Evaluation of Propofol Dose based on total body weight in Obese Compared to Non-Obese Patients Guided by Bispectral Index

Background: Propofol may be an appropriate agent for induction and maintenance of anesthesia in obese patients. However, there is a controversy regarding the propofol dose in such patients. This study was done to evaluate propofol dose, based on total body weight (TBW), in obese compared to non-obese patients. Methods: Fifty ASA I-II adult patients, who underwent different surgical procedures, were categorized into: group O; obese with body mass index (BMI) >30 kg/m2 and <40 kg/m2 and group N; non-obese with BMI ≤25 kg/m2. Propofol dose was given according to TBW guided by Bispectral index (BIS). Onset time (beginning of propofol infusion until BIS < 50), propofol infusion dose required to reach the onset time, rate and duration of infusion during maintenance, and total amount of propofol during anesthesia were recorded. Results: The mean onset time was significantly longer in group O (10.0 ± 1.5 min) compared to group N (6.2 ± 2.6 min) (p < 0.0001). The mean dose of propofol (mg/kg/h) required to achieve onset time was significantly higher in group O than group N (10.2 ± 2.3 vs. 8.6 ± 2.5; respectively) (p = 0.02). The relative mean rate of infusion (mg/kg/h) during maintenance was non-significant. However, the mean total propofol consumption (mg) was significantly higher in group O (p < 0.0001) during the entire anesthesia. Mean heart rate and blood pressure values were significantly lower in group O at 6 and 9 min following induction. Conclusions: From this study, with the guidance of BIS monitor, propofol dose for non-compromised obese patients can be calculated according to TBW.