Prolonged Field Care Podcast Prolonged Field Care Podcast: Ketamine Deep Dive
Aug 29, 2025
A technical deep dive into ketamine covering its mechanisms, dissociation versus analgesia, and differences between S‑ and R‑isomers. They explore pharmacokinetics, how physiology and perfusion change dosing, and risks like catecholamine depletion. Practical field advice includes individualized dosing, lower induction in shock, managing emergence reactions, and preparing rescue plans for complications.
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Rapid Onset And Short Duration Explained
- Ketamine is highly lipophilic with a pKa ~7.5, so it crosses the blood-brain barrier rapidly and works within seconds IV and minutes IM.
- Its effect ends mainly by rapid redistribution away from the brain, not just hepatic metabolism.
Always Individualize Ketamine Dosing
- Treat ketamine like a poison: individualize dose to patient physiology rather than the textbook mg/kg.
- For shocked or catecholamine-depleted patients, reduce standard induction doses dramatically to avoid cardiovascular collapse.
Cut Induction Doses For Shocked Trauma Patients
- When inducing a hypotensive or likely catecholamine-depleted trauma patient, cut the usual induction ketamine dose by up to 75%.
- Small IV boluses (30–50 mg) are safer than large IM shots that you can't reverse quickly.