A disadvantage of endotracheal intubation is that it:

• A. Bypasses the upper airway's physiologic functions of warming, filtering and humidifying
• B. Improves airway warming
• C. Filters bacteria better
• D. Increases humidification

Answer: (B)

Endotracheal intubation bypasses the upper airway’s job of conditioning inspired air. The nose and upper airway normally warm, humidify, and filter air before it reaches the lungs. With the tube in place, this natural conditioning is largely lost unless active humidification and warming are provided by the ventilator circuit. The result is cooler, drier air and less filtration reaching the lower airways, which can irritate the mucosa, impair mucociliary clearance, dry secretions, and increase the risk of infection. So the main disadvantage is the loss of those protective upper-airway functions. The idea that it improves warming is not correct, since warming must come from external humidification rather than the tube itself, and filtration is not enhanced by intubation.