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

Abstract

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. Prospective, randomised, double-blind, placebo-controlled study. University Hospital. 120 female patients scheduled for gynaecological laparoscopy. 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. Combined lignocaine 20mg and ketamine 5mg, with manual venous occlusion, is more effective than lignocaine 20mg alone for pain control during propofol injection.