title: Air travel hypoxemia vs. the hypoxia inhalation test in passengers with COPD.
abstract: BACKGROUND
  Limited data are available comparing air travel with the hypoxia inhalation test (HIT) in passengers with COPD. The aim of this study was to assess the predictive capability of the HIT to in-flight hypoxemia in passengers with COPD.
  
  
  METHODS
  Thirteen passengers (seven female passengers) with COPD (mean [+/- SD], FEV(1)/FVC ratio, 44 +/- 17%) volunteered for this study. Respiratory function tests were performed preflight. Pulse oximetry, cabin pressure, and dyspnea were recorded in flight. The HIT and a 6-min walk test were performed postflight. The in-flight oxygenation response was compared to the HIT results and respiratory function parameters.
  
  
  RESULTS
  All subjects flew without the use of oxygen, and no adverse events were recorded in-flight (mean cabin altitude, 2,165 m; altitude range, 1,892 to 2,365 m). Air travel caused significant desaturation (mean preflight oxygen saturation, 95 +/- 1%; mean in-flight oxygen saturation, 86 +/- 4%), which was worsened by activity (nadir pulse oximetric saturation [Spo(2)], 78 +/- 6%). The HIT caused mean desaturation that was comparable to that of air travel (84 +/- 4%). The mean in-flight partial pressure of inspired oxygen (Pio(2)) was higher than the HIT Pio(2) (113 +/- 3 mm Hg vs 107 +/- 1 mm Hg, respectively; p < 0.001). The HIT Spo(2) showed the strongest correlation with in-flight Spo(2) (r = 0.84; p < 0.001).
  
  
  CONCLUSIONS
  Significant in-flight desaturation can be expected in passengers with COPD. The HIT results compared favorably with the air travel data, with differences explainable by Pio(2) and physical activity. The HIT is the best widely available laboratory test to predict in-flight hypoxemia.
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: Leigh M
authors.initials: LM
authors.lastname: Seccombe
authors.forename: Chris
authors.initials: C
authors.lastname: Frampton
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Peters
authors.forename: Lutz
authors.initials: L
authors.lastname: Beckert
mesh_terms: D000368:Aged; D000401:Aircraft; D000531:Altitude; D005260:Female; D017408:Guidelines as Topic; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology; D001239:Inhalation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000150:complications; D012129:Respiratory Function Tests; D012307:Risk Factors
chemical_list: D010100:Oxygen