Time course of cognitive recovery after propofol anaesthesia: a level of processing approach.

The aim of this study was to investigate the time course of recovery of verbal memory after general anaesthesia, as a function of the level (shallow or deep) of processing induced at the time of encoding. Thirty-one patients anaesthetized with propofol and alfentanil were compared with 28 control patients receiving only alfentanil. Memory functions were assessed the day before and 1, 6 and 24 hr after operation. Results show that for the anaesthetized group, shallow processing was impaired for 6 hr after surgery whereas the deeper processing was not recovered even at 24 hr. In addition, no specific effect of age was found.