Chaturvedi A K, Sanders D C, Endecott B R, Ritter R M
Toxicology and Accident Research Laboratory (AAM 610), Federal Aviation Administration, US Department of Transportation, Oklahoma City, OK 73125-5066, USA.
J Appl Toxicol. 1995 Sep-Oct;15(5):357-63. doi: 10.1002/jat.2550150504.
Carbon monoxide (CO) and hydrogen cyanide (HCN) are generated during aircraft interior fires in sufficient amounts to incapacitate cabin occupants. For typical post-crash and in-flight fires, minimum protection periods of 5 and 35 min, respectively, have been suggested for breathing devices to protect the occupants from smoke. Relationships of blood carboxyhemoglobin (COHb) and cyanide (CN-) levels to incapacitation have not been well defined for these gases. Therefore, time to incapacitation (ti) and blood COHb and CN- at incapacitation were examined in rats exposed to CO (5706 ppm for 5-min ti; 1902 ppm for 35-min ti), HCN (184 ppm for 5-min ti; 64 ppm for 35-min ti) and their mixtures (equipotent concentrations of each gas that produced 5- and 35-min ti). Blood CO and HCN uptakes were evaluated at the two concentrations of each gas. With either gas, variation in ti was higher for the 35-min ti than the 5-min ti The COHb level reached a plateau prior to incapacitation at both CO concentrations, and COHb levels at the 5- and 35-min ti were different from each other. Blood CN- increased as a function of both HCN concentration and exposure time, but CN- at the 5-min ti was half of the 35-min ti CN- level. The HCN uptake at the high concentration was about three times that at the low concentration. In the high concentration CO-HCN mixture, ti was shortened from 5 to 2.6 min; COHb dropped from 81 to 55% and blood CN- from 2.3 to 1.1 microgram ml(-1). At the low-concentration CO-HCN mixture, where ti was reduced from 35 to 11.1 min, COHb decreased from 71 to 61% and blood CN- from 4.2 to 1.1 microgram ml(-1). Any alteration in the uptake of either gas by the presence of the other was minimal. Our findings suggest that specific levels of blood COHb and CN- cannot be correlated directly with the incapacitation onset and that postmortem blood COHb and CN- levels should be evaluated carefully in fire victims.
飞机内部起火时会产生大量一氧化碳（CO）和氰化氢（HCN），足以使机舱内人员丧失行动能力。对于典型的坠机后火灾和飞行中火灾，已建议呼吸装置的最短防护时间分别为5分钟和35分钟，以保护人员免受烟雾侵害。对于这些气体，血液中碳氧血红蛋白（COHb）和氰化物（CN-）水平与丧失行动能力之间的关系尚未明确界定。因此，对暴露于CO（5分钟丧失行动能力时间为5706 ppm；35分钟丧失行动能力时间为1902 ppm）、HCN（5分钟丧失行动能力时间为184 ppm；35分钟丧失行动能力时间为64 ppm）及其混合物（产生5分钟和35分钟丧失行动能力时间的每种气体的等效浓度）的大鼠，研究了其丧失行动能力的时间（ti）以及丧失行动能力时的血液COHb和CN-水平。评估了每种气体两种浓度下的血液CO和HCN摄取量。对于任何一种气体，35分钟丧失行动能力时间的ti变化都高于5分钟丧失行动能力时间的ti变化。在两种CO浓度下，COHb水平在丧失行动能力之前均达到平稳状态，且5分钟和35分钟丧失行动能力时间时的COHb水平彼此不同。血液CN-随HCN浓度和暴露时间的增加而增加，但5分钟丧失行动能力时间时的CN-是35分钟丧失行动能力时间时CN-水平的一半。高浓度下的HCN摄取量约为低浓度下的三倍。在高浓度CO-HCN混合物中，ti从5分钟缩短至2.6分钟；COHb从81%降至55%，血液CN-从2.3微克/毫升降至1.1微克/毫升。在低浓度CO-HCN混合物中，ti从35分钟减少至11.1分钟，COHb从71%降至61%，血液CN-从4.2微克/毫升降至1.1微克/毫升。另一种气体的存在对任何一种气体摄取量的影响都很小。我们的数据表明，血液COHb和CN-的特定水平不能直接与丧失行动能力的开始相关，并且在火灾受害者中应仔细评估死后血液COHb和CN-水平。
