A randomized controlled trial to compare effects of different volume and concentration of lidocaine for preventing propofol injection pain in adults

Background: Pain on propofol injection is an unwanted effect which can lead to decreased patient satisfaction. Although many studies have shown that pre-treatment with lidocaine injection is effective in this pain, nevertheless, very few studies have been done on different concentration and volume of lidocaine, effective of reducing pain significantly. Objective of the current study was to assess and compare the efficacy of intravenous lidocaine with 0.4% and 2% concentration in reducing the incidence and severity of propofol injection pain.Methods: A total of 126 American Society of Anesthesiologist grade I and II patients with age ≥18 years, scheduled for an elective surgery, were enrolled in the study. Patients were randomized into two equal groups of 63 each. Group A (n = 63) received pretreatment with 0.4% lidocaine and group B (n = 63) received 2% lidocaine. Propofol injection pain was measured by using Numeric Rating Scale (NRS) and Withdrawl Response Scale (WRS). Unpaired t test, ANOVA and Chi square test were used for statistical analysis.Results: A statistically significant decrease in the pain was recorded in group A (0.4% lidocaine) as compared to group B (2% lidocaine). Using NRS scale, 12% of patients in group A as compared to 33% patients of group B, experienced pain (p =0.02); while using WRS, 8% patients of group A as compared to 27% group B patients experienced pain (p= 0.04).Conclusions: The pain on injection of propofol is significantly decreased by the use of 0.4% lidocaine in comparison with 2% Lidocaine