Stepanek Jan, Cocco Daniela, Pradhan Gaurav N, Smith Benn E, Bartlett Jennifer, Studer Marc, Kuhn Fabian, Cevette Michael J
Aerospace Medicine and Vestibular Research Laboratory Mayo Clinic, Scottsdale, AZ 85259, USA.
Aviat Space Environ Med. 2013 Oct;84(10):1017-22. doi: 10.3357/asem.3616.2013.
Hypoxic incapacitation continues to be a significant threat to safety and operations at high altitude. Noninvasive neurocognitive performance testing is desirable to identify presymptomatic cognitive impairment, affording operators at altitude a tool to quantify their performance and safety.
There were 25 subjects enrolled in this study. Cognitive performance was assessed by using the King-Devick (K-D) test. The performance of the subjects on the K-D test was measured in normoxia followed by hypoxia (8% 02 equivalent to 7101 m) and then again in normoxia.
K-D test completion time in hypoxia for 3 min was significantly longer than the Baseline Test (54.5 +/- 12.4 s hypoxic vs. 46.3 +/- 10.4 s baseline). Upon returning to normoxia the completion time was significantly shorter than in hypoxia (47.6 +/- 10.6 s post test vs. 54.5 +/- 12.4 s hypoxic). There was no statistically significant difference between baseline test and post test times, indicating that all subjects returned to their normoxic baseline levels. SpO2 decreased from 98 +/- 0.9% to 80 +/- 7.8% after 3 min on hypoxic gas. During the hypoxic K-D test, SpO2 decreased further to 75.8 +/- 8.3%.
In this study the K-D test has been shown to be an effective neurocognitive test to detect hypoxic impairment at early presymptomatic stages. The K-D test may also be used to afford a reassessment of traditional measures used to determine hypoxic reserve time.
低氧性失能仍然是对高海拔地区安全和作业的重大威胁。非侵入性神经认知功能测试有助于识别症状前的认知障碍，为高海拔地区的作业人员提供一种量化其表现和安全性的工具。
本研究招募了25名受试者。使用King-Devick（K-D）测试评估认知表现。在常氧状态下测量受试者在K-D测试中的表现，随后在低氧状态（8%氧气，相当于海拔7101米）下测量，之后再次在常氧状态下测量。
低氧状态下3分钟的K-D测试完成时间显著长于基线测试（低氧状态下为54.5±12.4秒，基线测试为46.3±10.4秒）。恢复到常氧状态后，完成时间显著短于低氧状态（测试后为47.6±10.6秒，低氧状态下为54.5±12.4秒）。基线测试和测试后时间之间没有统计学上的显著差异，表明所有受试者都恢复到了常氧基线水平。在低氧气体环境中3分钟后，血氧饱和度（SpO2）从98±0.9%降至80±7.8%。在低氧K-D测试期间，SpO2进一步降至75.8±8.3%。
在本研究中，K-D测试已被证明是一种有效的神经认知测试，可在症状前早期阶段检测低氧损伤。K-D测试还可用于重新评估用于确定低氧储备时间的传统方法。
