A patient underwent pars plana vitrectomy with C3F8 gas tamponade 5 days ago. He now requires urgent general anaesthesia for an unrelated emergency procedure. Which inhalational agent is absolutely contraindicated?
- A Nitrous oxide ✓
- B Propofol-based total intravenous anaesthesia
- C Sevoflurane
- D Desflurane
Correct answer: A. Nitrous oxide
Explanation
Nitrous oxide is highly soluble in intraocular gases and diffuses into the bubble far faster than nitrogen leaves it, expanding the bubble up to threefold. In an eye filled with expansile gas this causes a dangerous rise in intraocular pressure and can lead to central retinal artery occlusion. The effect persists until the gas has been substantially absorbed, so nitrous oxide must be avoided for the entire life of the bubble. Sevoflurane, desflurane and intravenous agents do not diffuse into the bubble.
Reference: Kanski's Clinical Ophthalmology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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