Functional walking capacity as an outcome measure of laparoscopic prostatectomy : the effect of lidocaine infusion

Background: Intravenous lidocaine infusion has been shown to affect postoperative pain intensity. This present study was performed to assess the effect of intra- and postoperative lidocaine infusion on postoperative functional walking capacity, as a measure of surgical recovery. Methods: Forty patients undergoing laparoscopic prostatectomy were randomized to receive an i.v. infusion of either lidocaine 2 mg kg-1 h-1 during surgery and 1 mg kg-1 min-1 for the first 24 postoperative hours (lidocaine group) or an equivalent volume of saline 0.9% (control group). All patients received postoperative patient-controlled analgesia with i.v. morphine. Primary outcome was functional walking capacity, as assessed by distance attained during the 2 min walking test (2MWT), recorded daily for the first 3 postoperative days. Morphine consumption and pain intensity were recorded. Results: 2MWT distance decreased by an average of 60% (P<0.01) in both groups on postoperative day 1 (from 150 m before surgery to 53 m), but the decrease was 26 m less in the lidocaine group (P=0.009). During postoperative days 2 and 3, the 2MWT distance increased to an average of 96 m, still 30% less than the preoperative values. There was a significant negative correlation on postoperative days 1 and 2 between the 2MWT distance, pain intensity and fatigue, and morphine consumption. Lidocaine infusion was an independent predictor of the degree of postoperative decrease in 2MWT distance. More patients in the lidocaine group were free from PCA on the second postoperative day (P=0.011). Conclusions: Infusion of lidocaine during surgery and for the first postoperative day attenuated the deterioration in functional walking capacity, and had an opioid sparing effect.