42 patients age of 20 to 85, (ASA) physical status I-III undergoing nephrectomy/NSS procedures via lumbotomy in 1st Department of Anesthesiology in Warsaw will be enrolled in the study. Patients will be randomised into 2 groups - patients from the first group will undergo General Anesthesia (GA) with intravenous analgesia peri-operatively, patients from the second group will receive GA plus the Erector Spinae Plane Block (ESP block) unilaterally performed under ultrasound guidance with catheter left on the side of surgery. Ultrasound transducer will be placed in a longitudinal orientation 3 cm lateral to the Th7 spinous process. Three muscles will be identified superficial to the hyperechogenic transverse process shadow as follows: trapezius, rhomboid major, and erector spinae. An 8-cm 18-gauge block needle will be inserted in a cephalad-to-caudad direction until the tip gets in the interfascial plane between rhomboid major and erector spinae muscles, as evidenced by visualization of local anesthetic spreading in a linear pattern between erector spinae and the bony acoustic shadows of the transverse processes. . Patients in this group will be anesthetized with 20ml 0,25% bupivacaine + Adrenaline 1:200 000 via interfascial catheter. ESP block will be performed at the level of Th7-8 after proper positioning he patient in the sitting position before GA then standard technique of catheter application will be applied. After the surgery the elastomeric pump will be attached to the catheter with 0,125% bupivacaine with Adrenaline 1:200 000. Anaesthesia will be standardised In the both groups.

Inclusion Criteria:

• Pts undergoing nephrectomy/NSS procedures via lumbotomy in 1st Department of Anaesthesiology in Warsaw
• Pts consented for the study prior to surgery
• ASA 1-3

Exclusion Criteria:

• Pts without consent for trial
• Pts ASA 4-5
• Coagulation abnormalities
• Allergy to local anesthetics
• Skin lesions in the place of needle insertion