In a ventilated patient, peak airway pressure is 38 cmH2O and plateau pressure is 22 cmH2O. The resistance-derived pressure (Raw) is therefore 16 cmH2O. This elevated peak minus plateau pressure difference most likely indicates:
- A Decreased lung compliance (stiff lungs)
- B PEEP set too high
- C Pneumothorax
- D Increased airway resistance (bronchospasm, secretions, kinked ETT) ✓
Explanation
Peak airway pressure = plateau pressure + resistance-derived pressure (flow × resistance). Elevated peak minus plateau difference (>5–10 cmH2O) indicates elevated airway resistance. Causes include bronchospasm, endotracheal tube secretions/kinking, biting on tube, or circuit obstruction. Plateau pressure reflects lung compliance (static compliance = tidal volume / [plateau pressure – PEEP]). An elevated plateau pressure (>28–30 cmH2O) with normal peak minus plateau difference indicates reduced lung compliance (pneumothorax, pulmonary oedema, ARDS, bronchial intubation). This distinction guides clinical management.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.