Background

Aircrew members are required to attend hypoxia awareness training regularly to strengthen their memory of their personal hypoxia symptoms by undergoing training inside a hypobaric chamber. The aim of this study was to examine the association between hypoxia symptoms experienced during two training sessions that were 4 years apart.

Methods

This was a crossover study to compare hypoxia symptoms and self-reported physiological effects of trapped gas between a previous training session and a current training session in an altitude chamber. The subjects were military crew members who undertook a 25,000-feet refresher training course in 2018. We used a structured questionnaire to obtain the target information before and during hypoxia exposure. Data were analyzed using SPSS software.

Results

A total of 341 trainees participated in this survey and completely filled out the questionnaire. Gastrointestinal tract discomfort caused by the expansion of trapped gas was the main physiological reaction during the previous and current training sessions. Frequently reported symptoms were poor concentration (30.5%), impaired cognitive function (20.5%), visual disturbances (16.4%), hot flashes (15.8%), and paresthesia (12.6%) during both exposures. However, the proportions of participants reporting poor concentration (P = 0.378) and visual disturbances (P = 0.594) were not significantly different between the recalled and current training sessions. The five most common symptoms among the subjects with less than 1,000 flight hours were poor concentration (29.8%), visual disturbance (27.3%), impaired cognitive function (14.9%), dizziness/lightheadedness (11.6%), and hot flashes (9.9%), which overlapped substantially with the symptoms reported by other subjects. The occurrence of those five most common symptoms in the group with more than 1,000 flight hours did not significantly differ between the recalled training session and the current training session.

Conclusions

The most common hypoxia symptoms reported were similar between the recalled and current training sessions in an environment with a low oxygen concentration. This finding was also clearly affected by the duration of flight experience. Moreover, GI effects of the expansion of trapped gas were commonly observed at low atmospheric pressure.

中文翻译：

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召回暴露与当前暴露之间的低压缺氧症状比较。

背景

空勤人员必须定期参加缺氧意识培训，以通过在低压舱内进行训练来增强对自己的缺氧症状的记忆。这项研究的目的是检查两次相距4年的训练中经历的缺氧症状之间的关联。

方法

这是一项交叉研究，旨在比较先前训练课程和当前训练课程在高海拔舱室中的低氧症状和被困气体的自我报告的生理效应。受试者是在2018年进行了25,000英尺的进修培训的军方人员。我们使用结构化问卷调查了缺氧暴露前后的目标信息。使用SPSS软件分析数据。

结果

共有341名学员参加了该调查，并完整填写了调查表。在以前和当前的训练中，由滞留气体的膨胀引起的胃肠道不适是主要的生理反应。两次暴露期间，经常报告的症状为注意力不集中（30.5％），认知功能受损（20.5％），视觉障碍（16.4％），潮热（15.8％）和感觉异常（12.6％）。但是，报告集中注意力不佳（P = 0.378）和视觉障碍（P= 0.594）在召回的培训和当前的培训课程之间没有显着差异。飞行时间少于1,000小时的受试者中五个最常见的症状是注意力不集中（29.8％），视力障碍（27.3％），认知功能受损（14.9％），头晕/头晕（11.6％）和潮热（9.9） ％），与其他受试者报告的症状基本重叠。在飞行时间超过1,000小时的组中，这五个最常见的症状的发生在召回的培训课程和当前培训课程之间没有显着差异。

结论

在氧气浓度低的环境中，召回和当前的训练课程之间报告的最常见的缺氧症状相似。飞行时间的长短也明显影响了这一发现。此外，通常在低大气压下观察到了被捕集气体膨胀的胃肠道效应。