Airway, Ventilation, and Oxygenation
Airway first, but oxygenation is continuous
The transport airway ladder mirrors the hospital - positioning, basic adjuncts, supraglottic device, endotracheal tube, surgical airway - but the margin for failure is thinner because help is distant. Decide your rescue plan before you need it: who is the second airway operator, what device is immediately at hand if intubation fails, and what your trigger is to abandon a failing attempt.
Key concepts: oxygen delivery devices and their limits (nasal cannula 1-6 L/min, simple mask 6-10, nonrebreather 10-15, Venturi for a fixed FiO2); pulse oximetry lag and its failure in poor perfusion, motion, and abnormal hemoglobin (carboxyhemoglobin reads falsely reassuring, methemoglobin distorts); capnography as the standard for confirming and continuously monitoring tube position; and waveform shape as important as the number.
Ventilation: tidal volume 6-8 mL/kg predicted body weight, plateau pressure under 30 cmH2O, adequate PEEP, and recognition of auto-PEEP in asthma and COPD. Avoid hyperventilation in traumatic brain injury, and avoid permissive hypercapnia in the patient who cannot tolerate it.
Trap: an SpO2 of 100% on 15 L/min does not mean ventilation is adequate. A rising EtCO2 with a normal saturation is hypoventilation.
Worked example: the patient deteriorates on the ventilator. Run DOPE - Displacement, Obstruction, Pneumothorax, Equipment failure - in that order while you disconnect and hand-bag. If the waveform vanishes but the chest still rises, suspect the sample line or filter before you remove the tube.