Efficacy of 48-hour intravenous (IV) lidocaine infusions in open colorectal surgery.

Background Although i.v. lidocaine is used as a perioperative analgesic in abdominal surgery, evidence of efficacy in terms of surgical recovery, pain scores, and opioid use is limited. The infusion dose and duration remain unclear. This study aimed to investigate the effect of a longer low-dose 48-hour infusion regimen on these outcomes. Methods Fifty-eight adult patients undergoing elective open colorectal surgery were randomised into the lidocaine group (1.5 mg kg-1 followed by 1 mg kg-1 h-1 infusion for 48 hours) and control group (administered equal volumes of normal saline). After surgery, patients were given a patient-controlled analgesia (PCA) machine and time to first bowel movement (primary outcome) and flatus were recorded. Postoperative pain scores (numeric rating scale) and fentanyl PCA consumption were assessed for 72 post-operative hours. Results There was no significant difference in time to first bowel movement [80.1 (42.2) vs 82.5 (40.4) hours; (P=0.83)], time to first flatus [64.7 (38.5) vs 70.0 (31.2) hours; P=0.57], length of hospital stay [9 (8–13) vs 11 (9–14) days; P=0.53], nor post-operative pain scores in the lidocaine vs control arms. Cumulative opioid consumption was significantly lower in the lidocaine vs the control group from 24 hours onwards. At 72 hours, cumulative opioid consumption (mcg fentanyl) in the lidocaine group [1570 (825-3587)] was over 40% lower than in the placebo group [2730 (1778-5327); P=0.039]. Conclusion A 48-hour low-dose i.v. lidocaine infusion reduces postoperative opioid consumption. This is not associated with faster return of bowel function, hospital discharge, or lower pain scores.