Multimodal Analgesia Versus Peripheral Nerve Block for Postoperative Pain Management After Lower Limb Injury Surgery

In the femoral nerve block (FNB) group, the femoral nerve was blocked distal to the inguinal ligament and lateral to the femoral artery. Under sterile conditions and ultrasound guidance using a short-axis out-of-plane approach, a 22-gauge insulated needle was advanced adjacent to the femoral nerve. Following confirmation of correct needle tip placement, a 20 mL volume of either 266 mg liposomal bupivacaine (diluted as indicated) or 0.2% ropivacaine was injected. This was followed by a continuous infusion at a rate of 5-10 mL/hr. For pediatric patients, a continuous infusion of 0.2% ropivacaine was administered at an initial bolus of 0.2-0.5 mg/kg, followed by a continuous infusion of 0.1-0.3 mg/kg/hr.

In the combined sciatic and femoral nerve block (CS-FNB) group, the femoral nerve block was performed as described above. The sciatic nerve block was performed at either the gluteal region or popliteal fossa. Under sterile conditions and ultrasound guidance using either an in-plane or out-of-plane approach, a 22-gauge insulated needle was advanced adjacent to the sciatic nerve. Following confirmation of correct needle tip placement, a 20 mL volume of either 266 mg liposomal bupivacaine (diluted as indicated) or 0.2% ropivacaine was injected. This was followed by a continuous infusion at a rate of 5-10 mL/hr. For pediatric patients, a continuous infusion of 0.2% ropivacaine was administered at an initial bolus of 0.2-0.5 mg/kg, followed by a continuous infusion of 0.1-0.3 mg/kg/hr.

In the lumbar plexus block (LPB) group, the lumbar plexus was blocked paraspinally within the psoas muscle. Under sterile conditions, ultrasound guidance, or with the assistance of a nerve stimulator, using either an in-plane or out-of-plane approach, a 22-gauge insulated needle was advanced within the psoas muscle adjacent to the lumbar plexus. Following confirmation of correct needle tip placement, a 20 mL volume of either 266 mg liposomal bupivacaine (diluted as indicated) or 0.2% ropivacaine was injected. This was followed by a continuous infusion at a rate of 5-10 mL/hr. For pediatric patients, a continuous infusion of 0.2% ropivacaine was administered at an initial bolus of 0.2-0.5 mg/kg, followed by a continuous infusion of 0.1-0.3 mg/kg/hr.

For epidural analgesia, an initial bolus of 5-15 mL of 0.5% ropivacaine was administered followed by a continuous infusion of 0.2% ropivacaine at a rate of 3-10 mL/hr. For pediatric patients, an initial bolus of 0.2% ropivacaine at 0.5-1 mg/kg was administered, not exceeding a maximum total dose of 2-2.5 mg/kg, followed by a continuous infusion of 0.1-0.3 mg/kg/hr.

For intravenous patient-controlled analgesia (PCA), fentanyl was administered at a dose of 2 mcg/kg, diluted in 100 mL of normal saline. The basal infusion rate was set at 2 mL/hr, with a PCA dose of 2 mL and a lockout interval of 15 minutes.

Following administration of the regional anesthesia, general anesthesia with endotracheal intubation will be performed. Anesthesia induction will be achieved using propofol (1.5-2 mg/kg i.v.), rocuronium (1-2 mg/kg i.v.), and fentanyl (1-2 μg/kg i.v.). Anesthesia will be maintained using sevoflurane or desflurane, with inhaled concentration adjusted based on Bispectral Index (BIS) monitoring. A continuous infusion of remifentanil (0.05-0.2 μg/kg/min) will be administered, with adjustments to maintain blood pressure and heart rate within ±20% of baseline values. Following induction, patients will be mechanically ventilated in pressure-regulated volume control (PRVC) mode. The ventilator (Aestiva; GE Healthcare, Waukesha, Wisconsin, USA) settings will be: tidal volume 6-8 mL/kg, positive end-expiratory pressure 0 cm H2O, inspiratory to expiratory ratio 1:2, respiratory rate 16 breaths per minute (BPM), and fraction of inspired oxygen 41%.