The fate of lidocaine infiltrate during abdominoplasty and a comparative study of absorption of local anesthetic in 3 different regions: Experimental studies in a porcine model

Abstract

Background: Plasma lidocaine levels obtained during face lifts, breast surgery, and abdominoplasties showed an unexpectedly low absorption of anesthetics despite the use of doses exceeding the manufacturer's recommended maximum limit. Objective: With the use of an animal model, we sought to determine the amount of anesthetic lost during an abdominoplasty and the levels of anesthetic absorption in different areas of the body. Methods: In the first part of our study, 10 Duroc-Jersey pigs were infiltrated by using the same technique as for an abdominoplasty—specifically, with 14 mg/kg lidocaine (twice the manufacturer's recommended dose). Plasma lidocaine levels were determined at seven 15-minute intervals after surgery. After 2 days, abdomens of the same animals were infiltrated as before. An abdominoplasty was performed, and plasma lidocaine levels were obtained at 15-minute intervals during surgery. In a second study, we selected 10 pigs to analyze the absorption of anesthetics in different regions and tissues of the body. The axillary and pectoral regions, the face and neck area, and abdominal fat were each infiltrated with a solution containing 14 mg/kg lidocaine, with 2-day intervals between the infiltration of each region. For each region, samples were obtained at 15-minute intervals to determine plasma lidocaine levels. Results: In the first study, plasma lidocaine levels in the animals that underwent abdominoplasty were 32% less at 15 minutes after infiltration and approximately 50% less at the later time intervals than those in the nonoperated animals. In the second study (without surgery), the rate of total absorption of lidocaine was 5.6 μg in the thorax (under the pectoralis major and in the axilla), 3.5 μg in the face, 3.5 μg in the neck, and 2.8 μg in the abdominal fat tissue. Conclusions: In a porcine model, approximately half the injected lidocaine anesthetic is lost during an abdominoplasty. Without performance of surgery, The abdomen has the lowest rate of absorption of anesthetics, the pectoral region the highest, and the subcutaneous tissues of the face and neck an intermediate rate, all of which were within the safe limits recommended by the manufacturer. (Aesthetic Surg J 2001;21:418-422.)