[Effect of CPAP and BiPAP assisted breathing on pulmonary hemodynamics in patients with obstructive sleep apnea].

CPAP breathing increases alveolar and intrathoracic pressures. We aimed to investigate the effects of CPAP and BiPAP breathing on pulmonary haemodynamics in patients with OSA. Ten male patients with OSA (AHI = 48 +/- 22) were studied. In each patient intravascular and esophageal pressures were measured and mean transmural pulmonary artery and transmural wedge (Pwtm) pressures were calculated. After baseline recordings patients were submitted to 25 min. of CPAP and BiPAP breathing in random order. The pressure of 10 cm H20 for CPAP and 10/4 cm H20 for BiPAP was used. At baseline pulmonary arterial pressures and flow were normal. CPAP breathing resulted in an increase in mean pulmonary intravascular pressure from 15.5 +/- 1.8 mmHg to 17.1 +/- 2.3 mmHg (p < 0.05). Transmural pressure did not change. There was also no change in the cardiac output (CO) and pulmonary vascular resistance (PVR). At some time points pulmonary arterial pressures were higher during CPAP breathing than during BiPAP breathing (p < 0.01). BiPAP breathing had no effect on intravascular and transmural pressures, CO and PVR. We conclude that CPAP breathing increase pulmonary intravascular but not transmural, true, pressure. BiPAP breathing does not change pulmonary haemodynamics what may be of importance as pulmonary circulation is concerned.