Background: The reduced pressure in the aircraft cabin may cause significant hypoxemia in patients with cystic fibrosis (CF). Simple and reliable methods for predicting the need for supplemental oxygen during air travel have been requested. A pre-flight algorithm has previously been validated for COPD patients, but there are no specific recommendations for CF.

Aim: To evaluate if the pre-flight evaluation algorithm for COPD patients can be used in adults with CF.

Methods: In this prospective cross-sectional study, sea level oxygen saturation (SpO_2 SL) and exercise desaturation (SpO_{2 6MWT}) were used to evaluate whether the patient a) is fit to fly without further assessment, b) needs further evaluation with hypoxia-altitude simulation test (HAST) or c) should receive in-flight supplemental oxygen without further evaluation. HAST was used as reference method. SpO_2 HAST ?85% was the criterion for recommending in-flight supplemental oxygen.

Results: 79 CF patients, 38.0±13.4 years (mean±SD) with a FEV₁ of 71±23% pred underwent HAST (SpO_2 HAST 89.2±4.0%). Categories for SpO_2 SL were >95% (N=53), 92-95% (N=25), and <92%, (N=1), and the cut-off value for SpO_2 6MWT was <84%.

The HAST-results showed that CF patients with SpO_{2 SL} >95% can travel by air without further assessment. In-flight supplemental oxygen is needed if SpO_{2 SL} 92-95% combined with SpO_{2 6MWT} <84%, or if SpO_{2 SL} <92%. Otherwise, HAST should be performed. Using the algorithm, 21 (27%) of the patients would have needed referral to HAST. The algorithm correctly identified the 12 patients who needed and the 67 patients who did not need in-flight supplemental oxygen. 

Conclusions: The pre-flight algorithm for COPD patients may be used in the pre-flight evaluation of adult CF patients.