RESUMO
BACKGROUND: The safe upper limit of lidocaine dosage in tumescent anesthesia for liposuction has been reported to be 35 mg/kg. OBJECTIVE: This study was undertaken to: 1) evaluate the safety of tumescent anesthesia in liposuction when lidocaine doses greater than 35 mg/kg are required, 2) determine the time interval when the peak plasma lidocaine level occurs following administration of tumescent anesthesia, and 3) assess if the safety of large volume tumescent anesthesia is due to significant lidocaine removed by liposuction. METHODS: Sixty patients who underwent liposuction with a mean lidocaine dose of 57 mg/kg were prospectively evaluated for development of any signs or symptoms of lidocaine toxicity by multiple interviews over a 24-hour period. In addition, another 10 patients who received a mean lidocaine dose of 55 mg/kg had serial plasma lidocaine level measurements over a 24-hour period following liposuction. The lidocaine level of the aspirate was also measured to assess any significant lidocaine removed by liposuction. RESULTS: No evidence of lidocaine toxicity was found based on subjective evaluation of 60 patients as well as determined by plasma sampling of 10 patients. The peak plasma lidocaine concentration occurred at approximately 4 or 8 hours after infusion of tumescent anesthesia. The 24-hour plasma lidocaine level suggests that residual lidocaine is present in the subcutaneous tissue allowing for postoperative analgesia beyond this time. A negligible amount of lidocaine was removed by liposuction as determined by the lidocaine level of the aspirate. CONCLUSION: This study suggests that tumescent anesthesia with a total lidocaine dose of up to 55 mg/kg is safe for use in liposuction.