title: Normobaric hypoxia training: the effects of breathing-gas flow rate on symptoms.
abstract: BACKGROUND
  The U.S. Navy has replaced segments of refresher low-pressure chamber instruction with normobaric hypoxia training using a reduced oxygen breathing device (ROBD). A previous training evaluation revealed that this alternative instructional paradigm is a preferred means of training experienced jet aviators to recognize and recover from hypoxia. However, findings from this earlier work also indicated that air hunger was the most commonly reported symptom during ROBD training. This finding raised concern that air hunger could have resulted from a training artifact caused by the lower breathing-gas flow rate produced by the ROBD when compared to more familiar jet aircraft breathing systems. In an effort to address this issue, a software change was made that increased ROBD mask flow from 30 to 50 L x min(-1) (LPM). The purpose of this retrospective study was to determine if there are differences in the hypoxia symptoms reported by aviators trained on the ROBD upgrade (ROBD-50) compared to those trained on the original device (ROBD-30).
  
  
  METHODS
  Hypoxia training was provided to 156 aviators using the ROBD-50, and survey results were compared to those obtained from 121 aviators trained on the ROBD-30.
  
  
  RESULTS
  There was a significant decrease in the number of aviators who reported experiencing air hunger while training on the ROBD-50 (44.2%) as compared to the ROBD-30 (59.4%) [Pearson chi2 (1) = 5.45, P < 0.051.
  
  
  CONCLUSIONS
  These findings suggest that the ROBD breathing-gas flow rate is an important contributor to the symptom of air hunger and, therefore, may impact training fidelity.
authors.affiliation: Division of Occupational and Environmental Health Sciences, Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA. anthony.artino@usuhs.mil
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Artino
authors.forename: Richard V
authors.initials: RV
authors.lastname: Folga
authors.forename: Charles
authors.initials: C
authors.lastname: Vacchiano
mesh_terms: D000337:Aerospace Medicine; D001273:Atmosphere Exposure Chambers; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008397:Masks; D008889:Military Personnel; D012189:Retrospective Studies; D012984:Software; D014481:United States