The goal of this clinical trial is to assess the success rate of real-time ultrasound-guided thoracic epidural catheter placement at the first attempt in patients who will undergo thoracic or abdominal surgeries. The main aims are to: Assess the success rate of first-attempt thoracic epidural catheter placement. Assess the procedure duration of real-time ultrasound-guided epidural catheter placement Participants will be managed according to the following protocol The patient will have real-time ultrasound guided catheter placement using paramedian-cross view performed by an attending anesthesiologist who is also an investigator After being secured, the thoracic epidural catheter is tested with 3ml lidocaine 2% At 30 minutes after the test dose, the level of sensory block is assessed by using an ice cube to test cold sensation on the skin according to dermatome Epidural analgesia is initiated by a 0.1ml/kg bolus and maintained by continuous infusion of solution 0.1% ropivacaine combined with 1mcg/ml fentanyl during the surgery At the end of the surgery, the patients will paracetamol 15miligram per kilogram and nefopam 20 milligrams, the patient will receive another epidural bolus dose of 0,1ml/kg ropivacaine 0.1% combined with fentanyl 1mcg/ml After the surgery, the patient will receive paracetamol 15miligram per kilogram every 8 hours, nefopam 20mg every eight hours, continuous epidural infusion at rate 4-8 ml per hour, patient-controlled analgesia morphine 1mg bolus, lockout 15 minutes, maximum 4mg per hour. Additional bolus dose of 4ml ropivacaine 0.1% will be administered every 30 min if VAS pain score at rest exceed 4. After two top-up bolus doses of 4ml ropivacaine 0.1% , if VAS pain score at rest still exceed 4, the patient will receive 2mg morphine every 15 minutes until VAS score less than 4 The patient will be monitored for vital signs, pain scores, the level of sensory block, opioids consumption, pain site, other adverse effect of opioids such as respiratory depression, sedation. The patient is also monitored for other signs and symptoms associated with nerve injuries or epidural hematoma such severe back pain, radicular pain, numbness, loss of sensation below the level of epidural catheter placement, paralysis or limb motor weakness.