INDUCTION
In adults, intravenous induction is preferable.
Inhalational induction is reserved for patients with difficult airways or severe needle phobia.
Use only halothane or sevoflurane (isoflurane is too irritant). Halothane can cause hepatitis after repeated exposure within 3 months. Halothane sensitises the heart to catecholamines and may cause cardiac dysrhythmias, particularly if anaesthesia is too light or the patient hypercarbic.
Sevoflurane is not associated with these problems, has a faster onset and emergence time.
- Halothane, titrated to effect.
OR
- Sevoflurane, titrated to effect.
MAINTENANCE
In spontaneously breathing patients, the dose of a volatile agent is titrated to clinical effect. If a neuromuscular blocking agent has been used, the dose of the volatile agents must be adequate to prevent awareness. This is about 1 minimum alveolar concentration (MAC), but must be titrated according to clinical signs of awareness (e.g. tachycardia, hypertension, sweating, lacrimation).
- Isoflurane (MAC = 1.2%).