Isoflurane

Isoflurane is a nonflammable liquid and a general inhalation anesthetic drug. It is administered by inhalation delivered from a vaporizer specifically designed for use with isoflurane. Induction of and recovery from isoflurane anesthesia are rapid. It causes reversible loss of consciousness and pain sensations, suppression of voluntary motor activity, modification of autonomic reflexes, and depression of the respiratory and cardiovascular system. The minimum alveolar concentration (MAC) decreases with increasing patient age.

• Induction and maintenance of general anesthesia

Adult Dose (Inhalation):

• Induction: 1.5-3% (produces surgical anesthesia in 7-10 minutes)
• Maintenance: 1-2.5% with nitrous oxide; 1.5-3.5% with oxygen alone

Child Dose: Safety & efficacy not established

Common Side Effects:

• Shivering
• Nausea
• Vomiting
• High grade fever
• Decreased blood pressure
• Irregular heartbeat

Others: Delirium, agitation, breath holding, cough, laryngospasm, nodal arrhythmia

Precautions:

• Isoflurane may cause an increase in intracranial pressure which can affect ability to drive
• Caution in patients with known or suspected susceptibility to malignant hyperthermia
• Hepatic dysfunction has been reported with halogenated inhalational anesthetics
• QTc prolongation may occur
• Additional cardiac monitoring in patients with coronary artery disease
• Caution in hypovolemic, hypotensive or otherwise hemodynamically compromised patients

Contraindications:

• Known hypersensitivity to isoflurane or other halogenated agents
• Known or suspected genetic susceptibility to malignant hyperthermia
• History of confirmed hepatitis due to a halogenated inhalational anesthetic
• Porphyria

Drug Interactions:

• Opioids decrease the MAC of isoflurane
• Nitrous oxide decreases the MAC of isoflurane
• Potentiates the muscle relaxant effect of all muscle relaxants
• May lead to marked hypotension in patients treated with calcium antagonists
• Beta blockers may exaggerate cardiovascular effects of inhalational anesthetics
• MAO inhibitors may increase risk of hemodynamic instability

Food Interactions: It is unsafe to consume alcohol with Isoflurane.

Use in Pregnancy: No adequate and well-controlled studies in pregnant women; animal studies have shown harmful effects; doctor will weigh benefits and risks.

Use in Lactation: Probably safe; limited data suggests drug does not represent significant risk to baby; insufficient information regarding excretion in human milk, potential risks and benefits should be carefully considered.

Overdose: Stop drug administration, establish a clear airway and initiate assisted or controlled ventilation with pure oxygen; monitor cardiovascular function.