Webb James T, Morgan Thomas R, Sarsfield Sean D
Wyle Laboratories, San Antonio, TX, USA.
Aerosp Med Hum Perform. 2016 Jun;87(6):516-20. doi: 10.3357/AMHP.4390.2016.
Earlier research described a linear relationship between the highest 1 min of oxygen consumption (Vo2) during a recurring physical activity and incidence of decompression sickness (DCS) during research chamber exposures to high altitude. The current effort was designed to determine if that relationship holds true at a lower altitude.
Male subjects (20) were exposed without prebreathe to 22,500 ft (6858 m; 314 mmHg; 6.1 psi) for 4 h while seated, nonambulatory the entire time, with echo-imaging at 16-min intervals (Non-Amb Echo), breathing 100% oxygen. Average highest 1 min of Vo2 and level of activity was determined. Results during Non-Amb Echo were compared with earlier research data acquired under identical conditions except for higher levels of activity.
No DCS was reported or observed and no venous gas emboli were observed. Combined with earlier data, a strong linear relationship (r > 0.99) was observed between DCS incidence and level of activity.
These results suggest physiological envelopes might be expanded or prebreathe time reduced for some high-altitude aircraft operations that involve very low levels of physical activity. They may also help to explain the higher DCS risk for inside observers vs. trainees during altitude chamber training. The data imply potential for update of altitude DCS risk prediction models by adjustment with quantified level of activity during exposure.
早期研究描述了重复性体育活动中最高1分钟耗氧量（Vo2）与研究舱模拟高海拔暴露期间减压病（DCS）发病率之间的线性关系。当前的研究旨在确定在较低海拔高度时这种关系是否依然成立。
20名男性受试者在未进行预呼吸的情况下，以坐姿暴露于22,500英尺（6858米；314毫米汞柱；6.1磅力/平方英寸）的环境中4小时，期间全程保持非走动状态，每隔16分钟进行一次超声成像（非走动超声成像），呼吸100%的氧气。测定平均最高1分钟的Vo2和活动水平。将非走动超声成像期间的结果与早期在相同条件下（除活动水平较高外）获取的研究数据进行比较。
未报告或观察到DCS病例，也未观察到静脉气体栓塞。结合早期数据，观察到DCS发病率与活动水平之间存在强线性关系（r > 0.99）。
这些结果表明，对于一些涉及极低体力活动水平的高海拔飞行操作，生理耐受范围可能会扩大或预呼吸时间可能会缩短。它们还可能有助于解释在高空舱训练期间，内部观察者比学员患DCS的风险更高的原因。这些数据意味着通过调整暴露期间的量化活动水平来更新高空DCS风险预测模型具有可能性。
