On-demand sedation with propofol for colonoscopy—A prospective pilot study of the influence on short-term memory, psychomotor function and postural stability*

Background: After sedated colonoscopy, patients are discharged on the basis of their subjective judgment that they have recovered, corroborated by the nursing staff. The aim of this study was to assess objectively whether patients were in fact fully recovered at the time of discharge, and to demonstrate whether the methods of testing applied could detect any influence of sedation on short-term memory, psychomotor function and postural stability. Methods: Twenty-two patients were investigated. At the beginning of the procedure, a defined bolus of propofol/alfentanil was given intravenously. During the procedure, an additional bolus was injected one or more times as requested by the patient. After colonoscopy, the patients stayed in the recovery room until the patients judged that they had recovered completely, which was also the judgement of the nursing staff at that time. Before colonoscopy and again before discharge, tests were performed of short-term memory, psychomotor function and postural stability (balance). Results: A positive correlation was found between the duration of colonoscopy and the amount of sedative given (p < 0.03). No differences in short-term memory or postural control were found when measurements obtained before and after colonoscopy were compared. Reaction time was prolonged significantly after colonoscopy (p < 0.01), which was mainly due to prolongation of perception time (p < 0.003). No correlation was found between the observed reduction in psychomotor function and the amount of sedative given. Conclusions: The introduction of ultrashortacting sedative and hypnotic agents has facilitated out-patient colonoscopy. However, although they feel that they have recovered fully, some patients are still affected by the sedative at the time of discharge, as demonstrated by tests of short-term memory, reaction time and postural stability.