Difference between Halothane and Barbiturate Anesthesia in the Influence of Cerebral Ischemia on the Vagal Baroreflex in Dogs.

Abstract

ABSTRACT-In halothane-anesthetized dogs, a decrease in baroreflex sensitivity (BRS) of approximately 20% was observed during the reperfusion period following 5 min global cerebral ischemia. When compared with our previous study on animals under pentobarbital anesthesia, the extent of the decrease in BRS was smaller and apparently more severe ischemia was necessary to damage the vagal component of the baroreflex. Substitution of halothane with pentobarbital during the reperfusion period failed to affect either BRS or the ratio of the vagal component. In another group, pre and post-ischemic measurements of BRS was performed under halothane anes thesia, but the ischemic insult was given under thiopental anesthesia. In these animals, the extent of decrease in BRS (about 50%) was greater than that in animals subjected to ischemia under halothane anesthesia. The present results suggest that the anesthe tics used during the ischemic insult may affect the extent of post-ischemic dysfunction of the baroreflex. The vagal component of the baroreflex may be more resistant to ischemia under halothane anesthesia than under barbiturate anesthesia.

Protection by Halothane of the Vagal Baroreflex System from Transient Global Cerebral Ischemia in Dogs.

“…Figure 2 shows the correlation between the severity of ischemia and the extent of damage of the vagal com ponent of BRS. The correlation in the animals that were treated with halothane (open circles) was similar to that in the animals subjected to ischemia under halothane anesthesia in the previous study (4), where the correlation curve (dotted line H in Fig. 2) indicated that the vagal component of BRS survived an ischemic insult, if the mean residual blood flow during ischemia was greater than approximately 30%.…”

“…Admin istration of halothane or thiopental increased the depth of anesthesia, producing an intermittent burst suppression of the cortical EEG in 5 out of 8 or 4 out of 6 animals, respectively, and reducing a (8 to 12.5 Hz) and ,8 (13 to 32 Hz) components of the EEG in the rest of the animals. Since our previous study (4) indi cated that a period of 60 to 120 min was necessary for the recovery from anesthesia with thiopental (10 mg/kg, i.v. ), BRS was measured during the period la ter than 120 min of reperfusion in animals pretreated with thiopental to avoid any direct effect of the addi tional anesthesia on BRS measurement.…”