| Abstrakt: |
Twenty patients about to have coronary artery bypass grafts were studied before and after 15 min of 50% nitrous oxide added to either fentanyl (75 micrograms/kg) or enflurane (0.5%) anesthesia. Arterial and central pressures and cardiac output were measured, plus coronary sinus blood flow and arterio-coronary sinus differences in oxygen, hemoglobin, and lactate contents. Fentanyl-N2O and enflurane-N2O both decreased systemic resistance, heart rate, cardiac output, and hence arterial pressure. Stroke work decreased significantly with little or no change in wedge pressure: ventricular function was impaired. Coronary flow and myocardial O2 consumption decreased with fentanyl-N2O. Oxygen extraction increased with enflurane-N2O, as did lactate contents of coronary sinus blood. Hemodynamic depression occurred from the combined effects of nitrous oxide and fentanyl or enflurane. The beta-blocked myocardia of nonstimulated coronary patients were becoming ischemic globally on 50% oxygen, after significant hypotension. From this and other evidence, we conclude that nitrous oxide may not be benign in patients with coronary arterial disease. |
