Background: Conducting the regional anesthetic blocks including epidural catheterization has been well established in anesthetized pediatrics. However, the clinical outcomes and safety of thoracic epidural catheterization in anesthetized adult patients have not been well evaluated. 
Methods: Medical records of 549 successive patients who had received thoracic epidural catheterization before (n = 303) or after (n = 246) induction of anesthesia for major abdominal surgeries were reviewed retrospectively. We compared the procedure related clinical differences and complications between awake and anesthetized adult patients.
Result: The incidence of radicular pain during the procedure was 1.7 % (n = 5) of patients in awake. The time for epidural catheterization (median [Q1-Q3], 1.1 [0.7-2.0] vs. 0.7[0.5-1.2] min, P < 0.001) and the number of attempts for epidural catheterization (1[1-3] vs. 1[1-2], P = 0.003) were increased in awake than anesthetized patients. The incidence of dural puncture, vascular injury and postoperative paresthesia were similar between two groups. The median surgical site pain score using numerical rating scale (0 = no pain, 10 = worst pain imaginable) was lower in awake than anesthetized patients (3 vs. 4 on postoperative day 1, P < 0.001, and 2 vs. 3 on postoperative day 3, P = 0.002). Serious complications including meningitis, epidural abscess, epidural hematoma, spinal cord injury, spinal cord ischemia and paraplegia were not observed in both groups.
Conclusion: Overall complications of thoracic epidural catheterization were comparable regardless awake or anesthetized patients. However, long-term follow-up studies of more patients are 

02 / A clinical retrospective study comparing thoracic epidural catheterization between awake and anesthetized patients.