Sleep disordered breathing in adults living with a Fontan circulation and CPAP titration protocol

Background: Fontan-type single ventricle physiology has exquisite respiratory dependence. Obstructive sleep apnoea (OSA) and continuous positive airway pressure (CPAP) are likely to have deleterious haemodynamic consequences.

Methods: Asymptomatic and symptomatic Fontan-adults underwent diagnostic polysomnography; The overnight CPAP titration employed echocardiography and peripheral venous pressure (PVP) measurements to determine the upper limit of pressure prior to haemodynamic deterioration (> 20% rise in PVP or 20% fall in stroke volume).

Results: In asymptomatic adults (n = 7), mean age was 32 ± 9 years and awake oxygen saturations were 92 ± 3%. There was no significant OSA with Apnoea Hypopnoea Index (AHI) of 0.6 ± 1.1 events/h and mild nocturnal hypoxaemia (nadir 89 ± 4%). In sleepy patients (n = 7, age 36 ± 7 years, awake saturations 84 ± 5%, NYHA Class III ± I), sleep efficiency was 81 ±10% with mild OSA on average (AHI 7.9 ± 10.1) events/h) and marked desaturation (nadir of 76 ± 6%); Most episodes were obstructive in nature. BMI correlated with AHI (n = 14, R = 0.7, p = .005). Two of 7 (29%) had moderate OSA characterised by an early fall in PVP, 3 ± 1 mmHg and a 2 ± 1 mmHg increase at event termination. CPAP was successfully applied through in-laboratory titration (stroke volume fall was the end-point determinant in both).

Conclusion: Our cohort of asymptomatic adults did not have significant SDB but SDB was common in sleepy patients. Fontan-adults with symptoms suggestive of SDB should be offered polysomnography and can be safely treated with CPAP employing echocardiographic titration.