Sleep-disordered breathing in adults with precapillary pulmonary hypertension: Prevalence and predictors of nocturnal hypoxemia

Purpose: To evaluate the frequency of sleep-disordered breathing (SDB) and predictors of the presence of nocturnal desaturation in adults with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. Methods Outpatients with a hemodynamic diagnosis of precapillary pulmonary hypertension who underwent portable polysomnography were evaluated. Diagnosis and severity of SDB were assessed using three well-established respiratory disturbance index (RDI) thresholds: 5.0/h, 15.0/h, and 30.0/h, while nocturnal hypoxemia was defined by the average oxygen saturation (SpO 2 ) < 90%. Multiple linear regression analysis evaluated the potential relationships among explanatory variables with the dependent variable (average SpO 2 values), with comparisons based on the standardized regression coefficient (β). The R-squared (R 2 ; coefficient of determination) was used to evaluate the goodness-of-fit measure for the linear regression model. Results Thirty-six adults were evaluated (69.4% females). The majority of the participants (75.0%) had SDB (26 with obstructive sleep apnea [OSA] and one with central sleep apnea [CSA]); while 50% of them had nocturnal hypoxemia. In the linear regression model (R 2  = 0.391), the mean pulmonary artery pressure [mPAP] (β: -0.668; p = 0.030) emerged as the only independent parameter of the average SpO 2 . Conclusion Our study found that the majority of the participants had some type of SDB with a marked predominance of OSA over CSA, while half of them had nocturnal desaturation. Neither clinical and hemodynamic parameters nor the RDI was a predictor of nocturnal desaturation, except for mPAP measured during a right heart catheterization, which emerged as the only independent and significant predictor of average SpO 2 .