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.