSPatients' recall of awareness during cardiac surgery was assessed. One hundred patients undergoing coronary artery bypass grafting (CABG) in Chaoyang Hospital, Beijing, one hundred patients undergoing CABG and one hundred patients undergoing valve replacement or septal defect repair in Fuwai Hospital, Beijing, were interviewed 3-6 days after surgery. Every report about patients on recall of awareness was recorded. An independent research team, blinded to patients' surgery and anesthesia, assessed every report of awareness.

RESULTSThe incidence of awareness of patients received CABG under cardiopulmonary bypass (CPB), off -pump CABG, septal repair or valve replacement under CPB was 4.7% (5 of 106 cases), 9.6% (9 of 94 cases) and 4% (4 of 100 cases), respectively. CPB did not greatly affect the incidence of awareness during the period of CABG (P > 0.05). The incidence of awareness of patients who received CABG under CPB did not increase significantly, in comparison with that of patients who received septal repair or valve replacement under CPB in Fuwai Hospital (P > 0.05). Awareness easily occurred before bypass grafting or CPB.

CONCLUSIONSAwareness mainly occurs before bypass grafting or CPB in cardiac surgery. Most cases with awareness have auditory perceptions. CPB is not a main factor which affects the incidence of awareness of CABG. Surgical types do not affect the incidence of awareness of patients under CPB.