Expansion
Propofol for induction, volatile agents for maintenance
Expansion
Intravenous induction
- Propofol: rapid, smooth, antiemetic; causes hypotension and apnoea, and pain on injection. Propofol infusion syndrome with prolonged high-dose use
- Ketamine: NMDA antagonist. Maintains blood pressure and airway reflexes, provides analgesia and bronchodilatation; causes emergence delirium and raises secretions
- Thiopental: rapid, used in rapid sequence induction and status epilepticus
- Etomidate: haemodynamically stable but causes adrenal suppression
Inhalational maintenance
- Sevoflurane: sweet smelling, so it is used for gaseous induction, especially in children
- Isoflurane, desflurane
- Nitrous oxide: analgesic, but diffuses into air-filled spaces (contraindicated in pneumothorax and bowel obstruction) and inactivates vitamin B12
- MAC (minimum alveolar concentration) measures potency; it falls with age, opioids and hypothermia
Muscle relaxants
- Suxamethonium: depolarising, rapid onset and offset. Causes hyperkalaemia (avoid in burns, denervation, prolonged immobility), malignant hyperthermia, and prolonged block in cholinesterase deficiency
- Rocuronium, atracurium: non-depolarising, reversed by neostigmine or sugammadex