Roy Steven, Schielke Ryck K, Haffey Daniel, Coombs Heather
McGill University, Faculty of Medicine, Montreal, Québec, Canada.
University of Saskatchewan, College of Medicine, Saskatoon, Saskatchewan, Canada.
Wilderness Environ Med. 2019 Jun;30(2):186-190. doi: 10.1016/j.wem.2019.02.005. Epub 2019 May 2.
Point-of-care ultrasonography is a burgeoning field of practice and study. Although point-of-care ultrasonography has started to penetrate the field of wilderness medicine, its use in cold environments is often limited by poor battery performance. In the current study, we investigated the effect of chemical foot warmers on battery runtime of handheld ultrasound machines in cold weather.
This prospective study used a balanced, crossover randomization design to compare handheld ultrasound machines exposed to cold weather with and without the application of chemical foot warmers. Time to power off, ambient temperature, air humidity, and wind speed were recorded for each trial and compared in a mixed-effects model analysis of variance.
Ultrasound machines showed significantly decreased functional battery life with decreasing temperature (P<0.01) and increasing wind speed (P=0.01). Addition of the chemical foot warmer resulted in a statistically significant increase in handheld ultrasound machine runtime compared with controls (P<0.001). Overall machine runtime was increased by approximately 21.8 min (95% CI 16.2-27.3).
The application of chemical foot warmers to handheld ultrasound machines exposed to cold environments prolongs usable battery life and, consequently, may allow for extended scanning time in austere and remote environments.
即时超声检查是一个新兴的实践和研究领域。尽管即时超声检查已开始渗透到野外医学领域，但其在寒冷环境中的使用常常受到电池性能不佳的限制。在本研究中，我们调查了化学暖脚器对寒冷天气下手持式超声仪电池续航时间的影响。
这项前瞻性研究采用平衡交叉随机设计，比较在寒冷天气下使用和不使用化学暖脚器时手持式超声仪的情况。记录每次试验的关机时间、环境温度、空气湿度和风速，并在方差混合效应模型分析中进行比较。
超声仪的有效电池寿命随温度降低（P<0.01）和风速增加（P=0.01）而显著缩短。与对照组相比，添加化学暖脚器使手持式超声仪的运行时间有统计学意义的增加（P<0.001）。整机运行时间总体增加了约21.8分钟（95%CI 16.2-27.3）。
在暴露于寒冷环境的手持式超声仪上应用化学暖脚器可延长可用电池寿命，因此，可能允许在严峻和偏远环境中延长扫描时间。
