2021, Vol. 4, Issue 3, Part B

Background: Propofol is a popular intravenous anesthetic induction agent which produces a smooth, rapid induction with rapid clearance and recovery but Pain on injection with Propofol is a common problem and can be very distressing to the patient. Ketamine is a phencyclidine derivative routinely used as an inducing agent and Dexmedetomidine Hydrochloride, an imidazole compound is the alpha 2 agonist. The present study was undertaken to compare the efficacy of Ketamine (0.5 mg/kg) and Dexmedetomidine (0.5 mcg/kg) in preventing the incidence and reducing the severity of pain on Propofol injection.

Method: 150 patients, ASA I&II, 18-60 year old undergoing elective surgical procedure under general anaesthesia (GA) were randomly assigned into 3 equal groups. Group C, Group K and Group D. In Group C 10 ml Normal Saline, In Group K Ketamine 0.5 mg/kg diluted to 10 ml with normal saline and in Group D Dexmedetomidine 0.5 mcg/kg diluted to 10 ml with normal saline was infused over 10 minutes before injecting Propofol. All study medications were prepared in a 10ML syringe that was covered with black tape by an anaesthesiologist who was not involved in the study. HR,BP,SPO2and Pain Scores were noted at baseline, after premedication, while injecting study drugs at 3, 5 and 10 minutes and while injecting Propofol at the beginning, after half Propofol was injected, after complete Propofol was injected and at 1,3 and 5 minutes after completing the Propofol. Incidence and severity of pain and involuntary movements, verbal communication by the patient was watched constantly. Injection pain was graded using a 4-point scale. The pain score was evaluated as ‘0’ when there was no discomfort in the injection area (no pain), ‘1’ when the patient simply answered "yes" without any change in behaviour (slight), ‘2’ when there was a change in behaviour or voluntary complaint of pain (intermediate), and ‘3’ when the patient made a loud sound, grimaced, withdrew his or her arm, or shed tears (severe). Data was recorded in printed proforma. The Proper blinding procedure was followed; All data were tabulated and analyzed by appropriate statistical methods to compare between the three groups.

Results: All 3 groups were comparable with respect to age, weight, gender composition and ASA status. In Group C, there were no changes in vital parameters and pain scores till injecting study drugs, however when Propofol injection was started almost all patients had some degree of pain (2% patients had no pain, 46% patients had mild pain, 34% patients had moderate pain whereas 18% patient had severe pain resulting in limb withdrawal) resulting in transient increase in HR, SBP, DBP and MAP. Once the Propofol injection was completed there was a sudden fall in above mentioned parameters. In Group K, there was a negligible increase in the hemodynamic parameters till infusing ketamine which remained constant throughout the period of injecting Propofol except for the initial few seconds of injecting Propofol which showed a slight surge in HR and MAP but it was not significant. 94% patients had no pain and only 6% of patients complained mild pain while injecting Propofol. Vitals returned to baseline in the post Propofol injection period. In Group D, there was statistically significant but clinically non-significant fall in HR, SBP, DBP, and MAP while infusing Dexmedetomidine. 84% of patients had no pain, 12% of patients experienced mild pain and only 4% of patients experienced moderate pain while injecting Propofol. Vitals continued to fall slowly in the post Propofol injection period. The mean baseline pain scores in all the 3 groups were almost similar and there was no significant statistical difference. Pain scores were compared within the group as well as with each other. When pain scores were compared within the control group at different intervals it was found that increase in pain scores were statistically highly significant at the start of injecting Propofol, when half of Propofol was injected and when complete Propofol was injected as compared to baseline pain scores (P value < 0.001). When pain scores were compared in group K and group D at different intervals, they were statistically not significant (P value > 0.05) at any point of time.

Conclusion: Ketamine 0.5 mg/kg and Dexmedetomidine 0.5 mcg/kg both are effective in reducing the incidence and severity of pain of Propofol injection. Their efficacy in attenuation of pain is comparable; However, Ketamine 0.5 mg/kg infusion pre-treatment shows better hemodynamic stability than Dexmedetomidine 0.5 μg/kg infusion pre-treatment.