Background and Goal of Study: The aim of this study is to evaluate the effect of body mass index (BMI) on postoperative pain and postoperative analgesia requirements in paediatric surgical population.
Materials and Methods: 757 children, aged 1 to 15 years old, ASA PS I-III, were included in this study. Participants were allocated into four groups according to BMI classification and BMI percentile interpretation of WHO child growth standards: underweight (Group 1, n=110), normal weight (Group 2, n=456), overweight (Group 3, n=106) and obese (Group 4, n=85). All patients underwent elective surgical procedures under general anesthesia and received 0.003-0.005mg/kg fentanyl, 20mg/kg paracetamol and 0.02mg/kg nalbuphine intraoperatively according to standard department protocol. Demographic data were obtained from patients records. Postoperative pain scores with Hanallah and Wong Baker (WBFPS) pain scales at rest and movement (deep breath) and Aldrete score were assessed in 1(st) hour following surgery. Postoperative analgesic requirements after discharge were recorded. 
Statistical analysis was performed with ANOVA posthoc and chi square tests. Level significance was set at p< 0.05.
Results and Discussion: There were no differences in patients demographic data except for the body weight and BMI. Obese children (Group 4) reported statistically significant more pain in Hannalah scale compared to group 2 and 3 (p<0.05). No statistical differences were noted between groups regarding WBFPS at rest and movement. Underweight children (Group 1) received significantly less analgesics after recovery compared to normal (Group 2, p<0.05). Moreover, there was statistically significant difference in analgesia consumption in Group 2 compared to group 3 (p<0.05) and 4 (p<0.05). In group 3 NRS scale was statistically significant lower compared to group 1 (p<0.05). There was also statistically significant higher Aldrete scale score in group 2 compared to group 4 (p<0.05).   
Conclusion: BMI may relate with immediate postoperative pain scores and analgesia. Underweight and normal children received less analgesics and reported less pain compared to overweight and obese children, postoperatively 


01 / The effect of Body Mass Index (BMI) on postoperative pain in paediatric surgical population