Ultrasound Guided Thoracic Paravertebral Block for Hepatic Tumors Ablation

Patients undergo percutaneous radiofrequency ablation of hepatic tumors at Siriraj hospital normally receive only intravenous sedative drugs which sometimes can not provide effective pain control. TPVB is suitable for unilateral operations. And it is increasing popular nowadays because of using ultrasound guided which make it is more reliable and has less side effects especially the severe one such as pneumothorax. To cover all nerve supply liver, we decided to use right TPVB at T5-6, T7-8, and T9-10. The aim of this study is to prove that TPVB can provide an effective pain control for patients undergo liver RFA both at rest and movement (cough). We are going to measure the pain score at recovery room and the effective pain control means patients has mild pain (pain score less \</= 3 and do not ask for analgesic drugs).