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首页> 外文期刊>Aviation, space, and environmental medicine. >Decompression sickness risk at 6553 m breathing two gas mixtures.
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Decompression sickness risk at 6553 m breathing two gas mixtures.

机译：呼吸两种气体混合物在6553 m时有减压病的危险。

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INTRODUCTION: The risk of severe decompression sickness (DCS) increases rapidly above 6248 m (20,500 ft) and is greater when breathing higher proportions of inert gas. Contemporary aircrew may be exposed to higher cabin altitudes while breathing molecular sieve oxygen concentrator (MSOC) product gas containing variable concentrations of oxygen, nitrogen, and argon. This study assessed the risk of DCS at 6553 m (21,500 ft) breathing two simulated MSOC product gas mixtures. METHODS: In a hypobaric chamber, 10 subjects each undertook 2 4-h exposures at 6553 m breathing either 75% O2:21% N2:4% Ar or 56% 02:42% N2:2% Ar. Subjects undertook regular activities simulating in-flight movements of fast jet aircrew. Venous gas emboli (VGE) "bubble" load was graded every 15 min using 2D and Doppler echocardiography by experienced operators blinded to breathing gas composition. RESULTS: DCS occurred in five exposures (25%), the earliest after less than 90 min at altitude. All were minor, single-site, uncomplicated limb bends that resolved with recompression. VGE occurred in 85% of exposures with some early-onset, heavy loads. Survival (Probit) analysis indicated that breathing 56% oxygen significantly decreased VGE latency relative to breathing 75% oxygen (relative potency 3.05). CONCLUSIONS: From 20 experimental exposures, the risk of DCS at 6553 m is estimated at 5% by 90 min and 20% at 3 h. Exploiting the negative predictive value of VGE latency as a surrogate measure of protection from DCS, at high cabin altitudes better MSOC performance (higher product gas oxygen concentrations) will protect more aircrew for longer.
机译：简介：严重减压病（DCS）的风险在6248 m（20,500 ft）以上迅速增加，并且在呼吸更高比例的惰性气体时会更大。当代的机组人员可能在呼吸含有可变浓度的氧气，氮气和氩气的分子筛氧气浓缩器（MSOC）产品气体时暴露于更高的机舱高度。这项研究评估了呼吸两种模拟的MSOC产物气体混合物在6553 m（21,500 ft）处DCS的风险。方法：在减压室中，每位10名受试者在6553 m处进行2次4小时暴露，呼吸频率为75％O2：21％N2：4％Ar或56％02：42％N2：2％Ar。受试者定期进行模拟快速喷气机机组飞行中活动的活动。经验丰富的操作员对呼吸气体成分视而不见，使用二维和多普勒超声心动图技术每15分钟对静脉气体栓塞（VGE）“气泡”负荷进行分级。结果：DCS发生在五次暴露中（25％），最早发生在海拔不到90分钟之后。所有这些都是轻微的，单一部位的，简单的四肢弯曲，可通过再压缩来解决。 VGE发生在85％的暴露中，有一些早期发作，重负荷。生存（Probit）分析表明，相对于呼吸75％的氧气，呼吸56％的氧气显着降低了VGE潜伏期（相对效度3.05）。结论：从20次实验暴露中，估计到DCS在6553 m处的风险在90分钟时为5％，在3 h时为20％。利用VGE潜伏期的负面预测值作为DCS保护的替代措施，在较高的机舱高度，更好的MSOC性能（较高的产品气体氧气浓度）将为更多的机组人员提供更长的保护时间。

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