Psychomotor recovery after outpatient anaesthesia: individual impairment may be masked by group analysis

Recovery from outpatient anaesthesia with propofol was followed in 10 patients, using a semantic recognition memory test (SemRT) (in a new implementation on a Psion hand-held microcomputer), choice reaction time (CRT) and critical flicker fusion threshold (CFFT). Group analysis of results revealed an effect on psychomotor performance as measured by the SemRT and CFFT (but not the CRT), 30 min after the end of the procedure. Performance on all three tasks had returned to baseline values within 60 min of completing the anaesthetic. Group analysis, however, masks individual impairment which may be clinically important. There was no statistically significant correlation between post-anaesthetic task performance and age, sex, dose of propofol, anxiety or depression score.