• Benjamin Zendejas, David A Cook, and David R Farley.
• Department of Surgery, College of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
• J Surg Educ. 2010 Nov 1; 67 (6): 432-8.

ObjectiveThe optimal timing of instruction in simulation-based scenarios remains unclear. We sought to determine how varying the timing of instruction, either before (teaching first) or after (teaching last) the simulation, affects knowledge outcomes of surgical trainees.DesignWe conducted a pretest/posttest crossover study in which fourth-year medical students and general surgery residents (PGY 1-3) participated in 3 instructional modules, each repeated twice in consecutive weeks: endocrine surgery (sessions 1 and 2), trauma resuscitation (sessions 3 and 4), and team training (sessions 5 and 6). Each session comprised 3 cases, each involving a prescenario briefing, a simulated scenario, and a postscenario debriefing. The timing of instruction varied between sessions. For the teaching-first sequence (sessions 1, 4, and 6), participants received a lecture during each prescenario briefing. In the teaching-last sequence (sessions 2, 3, and 5), trainees received an identical lecture during the postscenario debriefings. We assessed attitudes and knowledge using a postsession survey and identical 10-question multiple-choice tests at the start (pretest) and end (posttest) of each session, respectively. The mean differences in knowledge scores between groups were analyzed with repeated-measures analysis of variance (ANOVA).ResultsForty-nine participants (11 medical students and 38 surgical residents) attended at least 1 session, providing 76 observations. Mean pretest scores were equivalent (p > 0.05). The change in scores from pretest to posttest varied between the 2 groups (p = 0.002). The mean posttest score was 8.24 (standard error [SE], 0.29) for the teaching-last group and 6.68 (SE, 0.27) for the teaching-first group (mean difference, 1.56; 95% confidence interval, 0.79-2.33). Both teaching-last and teaching-first group participants preferentially rated debriefings and scenarios, respectively, as the better learning experience.ConclusionsParticipants who received instruction after simulated scenarios achieved higher mean knowledge scores than those who received instruction before simulated scenarios. Cognitive overload, stress, or activation of prior knowledge could all be involved as causal mechanisms.Copyright © 2010 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

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