Clinical Research Directory

Patients will be induced with general anesthesia, consisting of propofol (1.5-2 mg/kg intravenously), rocuronium (1-2 mg/kg intravenously), and fentanyl (1-2 μg/kg intravenously). Anesthesia will be maintained with inhaled sevoflurane or desflurane, adjusted according to BIS values. Remifentanil (0.05-0.2 μg/kg/min) will be administered via continuous infusion, with the infusion rate adjusted to maintain blood pressure and heart rate within ±20% of baseline. Following induction, patients will be mechanically ventilated in pressure-regulated volume control (PRVC) mode using an Aestiva anesthesia machine (GE Healthcare, Waukesha, Wisconsin, USA). Ventilator settings will be as follows: tidal volume 6-8 mL/kg, positive end-expiratory pressure 0 cmH2O, inspiratory-to-expiratory ratio 1:2, respiratory rate 16 breaths per minute (BPM), and inspired oxygen concentration of 41%.

For epidural analgesia, an initial bolus of 5-15 mL of 0.5% ropivacaine will be administered, followed by a continuous infusion of 0.2% ropivacaine at a rate of 3-10 mL/hour. In pediatric patients, the initial bolus will consist of 0.2% ropivacaine at a dose of 0.5-1 mg/kg, not to exceed 2-2.5 mg/kg, followed by a continuous infusion of 0.1-0.3 mg/kg/hour.

For paravertebral blocks, patients will be positioned either sitting or in the lateral decubitus position to fully expose the target area of the spine. The spinous process of the target vertebra will be palpated, and the puncture site identified. Using ultrasound guidance, the paravertebral space will be located. After standard skin preparation, a blunt needle will be advanced perpendicular to the skin. Once the needle tip contacts the transverse process, it will be withdrawn 1-2 mm, and then slightly angled caudally to pass through the paravertebral ligament and enter the paravertebral space. After negative aspiration for blood or cerebrospinal fluid, a 5 mL test dose of local anesthetic will be slowly injected, and the patient observed for adverse effects. If none are noted, an additional 5 mL of local anesthetic will be injected. The local anesthetic solution will be either liposomal bupivacaine (266 mg diluted to 20 mL) or 0.2% ropivacaine.

For TAP blocks, patients will be positioned supine with the abdomen exposed. Following standard skin preparation, a needle will be advanced perpendicular to the skin using ultrasound guidance, through the external oblique and internal oblique muscles to reach the fascial plane between the transversus abdominis and internal oblique muscles. After negative aspiration for blood, a 5 mL test dose of local anesthetic will be slowly injected, and the patient observed for adverse effects. If none are noted, an additional 10 mL of local anesthetic will be injected. The local anesthetic solution will be either liposomal bupivacaine (266 mg diluted to 20 mL) or 0.2% ropivacaine.

For intrathecal analgesia, adults will receive 0.1-0.2 mg of morphine intrathecally. For pediatric patients, the dose of intrathecal morphine will be 5-10 mcg/kg.

For intravenous PCA, a solution of fentanyl 2 mcg/kg will be diluted to a total volume of 100 mL with normal saline. The PCA settings will be as follows: a basal rate of 2 mL/hour, a PCA dose of 2 mL, and a lockout interval of 15 minutes.