RESUMEN
Propofol is a popular IV anesthetic induction drug that causes pain when given IV, the incidence of which is between 28%-90%. We plan to determine the optimal dose of ketamine in the prevention of propofol injection pain and compare it with lidocaine, the commonly proposed pre-treatment. In a double-blind randomized study 500 Patients [ASA I,II] scheduled for elective strabismus surgery under general anesthesia were randomly allocated into five groups. After obtaining the informed consent., patients received normal saline [Group NS], lidocaine 1mg.kg[-1] [Group L], and different doses of ketamine 50-75-100 micro g.kg[-1] [Group K50-K75-K100 respectively], immediately before the injection of 2.5 mg.kg[-1] propofol. Each patient's pain scores were measured at five seconds intervals by a blinded anesthesiologist. Statistical analysis were made by SPSS vs 11.5. The incidence and intensity of pain in all study groups were significantly lower than placebo group [Group NS] [P<0.005]. Patients in the K100 Group had significantly lower incidence of pain and lower pain scores compared with the K50 and L Groups [P<0.001]. There were no significant differences in hemodynamic parameters between groups. Administration of ketamine 100 micro g.kg[-1] immediately before propofol injection is a safe and effective method in preventing propofol injection pain