Effect of Ultrasound-Guided Quadro-Iliac Plane Block on Postoperative Analgesia After Lumbar Spinal Surgery

This is a single-center, prospective observational cohort study conducted in patients undergoing elective lumbar spinal surgery under general anesthesia. The study is designed to assess the effects of ultrasound-guided Quadro-Iliac Plane Block (QIPB) on postoperative analgesia when used as part of routine multimodal pain management. Eligible patients aged 18-65 years with American Society of Anesthesiologists (ASA) physical status I-III and a body mass index below 35 kg/m² will be included after providing written informed consent. All patients will receive standardized general anesthesia and postoperative intravenous patient-controlled analgesia (PCA) with tramadol as part of routine care. The decision to perform QIPB will be made by the attending anesthesiologist according to clinical judgment and routine practice, without any intervention or assignment by the research team. Ultrasound-guided QIPB, when applied, will be performed bilaterally under sterile conditions in the prone position at the end of surgery. In patients who do not receive QIPB, the surgeon will perform local anesthetic infiltration (LAI) of the incision site as part of routine postoperative analgesia. Patients will be observed in two cohorts: those receiving PCA with LAI and those receiving PCA with QIPB. Postoperative outcomes will be assessed in the post-anesthesia care unit and at 1, 6, 12, and 24 hours postoperatively. Pain intensity will be evaluated using the Numeric Rating Scale (NRS) at rest and during movement. Secondary outcomes will include total opioid consumption, time to first rescue analgesic requirement, incidence of postoperative nausea and vomiting, sedation level, and patient satisfaction assessed using a 5-point Likert scale at 24 hours. Any block-related complications will also be recorded. Data will be analyzed using appropriate statistical methods to compare postoperative analgesic outcomes between the two cohorts. This observational study aims to reflect real-world clinical practice and contribute to the growing evidence on the role of QIPB in postoperative pain management after lumbar spinal surgery.