Paravertebral Block for Postoperative Pain Management in Adult Patients Undergoing Appendectomy

Patients undergoing appendectomy will be randomly allocated into two equal groups using the sealed envelope technique. All patients will receive general anesthesia (GA). Patients in group I will receive two PVB injections at levels T12-L1 and L1-L2 using anesthetic mixture, while patients in Group II will receive placebo.

Paravertebral Block Technique Unilateral right side nerve stimulator-guided PVB is performed while patients are in the left lateral decubitis position. The appropriate levels for the PVB are determined by palpation of the spinous processes. An intervertebral line is drawn at the appropriate levels and the injection site is marked 2.5 cm lateral to the midline. After aseptic preparation of the skin, 1 mL 1% lidocaine is infiltrated at the injection sites. A 21-G nerve stimulation needle (Stimuplex; B. Braun, Melsungen, Germany) is advanced 1-2 cm perpendicularly to the skin using a nerve stimulating current of 2.5-5.0 mA, while closely watching for contractions of the abdominal muscles. The tip of the needle is adjusted to maintain muscle contractions while reducing the stimulating current to approximately 0.5-0.6 mA.

4 mL of the local anaesthetic mixture is injected at each injection site. Each 20 mL of the local anaesthetic mixture contains: 8mL lidocaine 2%, 8 mL lidocaine 2% with epinephrine 5µg/mL and 4 mL bupivacaine 0.5%.