Considerable public interest and anxiety exist about patients waking up during general anaesthesia with explicit memories of painful and terrifying intraoperative events. Using conventional clinical signs, anaesthetists find it almost impossible to recognise conscious awareness in patients with complete neuromuscular blockade.1 In elective surgery such awareness is often due to the anaesthetists not realising that the delivery of anaesthetic has failed. Occasionally there are fictitious claims of conscious awareness, and rarely there are cases with no obvious explanation.

Fortunately, the incidence of conscious awareness with pain during surgery is only 0.01% during elective general anaesthesia.2 The incidence has fallen considerably since the 1960s, when Hutchinson found that 0.6% of patients anaesthetised with unsupplemented nitrous oxide were awake and in pain.3 The incidence is much higher during operations for major trauma, where anaesthetic concentrations are reduced to preserve cardiovascular function.4

The psychological consequences of conscious awareness with explicit memory of pain are not known. Moerman et al described the sequelae in 26 patients.1 Eleven had a persistent fear of anaesthesia; seven had sleep disturbances, nightmares, anxiety, or mental distress; and eight had no ill effects. The proportion of …