EFFECTS OF THORACIC EPIDURAL ANALGESIA ON CORONARY HEMODYNAMICS AND MYOCARDIAL-METABOLISM IN CORONARY-ARTERY BYPASS-SURGERY

Objectives: A possible influence of thoracic epidural analgesia on cor onary hemodynamics and myocardial metabolism in coronary artery bypass grafting was investigated. Design: The study was prospective and rand omized. Setting: The study was performed in a university hospital. Par ticipants: Thirty male patients less than 65 years of age and with eje ction fraction greater than 0.5 participated. They were randomized int o 3 groups: the high-fentanyl (HF) group receiving high-dose fentanyl (55 mu g/kg) anesthesia, the HF + thoracic epidural analgesia (TEA) gr oup receiving the same general anesthesia plus thoracic epidural analg esia, and the low-fentanyl (LF) + TEA group receiving low-dose fentany l (15 mu g/kg) anesthesia plus thoracic epidural analgesia. Interventi ons: A thoracic epidural catheter, a peripheral and central venous cat heter, a radial artery catheter, a thermodilution pulmonary artery cat heter, and a coronary sinus reverse thermodilution catheter were inser ted. Measurements and Main Results: Coronary circulatory parameters, m yocardial oxygenation, and myocardial substrate utilization were inves tigated before bypass and for 9 hours after bypass. Before bypass, the most striking finding was a reduction in myocardial lactate extractio n in all groups, but also coronary flow and myocardial oxygen consumpt ion decreased compared with baseline. After bypass, the only significa nt finding was a lower coronary vascular resistance early postoperativ ely in the epidural groups, but coronary blood flow was adequate in al l groups. Myocardial metabolism was essentially unchanged both with an d without epidural analgesia after bypass. Conclusion: With regard to the coronary circulation and myocardial metabolism, no hard data suppo rting the use of thoracic epidural analgesia in coronary artery bypass grafting were found. (C) 1995 by W.B. Saunders Company