Effects of thoracic epidural analgesia on coronary hemodynamics and myocardial metabolism in coronary artery bypass surgery

Abstract

Objective: A possible influence of thoracic epidural analgesia on coronary hemodynamics and myocardial metabolism in coronary artery bypass grafting was investigated.

Design: The study was prospective and randomized.

Setting: The study was performed in a university hospital.

Participants: Thirty male patients less than 65 years of age and with ejection fraction greater than 0.5 participated. They were randomized into 3 groups: the high fentanyl (HF) group receiving high-dose fentanyl (55 micrograms/kg) anesthesia, the HF + thoracic epidural analgesia (TEA) group receiving the same general anesthesia plus thoracic epidural analgesia, and the low-fentanyl (LF) + TEA group receiving low-dose fentanyl (15 micrograms/kg) anesthesia plus thoracic epidural analgesia.

Interventions: A thoracic epidural catheter, a peripheral and central venous catheter, a radial artery catheter, a thermodilution pulmonary artery catheter, and a coronary sinus reverse thermodilution catheter were inserted.

Measurements and main results: Coronary circulatory parameters, myocardial oxygenation, and myocardial substrate utilization were investigated before bypass and for 9 hours after bypass. Before bypass, the most striking finding was a reduction in myocardial lactate extraction in all groups, but also coronary flow and myocardial oxygen consumption decreased compared with baseline. After bypass, the only significant finding was a lower coronary vascular resistance early postoperatively in the epidural groups, but coronary blood flow was adequate in all groups. Myocardial metabolism was essentially unchanged both with and without epidural analgesia after bypass.

Conclusion: With regard to the coronary circulation and myocardial metabolism, no hard data supporting the use of thoracic epidural analgesia in coronary artery bypass grafting were found.