title: Hypoxic Challenge Testing for Fitness to Fly with Severe Asthma.
abstract: BACKGROUND
  Commercial airline travel poses a recognized risk to patients with respiratory disease, including in those with asthma. Hypoxic challenge testing (HCT) is typically employed to mitigate this risk by dictating in-flight oxygen requirement.
  
  
  METHODS
  The role of HCT has not been formally studied in patients with severe asthma and we therefore evaluated HCT assessment in a cohort of patients with severe asthma (N = 37).
  
  
  RESULTS
  Over half (57%) of patients had a positive HCT. Baseline oxygen saturation (S(p)o(2)) was poorly predictive of a recommendation for supplementary oxygen in flight; two-thirds of those deemed to require oxygen had a baseline S(p)o(2) > 95%. A combination of any two of: P(a)o(2) ≤ 10.5 kPa, FEV(1) ≤ 60% predicted, and PEF ≤ 350 L · min(-1) predicted the need for in-flight oxygen with a sensitivity of 89% and a specificity of 69%. Furthermore, no patient with an S(p)o(2) > 95% and FEV(1) > 85% predicted had a positive HCT.
  
  
  CONCLUSIONS
  Overall, the findings indicate that HCT should be considered for all patients with severe asthma, regardless of resting oxygen saturation level.
authors.affiliation: Department of Respiratory Medicine, Royal Brompton Hospital, London, UK.
authors.forename: Peter M
authors.initials: PM
authors.lastname: George
authors.forename: Christopher
authors.initials: C
authors.lastname: Orton
authors.forename: Simon
authors.initials: S
authors.lastname: Ward
authors.forename: Andrew
authors.initials: A
authors.lastname: Menzies-Gow
authors.forename: James H
authors.initials: JH
authors.lastname: Hull
mesh_terms: D000328:Adult; D000368:Aged; D064870:Air Travel; D001249:Asthma / Q000150:complications* / Q000503:physiopathology* / Q000628:therapy; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis / Q000209:etiology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D020380:Needs Assessment; D010102:Oxygen Inhalation Therapy; D011237:Predictive Value of Tests; D012129:Respiratory Function Tests