The Effect of Propofol Infusion Before Administration of Its Bolus Dose on Propofol Injection Pain and Serum Complement C3 Levels; A Randomized Clinical Trial

BACKGROUND: Pain on injection with propofol is still a major problem associated with anesthesia. Several factors involved in this event have been studied with respect to their pain attenuating effects. OBJECTIVES: The purpose of this study was to evaluate the effect of propofol infusion before administration of its bolus dose of propofol on the resulted pain at its induction dose and on serum complement C3 levels. METHODS: This clinical trial was performed on patients undergoing surgery under general anesthesia divided into three groups, including A (without intervention), B (propofol infusion at a dose of 50 µg/kg/min before anesthesia induction), and C (propofol infusion at a dose of 100 µg/kg/min 100 before anesthesia induction). During anesthesia induction by propofol, the presence, absence or severity of pain was determined using the Numerical Rating Pain Scale. Serum complement C3 levels were measured and their relationships with pain scores were compared between three groups. The data were analyzed using SPSS V. 22 software. RESULTS: There were significant differences in the mean pain scores between three groups (P < 0.05). However, no significant difference in the mean pain scores was observed between the groups B and C (P > 0.05). The mean and standard deviation of the differences in complement C3 values in the three groups before and after injection were 72.15 ± 14.9, 27.65 ± 9.82, and 18.95 ± 4.68, respectively, which demonstrated a significant difference between three groups (P < 0.05). However, the difference in complement C3 values between the groups B and C was not significant (P > 0.05). CONCLUSIONS: According to the obtained results, the low doses of infused propofol, 2 minutes before administration of its bolus dose, seems to have a considerable attenuating effect on its pain score.