URI and N₂O Contraindication — NDEB AFK MCQ
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Correct answer: A — Current upper respiratory tract infection with nasal congestion
A current upper respiratory tract infection (URI) with nasal congestion is a relative contraindication for nitrous oxide sedation because: (1) nasal congestion prevents adequate nasal breathing, reducing N₂O delivery and effectiveness; (2) N₂O cannot be reliably titrated through a congested nasal passage; (3) Eustachian tube dysfunction from the URI increases the risk of middle ear barotrauma from N₂O diffusion into the middle ear. The appointment should be rescheduled until the URI resolves.
Reference: Malamed – Sedation: A Guide to Patient Management, 6th ed., 2018