Cardiopulmonary coupling and serum cardiac biomarkers in obesity hypoventilation syndrome and obstructive sleep apnea with morbid obesity.

STUDY OBJECTIVES: The main cause of death in patients with obesity hypoventilation syndrome (OHS) is cardiac rather than respiratory failure. Here, we investigated autonomic-respiratory coupling and serum cardiac biomarkers in patients with OHS and obstructive sleep apnea (OSA) with comparable body mass index and apnea-hypopnea index. METHODS: Cardiopulmonary coupling (CPC) and cyclic variation of heart rate analysis was performed on the electrocardiogram signal from the overnight polysomnogram. Cardiac serum biomarkers were obtained in patients with OHS and OSA with a body mass index > 40 kg/m2. Samples were obtained at baseline and after 3 months of positive airway pressure (PAP) therapy in both groups. RESULTS: Patients with OHS (n = 15) and OSA (n = 36) were recruited. No group differences in CPC, cyclic variation of heart rate, and serum biomarkers were observed at baseline and after 3 months of PAP therapy. An improvement in several CPC metrics, including the sleep apnea index, unstable sleep (low-frequency coupling and elevated low-frequency coupling narrow band), and cyclic variation of heart rate were observed in both groups with PAP use. However, distinct differences in response characteristics were noted. Elevated low-frequency coupling narrow band coupling correlated with highly sensitive troponin-T (P < .05) in the combined cohort. Baseline highly sensitive troponin-T inversely correlated with awake oxygen saturation in the OHS group (P < .05). CONCLUSIONS: PAP therapy can significantly improve CPC stability in patients with obesity with OSA or OHS, with key differences. Elevated low-frequency coupling narrow band may function as a surrogate biomarker for early subclinical cardiac disease. Low awake oxygen saturation could also increase this biomarker in OHS. CLINICAL TRIAL REGISTRATION: Registry: Australian New Zealand Clinical Trials Registry; Name: Obesity Hypoventilation Syndrome and Neurocognitive Dysfunction; URL: https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367492; Identifier: ACTRN12615000122550. CITATION: Sivam S, Wang D, Wong KKH, et al. Cardiopulmonary coupling and serum cardiac biomarkers in obesity hypoventilation syndrome and obstructive sleep apnea with morbid obesity. J Clin Sleep Med. 2022;18(4):1063-1071.

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.