Comparison of the Effects of Isoflurane and Desflurane on Cardiovascular Dynamics and Regional Blood Flow in the Chronically Instrumented Dog

Abstract

Seven mongrel dogs were chronically instrumented for the measurement of aortic and left ventricular blood pressures, cardiac output, left ventricular wall thickening, left ventricular dP/dt, and circumflex coronary, renal, hepatic and portal blood flows under the influence of desflurane (D) and isoflurane (I). Administration of the two anesthetics, was randomized, as was the order of the concentrations administered. Each dog was studied awake and at 1.2,1.4,1.75, and 2.0 MAC of each anesthetic on different days. Both anesthetics decreased mean arterial pressure, stroke volume, systemic vascular resistance, left ventricular dP/dt, and wall thickness. The decreases were dose-dependent for mean arterial pressure (percent of awake values: D 78,I 85 at 1.2 MAC, and D 67, I 69 at 2.0 MAC); stroke volume (D 66,I 72 at 1.2 MAC, and D 52,I 57 at 2.0 MAC); dP/dt (D 61,I 64 at 1.2 MAC, and D 46,I 49 at 2.0 MAC); and WT (D 68, I 70 at 1.2 MAC, and D 47, I 60 at 2.0 MAC). Systemic vascular resistance decreased approximately the same at 1.2 MAC (D 71, I 87%) as at 2.0 MAC (D 71,I 79%). Heart rate increased but also not in a dose-dependent fashion (percent of awake values: D 177,I 145 at 1.2 MAC, and D 176,I 155 at 2.0 MAC). Coronary blood flow was increased by both anesthetics at all concentrations (percent of awake values: I 136 at 1.2 MAC and 161 at 2.0 MAC of awake, and D 131 at 1.2 MAC and 138 at 2.0 MAC). Both anesthetics decreased coronary vascular resistance in a dose-dependent fashion. Hepatic arterial blood flows were maintained by desflurane and slightly increased by isoflurane. Hepatic vascular resistance was decreased only by isoflurane. Portal blood flow was slightly decreased at some anesthetic concentrations by both drugs. The combined total hepatic blood flow (portal plus hepatic arterial) as a result was significantly decreased by desflurane at the two high anesthetic concentrations but not significantly changed by isoflurane. Renal blood flow also was not significantly affected by either anesthetic, and consequently, renal vascular resistance was decreased by both anesthetics. There were no significant differences at any anesthetic concentrations between desflurane and isoflurane with regard to systemic or regional hemodynamics. Thus, the effects of desflurane and isoflurane on systemic, coronary, hepatic and renal hemodynamics were the same.