Cognitive responses to hypobaric hypoxia: implications for aviation training

Abstract

The aim of this narrative review is to provide an overview on cognitive responses to hypobaric hypoxia and to show relevant implications for aviation training. A principal element of hypoxia-awareness training is the intentional evocation of hypoxia symptoms during specific training sessions within a safe and controlled environment. Repetitive training should enable pilots to learn and recognize their personal hypoxia symptoms. A time span of 3–6 years is generally considered suitable to refresh knowledge of the more subtle and early symptoms especially. Currently, there are two different technical approaches available to induce hypoxia during training: hypobaric chamber training and reduced-oxygen breathing devices. Hypoxia training for aircrew is extremely important and effective, and the hypoxia symptoms should be emphasized clearly to aircrews. The use of tight-fitting masks, leak checks, and equipment checks should be taught to all aircrew and reinforced regularly. It is noteworthy that there are major differences in the required quality and quantity of hypoxia training for both military and civilian pilots.

Insight into potential mechanisms of hypobaric hypoxia–induced learning and memory deficit – Lessons from rat studies

“…It has been shown that exposure to hypobaric hypoxia (F I O 2 < 20.9%; PB < 760 mmHg) and NH (F I O 2 < 20.9%; PB ¼ 760 mmHg) may or may not result in different physiological responses in human subjects. [41][42][43] In a study by Shukitt-Hale et al, 44 23 nonacclimatized males were exposed to 500, 4200 or 4700 m in an altitude chamber for 4-5 h. The study demonstrated that the higher the altitude and the longer the duration of exposure, the more severe mood and memory impairment. A similar study was later conducted by Du et al 45 involving 18 healthy young male subjects exposed to 300 m (control group), 2800, 3600 and 4400 m altitude in hypobaric chamber.…”

The Impact of Different Environmental Conditions on Cognitive Function: A Focused Review

“…It is generally accepted that there is a negative correlation between altitude and cognitive function (Table 5 ; Li et al, 2000 ; Pickard, 2002 ; Rainford and Gradwell, 2006 ; Merz et al, 2013 ; Neuhaus and Hinkelbein, 2014 ; Xu et al, 2014 ). Increases in reaction time (simple task) have been observed at altitudes exceeding 5000 m, an effect which persisted 75 days after participants returned to sea level following acute altitude exposure (Cavaletti and Tredici, 1993 ).…”

“…It is clear from previous work that different environmental conditions can negatively impact cognitive function. Past research has shown that hot (Hocking et al, 2001 ; Bandelow et al, 2010 ; Morley et al, 2012 ; Parker et al, 2013 ), cold (Marrao et al, 2005 ; Mäkinen et al, 2006 ; Adam et al, 2008a ; Spitznagel et al, 2009 ; Muller et al, 2012 ; Taylor et al, 2014 ), and hypoxic (Kourtidou-Papadeli et al, 2008 ; de Aquino Lemos et al, 2012 ; Muller et al, 2012 ; Ando et al, 2013 ; Neuhaus and Hinkelbein, 2014 ) exposures can impair these cognitive processes in humans, and it appears that a combination of interrelated psycho-physiological pathways may be responsible for these deficits (as will be subsequently be reviewed). Moreover, we will discuss the pathways responsible for such cognitive alterations, relevant interventional strategies which may acquiesce these deficits, and finally recommendations for future research.…”

Comparison of hypobaric hypoxia symptoms between a recalled exposure and a current exposure

“…In addition, they have to acquire the essential skills to correctly operate the on-board oxygen supply system to avoid hypoxic accidents and to cope with the physiological issues induced by the change in air pressure [9]. In most countries, refresher training every 3-5 years is mandatory to maintain accurate memories [10].…”