Frånberg Oskar, Ericsson Mikael, Larsson Agneta, Lindholm Peter
Department of Environmental Physiology, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden.
Undersea Hyperb Med. 2011 Jan-Feb;38(1):61-72.
This paper describes the examination of a Halcyon RB80 semi-closed underwater breathing apparatus used in a diving accident in 2007. The apparatus was supplied with trimix (oxygen, nitrogen and helium) containing 31% oxygen. The duration of the dive was 105 minutes at 28 meters' average depth in fresh water, with a 19-minute oxygen decompression stop at 6 meters. Upon surfacing the diver experienced seizures and signs of severe neurological deficits. The apparatus was tested with regard to the oxygen fraction drop from the supply gas to the breathing loop--i.e., the oxygen fraction inhaled by the diver (FiO2) was investigated. The FiO2 was measured and found to be lower than the value stated on the manufacturer's web page at the time of the accident. This investigation suggests that during the dive, the actual FiO2% was 17.9-25.3%, which is considerably lower than the FiO2% used for decompression calculations (30%). The underestimation of FiO2 resulted in too short and/or too few decompression stops during ascent. The low FiO2 would also put a diver at risk of hypoxia at shallow depths. It is concluded that inadequate information on the performance of the rebreather was a major contributing factor to this accident.
本文描述了对一台2007年潜水事故中使用的Halcyon RB80半封闭水下呼吸器的检查情况。该呼吸器配备了含31%氧气的混合气（氧气、氮气和氦气）。潜水在淡水中平均深度28米处持续了105分钟，在6米处有19分钟的氧气减压停留。浮出水面后，潜水员出现了癫痫发作和严重神经功能缺损的症状。对该呼吸器进行了关于从供气到呼吸回路的氧分数下降的测试——即研究潜水员吸入的氧分数（FiO2）。测量发现FiO2低于事故发生时制造商网页上公布的值。本次调查表明，在潜水过程中，实际FiO2%为17.9 - 25.3%，远低于用于减压计算的FiO2%（30%）。FiO2的低估导致上升过程中的减压停留时间过短和/或次数过少。低FiO2也会使潜水员在浅深度面临缺氧风险。得出的结论是，关于该再循环呼吸器性能的信息不足是此次事故的一个主要促成因素。
