title: Impairment from gas narcosis when breathing air and enriched air nitrox underwater.
abstract: BACKGROUND
  Nitrogen (N2) in air causes cognitive impairment from gas narcosis when breathed at increased ambient pressures. This impairment might be reduced by using enriched air nitrox (EANx) mixtures, which have a higher oxygen and lower N2 content compared to air. This study aimed to investigate if divers differed in memory ability and self-assessment when breathing air and EANx30.
  
  
  METHODS
  The effect of depth (shallow vs. deep) and breathing gas (air vs. EANx30) on memory ability and subjective ratings of impairment was compared in 20 divers.
  
  
  RESULTS
  Memory performance was significantly worse in deep water (Air: M = 22.1%, SD = 21.7%; EANx30: M = 22.1%, SD = 17.2%) compared to shallow water (Air: M = 29.2%, SD = 18.3%; EANx30: M = 33.3%, SD = 18.2%), but this impairment did not differ significantly between air and EANx30. Subjective ratings of impairment increased significantly from shallow water (Air: M = 5.2, SD = 5.9; EANx30: M = 3.0, SD = 4.4) to deep water (Air: M = 36.8, SD = 25.3; EANx30: M = 24.8, SD = 16.1) when breathing both air and EANx30. However, ratings were significantly lower when breathing EANx30 compared to air when in the deep water.
  
  
  CONCLUSIONS
  It was concluded EANx30 does not reduce narcotic impairment over air. Additionally, divers were able to make a correct global self-assessment they were impaired by narcosis, but were unable to make a finer assessment, leading them to erroneously believe that EANx30 was less narcotic than air.
authors.affiliation: Faculty of Media, Arts & Society, Southampton Solent University, Southampton, Hampshire, UK.
authors.forename: Malcolm B
authors.initials: MB
authors.lastname: Hobbs
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000388:Air; D004242:Diving / Q000502:physiology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D007222:Inert Gas Narcosis / Q000503:physiopathology*; D008297:Male; D008569:Memory Disorders / Q000503:physiopathology*; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D009584:Nitrogen / Q000008:administration & dosage / Q000009:adverse effects*; D010100:Oxygen / Q000008:administration & dosage / Q000009:adverse effects*; D055815:Young Adult
chemical_list: C041364:nitrox; D009584:Nitrogen; D010100:Oxygen