Intrathecal Pethidine Plus Dexamethasone Versus Intrathecal Bupivacaine in Lower Extremity Orthopedic Surgeries: A Randomized Clinical Trial

Background: Spinal anesthesia remains the preferred technique for lower abdominal and orthopedic procedures. Objectives: This study compares the effects of an intrathecal injection of pethidine combined with dexamethasone versus intrathecal bupivacaine alone in patients undergoing lower extremity orthopedic surgeries. Methods: In this prospective, randomized, controlled, double-blinded study, 46 participants scheduled for elective lower extremity orthopedic surgeries were randomly allocated into two groups. Group PD (n = 23) received an intrathecal injection of 1 mg/kg preservative-free pethidine combined with 4 mg dexamethasone, diluted with 0.9% sodium chloride saline to a total volume of 3 mL. Group B (n = 23) received an intrathecal injection of 3 mL (15 mg) of 0.5% hyperbaric bupivacaine alone. The primary outcome measured was the time to the first need for rescue analgesia. Secondary outcomes included spinal anesthesia characteristics, intraoperative hemodynamic stability, and incidence of perioperative adverse events. Results: The time to first need for rescue analgesia was significantly longer in Group PD (7.76 ± 0.79 hours) compared to Group B (4.48 ± 0.63 hours). Differences in the onset of sensory and motor blocks between Group PD (6.39 ± 1.12 and 10.09 ± 2.23 minutes, respectively) and Group B (6.43 ± 1.99 and 9.96 ± 2.33 minutes, respectively) were statistically non-significant. However, the regression time for sensory and motor blocks was significantly shorter in Group PD compared to Group B (146.74 ± 15.35 and 119.56 ± 14.13 minutes vs. 188.44 ± 6.84 and 168.04 ± 5.25 minutes, respectively). Incidence of hypotension and shivering was also less frequent in Group PD than in Group B. Conclusions: Intrathecal administration of 1 mg/kg pethidine plus 4 mg dexamethasone provided improved spinal anesthesia, with extended postoperative analgesia, minimal intraoperative hemodynamic disturbances, and reduced incidence of shivering compared to bupivacaine alone in patients undergoing lower extremity orthopedic surgeries. This approach may be particularly beneficial for patients with hypersensitivity to ester or amide local anesthetics, offering a cost-effective alternative to standard local anesthetics.