Effects of Intrathecal Sufentanil at Different Doses on Postoperative Pain Relief and Opioid Consumption in Elderly Patients Undergoing Lower Limb Orthopedic Surgery: A Randomized Controlled Trial

Introduction: Fine-needle isobaric spinal anesthesia is preferred for elderly patients undergoing lower limb fracture surgery. However, single-agent local anesthetics are limited by short block duration, hemodynamic instability, and inadequate analgesia. Intrathecal sufentanil, as an adjunct, enhances analgesia, prolongs block duration, and promotes recovery. Yet, the dose-dependent effects of intrathecal sufentanil remain understudied. This study evaluates different doses of intrathecal sufentanil in this population, aiming to optimize dosing through evidence-based strategies. Methods: We randomly allocated 231 elderly patients into three groups: Group B (bupivacaine only), Group BS1 (bupivacaine + 5 mu g sufentanil), and Group BS2 (bupivacaine + 10 mu g sufentanil). We assessed baseline data, sensory and motor block characteristics, NRS scores, rescue opioid consumption, and complications. Results: BS1 and BS2 had delayed motor block onset (median = 3 min) compared to Group B (median = 2 min), but significantly longer motor block duration (BS2: 279.5 min, P = 0.001; BS1: 268.0 min, P = 0.022 vs Group B: 223.0 min). On postoperative day 2, BS1 and BS2 showed lower NRS scores and less analgesic use than Group B. Nausea was most common in BS1, while pruritus increased in BS2. Hypoxemia was highest in BS2 on postoperative day 1. Conclusion: Bupivacaine and sufentanil combined is a safe and effective regimen, prolonging analgesia and reducing postoperative pain and opioid use. BS2 (bupivacaine + 10 mu g sufentanil) provided the best pain relief, ideal for high pain control needs, but higher pruritus and hypoxemia in BS2 suggest careful dosage adjustment based on patient tolerance.