The Chalactalistcs of Inhalational Anesthesia for Cats

Objective: While clinical use of sevoflurane has been increasing in veterinary medicine, this anaesthetic can cause dose-dependent hypotension, hypoventilation, impaired cardiac contractility, and hypothermia. Because of these side effects, sevoflurane must be carefully titrated and vigilantly monitored to avoid excessive anaesthetic depth. One of the anaesthetic depth evaluation using a minimum alveolar concentration (MAC) has been defined as “produces immobility in 50% of animals exposed to noxious stimulus.” Limited information regarding the MAC of sevoflurane required for blunting adrenergic responses (MAC-BAR) in cats currently exists. Therefore, this study was designed to compare the MAC and MAC-BAR of sevoflurane required to prevent autonomic responses and purposeful movements in cats.

Methods: Six adult healthy domestic short haired cats (1year old, 3 males and 3 females) were anaesthetized with sevoflurane on two occasions with a minimum 14-day washout period to determine sevoflurane MAC and MACBAR.

Results: The difference between sevoflurane MAC (2.92 ±0.47%) and MAC-BAR (3.24 ± 0.41%) was not statistically significant.

Conclusions and Clinical Relevance: These results suggested that the detrimental cardiovascular side effects such as hypotension and impaired cardiac contractility can easily occur in sevoflurane-anaesthetized cats.