Inspiratory muscle training did not improve exercise capacity and lung function in adult patients with Fontan circulation: A randomized controlled trial

Backgrounds: Patients with Fontan circulation have no subpulmonary ventricle and a passive pulmonary perfusion. Considerable percentage of the pulmonary blood flow is driven by pressure shift due to respiration. Impairments in respiratory musculature strength are associated with a reduced exercise capacity. This study investigated the effect of a daily six months inspiratory muscle training (IMT) on exercise and lung capacity in adult Fontan patients. Methods: After a lung function and cardiopulmonary exercise test (CPET), 42 Fontan patients (50% female; 30.5 ± 8.1 years) were randomized into either an intervention group (IG), or a control group (CG). The IG performed a telephone-supervised, daily IMT of three sets with 10–30 repetitions for six months. Results: After six months of IMT, the IG did not improve in any exercise and lung capacity parameter compared to CG. VO₂peak (ΔVO₂peak: IG: 0.05 [−1.53; 1.33] ml/kg/min vs. CG: −0.50 [−1.20; 0.78] ml/kg/min; p = .784) and FVC (ΔFVC: IG: 0.07 [−0.16; 0.22] l vs. CG:−0.05 [−0.24; 0.18] l; p = .377) remained unchanged, while FEV1 trended to improve (ΔFEV₁: IG: 0.05 [−0.07; 0.13] l vs. CG: −0.10 [−0.19; 0.03] l; p = .082). Only oxygen saturation at rest improved significantly (ΔSpO₂: IG: 1.50 [−0.25; 3.00] % vs. CG: −0.50 [−1.75; 0.75] %; p = .017). Conclusions: A daily six months IMT did not improve exercise and lung capacity and lung volumes in Fontan patients.