Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial

Souday, Vincent; Koning, Nick J.; Perez, Bruno; Grelon, Fabien; Mercat, Alain; Boer, Christa; Seegers, Valérie; Radermacher, Peter; Asfar, Pierre

doi:10.1371/journal.pone.0154761

Cited by 9 publications

(6 citation statements)

References 14 publications

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“…Underwater divers face several potential neurological hazards when breathing compressed air or different gas mixtures because they are exposed to increased ambient pressure. The increased absorption of inert gases (helium and nitrogen) leads to several abnormal consequences, such as nitrogen narcosis (Grover and Grover 2014), decompression sickness (Bove 2014;Souday et al 2016), highpressure nervous syndrome (HPNS) risk (Kot 2012) and oxygen toxicity (4), which are related to oxygen partial pressure and the number of free oxygen radicals in the central nervous system that overwhelm the antioxidant capacity of our antioxidant metabolism.…”

Section: Introductionmentioning

confidence: 99%

“…Enriched air nitrox (EANx) includes a lower nitrogen content, Trimix is a mixture of oxygen, helium and nitrogen, and Heliox lacks nitrogen. These alternatives hope to (a) reduce the risk of decompression sickness (DCS) (Souday et al 2016) via lowering the inert gas content and potential bubble production during decompression, (b) reduce the density of the gas mixture with the use of helium to allow deeper dives (Mitchell and Doolette 2013) while maintaining acceptable breathing, and (c) reduce the nitrogen narcosis risk. However, Heliox increases HPNS (Kot 2012) more than Trimix at depths greater than 200 m.…”

Section: Introductionmentioning

confidence: 99%

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Inert gas narcosis in scuba diving, different gases different reactions

et al. 2018

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Purpose Underwater divers face several potential neurological hazards when breathing compressed gas mixtures including nitrogen narcosis which can impact diver's safety. Various human studies have clearly demonstrated brain impairment due to nitrogen narcosis in divers at 4 ATA using critical flicker fusion frequency (CFFF) as a cortical performance indicator. However, recently some authors have proposed a probable adaptive phenomenon during repetitive exposure to high nitrogen pressure in rats, where they found a reversal effect on dopamine release. Methods Sixty experienced divers breathing Air, Trimix or Heliox, were studied during an open water dive to a depth of 6 ATA with a square profile testing CFFF measurement before (T 0 ), during the dive upon arriving at the bottom (6 ATA) (T 1 ), 20 min of bottom time (T 2 ), and at 5 m (1.5 ATA) (T 3 ). Results CFFF results showed a slight increase in alertness and arousal during the deep dive regardless of the gas mixture breathed. The percent change in CFFF values at T 1 and T 2 differed among the three groups being lower in the air group than in the other groups. All CFFF values returned to basal values 5 min before the final ascent at 5 m (T 3 ), but the Trimix measurements were still slightly better than those at T 0 . Conclusions Our results highlight that nitrogen and oxygen alone and in combination can produce neuronal excitability or depression in a dose-related response. Keywords Nitrogen narcosis • Divers' safety • Critical flicker fusion frequency • GABA receptors Abbreviations ATA Atmospheres of pressure absolute 1 ATA = 1.01325 bar, 760 mmHg, 10 m H 2 O CFFF Critical flicker fusion frequency DCS Decompression sickness EAN Enriched air nitrox GABA receptors Gamma aminobutyric acid receptors HELIOX Helium and oxygen HPNS High pressure nervous syndrome TRIMIX Mixture of nitrogen, helium and oxygen Communicated by Jean-René Lacour.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Inert gas narcosis in scuba diving, different gases different reactions

et al. 2018

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“…Impairment in cognitive performance below sea level is usually when a person is underwater for prolonged periods of time, and they must breathe compressed air to survive. Compressed air, typically comprising of mixtures of oxygen, helium, and nitrogen, has several effects on human performance including impaired cardiovascular function (Marinovic et al, 2009), manual dexterity (Adolfson, 1965), and risk of decompression sickness (Souday et al, 2016) and high-pressure nervous syndrome (Kot, 2012). When diving, the impairments in cognitive performance are likely a consequence of the narcotic action of the inert gases, rather than simply increased pressure (Abraini, 1997).…”

Section: Below Sea Levelmentioning

confidence: 99%

The Impact of Environmental Stress on Cognitive Performance: A Systematic Review

et al. 2019

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Objective: In this review, we detail the impact of environmental stress on cognitive and military task performance and highlight any individual characteristics or interventions which may mitigate any negative effect. Background: Military personnel are often deployed in regions markedly different from their own, experiencing hot days, cold nights, and trips both above and below sea level. In spite of these stressors, high-level cognitive and operational performance must be maintained. Method: A systematic review of the electronic databases Medline (PubMed), EMBASE (Scopus), PsycINFO, and Web of Science was conducted from inception up to September 2018. Eligibility criteria included a healthy human cohort, an outcome of cognition or military task performance and assessment of an environmental condition. Results: The search returned 113,850 records, of which 124 were included in the systematic review. Thirty-one studies examined the impact of heat stress on cognition; 20 of cold stress; 59 of altitude exposure; and 18 of being below sea level. Conclusion: The severity and duration of exposure to the environmental stressor affects the degree to which cognitive performance can be impaired, as does the complexity of the cognitive task and the skill or familiarity of the individual performing the task. Application: Strategies to improve cognitive performance in extreme environmental conditions should focus on reducing the magnitude of the physiological and perceptual disturbance caused by the stressor. Strategies may include acclimatization and habituation, being well skilled on the task, and reducing sensations of thermal stress with approaches such as head and neck cooling.

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“…In contrast, the decreased partial nitrogen pressure (pN 2 ) of nitrox exerts beneficial effects, particularly with respect to reducing N 2 bubble formation after simulated ( Souday et al, 2016 ) and real dives ( Marinovic et al, 2012 ) ( Brebeck et al, 2018 ), thereby reducing the risk of decompression sickness. In addition, nitrox could protect against decreased neuro-cognitive performance induced by inert gas narcosis ( Germonpre et al, 2017 ) ( Lafere et al, 2019 ) ( Rocco et al, 2019 ), and so help to maintain alertness and memory ( Brebeck et al, 2017 ).…”

Section: Oxygen-enriched Airmentioning

confidence: 99%