The effects of remifentanil and thoracic epidural on oxygenation and pulmonary shunt fraction during one-lung ventilation.

OBJECTIVE To compare the effects of remifentanil and thoracic epidural analgesia on the hemodynamic changes and pulmonary shunt fraction during one-lung ventilation (OLV) for thoracotomy. DESIGN Prospective, single crossover design. SETTING Tertiary care hospital. PARTICIPANTS Thirty-four patients undergoing OLV for thoracic surgery. INTERVENTIONS During general anesthesia with 2-lung ventilation, one-lung ventilation with remifentanil infusion, and one-lung ventilation with thoracic epidural anesthesia (TEA), hemodynamic parameters and arterial and mixed venous blood gases were taken from the radial and pulmonary artery catheters. During these 3 study periods, cardiac index (CI) was measured using thermodilution technique while shunt fraction (Qs/Qt), alveolar arterial oxygen gradient (A-a O(2)), and systemic (SVRI) and pulmonary vascular resistances indices (PVRI) were calculated. A p value <0.05 was taken to be statistically significant. MEASUREMENTS AND MAIN RESULTS When OLV was instituted, there was a significant decrease in mean arterial blood pressure. Arterial oxygenation decreased, whereas CI and Qs/Qt increased during OLV, but there was no significant difference between remifentanil infusion and thoracic epidural analgesia. CONCLUSIONS Both remifentanil infusion and TEA are suitable for analgesia during thoracic surgery when OLV is used. There was no significant difference in PaO(2) and Qs/Qt during each administration.