Learn Anesthesia

Inhalational Agents – Hypnosis

  • Desflurane:
    • Mechanism: GABA receptor agonist, leading to neuronal depression and hypnosis. Least potent out of the three inhalational anesthetics.
    • Uses: Maintenance of anesthesia in surgeries requiring rapid wake-up.
    • Best for: Short procedures, obese patients (low blood-gas solubility allows fast recovery).
    • Special considerations: Highly pungent, airway irritant (can cause coughing, breath-holding, laryngospasm), requires special heated vaporizer.
    • Population/Clinical Use: Ideal for patients needing fast emergence (e.g., outpatient surgeries). Avoid in patients with reactive airway disease (asthma, COPD).
  • Isoflurane:
    • Mechanism: Potentiates GABA and inhibits NMDA receptors, leading to hypnosis. Lowest MAC —> therefore most potent.
    • Uses: Maintenance of general anesthesia.
    • Best for: Hemodynamically stable patients requiring deep anesthesia.
    • Special considerations: Causes dose-dependent hypotension, pungent odor (not ideal for mask induction), potent vasodilator.
    • Population/Clinical Use: Used in longer surgeries requiring stable anesthesia depth. Avoid in patients prone to hypotension or those requiring rapid emergence.
  • Sevoflurane:
    • Mechanism: Enhances GABA receptor activity, causing neuronal inhibition. Less potent than isofluorane but more potent than desflurane. This is the most commonly used inhaled anesthetic.
    • Uses: Induction and maintenance of general anesthesia.
    • Best for: Pediatric anesthesia (non-irritating), inhalational induction, routine surgeries.
    • Special considerations: Minimal airway irritation, can cause nephrotoxicity in rare cases due to compound A formation in low-flow anesthesia.
    • Population/Clinical Use: Preferred for pediatric and adult anesthesia, especially for mask induction in children. Avoid in patients with severe renal impairment.

📚 References

1️⃣ Miller RD. Miller’s Anesthesia. 9th ed. Philadelphia, PA: Elsevier; 2020.

2️⃣ Morgan GE, Mikhail MS, Murray MJ. Morgan & Mikhail’s Clinical Anesthesiology. 6th ed. New York, NY: McGraw Hill; 2018.

3️⃣ Steiner J. Anesthesia Made Easy: The Survival Guide to Make Your First Anesthesia Rotation a Success. 2nd ed. Independently Published; 2019.