[Pulmonary hemodynamics in obstructive sleep apnea or overlap syndrome].

We studied pulmonary haemodynamics at rest and on exercise in 44 consecutive patients with moderate to severe obstructive sleep apnea (OSA), mean AHI > 40. The diagnosis was confirmed by standard polysomnography (PSG). According to history and results of spirometric measurements patients were divided to two groups, pure OSA and OSA complicating chronic obstructive pulmonary disease (overlap syndrome). In 34 pts with OSA (31 M, 3 F), means: age 45 +/- 8 years, body weight 108 +/- 22 kg, BMI49, VC 107 +/- 16% of N, FEV1 101 +/- 15% of N, PaO2 71 +/- 10 mmHg, PaCO2 39 +/- 3 mmHg, PSG showed AHI 66 +/- 15. Pulmonary haemodynamics at rest were within normal limits: PPA 16 +/- 5 mmHg, PW 7 +/- 3 mmHg, CO 4.5 +/- 1.5 l/min, PVR 184 +/- 92 dyne.s.cm-5. On low grade exercise (40 W) PPA increased to 31 +/- 10 mmHg, Pw to 12 +/- 6 mmHg and CO to 8.6 +/- 4.0 l/min, PVR remained unchanged. In eight pts abnormal rise in PPA on exercise resulted from the increase in driving pressure (PPA-Pw). In 2 pts it was due to abnormal increase in wedge pressure. In ten male pts presenting with COPD means: age 53 +/- 8 y, body weight 109 +/- 11 kg, BMI49, VC 53 +/- 14% of N, FEV1 36 +/- 16% of N, PaO2 57 +/- 10 mmHg, PaCO2 47 +/- 7 mmHg, PSG showed AHI 63 +/- 20. All pts presented with pulmonary hypertension (PH) at rest, PPA ranging from 21 to 37 mmHg, mean 26 +/- 5 mmHg. We conclude that patients with OSA have normal PPA at rest, 1/2 of them have PH on exercise due to restriction of pulmonary arterial bed and/or left ventricle dysfunction. Pts with overlap syndrome have moderate resting PH resulting from alveolar hypoxia.