BackgroundHelicopter emergency medical services personnel operating in mountainous terrain are frequently exposed to rapid ascents and provide cardiopulmonary resuscitation (CPR) in the field. The aim of the present trial was to investigate the quality of chest compression only (CCO)‐CPR after acute exposure to altitude under repeatable and standardized conditions.Methods and ResultsForty‐eight helicopter emergency medical services personnel were divided into 12 groups of 4 participants; each group was assigned to perform 5 minutes of CCO‐CPR on manikins at 2 of 3 altitudes in a randomized controlled single‐blind crossover design (200, 3000, and 5000 m) in a hypobaric chamber. Physiological parameters were continuously monitored; participants rated their performance and effort on visual analog scales. Generalized estimating equations were performed for variables of CPR quality (depth, rate, recoil, and effective chest compressions) and effects of time, altitude, carryover, altitude sequence, sex, qualification, weight, preacclimatization, and interactions were analyzed. Our trial showed a time‐dependent decrease in chest compression depth (P=0.036) after 20 minutes at altitude; chest compression depth was below the recommended minimum of 50 mm after 60 to 90 seconds (49 [95% CI, 46–52] mm) of CCO‐CPR.ConclusionsThis trial showed a time‐dependent decrease in CCO‐CPR quality provided by helicopter emergency medical services personnel during acute exposure to altitude, which was not perceived by the providers. Our findings suggest a reevaluation of the CPR guidelines for providers practicing at altitudes of 3000 m and higher. Mechanical CPR devices could be of help in overcoming CCO‐CPR quality decrease in helicopter emergency medical services missions.RegistrationURL: https://www.clinicaltrials.gov; Unique identifier: NCT04138446.

中文翻译：

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急性高原暴露对直升机紧急医疗服务人员仅胸外按压心肺复苏质量的影响：一项随机、对照、单盲交叉试验

背景在山区作业的直升机紧急医疗服务人员经常暴露于快速上升并在现场提供心肺复苏术（CPR）。本试验的目的是调查在可重复和标准化条件下急性暴露于高原后仅胸外按压 (CCO)-CPR 的质量。方法和结果 48 名直升机紧急医疗服务人员被分为 12 组，每组 4 名参与者；每组被分配在低压舱中以随机控制的单盲交叉设计（200、3000 和 5000 m）在 3 个高度中的 2 个高度对人体模型进行 5 分钟的 CCO-CPR。生理参数持续监测；参与者在视觉模拟量表上对他们的表现和努力进行了评分。对 CPR 质量变量（深度、频率、后坐力和有效胸外按压）进行了广义估计方程，并分析了时间、海拔、携带、海拔序列、性别、资格、体重、预适应和相互作用的影响。我们的试验显示胸外按压深度随时间减少（P = 0.036) 在海拔 20 分钟后；在 CCO-CPR 60 到 90 秒（49 [95% CI，46-52] mm）后，​​胸部按压深度低于推荐的最小值 50 mm。结论该试验显示直升机提供的 CCO-CPR 质量随时间下降紧急医疗服务人员在急性暴露于高海拔时，提供者没有察觉。我们的研究结果建议重新评估在海拔 3000 米及更高处执业的提供者的心肺复苏指南。机械 CPR 设备可能有助于克服直升机紧急医疗服务任务中 CCO-CPR 质量下降的问题。注册网址：https://www.clinicaltrials.gov；唯一标识符：NCT04138446。