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.