Hypoxic challenge flight assessments in patients with severe chest wall deformity or neuromuscular disease at risk for nocturnal hypoventilation

Background:The British Thoracic Society (BTS) recommendations for patients with respiratory disease planning air travel suggest that an oxygen saturation (SaO2) >95% precludes the need for any further assessment of the need for supplemental oxygen during flight. A hypoxic challenge test (HCT) is recommended for patients with a resting SaO2 between 92% and 95% with an additional risk factor, including kyphoscoliosis (KS) or neuromuscular disease (NMD). However, this recommendation was based on very few data.Patients and methods:HCTs were performed on 19 adult patients with KS and/or NMD (age 22–73 years, forced expiratory volume in 1 s (FEV1) 0.76, forced vital capacity (FVC) 0.92, SaO2 95%, partial pressure of arterial CO2 (PaCO2) 5.7 kPa) who were at risk for nocturnal hypoventilation. 15 were home ventilator users. Arterial blood gas measurements were made before and at the end of the hypoxic challenge.Results:The results of HCTs show that the majority (15 of 19) of this cohort of patients met the criteria suggested by the BTS Standards of Care Committee for in-flight oxygen regardless of baseline SaO2.Conclusions:This finding suggests that all patients with severe extrapulmonary restrictive lung disease should undergo assessment with HCT prior to air travel. The study confirms that even patients with a resting saturation of >95% can desaturate significantly during hypoxic challenge. This study does not address the question of whether desaturation at altitude has any adverse consequences for patients. A decision as to whether it is safe for a patient to fly should be made by an experienced clinician and based on a number of factors, which should include previous travel experience, the patient’s overall condition and the results of an HCT.