During diving, arterial Pco(2) (Pa(CO(2))) levels can increase and contribute to psychomotor impairment and unconsciousness. This study was designed to investigate the effects of the hypercapnic ventilatory response (HCVR), exercise, inspired Po(2), and externally applied transrespiratory pressure (P(tr)) on Pa(CO(2)) during immersed prone exercise in subjects breathing oxygen-nitrogen mixes at 4.7 ATA. Twenty-five subjects were studied at rest and during 6 min of exercise while dry and submersed at 1 ATA and during exercise submersed at 4.7 ATA. At 4.7 ATA, subsets of the 25 subjects (9-10 for each condition) exercised as P(tr) was varied between +10, 0, and -10 cmH(2)O; breathing gas Po(2) was 0.7, 1.0, and 1.3 ATA; and inspiratory and expiratory breathing resistances were varied using 14.9-, 11.6-, and 10.2-mm-diameter-aperture disks. During exercise, Pa(CO(2)) (Torr) increased from 31.5 +/- 4.1 (mean +/- SD for all subjects) dry to 34.2 +/- 4.8 (P = 0.02) submersed, to 46.1 +/- 5.9 (P < 0.001) at 4.7 ATA during air breathing and to 49.9 +/- 5.4 (P < 0.001 vs. 1 ATA) during breathing with high external resistance. There was no significant effect of inspired Po(2) or P(tr) on Pa(CO(2)) or minute ventilation (Ve). Ve (l/min) decreased from 89.2 +/- 22.9 dry to 76.3 +/- 20.5 (P = 0.02) submersed, to 61.6 +/- 13.9 (P < 0.001) at 4.7 ATA during air breathing and to 49.2 +/- 7.3 (P < 0.001) during breathing with resistance. We conclude that the major contributors to increased Pa(CO(2)) during exercise at 4.7 ATA are increased depth and external respiratory resistance. HCVR and maximal O(2) consumption were also weakly predictive. The effects of P(tr), inspired Po(2), and O(2) consumption during short-term exercise were not significant.
Introduction
“Simulation Roulette” is a new method of “on-the-fly” simulation scenario creation that incorporates a game-like approach to critical scenarios and emphasizes pre-scenario preparation. We designed it to complement our traditional anesthesia simulation curriculum, in which residents are exposed to pre-defined “critical” scenarios. During typical scenarios trainees are often given minimum preparatory information; they then start the scenario knowing only that “something bad” is going to happen. As a result, trainees often report anxiety, which can be a barrier to learning. To overcome this barrier and to augment traditional critical incident training, we developed the “Simulation Roulette” game.
Materials and methods
“Simulation Roulette” consists of pre-made cards that are randomly selected to create a patient, another set of pre-made cards to assist in selecting “complications”, worksheets to guide a thorough “prebrief” discussion prior to the scenario, and scoresheets to facilitate the “debrief” discussion at the end. Similar to traditional scenarios, it requires coordination by a facilitator to ensure plausible scenarios and evaluation of trainee performance.
Results
Although we have not conducted formal testing, we believe that 1) incorporating an element of random chance to scenario selection, 2) using a game-like framework, and 3) emphasizing the “prebrief” portion of simulation all have the potential to decrease trainee anxiety.
Conclusions
We present the rationale for designing such a game; examples of instructions, cards, and scoresheets; and our initial experience with implementing this game within our simulation curriculum.
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