effects in these patients with possible kidney injury, other regional techniques like epidural and paravertebral blocks can be pretty invasive. Patients posted for PCNL surgery often have suboptimal renal function and non-steroidal anti-inflammatory drugs (NSAID) are potentially nephrotoxic. Therefore novel regional anesthetic techniques that would provide optimal pain control without significant adverse effects need to be explored.

Erector Spinae Plane Block (ESPB) is a novel analgesic technique which was first described in 2016 for thoracic neuropathic pain. It has subsequently found efficacious for acute pain control after surgeries like Mastectomies, Percutaneous Nephrolithotomy, Lumbar spine surgeries, Laparoscopic Cholecystectomy. ESPB involves injection of the local anaesthetic into the plane between the erector spinae muscle sheath and the transverse process of the vertebra. When injected, the injectate spreads cranio-caudally

resulting in the blockage of multiple vertebral levels. ESPB affects both the ventral and dorsal rami, leading to blockage of both visceral and somatic pain.

Local anesthetic infiltration of incision site is another novel modality of pain relief in PCNL surgery (skin, subcutaneous tissue, renal capsule, and parenchymal tract) is done with local anesthetic drugs. This can produce significant reduction of pain as assessed by visual analog scale (VAS) score with less demand for rescue analgesia.

This study was designed to compare the efficacy of USG guided ESPB with local infiltration at the incision site in providing postoperative analgesia following PCNL.