Isoflurane

Isoflurane: Uses, Dosage and Side Effects

Overview

• Volatile anaesthetic agents.

Uses of Isoflurane

• Induction and maintenance of anaesthesia

Dose of Isoflurane in Dogs and Cats

Dogs:

• The expired concentration required to maintain surgical anaesthesia in 50% of dogs is 1.2% (minimum alveolar concentration).
• Administration of other anaesthetic agents and opioid analgesics reduces the dose requirement of isoflurane, therefore, the dose should be adjusted according to individual
  requirement.
• 3–5% isoflurane concentration is required to induce anaesthesia in unpremedicated patients.

Cats:

• The expired concentration required to maintain surgical anaesthesia in 50% of cats is 1.6% (minimum alveolar concentration).

Side Effects of Isoflurane in Dogs and Cats

• Isoflurane induces dose-dependent hypotension via vasodilation, especially in skeletal muscle.
• This negative effect does not diminish over time.
• Isoflurane is a more potent respiratory depressant than halothane, and dose-dependent respiratory depression is observed.
• Isoflurane does not sensitise the myocardium to catecholamines to the same extent as halothane, but it can produce arrhythmias under certain circumstances.
• Isoflurane is not metabolised by the liver (0.2%), and it has a smaller impact on hepatic blood flow than halothane.

Contraindications of Isoflurane in Dogs and Cats

• No information is available.

Some Notes:

• Sedatives, opioid agonists and N2O reduce the concentration of isoflurane required to achieve surgical anaesthesia.
• The duration of action of non-depolarizing neuromuscular blocking agents is longer with isoflurane compared with halothane anaesthetized animals.