Introduction Preventing in-flight hypoxia in pilots is typically achieved by wearing oxygen masks. These masks must be as comfortable as possible to allow prolonged and repeated use. The consequences of mask-induced facial contact pressure have been extensively studied, but little is known about mask-induced breathing discomfort. Because breathlessness is a strong distractor and engages cerebral resources, it could negatively impact flying performances.
Methods Seventeen volunteers (age 20–32) rated respiratory discomfort while breathing with no mask and with two models of quick-donning full-face crew oxygen masks with regulators (mask A, mask B). Electroencephalographic recordings were performed to detect a putative respiratory-related cortical activation in response to inspiratory constraint (experiment 1, n=10). Oxygen consumption was measured using indirect calorimetry (experiment 2, n=10).
Results With mask B, mild respiratory discomfort was reported significantly more frequently than with no mask or mask A (experiment 1: median respiratory discomfort on visual analogue scale 0.9 cm (0.5–1.4), experiment 1; experiment 2: 2 cm (1.7–2.9)). Respiratory-related cortical activation was present in 1/10 subjects with no mask, 1/10 with mask A and 6/10 with mask B (significantly more frequently with mask B). Breathing pattern, sigh frequency and oxygen consumption were not different.
Conclusions In a laboratory setting, breathing through high-end aeronautical full-face crew oxygen masks can induce mild breathing discomfort and activate respiratory-related cortical networks. Whether or not this can occur in real-life conditions and have operational consequences remains to be investigated. Meanwhile, respiratory psychometric and neuroergonomic approaches could be worth integrating to masks development and evaluation processes.
- control of breathing
- respiratory-related cortical activation
- in-flight hypoxia
- oxygen masks
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Contributors M-CN: data collection; data analysis; data interpretation; draft manuscript. MR: study design; data analysis; data interpretation; draft manuscript. SR: data collection; data analysis; data interpretation. JG-B: study design; data analysis; data interpretation; draft manuscript. GB: data collection; data analysis; data interpretation. CS: study design; data interpretation; draft manuscript. IR (certified statistician); statistical analysis; data interpretation. CM-P: data analysis; data interpretation; draft manuscript. TS: study design, data interpretation; draft manuscript. All authors critically revised the final manuscript and contributed to intellectual content.
Funding The study was funded by ‘Association pour le Développement et l'Organisation de la Recherche en Pneumologie et sur le Sommeil’ (ADOREPS), a non profit organisation devoted to further the research activities of the authors’ institution.
Competing interests SR, JG-B, GB, IR and CM-P report no conflict of interest, financial or otherwise, relevant to this study. MR, CS and TS are listed as inventors on patents and patents applications belonging to Sorbonne Université as their employer and that describe various methods to identify electroencephalographic signatures of respiratory discomfort. A prelicensing agreement has been signed with Air Liquide Medical Systems and MyBrain Technologies, two French companies, regarding the exploitation of these patents in the field of mechanical ventilation. MR, CS and TS have no other conflicts of interest relevant to this study.
Patient consent Obtained.
Ethics approval The study protocol was approved in advance by the appropriate legal and ethical authority (‘Comité Consultatif de Protection des Personnes se prêtant à des Recherches Biomédicales’, Pitié-Salpêtrière hospital, Paris, France) as a component of a wider respiratory electroencephalography program. Each subject provided written informed consent before participating.
Provenance and peer review Not commissioned; internally peer reviewed.
Data sharing statement The data underlying this study can be accessed by any researcher, provided that the motive for request is provided and that no publication will be undertaken without consulting with the authors. To this aim, a request should be sent to the corresponding authors. The study does not include unpublished data.
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