The importance of completing the hipoxic challenge test in assessing the risk of altitude in air travel: Experience of flight fitness evaluation

The atmospheric pressure in cabin of the pressurized commercial aircraft is not equivalent to the pressure at sea level. If this hypobaric environment doesn't trigger symptoms in most of people, the same is not true for patients with respiratory disease. Since the increase of air travel and the need to advice the patients to this particular setting, British Thoracic Society (BTS) have published recommendations to evaluate and prescript supplemental oxygen in these conditions. The present study describes 2 years' experience in advice respiratory patients on flight fitness in Hospital Santa Maria. During this period, 64 patients were evaluated (54% men, mean age 46±21 years) and underwent Hypoxic Challenge Test (HCT) with a protocol in agreement with BTS guidelines. Relatively to diagnosis, 46% had cystic fibrosis, 18% chronic obstructive pulmonary disease, 12% intersticial lung disease, 7% thoracic neoplasm, 7% bronchiectasis and 3% had obstructive sleep apnoea. Six of these patients had respiratory failure and were on long-term oxygen therapy (LTOT). At baseline, 60% of patients had SpO 2 > 95%, 31% between 92-95% and 9% 95% maintained their PaO 2 >55 mmHg. Twelve patients with a sea level SpO 2 between 92-95% desaturated to PaO 2 <55mmHg. Supplemental oxygen therapy was prescribed to 31 patients and in the 6 patients on LTOT the debit was measured and increased in all of them. In conclusion, despite the recommendations indicate only the HCT for patients with SpO 2 < 95%, our experience showed that this limit not allow to predict those who need supplemental oxygen in air travel.