Unpressurized aircraft routinely operate at altitudes where hypoxia may be of concern. A systematic literature review was conducted regarding hypoxic impairment, including mental functions, sensory deficits, and other pertinent research findings that may affect aviation-related duties at moderate altitude (8000 to 15,000 ft/2438 to 4572 m). The results of this review suggest that cognitive and psychomotor deficits may include learning, reaction time, decision-making, and certain types of memory. However, results are difficult to quantify and reliably reproduce. Inconsistency of results may be related to the subtlety of deficits compared to high altitude, differences among individual compensatory mechanisms, variation in methodology or sensitivity of metrics, presence or absence of exercise, heterogeneous neuronal central nervous system (CNS) response, and interindividual variation. Literature regarding hypoxic visual decrements is more consistent. Rod photoreceptors are more susceptible to hypoxia; visual degradation has been demonstrated at 4000 to 5000 ft (1219 to 1524 m) under scotopic and 10,000 ft (3048 m) under photopic conditions. Augmented night vision goggle resolution demonstrates more resilience to mild hypoxic effects than the unaided eye under starlight conditions. Hypocapnia enhances visual sensitivity and contrast discrimination. Hyperventilation with resulting respiratory alkalosis and cerebral vasoconstriction may confound both cognitive/ psychomotor and visual experimental results. Future research should include augmentation of validated neuropsychological metrics (surrogate investigational end points) with actual flight metrics, investigation of mixed gas formulations, contribution of hypocapnic vasoconstrictive effects on hypoxic performance, and further investigation into cellular- and systems-level approaches for heterogeneous CNS response. Research is also required into the contribution of mild-moderate hypoxia in human factors- and spatial disorientation-related mishaps.
Low back pain remains a significant issue among helicopter aircrew. There is a considerable body of scientific literature devoted to the problem, including epidemiologic and experimental studies addressing prevalence, characteristics, primary etiology, and contributing factors. It is endemic and multinational, with a prevalence ranging from 50-92%. Archetypal pain begins with flight or within hours of flight, is mostly targeted in the low back/lumbar region and/or buttocks, is transient, and is commonly described as dull and achy. A minority develop chronic, persistent pain that is variously described with dissimilar characteristics. The pernicious effects of back pain or discomfort while piloting may affect flight performance and safety, including reduced operational effectiveness and lost duty time, occupational attrition, curtailed or cancelled missions, compromised emergency egress, and performance deficits during critical phases of flight. The majority of etiologic studies have focused on the pathophysical posture adopted by pilots for aircraft control and exposure to whole body vibration. With more evidence for the former, it remains likely that both, as well as other factors, may have a contributory and perhaps integrative or concerted role. Corrective and mitigation strategies have addressed lumbar support, seat and cockpit ergonomic redesign, and improved aircrew health. Flight surgeons should be familiar with this prevalent issue and future research must address longitudinal cohort studies with clear definitions, relevant and valid exposure data, dose-response detail, and control for contributing factors and confounders.
While the results of this study support the efficacy of modafinil, the main finding is the large literature gap evaluating the short- and long-term effects of these drugs in healthy adults.
Back pain rates were consistent with previous studies. The relationship of age to back pain in this study may highlight unique pathophysiological pathways that should be further investigated within an occupational context to better understand the etiologic role. Enhanced seated lumbar support and combat-related survival equipment remain relatively low-cost/high-yield topics worthy of further investigation for exploiting efficient means to improve health, safety, and operational performance.Kelley AM, MacDonnell J, Grigley D, Campbell J, Gaydos SJ. Reported back pain in army aircrew in relation to airframe, gender, age, and experience. Aerosp Med Hum Perform. 2017; 88(2):96-103.
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