Epidural fentanyl effect on cardiac output and hepatic blood flow

Epidural opioids provide high quality analgesia with no clinically apparent effect on the circulation or on specific organ blood flow. Little investigative data is available to support these impressions of circulatory stability. Ten patients presenting for thoracotomy were studied at rest preoperatively to determine if epidural fentanyl had any effect on the systemic circulation or hepatic blood flow. Intravascular pressure measurements, cardiac output estimation using the dye-dilution technique and estimation of altered hepatic blood flow by measuring the clearance of indocyanine green were performed. No significant changes in heart rate, perfusion pressure, cardiac output or hepatic blood flow were detected following the administration of fentanyl 50 micrograms into the epidural space.