Real-time effects of normobaric, transient near-anoxia on performance

Recent physiological incidents involving pilots of high performance fighter aircraft have raised the question of whether inadvertent, short bursts of significantly reduced oxygen could negatively impact real-time performance. This study evaluated normobaric, real-time performance in the setting of transient near-anoxia to inform future countermeasure development.

The study was performed on 12 healthy subjects without significant medical history. Following collection of baseline data, real-time performance changes were evaluated during sequentially increasing periods of near-anoxic gas exposure (F(I)0(2) = 1%) using a computer-based performance assessment tool. Both room air and 100% oxygen were used as the prebreathe/recovery gases. Statistical analysis was performed on the results.

Under normobaric conditions, subjects inspiring up to five near-anoxic breaths showed no significant performance decrement in either accuracy or effective actions per minute. Mean accuracy up to five near-anoxic breaths was 0.67 (SD = 0.01) as compared to a baseline mean of 0.68 (SD = 0.02). Hyperoxia had a protective effect on subject physiological response to near anoxia.

These normobaric findings offer an assessment of real-time performance changes in the setting of transient, near-anoxic gas exposure. Overall, the results help inform the design of increasingly complex aircraft oxygen delivery systems in terms of how tightly such systems must match the sea-level gas equivalent with increasing altitude. This is particularly relevant as such systems are being called upon to ensure safe aircrew operations across an expanding operational flight envelope.