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DOI: 10.1055/s-0039-3403079
Obstructive Sleep Apnoea and Hypoxia in Precapillary Pulmonary Hypertension: Prevalence, Determinants and Daytime Clinical, Respiratory and Cardiac MRI Correlates
Publication History
Publication Date:
28 February 2020 (online)
Background and objective: In patients with precapillary pulmonary hypertension (PH) (pulmonary arterial hypertension and/or chronic thromboembolic pulmonary hypertension) obstructive sleep apnoea (OSA) may be highly prevalent and may be associated with worse daytime functional status, respiratory and cardiac abnormalities. However, in PH OSA pathophysiological determinants and clinical associations have not yet been investigated in a multimodal manner.
Methods: 71 patients with PH (age 63 ± 15 years, 41% male) and age, gender and BMI matched (2 : 1) controls prospectively underwent polygraphic sleep study, clinical examination, capillary blood gas analysis and lung function testing. Assay of amino-terminal pro-brain natriuretic peptide (NT-proBNP) levels, and cardiac magnetic resonance imaging (subset of 34 PH patients) were performed to evaluate cardiac function and structure. Exercise capacity was determined using the 6-minute walk distance (6MWD).
Results: OSA and nocturnal hypoxia were significantly more prevalent in PH patients than in controls: 48 of 71 patients showed OSA (68%) half of which was mild (AHI 5 – 15/h) while the remainder half was moderate to severe (AHI > 15/h). PH patients with OSA did not differ from patients without OSA in exercise intolerance, sleep complaints, lung function and cardiac function with the only exceptions being increased end-expiratory CO2 and a higher proportion of left atrial enlargement in patients with PH and OSA. ~ 50% of all PH patients were hypoxic at night and nocturnal mean oxygen saturation correlated inversely with daytime right ventricular end-diastolic (r = − 0.39, p = 0.03) and end-systolic (r = − 0.36, p = 0.04) volume. Other than this none of the daytime measures of functional, clinical, heart and lung status differed between hypoxic and normoxic patients.
Conclusions: In patients with PH there is an increased prevalence of OSA, but not of CSA. However, in PH OSA per se is not associated with significant alterations in sleep complaints, daytime functional status, respiratory and cardiac function or structure or prognostic significance. On the contrary nocturnal hypoxia does relate to structural right heart abnormalities in PH patients.
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