Efficacy of Hyaluronidase Added to Bupivacaine in Ultrasound-guided Erector Spinae Plane Block in Percutaneous Nephrolithotomy.

ESP block is most often performed using an in-plane ultrasound-guided technique. It is a paraspinal fascial plane block in which the needle placement is between the erector spinae muscle and the thoracic transverse processes, and a local anesthetic is administered, blocking the dorsal and ventral rami of the thoracic and abdominal spinal nerves