Insertion of an NG tube

Contraindications
Maxillofacial trauma
- to avoid passage of tube into cranial vault through disrupted cribriform plate.

Esophageal abnormalities 
- Esp in patients with recent hx of ingestion of caustic substances or in those with esophageal strictures or diverticula

Altered mental status and impaired defenses
- NG intubation may precipitate vomiting so should be avoided in these patients.
- Endotracheal intubation is prefered.

Thomsen TW., Shaffer RW., Setnik GS. (2006). Nasogastric Intubation. NEJM. 354:17

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