Ultrasonographic Abdominal Fat Thickness and Driving Pressure During Prone Spinal Surgery

This prospective observational study aims to evaluate the association between preoperative abdominal subcutaneous fat thickness measured by ultrasonography and intraoperative driving pressure in adult patients undergoing elective spinal surgery in the prone position under general anesthesia. Anthropometric measurements including body mass index, waist circumference, waist-to-height ratio, and neck circumference will also be evaluated for their association with respiratory mechanics. No additional intervention beyond routine clinical care will be performed.