[Is intravenous lidocaine infusion suitable for postoperative pain management?]

Intravenous administration of local anaesthetics has repeatedly been recommended for the treatment of chronic pain. Some authors have also reported on their use in postoperative pain management. However, most of these publications are case reports or refer to rather old studies or investigations based on study designs that fail to meet present scientific standards. We therefore performed a randomized prospective, double-blind study in 40 patients undergoing elective tonsillectomy, 20 of whom received an infusion of lidocaine at a dose of 1.5 mg/kg body weight (over 10 min) 30 min before the beginning of surgery, followed by 2 mg/kg body weight per h over 6 h and 0.5 mg/kg body weight per h for another 18 h. The patients in the control group received identical volumes of 0.9% NaCl solution. Mean lidocaine plasma concentrations determined 30 min and 3, 6, and 24 h after the beginning of surgery ranged between 2.29 and 0.58 mug/ml. Postoperative pain evaluation on the visual analogue scale and the 101-point numerical rating scale did not reveal,significantly lower pain scores in the lidocaine group than in the control group. During the first 24 h after surgery 12 patients in the lidocaine group required a total of 550 mg meperidine in addition, while 8 patients in the control group required a total of 300 mg meperidine. The postoperative meperidine consumption was not significantly diffent between the lidocaine group and the control group. Intravenous lidocaine infusion did not significantly reduce postoperative pain after tonsillectomy in the dosage used.