Background The reduced pressure in the aircraft cabin may cause significant hypoxaemia and respiratory distress in patients with chronic obstructive pulmonary disease (COPD). Simple and reliable methods for predicting the need for supplemental oxygen during air travel have been requested.

Objective To construct a pre-flight evaluation algorithm for patients with COPD.

Methods In this prospective, cross-sectional study of 100 patients with COPD referred to hypoxia-altitude simulation test (HAST), sea level pulse oximetry at rest (SpO_{2 SL}) and exercise desaturation (SpO_{2 6MWT}) were used to evaluate whether the patient is fit to fly without further assessment, needs further evaluation with HAST or should receive in-flight supplemental oxygen without further evaluation. HAST was used as the reference method.

Results An algorithm was constructed using a combination of SpO_{2 SL} and SpO_{2 6MWT}. Categories for SpO_{2 SL} were >95%, 92–95% and <92%, the cut-off value for SpO_{2 6MWT} was calculated as 84%. Arterial oxygen pressure (PaO_{2 HAST}) <6.6 kPa was the criterion for recommending supplemental oxygen. This algorithm had a sensitivity of 100% and a specificity of 80% when tested prospectively on an independent sample of patients with COPD (n=50). Patients with SpO_{2 SL} >95% combined with SpO_{2 6MWT} ≥84% may travel by air without further assessment. In-flight supplemental oxygen is recommended if SpO_{2 SL}=92–95% combined with SpO_{2 6MWT} <84% or if SpO_{2 SL} <92%. Otherwise, HAST should be performed.

Conclusions The presented algorithm is simple and appears to be a reliable tool for pre-flight evaluation of patients with COPD.