Comparison of respiratory and cardiovascular effects of halothane, isoflurane, and enflurane delivered via the Jackson-Rees breathing system in rats. New anaesthesia model for small animal surgery.

We studied the respiratory (R) and cardiovascular (CV) effects of 1.25 MAC halothane (H), isoflurane (I) and enflurane (E) in oxygen, delivered by the Jackson-Rees breathing system in 5 normothermic rats. Mean arterial pressure (MAP), heart rate (HR) were depressed after 30 minutes than stabilized after 2 hours anaesthesia regardless of the inhalational agent. Respiratory rate (RR) slowed down markedly unter I and E anaesthesia. Significant R depression was developed (PCO2 53.5 +/- 2.44 Torr) under E. Stabil metabolic condition was maintained. The R and CV changes caused by H and I were far less than changes produced by E. H or I is preferable to E for small animal anaesthesia with spontaneous breathing. Maintenance of constant temperature minimizes the CV and R disturbances.