RIGHT-VENTRICULAR DYSFUNCTION IN OBSTRUCTIVE SLEEP-APNEA - REVERSAL WITH NASAL CONTINUOUS POSITIVE AIRWAY PRESSURE

The incidence and pathogenesis of right ventricular dysfunction in obs tructive sleep apnoea (OSA) remains controversial, Using nuclear ventr iculography, the prevalence of right ventricular dysfunction (RVD) was therefore determined in obese patients with OSA, as well as their cli nical characteristics, arterial blood gas values, spirometry and sleep parameters, The reversibility of RVD was evaluated after long-term us e of nasal continuous positive airway pressure (nCPAP). We studied 112 obese patients with OSA by nuclear ventriculography, 35 with RVD (Gro up 1), 77 without RVD (Group 2), and 14 patients without OSA as contro ls (Group 3), Repeat nuclear ventriculography was performed in seven p atients who used nCPAP nightly for 6-24 months. The mean right ventric ular ejection fractions (RVEF) were 31%, 47% and 44% in Groups 1, 2 an d 3, respectively, Group 1 also had a lower left ventricular ejection fraction (LVEF) of 55 vs 63% in Group 2, The OSA groups did not differ in mean spirometric or arterial blood gas values, Group 1 had a lower mean nocturnal arterial oxygen saturation (Sa,O-2) Of 82 vs 87% in Gr oup 2, and a longer apnoea duration of 22.3 vs 19.2 s, All but two pat ients in Group 1 had either awake alveolar hypoventilation or an apnoe a + hypopnoea index >40 disordered breathing events . h(-1). Repeat nu clear ventriculography after nCPAP revealed an increase in RVEF from 3 0 to 39%. In conclusion, right ventricular dysfunction is common in ob structive sleep apnoea, but it is reversible with nasal continuous pos itive airway pressure treatment and appears to be related to nocturnal oxygen desaturation.