Makindo Medical Notes

💉 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

• Ketamine BNF

📝 Revisions

• Last updated 2025.