Lipid Emulsion Pretreatment Decreased the Maximum Total and Free Plasma Concentration of Levobupivacaine for Femoral and Sciatic Nerve Block in Below-Knee Fracture Surgery.

Abstract

Although intravenous lipid emulsion has been proved a powerful antidote for local anesthetic toxicity, there are few pharmacokinetic data on using lipid infusion as a pretreatment for other clinical applications. We assessed the influence of lipid pretreatment on the pharmacodynamics and pharmacokinetics of levobupivacaine. Altogether, 12 patients undergoing below-knee surgery for a fracture were randomly assigned to 2 groups (6 patients per group): pretreatment with 1.5 mL/kg lipid infusion (lipid group) or saline infusion (control subjects) followed by complete femoral and sciatic nerve block with 0.375% levobupivacaine (2.5 mg/kg). Total and free (non-protein bound) plasma levobupivacaine concentrations and triglycerides in the lipid group were determined. Results were given as means ± SD. Total and free maximum plasma levobupivacaine concentrations were lower in the lipid group than in control subjects (865 ± 98 vs 1145 ± 177 μg/L and 56.8 ± 7.5 vs 78.2 ± 13.7 μg/L, respectively; P < 0.01). Apparent volume of distribution and clearance were higher in the lipid group than in control subjects (211 ± 35 vs 170 ± 21 L and 35.1 ± 8.0 vs 25.8 ± 2.6 L/h, respectively; P < 0.05). Triglyceride level was significantly higher at the end of lipid infusion than baseline values (7.59 ± 1.32 vs 1.34 ± 0.39 mmol/L; P < 0.01). Lipid pretreatment increased the apparent volume of distribution and clearance and decreased the maximum total and free levobupivacaine concentrations, thus offering a reasonable explanation for the effects of lipids on local anesthesia-related toxicity in humans. Rapid lipid infusion induced hypertriglyceridemia without other apparent risks in this study. This study was registered at the Chinese Clinical Trial Registry, identifier ChiCTR-TRC-14005203.