Effect of small-dose ketamine in the prevention of pain on propofol injection: A prospective randomized controlled study

Abstract

Background: Propofol is a commonly used intravenous anesthetic agent that produces pain when used for induction. In this study, small doses of ketamine are being used in comparison with lignocaine and placebo for alleviating pain on propofol injection. Aims and Objectives: The aim is to assess the effect of ketamine to prevent the pain on injection of propofol and to establish an optimal dose for this purpose. Materials and Methods: We conducted a prospective randomized double-blinded study (placebo controlled) in 160 patients belonging to the American Society of Anaesthesiologists grade 1 and 2 who were posted for elective surgeries to be done under general anesthesia. They were allocated randomly into five groups. Patients were administered normal saline (NS) (Group NS), lignocaine 1.5 mg/kg (Group lignocaine), ketamine 0.1 mg/kg (Group KT1), ketamine 0.3 mg/kg (Group KT2), and ketamine 0.5 mg/kg (Group KT3) just before injection of 1% propofol in a dose of 2.5 mg/kg. Pain scores of patients were assessed at intervals of 10 s by an anesthesiologist who was blinded to the test drug. Efficacy of the pretreatment drug was assessed based on pain score and the occurrence of pain. Results: The occurrence and intensity of pain were significantly higher in the placebo group (Group NS) compared to other study groups. The occurrence of pain and pain scores were lower in the KT2 and KT3 groups compared with the KT1 and lignocaine groups. Conclusion: This study concluded that ketamine administration in a dose of 0.3 mg/kg before propofol injection is beneficial and safe in preventing pain caused by injection of propofol.