Efficacy of Lignocaine plus Ketamine at Different Doses in the Prevention of Pain Due to Propofol Injection

Abstract

Objective: Pain on injection is still a major problem with propofol. Lignocaine (lidocaine) is effective in preventing propofol-induced pain on injection, but cannot entirely control the pain. The purpose of this study was to examine the effect of lignocaine plus ketamine, an N-methyl-D-aspartate receptor antagonist, on pain on injection of propofol.

Design: Prospective, randomised, double-blind, placebo-controlled study.

Setting: University Hospital.

Patients: 120 female patients scheduled for gynaecological laparoscopy.

Interventions: Patients received intravenously lignocaine 20mg plus either placebo (saline) or ketamine at three different doses (2.5mg, 5mg and 10mg), with manual venous occlusion for 1 minute, followed by administration of propofol 0.5 mg/kg into a dorsal hand vein (n = 30 in each group). A blinded researcher asked the patients to assess pain during the propofol injection. MAIN OUTCOMES MEASURES AND RESULTS: Twelve of 30 patients (40%) complained of pain in the lignocaine/placebo group compared with three (10%) in the lignocaine/ketamine 5mg group and three (10%) in the lignocaine/ketamine 10mg group (both p = 0.015). No significant differences were found between the lignocaine/ketamine 2.5mg (10 patients [33%]) and lignocaine/placebo groups. No complications such as pain, oedema, wheal or flare response were observed at injection sites within the first 24 hours after anaesthesia.

Conclusion: Combined lignocaine 20mg and ketamine 5mg, with manual venous occlusion, is more effective than lignocaine 20mg alone for pain control during propofol injection.