Airway Management: Devices, Confirmation, and Sizing Rules
From maneuvers to artificial airways
Basic management begins with positioning and manual maneuvers: head tilt–chin lift (trauma: jaw thrust) and suction. An oropharyngeal airway is sized from the corner of the mouth to the earlobe and is only for patients without a gag reflex; a nasopharyngeal airway suits the semiconscious patient but is avoided with basilar skull fracture or coagulopathy. Supraglottic devices (LMA, King) sit above the cords; the endotracheal tube remains the definitive airway, and tracheostomy is used for prolonged ventilation.
Confirmation and care
Confirm tube placement with continuous waveform capnography - the gold standard - plus bilateral breath sounds, chest rise, and a chest radiograph showing the tip 2–4 cm above the carina. In adults, depth at the lip is roughly 3 × tube internal diameter (7.0 mm → 21 cm). Secure the tube, document the depth, and keep cuff pressure at 20–30 cm H2O with a manometer.
Traps
Esophageal intubation shows no sustained capnographic waveform; epigastric gurgling with absent breath sounds supports the suspicion. An OPA in a patient with a gag reflex provokes vomiting and aspiration. Suction catheters should not exceed half the tube's internal diameter - French size ≈ 2 × ETT size (7.5 mm → 15 Fr).
Worked example
A 7.5 mm ETT is secured at 22–23 cm at the lip and the cuff inflated to 25 cm H2O. If the tube migrates out to 25 cm, the tip may approach the carina or slip into the right mainstem bronchus - reassess and reposition immediately.