Comparative analysis of systemic and coronary hemodynamics during sevoflurane- and isoflurane-induced hypotension in dogs

We studied the effects of sevoflurane on myocardial contractility and syste mic and coronary hemodynamics, as compared with the effects of isoflurane i n dogs under the same cardiac work conditions. Sixteen mongrel dogs were an esthetized with alpha-chloralose. Heart was paced at 100 beats/min after pr oducing a complete atrioventricular (A-V) block. Controlled hypotension to a mean arterial pressure (MAP) of 60 mm Hg was induced and maintained by in halation of either anesthetic, lasting for 60 min. Measurements were made a t baseline, 15 min (T1), and 60 min (T2) after starting hypotension, and 30 min after discontinuing equihypotension (T3). Although left ventricular sy stolic segment shortening (%SS) decreased similar to 20% in both groups, ca rdiac output (CO) decreased only in sevoflurane during equihypotension (-27 .6% at T2). Sevoflurane decreased the coronary blood flow (CBF; -34.8% at T 2) with no significant change of coronary vascular resistance (CVR), wherea s isoflurane produced a significant decrease in CVR resulting in no change of CBF despite of decreased coronary perfusion pressure (-37.4% at T2). The se systemic and coronary vascular effects were continued even at T3. In con clusion, myocardial depressant effects were comparable between sevoflurane and isoflurane. Both systemic and coronary vasodilatory effects of isoflura ne are greater than those of sevoflurane.