title: Normobaric hypoxia inhalation test vs. response to airline flight in healthy passengers.
abstract: BACKGROUND
  There is little data available to determine the normal response to normobaric hypoxia inhalation testing (NHIT) and air travel. Quantifying a healthy response may assist in the evaluation of passengers considered at risk for air travel. The aims of this study were: (1) to quantify the degree of desaturation in healthy subjects during a NHIT and air travel; and (2) assess the validity of the NHIT when compared with actual in-flight responses.
  
  
  METHODS
  There were 15 healthy adults (age 23-57; 10 women) who volunteered for this study. Preflight tests included lung function, arterial blood gas, pulse oximetry (SpO2), and NHIT (inspired oxygen 15%). SpO2 and cabin pressure were measured continuously on each subject during a commercial air flight (mean cabin altitude 2178 m; range 1719-2426 m). In-flight oxygenation was compared with the preflight NHIT.
  
  
  RESULTS
  Lung function testing results were normal. There was significant desaturation (SpO2) during the NHIT (pre: 98 +/- 2%; post: 92 +/- 2%) and at cruising altitude (pre: 97 +/- 1%; cruise: 92 +/- 2%). There was no difference between the final NHIT SpO2 and the mean in-flight SpO2. There was a significant difference between the lowest in-flight SpO2 (88 +/- 2%) vs. the lowest NHIT SpO2, (90 +/- 2%).
  
  
  CONCLUSIONS
  Oxygen saturation decreases significantly during air travel in normal individuals. In this group of healthy passengers the NHIT approximates some, but not all, aspects of in-flight oxygenation. These results can be used to describe a normal response to the NHIT and air-travel.
authors.affiliation: Respiratory Physiology Laboratory, Christchurch Hospital, Christchurch, New Zealand. paul.kelly@cdhb.govt.nz
authors.forename: Paul T
authors.initials: PT
authors.lastname: Kelly
authors.forename: Maureen P
authors.initials: MP
authors.lastname: Swanney
authors.forename: Chris
authors.initials: C
authors.lastname: Frampton
authors.forename: Leigh M
authors.initials: LM
authors.lastname: Seccombe
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Peters
authors.forename: Lutz E
authors.initials: LE
authors.lastname: Beckert
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D000531:Altitude; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D012129:Respiratory Function Tests; D014195:Travel
chemical_list: D010100:Oxygen