isoflurane: clinical use

Prescribing considerations

• Administer only in a fully equipped anaesthetising environment using an isoflurane-calibrated vaporiser.
• Use caution with QT-prolongation risk, mitochondrial disorders, increased intracranial pressure, hypovolaemia, hypotension, bronchoconstriction or neuromuscular disease.
• Review previous exposure to halogenated anaesthetics and pre-existing liver disease because rare severe hepatic injury has occurred.
• Not recommended for inhalational induction in children because coughing, breath-holding, desaturation, secretions and laryngospasm may occur.
• Prevent carbon-monoxide formation by ensuring carbon-dioxide absorbents do not become desiccated.

Contraindications and cautions

• Hypersensitivity to isoflurane or another halogenated anaesthetic
• Known or suspected genetic susceptibility to malignant hyperthermia

Monitoring

• Anaesthetic depth and inspired or expired anaesthetic concentration
• Blood pressure, heart rate, rhythm, oxygenation and ventilation
• Temperature and early clinical or metabolic signs of malignant hyperthermia
• Neuromuscular blockade when muscle relaxants are used
• Potassium, creatine kinase and myoglobinuria when perioperative hyperkalaemia or occult neuromuscular disease is suspected

Clinical pharmacology

A volatile halogenated general anaesthetic acting at multiple inhibitory and excitatory ion channels. Anaesthetic depth changes rapidly when delivery is adjusted, and relatively little absorbed isoflurane is metabolised.

Formulation and product differences

• The selected product is an inhalation vapour liquid containing isoflurane without excipients.
• It is supplied in amber glass bottles and requires a specifically calibrated vaporiser.
• Efficient extraction of waste anaesthetic vapour is recommended.