EFFECTS OF SEVOFLURANE AND ISOFLURANE ON CARDIAC AND CORONARY DYNAMICS IN CHRONICALLY INSTRUMENTED DOGS

To assess the hemodynamic properties of the new inhalational anesthetic sevoflurane, 22 dogs were chronically instrumented for measurement of heart rate, aortic, left ventricular and left atrial pressures, cardiac output, and coronary blood flow. Dogs were randomly assigned to two groups, receiving either 1.2 and 2 MAC of sevoflurane (n = 11) or isoflurane (n = 11). At 1.2 and 2 MAC, sevoflurane produced an increase in heart rate (+60 ± 12% and +54 ± 9%, respectively), dose-dependent aortic hypotension (-22 ± 4% and -38 ± 4%, respectively), systemic vasodilation (-22 ± 5% and -19 ± 5%, respectively), dose-dependent decrease in stroke volume (-31 ± 6% and -48 ± 4%, respectively), and left ventricular dP/dt (-40 ± 4% and -61 ± 10%, respectively). Cardiac output decreased only at 2 MAC (-17 ± 6%). Finally, coronary blood flow increased at 1.2 MAC of sevoflurane (+29 ± 8%). Except for heart rate, sevoflurane and isoflurane produced similar effects. At 1.2 MAC, sevoflurane produced a greater increase in heart rate than isoflurane (+60 ± 12% vs. +33 ± 9%). The authors conclude that, except for heart rate, the effects of sevoflurane on cardiac function and coronary blood flow are almost identical to those induced by isoflurane in the chronically instrumented dog.