Background: The incidence of pain due to propofol injection is high, but the most efficacious method of preventing this pain has not been identified.
Objective: The aim of this study was to investigate the efficacy of lidocaine, at different doses and schedules, on propofol injection pain.
Methods: In this open-label study, conducted at the Department of Anaesthesiology, Erciyes University Gevher Nesibe Hospital (Kayseri, Turkey), patients with American Society of Anesthesiologists Patient Acuity Classification I-II (ASA I-II) (ie, patients with absent [I] or mild [II] underlying systemic disease) aged 18 to 60 years undergoing various types of surgery were eligible. Patients were randomized to 1 of 4 treatment groups: group 1 received propofol; group 2, a combination of propofol plus lidocaine 10 mg; group 3, lidocaine 10 mg 30 seconds before propofol administration; and group 4, lidocaine 1 mg/kg 30 seconds before propofol administration (all drugs were administered intravenously). After cessation of the standard replacement fluid infusion (isotonic saline), propofol was given at a rate of 2 mL every 5 seconds until a dose of 2 mg/kg was reached. The patients were asked to rate their pain according to the following scale: 0 = none, 1 = mild, 2 = moderate, and 3 = severe.
Results: A total of 120 patients (61 men, 59 women; mean [SD] age, 38.7 [8.9] years) were enrolled in the study (n = 30 patients in each group). The incidence of injection pain in groups 2 and 4 was significantly lower than that in groups 1 and 3 (all P<0.05), but no significant difference in the incidence of pain was found between groups 1 and 3. The incidence of pain in group 2 was significantly lower than that in group 4 (P<0.05).
Conclusions: In this study population, the addition of 10 mg of lidocaine to propofol 2 mg/kg, or the administration of 1 mg/kg of lidocaine 30 seconds before the administration of propofol 2 mg/kg, effectively decreased pain caused by propofol injection. Furthermore, a lower dose of lidocaine could be used. Based on our results, we suggest mixing propofol with 10 mg of lidocaine to decrease pain due to propofol injection during anesthesia induction.
Keywords: injection pain; lidocaine; local anesthetics; propofol.