Pulmonary circulation at rest and during exercise in patients with obstructive sleep apnea before and after one year of treatment with CPAP

: We studied pulmonary haemodynamics in 19 male patients, mean age 45 +/- 5 years, suffering from severe OSA, mean apnea/hypopnea index (AHI) 68 +/- 17. Pulmonary haemodynamisc were studied using Swan-Ganz thermodilution catheter in the supine position at rest, and at the end of the 7th minute of steady-state exercise (40 W). Investigations were repeated after one year of treatment with nasal CPAP. At rest mean pulmonary artery pressure (PPA), pulmonary wedge pressure (PW) and cardiac output (CO) were normal, PPA = 16.6 +/- 5.7 mmHg, PW = 5.2 +/- 1.8 l/min. Pulmonary vascular resistance (PVR) was slightly elevated = 155 +/- 65 d.sec.cm-5. On exercise only PVR remained unchanged. After a year of treatment PPA changed to 15.8 +/- 4.0 mmHg (NS), Pw-7.5 +/- 3.1 mmHg (NS), CO-4.9 +/- 1.6 L/min (NS), PVR - 145 +/- 35 d.sec.cm-5 (NS). In two patients with resting hypertension PPA dropped from 33 mmHg to 25 mmHg and 28 mmHg to 18 mmHg respectively. Statistical analysis showed no significant change in any of the studied variables after one year of the CPAP therapy.