PURPOSE: The association of sleep disordered breathing (SDB) and pulmonary arterial hypertension (PAH) remains unclear. A low prevalence of PAH has been reported in obstructive sleep apnea (OSA) and in most cases, risk factors other than obstructive apnea may contribute to PAH. However, the role of SDB and nocturnal hypoxemia has not been evaluated in patients with PAH without presenting symptoms of SDB. We sought to determine if SDB independently predicts mean pulmonary artery pressure (mPAP) in patients undergoing evaluation for PAH.
METHODS: 29 patients, 7 males and 22 females, age 55.6 ± 11.96 years, BMI 31.2 ± 9.18 kg/m2, undergoing evaluation for PAH who had right heart catheterization, not selected for clinical symptoms of SDB, underwent nocturnal polysomnography (nPSG) breathing room air and pulmonary function evaluation. 25 of these had PAH defined as mPAP >25mmHg and PCWP<18mmHg.
RESULTS: Group mPAP was 41.4±15.12, range 16–73 mmHg. Daytime resting SaO2 was 94.9 ± 3.69%. FVC% predicted: 80.3 ± 37.04%; FEV1% predicted 79.1±38.47%; DLCO% predicted 56.2±30.94%; TLC% predicted 81.9±23.0%. nPSG parameters: AHI: 11.9±20.04/hr; Sleep time<90% SaO2 (T90): 96.9±117.72 minutes. 9/25 patients had an AHI > 5/h, and 22/25 spent > 0.1% of sleep time < 90% SaO2. A best subsets multivariate linear regression analysis to determine factors predicting mPAP was performed and showed that AHI (p=0.03) and T90 (p=0.04) were the only significant predictors of mPAP. Resting daytime SaO2, age, BMI, FVC, FEV1, TLC and DLCO were not significant predictors of mPAP.
CONCLUSION: AHI and nocturnal hypoxemia were the only variables that were significantly associated with mPAP in patients without presenting symptoms of SDB undergoing evaluation for PAH. Daytime oxygen saturation and pulmonary function were not significant predictors of mPAP.
CLINICAL IMPLICATIONS: Since nocturnal hypoxemia and obstructive apnea may contribute to worsening of PAH, assessment for SDB should be considered in patients with PAH.
DISCLOSURE: Arunabh Talwar, None.