Percutaneous radiofrequency ablation of liver lesions causes patients acute pain during and after the procedure. During the procedure patients need deep sedation and cannot be collaborative. Furthermore post-operative analgesia is necessary. The aim of this study is to evaluate if the ultrasound-guided paravertebral block (TPVB)with a single injection can provide anesthesia and post-operative analgesia in these patients.

The purpose of this study is to evaluate if single injection TPVB, ultrasound guided, ENS assisted, is advantageous compared to deep sedation (DS)in patients undergoing percutaneous radiofrequency ablation of liver lesions with respect to post-operative analgesia (at rest and in movement)and vomiting. Furthermore we collect data on operator and patient satisfaction.

In this study patients are randomly divided into two groups (20 patient each): TPVB and DS. In TPVB group the block is performed in lateral position at level of T7 with bupivacaine 5mg/ml. In DS group the procedure is conducted under local and intravenous anesthesia, and a post-operative analgesia is assigned. Data on patient, on procedures (duration, number and position of lesions etc.), complications with the anesthesiological technique are collected. The intensity of post-operative pain is assessed at 3-6-12 and 24 hours after procedure in both group using VRS pain scale at rest and in movement. Any concomitant event like nausea, vomiting, respiratory complications etc are recorded.

Inclusion Criteria:

• written consent ASA I-III

Exclusion Criteria:

• allergy to local anesthetic infection in the site of planned injection

In this study 40 patients undergoing elective procedure of radiofrequency ablation of liver lesions are enrolled after written informed consent is obtained.