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West J Emerg Med. 2017 Oct;18(6):1025-1034. doi: 10.5811/westjem.2017.8.34236. Epub 2017 Sep 11.

Team Size and Stretching-Exercise Effects on Simulated Chest Compression Performance and Exertion.

Author information

Alpert Medical School of Brown University, Department of Emergency Medicine, Providence, Rhode Island.
Lifespan Medical Simulation Center, Providence, Rhode Island.
Mayo Clinic Rochester, Department of Emergency Medicine, Rochester, Minnesota.
Rhode Island Hospital, Biostatistics Core, Providence, Rhode Island.



Investigators conducted a prospective experimental study to evaluate the effect of team size and recovery exercises on individual providers' compression quality and exertion. Investigators hypothesized that 1) larger teams would perform higher quality compressions with less exertion per provider when compared to smaller teams; and 2) brief stretching and breathing exercises during rest periods would sustain compressor performance and mitigate fatigue.


In Phase I, a volunteer cohort of pre-clinical medical students performed four minutes of continuous compressions on a Resusci-Anne manikin to gauge the spectrum of compressor performance in the subject population. Compression rate, depth, and chest recoil were measured. In Phase II, the highest-performing Phase I subjects were placed into 2-, 3-, and/or 4-compressor teams; 2-compressor teams were assigned either to control group (no recovery exercises) or intervention group (recovery exercises during rest). All Phase II teams participated in 20-minute simulations with compressor rotation every two minutes. Investigators recorded compression quality and real-time heart rate data, and calculated caloric expenditure from contact heart rate monitor measurements using validated physiologic formulas.


Phase I subjects delivered compressions that were 24.9% (IQR1-3: [0.5%-74.1%]) correct with a median rate of 112.0 (IQR1-3: [103.5-124.9]) compressions per minute and depth of 47.2 (IQR1-3: [35.7-55.2]) mm. In their first rotations, all Phase II subjects delivered compressions of similar quality and correctness (p=0.09). Bivariate analyses of 2-, 3-, and 4-compressor teams' subject compression characteristics by subsequent rotation did not identify significant differences within or across teams. On multivariate analyses, only subjects in 2-compressor teams exhibited significantly lower compression rates (control subjects; p<0.01), diminished chest release (intervention subjects; p=0.03), and greater exertion over successive rotations (both control [p≤0.03] and intervention [p≤0.02] subjects).


During simulated resuscitations, 2-compressor teams exhibited increased levels of exertion relative to 3- and 4-compressor teams for comparable compression delivery. Stretching and breathing exercises intended to assist with compressor recovery exhibited mixed effects on compression performance and subject exertion.

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Conflict of interest statement

Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. This material is based upon work supported by the Department of Emergency Medicine, Alpert Medical School of Brown University; and the Lifespan Medical Simulation Center. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the Department or LMSC.

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