Hypoxic Challenge Testing for Fitness to Fly with Severe Asthma.

Abstract

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. 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). 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. Overall, the findings indicate that HCT should be considered for all patients with severe asthma, regardless of resting oxygen saturation level.