Abstract
Objective
To compare mask anesthesia induction and recovery characteristics between 2 inhalant anesthetic agents: isoflurane and sevoflurane.
Animals
16 clinically normal, young adult Beagles.
Procedure
Using a cross-over design, dogs were randomly selected to receive sevoflurane or isoflurane via a face mask and a circle anesthetic system. Vaporizer setting concentrations were increased in step-wise, equal minimum alveolar concentrations (MAC) for each anesthetic until the vaporizer setting of 2.6% for isoflurane or 4.8% for sevoflurane (2 MAC) was reached. Concentration was kept constant until the dog had a negative tail clamp response and was intubated. End-tidal concentration was maintained at 1.8 to 2.0% or 3.3 to 3.8% for isoflurane or sevoflurane, respectively (1.4 to 1.6 MAC) for 30 minutes. Dogs were allowed to recover with only tail clamp stimulation until a positive response was obtained. Extubation was performed when a spontaneous swallow reflex was observed. Dogs were allowed to achieve sternal recumbency and stand unassisted without further stimulation.
Results
Sevoflurane induction resulted in shorter time to loss of palpebral reflex, negative tail clamp response, and time to tracheal intubation, and was of better quality than isoflurane induction. Both anesthetics were associated with rapid and smooth recovery.
Conclusions
Sevoflurane mask induction is faster and of better quality, compared with isoflurane, in adult dogs. Recovery time and quality are comparable.
Clinical Relevance
On the basis of these results, sevoflurane is a suitable inhalant anesthetic for mask induction and recovery in adult dogs and appears to have some advantages over isoflurane, including faster and smoother mask induction. (Am J Vet Res 1998;59:478–481)
