Plasma concentrations of lidocaine and alpha1-acid glycoprotein during and after breast augmentation.

Plasma levels of lidocaine and the main binding proteins of lidocaine in plasma alpha1-acid glycoprotein (AAG) and albumin were measured in 10 otherwise healthy women during and after breast augmentation. A total dose of 825 to 1280 mg of 0.2% and 0.5% lidocaine with epinephrine corresponding to 16.3 to 21.8 mg/kg (mean 18.2 mg/kg) was injected in the spatium between the pectoralis muscle and the mammary gland. The peak plasma concentrations of lidocaine varied between 0.96 and 3.12 microg/ml (mean 1.49 microg/ml) and occurred between 4 and 12 hours (mean 7.3 hours) postoperatively. The plasma concentration of AAG varied between 0.42 and 1.73 g/liter (mean 0.49 g/liter, normal range 0.54 to 1.17 g/liter). There was a significant correlation between the plasma concentration of AAG and lidocaine. The mean concentration of albumin was 37.2 g/liter, ranging from 33 to 42 g/liter (normal range 35 to 50 g/liter). No patient showed signs of lidocaine toxicity. These data indicate that a dose of 20 mg/kg of lidocaine with epinephrine probably is safe in breast augmentation when the drug is administrated as described in this study. There are significant individual differences in the plasma concentration curves between patients, partly explained by different concentrations of AAG. Further studies with a larger number of patients are needed to establish definitive recommendations of safe maximal doses.