PULMONARY-HYPERTENSION IN OBSTRUCTIVE SLEEP-APNEA

To determine the frequency and correlates of pulmonary hypertension in sleep-disordered breathing, pulmonary artery pressure, lung function and arterial blood gases were measured in 100 consecutive patients wit h obstructive sleep apnoea (OSA) (respiratory disturbance index (RDI) of >20 episodes . h(-1)). Twenty six of the patients had significant c hronic airflow limitation (CAL). Overall, 42% of patients had awake pu lmonary artery pressure >20 mmHg. Patients with pulmonary hypertension were older, had higher arterial carbon dioxide tension (Paco(2)), low er arterial oxygen tension (Pao(2)) and lower forced expiratory volume in one second (FEV(1)) values compared with normotensive patients, Pa o(2), Paco(2) and FEV(1) were correlated with the levels of pulmonary artery pressure (correlation coefficient (r(2)) 0.50, 0.46 and 0.49, r espectively), These three factors combined could explain 33% of the va riability in pulmonary artery pressure, Six patients had pulmonary hyp ertension despite a Pao(2) in excess of 10.7 kPa (80 mmHg). We conclud e that pulmonary hypertension is common in patients with moderate and severe sleep apnoea, especially those with coexisting chronic airflow limitation, The presence of daytime hypoxaemia is not a prerequisite i n the development of pulmonary hypertension in these patients.