A prospective, randomized, double-blind study to compare the efficacy of lidocaine + metoclopramide and lidocaine + ketamine combinations in preventing pain on propofol injection.

PURPOSE: Propofol injection is known to cause distressing pain, and various methods have been used to decrease this pain. We investigated the efficacy of the lidocaine + metoclopramide and lidocaine + ketamine combinations on modulating propofol injection pain.

METHODS: Ninety ASA I/II patients aged 20-60 years were randomly assigned to three groups to receive lidocaine 20 mg (group L), lidocaine 20 mg + metoclopramide 10 mg (group LM), or lidocaine 20 mg + ketamine 5 mg (group LK), respectively, with venous occlusion for 1 min using a forearm tourniquet. Propofol 0.5 mg/kg was subsequently administered into a dorsal hand vein, and pain was assessed during its injection using a verbal rating score. The results were analyzed statistically with analysis of variance, the chi-square test, and the Wilcoxon rank sum test, where appropriate. The significance level was set at p < 0.05.

RESULTS: The incidence of pain was rated to be significantly less in patients in groups LM (40 %) and LK (6.7 %) than in those in group L (83.3 %) (p = 0.001 and p < 0.001, respectively). The pain score [median (range)] was also significantly less in patients in groups LM [0 (0-3)] and LK [0 (0-2)] than in those in group L [2 (0-3)] (p = 0.001 for both groups).

CONCLUSION: The lidocaine-ketamine combination is most effective for decreasing the pain on propofol injection.