Ketamine
💉 Ketamine is an excellent and safe sedative–analgesic with a short duration of action, widely used in the ED for procedural sedation and pain management.
It provides sedation, amnesia, and analgesia while maintaining airway reflexes and cardiovascular stability.
📖 About
- Always check the BNF link here for detailed prescribing information.
- Commonly used as an induction agent for anaesthesia and sedation.
- Particularly useful in asthma, shock, burns, and trauma where cardiovascular support is needed.
- Also a drug of abuse in recreational settings.
🔬 Basics
- Derivative of phencyclidine.
- High lipid solubility → rapid CNS penetration.
- Acts via non-competitive antagonism at the NMDA receptor Ca²⁺ channel pore.
⚙️ Mode of Action
- Onset: 15–30 seconds IV; Duration: 15–30 minutes.
- Provides analgesia, sedation, amnesia.
- Sympathomimetic effect: increases heart rate, BP, and cardiac output.
- Maintains airway reflexes and causes bronchodilation (unique among induction agents).
💊 Indications/Dose
- Induction agent: especially useful in bronchospasm, haemodynamic instability, and burns.
- IV (adults): 1–4.5 mg/kg (over ≥60 sec).
Usual dose 2 mg/kg → 5–10 min anaesthesia.
- IM (adults): 6.5–13 mg/kg.
10 mg/kg → 12–25 min surgical anaesthesia.
- Sedation: Often 1 mg/kg IV with top-ups as required.
⚠️ Cautions
- Use with caution in shock, dehydration, elderly patients, head injury, seizures.
- May increase ICP, IOP, and BP → avoid in stroke or uncontrolled hypertension.
- Use caution in severe anaemia or haemorrhage due to myocardial workload.
⛔ Contraindications
- Unstable airway or risk of laryngospasm.
- History of psychosis or psychiatric illness.
- Acute porphyria, (pre-)eclampsia.
- Significant cardiovascular disease (IHD, arrhythmias, uncontrolled hypertension).
💥 Side Effects
- Emergence phenomena: hallucinations, nightmares, agitation.
- Cardiovascular: ↑ HR and BP.
- Respiratory: Laryngospasm, hypersalivation (pre-treat with anticholinergic if needed).
- Other: Nausea, vomiting, diplopia.
📚 References
📝 Revisions
