Lipid therapy with two agents in ropivacaine-induced toxicity: experimental study in Swine.

BACKGROUND AND OBJECTIVE Compare hemodynamic changes after ropivacaine-induced toxicity followed by treatment with two lipid emulsions in swine. METHODS Large White pigs were anesthetized with thiopental, followed by intubation, and kept on mechanical ventilation. Hemodynamic variables at rest were recorded with invasive pressure monitoring and pulmonary artery catheterization. After 30 minutes, 7mg.kg(-1) ropivacaine were injected intravenously and new hemodynamic measurements were performed within one minute. The animals were then randomly allocated into three groups and received: 4mL.kg(-1) saline solution, or 4mL.kg(-1) lipid emulsion with long-chain triglycerides, or 4mL.kg(-1) lipid emulsion with longand medium-chain triglycerides. Hemodynamic changes were reevaluated at 5, 10, 15, 20 and 30 minutes. RESULTS Ropivacaine-induced toxicity mainly caused a drop in blood pressure and cardiac index without significant changes in vascular resistance. Therapy with lipid emulsions restored blood pressure primarily through increased vascular resistance, as cardiac index showed no significant improvement. Lipid emulsion with medium-chain triglycerides caused a greater increase in vascular resistance, particularly pulmonary. CONCLUSION In groups receiving lipid emulsions, hemodynamic results were better than in control group. There were no differences in systemic arterial pressure and cardiac index between animals receiving lipid emulsion with long-chain triglycerides and mixed long- and medium-chain triglycerides.