Exercise-induced hypoxia predicts hypobaric hypoxia during flight in patients after Fontan operation.

BACKGROUND

Hypobaric hypoxia (HH) during flight might be more detrimental to pulmonary circulation in Fontan patients compared healthy individuals. This study was designed to clarify whether exercise-induced hypoxia could predict HH during flight in Fontan patients.

METHODS AND RESULTS

Percutaneous oxygen saturation (SpO) was analyzed during flight in 11 Fontan patients and eight volunteers. SpO was measured before taking off (S1), at the initial (S2), the end of stabilization (S3), and after landing (S4). The SpO-dynamics were compared with SpO-dynamics during cardiopulmonary exercise testing (CPX), pulmonary function, and hemodynamics in the Fontan patients. At all measurements, SpO was lower in the Fontan patients than the volunteers during flight. The total SpO decline from S1 to S3 was greater in the Fontan patients than the volunteers. While SpO change from S2 to S3 was negative in the Fontan patients, it was stable in the volunteers. In the Fontan patients, the median value of exercise-induced SpO decline (Ex-dSpO), SpO at rest, and SpO at peak was -6%, 93%, and 88%, respectively. In addition to exercise capacity and pulmonary function, the Ex-dSpO was correlated strongly with SpO at all phases during flight (r = 0.75-0.98, p < 0.01 for all). Flight-associated adverse events occurred in two patients with SpO < 80% at S3.

CONCLUSIONS

Both the Fontan patients and the volunteers demonstrated similar SpO-dynamics during flight with a greater HH in the Fontan patients. CPX with SpO monitoring is useful in predicting SpO-dynamics and adverse events during flight in these patients.