Abstract

The purpose of the study was to measure recovery from general anesthesia. A group of 23 patients underwent surgery under general anesthesia with enflurane (N = 21) or halothane (N = 2). Anesthesia lasted 25120 min (mean = 52 min). Patients were measured before induction of anesthesia (trial 1) and 1, 2 and 3 h later (trials 2, 3, and 4). A control group (N = 23) underwent the same procedure. The instrument measured subjects' reaction times to a green light. A white light preceded the onset of the stimulus light. The foreperiod lasted successively 3, 2, and 4 s in each of three trials. Reaction time was longer (F = 5.09, p) on trials 2 and 3; patients reached the baseline level (t = 0.94) on trial 4. The performance of the control group was constant within an equivalent length of time (F = 0.62). The same experiment was repeated in order to compare the effects of a visual warning signal (VWS) and an auditory warning signal (AWS). Anesthesia was maintained with isoflurane (N = 18) or enflurane (N = 12). A buzzer (AWS) or a white light (VWS) was heard or seen at a distance of 1 m. Conditions were counterbalanced. The differences between the four trials were significant when patients were submitted to an AWS (F3, 119 = 17.06, p) or a VWS (F3, 119 = 25.87, p). The differences between reaction times with an AWS and those with a VWS were significant on the four trials. Reaction time was systematically shorter with an AWS than with a VWS and yielded a biased measure of recovery from general anesthesia.

© 1990 Optical Society of America