This is a double blind, randomized controlled trial to evaluate the efficacy of ESPB(Erector Spinae Plane Block) on postoperative analgesia in RFA( Radiofrequency Ablation therapy). We will include 80 patients, and randomly assign to ESPB(Chirocaine) group and control group(normal saline).We deduce Erector spinae plane block can be use as a postoperative analgesic way for patients who receive radiofrequency ablation of hepatocellular carcinoma.

Computed tomography guided radiofrequency ablation of hepatocellular carcinoma(HCC) has became a popular way to treat HCC. Although the wound is small and the patients can discharge on the next day, they have to suffer from moderate to severe pain. Nowadays Erector spinae plane block has been applied to many surgery as a postoperative analgesic strategy. We deduce Erector spinae plane block can be use as a postoperative analgesic way for patients who receive radiofrequency ablation of hepatocellular carcinoma. Besides, we will add contrast medium to evaluate the spread area of local anesthetics.

Patients undergoing computed tomography guided radiofrequency ablation of hepatic tumor under scheduled general anesthesia, and fulfilled one of following inclusion criteria:

1. diameter of hepatic tumor is larger than 2 cm
2. distance of tumor site is near the hepatic surface < 2cm

Exclusion criteria:

1. A history of allergic reaction to local anesthetics or iohexol
2. Renal insufficiency, creatinine clearance < 30mL/min
3. Coagulopathy or other bleeding disorder that cannot perform nerve block
4. Under pregnancy or lactation
5. Opioid tolerant patient