Impact of Age and BMI on Spinal Anesthesia Characteristics in Pediatric Patients: A Retrospective Study

<i>Background and Objectives</i>: Spinal anesthesia is increasingly preferred in pediatric surgeries due to its rapid onset, high success rate, and low risk of systemic complications. However, the influence of age and body mass index (BMI) on block characteristics in adolescents remains insufficiently studied. <i>Materials and Methods</i>: This retrospective study evaluated 190 pediatric patients (aged 9-18 years; 154 male, 36 female) undergoing elective surgery with spinal anesthesia. Patients were stratified by age (Group 1: 9-14 years; Group 2: 15-18 years) and BMI (Group A: 16.00-19.65 kg/m²; Group B: 19.66-23.31 kg/m²). The primary outcome was sensory block duration. Secondary outcomes included sedation requirements, complications, analgesic requirement times, and Visual Analog Scale (VAS) scores. <i>Results</i>: Group 2 had significantly longer sensory block duration and lower postoperative VAS scores at 3 and 12 h compared to Group 1 (<i>p</i> < 0.001). Lower BMI was associated with greater sedation requirements (<i>p</i> < 0.001) and a higher incidence of intraoperative nausea and vomiting (<i>p</i> = 0.013). Complications were infrequent (hypotension 6.3%, bradycardia 2.1%, PONV 7.1%, postoperative headache 3.1%) and managed conservatively. <i>Conclusions</i>: Age and BMI meaningfully influence spinal anesthesia characteristics in pediatric patients. Older adolescents achieved longer sensory block durations and better postoperative analgesia, whereas younger and lower-BMI patients required more sedation and had higher nausea rates. Individualized spinal anesthesia planning, considering age, BMI, and developmental stage, may optimize clinical outcomes. Prospective studies are warranted to validate these findings.