A Randomized Crossover Trial of Conventional versus Modified "Koch" Chest Compressions in a Height-Restricted Aeromedical Helicopter.

Aim: Low overhead height can negatively affect chest compression performance. An adapted compression technique has been proposed by paramedic H. Koch (pron. "Cook"). This study compares conventional to Koch technique in a height-restricted aeromedical helicopter. Methods: Eighteen clinicians were randomized to 2 minutes of conventional or Koch compressions, then crossed-over. Koch technique uses a forearm/elbow instead of overlapping hands. Compression quality was assessed with a Skill Reporting Laerdal Resusci-Anne manikin. Quality variables were: the number and rate of compressions, compression depth, release, land marking, and overall aggregate quality score. Participant feedback was collected using the Borg Scale of Perceived Exertion, and compression difficulty using a zero-to-ten scale. Furthermore, we solicited open-ended descriptive responses. Results: The average overall quality score was 63% for conventional compressions versus 79% for Koch compressions (p = 0.04). On average, the Koch compression method increased compression depth by 5 mm (95% CI 4.3 to 5.7) and the proportion of compressions at the correct depth by 17% (95% CI 7.55 to 26.45), although these were not statistically significant. Correct release and land marking showed no statistically significant difference between techniques. Koch compressions resulted in statistically significant reductions in physical exertion and difficulty (p < 0.001). Qualitative feedback described modified compressions as easier and more sustainable. Conclusions: In a height-restricted aeromedical helicopter, the average overall quality score improved using Koch compressions, although the mean rate, mean depth, correct release and land marking were found to be similar between techniques. Qualitative feedback described Koch compressions as easier and more sustainable. In settings where the compressor is affected by reduced overhead working height, Koch compressions may be an advisable alternative.