Airway Management and Ventilation
What this domain tests
Airway items test prediction, preparation, and rescue: can you oxygenate, can you intubate, and what will you do when both fail?
Core rules
- Predictors: mouth opening <3 cm, Mallampati 3-4, thyromental distance <6 cm, reduced neck mobility, obesity, beard, edentulous state, and prior difficulty. No single test is sensitive; combine findings and prepare.
- Preoxygenation: 3 minutes of tidal breathing or 8 vital-capacity breaths with a tight seal; apneic oxygenation by nasal cannula extends safe apnea.
- Rapid sequence induction: preoxygenate, optimize position, induce, apply cricoid pressure only if aspiration risk, intubate. Succinylcholine 1-1.5 mg/kg or rocuronium 1.2 mg/kg; sugammadex 16 mg/kg reverses rocuronium.
- Confirm with continuous waveform capnography, not auscultation alone.
- Ventilation: lung-protective 6-8 mL/kg predicted body weight, PEEP, plateau <30 cmH2O, driving pressure <15 cmH2O.
- ASA algorithm: oxygenate; awake fiberoptic or video laryngoscopy; supraglottic rescue; final option is emergency front-of-neck access.
Worked example
A 55-year-old with a 3-cm mouth opening, Mallampati 4, and radiation fibrosis fails video laryngoscopy after two attempts with SpO2 88%. The correct move is not a third look; it is to insert a second-generation supraglottic airway, oxygenate, and either wake the patient or proceed through the device. If oxygenation falls below 80% with no capnography, declare cannot-intubate-cannot-oxygenate and perform scalpel-bougie-tube cricothyrotomy. The reasoning is that repeated attempts consume oxygen reserves and cause edema; rescue is prioritized over intubation success.
Traps
Assuming a grade 1 view excludes difficulty; relying on a single predictor; forgetting apneic oxygenation; giving succinylcholine to a hyperkalemic or burn patient; confirming tube position by chest rise alone; using large tidal volumes in a 50 kg patient because the ICU does so.
Key points
- Combine airway predictors; no single test is reliable.
- Preoxygenation and apneic oxygenation extend safe apnea time.
- RSI uses succinylcholine 1-1.5 mg/kg or rocuronium 1.2 mg/kg.
- Confirm intubation with continuous waveform capnography.
- CICO is treated with emergency front-of-neck access, not more attempts.