Hypoxic Challenge Testing (Fitness to Fly) in children with complex congenital heart disease

Objective Commercial airplanes fly with an equivalent cabin fraction of inspired oxygen of 0.15, leading to reduced oxygen saturation (SpO 2 ) in passengers. How this affects children with complex congenital heart disease (CHD) is unknown. We conducted Hypoxic Challenge Testing (HCT) to assess need for inflight supplemental oxygen. Methods Children aged 2 (≥95% vs 2 , heart rate, QT interval corrected for heart rate and partial pressure of carbon dioxide measured transcutaneously (PtcCO 2 ). A test failed when children with (1) normal baseline SpO 2 desaturated to 85%, (2) baseline SpO 2 85%–94% desaturated by 15% of baseline; and (3) baseline SpO 2 75%–84% desaturated to 70%. Results There were 68 children, mean age 3.3 years (range 10 weeks–14.5 years). Children with normal (n=36) baseline SpO 2 desaturated from median 99% to 91%, P 2 (n=32) desaturated from median 84% to 76%, P 2 , heart rate and QT interval corrected for heart rate were unaffected by the hypoxic state. Conclusions This is the first evidence to help guide which children with CHD need a preflight HCT. We suggest all children with an actual or potential R–L shunt should be tested.