Reduction of pain on injection of propofol: combination of nitroglycerin and lidocaine

Pain on propofol injection is a common adverse effect. This study examined the effect of a combination of nitroglycerin and lidocaine on pain during propofol injection compared to lidocaine alone.

In a double-blind, prospective trial, 90 patients scheduled to undergo elective plastic surgery were allocated randomly to three groups, to receive lidocaine 20 mg (n = 30), a combination of lidocaine 20 mg and nitroglycerin 0.1 μg/kg (n = 30), or normal saline as a placebo (n = 30), with venous occlusion for 1 min, followed by the administration of 25 % of the total calculated dose of propofol (2 mg/kg) into a dorsal hand vein. The pain intensity during the propofol injection was assessed using a four-point scale (0 = none, 1 = mild, 2 = moderate, 3 = severe). Hemodynamic variables–mean arterial pressure and heart rate–were measured during the preoperative and intraoperative periods.

A significantly higher proportion of patients in the placebo group (83 %) experienced pain compared to the lidocaine and combination groups (43 and 7 %, respectively; both, P < 0.01). The incidence of pain in the combination group was lower than that in the lidocaine group (P < 0.01). The pain score (median) was lower in the lidocaine (0) and combination (0) groups than in the placebo group (2); (P < 0.01). The hemodynamic variables were similar in the three groups.

A combination of nitroglycerin 0.1 μg/kg and lidocaine 20 mg with venous occlusion for 1 min was more effective than lidocaine 20 mg alone in decreasing pain during propofol injection.