Correlation of pulmonary hypertension severity with metrics of comorbid sleep-disordered breathing

We performed nocturnal polysomnography in patients with pulmonary hypertension (PH) of varying etiologies to determine the association of metrics describing sleep-disordered breathing (SDB) with measures of PH severity.

Consecutive patients referred for evaluation of dyspnea on exertion and elevated pulmonary arterial pressure >30 mmHg on echocardiography, who underwent right and left heart catheterization and polysomnography, were included. Patients were not pre-selected for symptoms of sleep-disordered breathing.

Twenty-eight patients including 22 females and six males with a mean age of 55.2 ± 11.9 years were evaluated. Etiologies of PH were idiopathic (32%) and PH associated with other diseases (68%). Most were World Health Organization (WHO) Functional class II (39%) and III (39%). The group mean pulmonary arterial pressure (mPAP) was 40.9 ± 15.1 mmHg. Diurnal resting and exercise arterial oxygen saturations (SaO₂) were 94.9 ± 3.7% and 88.3 ± 8.9%. The mean apnea–hypopnea index (AHI) was 11.4 ± 19.8/h; 50% of all patients had an AHI ≥ 5/h; 30.6 ± 36.0% of total sleep time was spent with SaO₂ < 90% (T90%); 66% of subjects with an AHI ≥ 5/h of sleep reported snoring, and 60% noted daytime somnolence; however, only 29% had an Epworth Sleepiness Scale ≥10. Right atrial pressure and mPAP were significantly correlated with AHI and T90%. The best predictive model relating PH severity to metrics of SDB was a highly significant association (p = 0.005) between mPAP and a linear combination of AHI and T90%.

SDB comprised of obstructive apneas, hypopneas, and nocturnal hypoxemia is prevalent in PH and cannot be accurately predicted by sleep apnea signs and symptoms or diurnal rest and exercise SaO₂. The association of AHI and T90% with mPAP suggests a potential relationship between the pathophysiology of sleep-disordered breathing and PH.