Impact of Gender Variation on Calculated Plasma Concentration of Propofol (Cp50calc) to Prevent Movement Response to Surgical Stimulus in South Indian Population: A Comparative Study

Objective: To find out the gender differences in Cp50calc of propofol required to prevent movement response to surgical stimulus in South Indian population. Materials and Methods: A comparative study was performed on sixty American Society of Anesthesiologists I–II patients of both sexes undergoing elective surgery at a tertiary care institution. A bolus dose of 1.5 mg/kg propofol for 2 min, followed by a 150 μg/ kg infusion for 10 min was administered and movement response to surgical incision was noted. Propofol maintenance infusion rate was determined by Dixon’s up‑and‑down method, increased by 10 µg/kg/min for patient movement on surgical stimulus and reduced by 10 µg/kg/ min for no movement for successive patient. The plasma concentration (Cpcalc) was calculated by formula used in the marsh pharmacokinetic model using Rugloop II propofol calculation validation Excel Spreadsheet by feeding patient’s age, weight, and propofol dose. Cp50calc of propofol, the calculated plasma concentration of propofol, at which 50% of patients anesthetized with propofol do not respond to standard surgical stimulus is calculated by the mean of the midpoint concentration of all independent pair of patients who manifested a consecutive three crossovers from movement‑to‑no movement response to ensure reaching steady state. Results: No statistically significant difference observed in hemodynamic parameters between the groups. Cp50calc of propofol was 6.336 + 0.14 µg/ml in males and 5.664 + 0.14 µg/ml in females, which was statistically significant (P < 0.05). Conclusion: Males require more propofol than women for anesthetic induction. Hence, gender variable can also be incorporated in the target‑controlled pumps for accurate prediction.