Oculometric Feature Changes During Acute Hypoxia in a Simulated High-Altitude Airdrop Scenario

BACKGROUND: severe acute hypoxia results in a rapid deterioration of cognitive functioning and thus poses a risk for human operations in high altitude environments. this study aimed at investigating the effects of oxygen system failure during a highaltitude high-opening (hahO) parachute jump scenario from 30,000 ft (9144 m) on human physiology and cognitive performance using a noncontact eye-tracking task. methods: Nine healthy male volunteers (ages 27-48) were recruited from the Norwegian Special Operations Commandos. Eye-tracking data were collected to derive information on cognitive performance in the context of rapid dynamic changes in pressure altitude while performing a modified King-Devick test. the baseline data was collected at 8000 ft (2438 m) while breathing 100% oxygen during decompression. For every test, the corresponding arterial blood gas analysis was performed. results: the study subjects endured severe hypoxia, which resulted in significant prolongations of fixation time (range: 284.1-245.6 ms) until 23,397 ft (131 m) and fixation size (range: 34.6-32.4 mm) until 25,389 ft (7739 m) as compared to the baseline (217.6 ± 17.8 ms and 27.2 ± 4.5 mm, respectively). the increase in the saccadic movement and decrease in the saccadic velocity was observed until 28,998 ft and 27,360 ft (8839 and 8339 m), respectively. discussion: this is the first study to investigate cognitive performance from measured oculometric variables during severe hypobaric hypoxia in a simulated high-altitude airdrop mission scenario. the measurement of altered oculometric variables under hypoxic conditions represents a potential avenue to study altered cognitive performance using noncontact sensors that^:canderiveinforma tion^:andser vetoprovidetheindividual with a warning from impending incapacitation.