Myocardial blood flow and oxygen consumption during high-dose fentanyl anesthesia in patients with coronary artery disease.

The effects of high-dose fentanyl-oxygen anesthesia (100 micrograms/kg) on myocardial blood flow (argon washin), myocardial oxygen consumption, myocardial lactate balance, and cardiovascular dynamics were studied in nine patients undergoing three-vessel coronary artery bypass operations. All patients had been on maintenance doses of a beta-receptor blocker (pindolol). Except for pindolol all medication had been discontinued 48 hours prior to the study. Measurements were performed in the awake state, after 10 micrograms/kg fentanyl, after 100 micrograms/kg fentanyl, and during sternotomy. Moderate doses of fentanyl (10 micrograms/kg) produced minimal changes in myocardial blood flow, myocardial oxygen consumption, and cardiovascular dynamics; myocardial oxygen balance as well maintained. Large doses of fentanyl (100 micrograms/kg) produced a 16 per cent decrease in mean aortic pressure, cardiac index did not change significantly, while stroke volume index decreased by 23 per cent. Myocardial oxygen consumption decreased by 14 per cent and myocardial blood flow by 10 per cent. Myocardial lactate production was observed in five patients, indicating myocardial ischemia. During sternotomy arterial pressure and heart rate increased 8 per cent and 29 per cent, respectively, resulting in an increase in myocardial work, as reflected by a 38 per cent increase in myocardial oxygen consumption and by a 54 per cent increase in myocardial blood flow. Myocardial lactate production was observed in seven of nine patients. Our data demonstrate that in patients on maintenance doses of beta-receptor blockers, large doses of fentanyl as the sole "anesthetic" produce incomplete anesthesia and fail to protect the myocardium from ischemia due to noxious stimuli during coronary artery surgery.