Introduction: Although the major risk, still unreported, of HTEA for coronary surgery is the development of epidural/spinal haematoma leading to paraplegia, this technique has indeed a failure rate and a rate of minor complications reported only by a few authors.
Method: To determine the failure rate of HTEA and the rate of minor complications, we retrospectively reviewed the database of all the patients undergoing HTEA for coronary surgery at this Institution from November 1999 to December 2003. In the morning of surgery, in the OR, in the sitting position, HTEA was performed (max three attempts) at the T1-T2 or T2-T3 interspace employing the median approach and the hanging-drop technique, inserting a 19-gauge flexible-tip polyurethane catheter through a 17-gauge Tuohy needle. Fifteen min after bolus (0.1 mL Kg−1 LA plus opioid) loss of sensation to cold was tested. Definition of failed puncture was either inability to find the epidural space (Fail. space) or to place the catheter (Fail. cath.). Failed block was described either as an incomplete block (less than T1-T7) as assessed by ice test preoperatively, or evidence of insufficient sympathetic blockade (HR >80 beat min−1 and hypertension at sternotomy), or poor analgesia after surgery). Minor complications included dural puncture, bloody tap and vagal symptoms during puncture.
Discussion: Rate of failed puncture (Fail space plus Fail cath.), even subtracting pts returned to the supine position for vagal symptoms, is higher than reported  and could reflect difference in technique and the fact that even the junior anaesthetists performed HTEA. Failed block included not only scarce postoperative analgesia but also insufficient sympathetic blockade, a cornerstone of HTEA not considered by others [1,2]. Blood tap (1%), even if venous, prompted us to a 24-hour delay in surgery, and dural puncture required a change in interspace. In conclusion the rate of failure and minor complications lower the efficacy of HTEA to 91% of the pts submitted to epidural puncture. However, so long as a strict protocol for anticoagulation is followed, and awaiting future studies to demonstrate a better patient outcome, we consider HTEA an effective adjunct for anaesthesia for coronary surgery.
1 Pastor MC, Sánchez MJ, Casas MA, et al. Thoracic epidural analgesia in coronary artery bypass graft surgery: seven years' experience. J Cardiothorac Vasc Anesth.
2 Sanchez R, Nygård E. Epidural anesthesia in cardiac surgery: is there an increased risk? J Cardiothorac Vasc Anesth.