Peak vs Plateau Pressure: What the Difference Tells You

On a mechanically ventilated patient, two airway pressures matter most: the peak inspiratory pressure and the plateau pressure. Learning to read the gap between them is one of the fastest ways to troubleshoot a rising-pressure alarm and to protect the lung. This guide explains what each pressure means and how their difference points you to the problem.

Peak Inspiratory Pressure

The peak pressure is the highest pressure measured during inspiration. It reflects two things together: the resistance to airflow through the circuit and airways, plus the compliance (stiffness) of the lungs and chest wall. Because it includes resistance, the peak pressure is sensitive to anything that narrows or obstructs the airway.

Plateau Pressure

The plateau pressure is measured during a brief inspiratory hold, when airflow stops. With no flow, resistance drops out of the equation, so the plateau reflects the pressure distending the alveoli, that is, the compliance of the lung and chest wall alone. Keeping plateau pressure under about 30 cm H2O is a core target of lung-protective ventilation.

Reading the Gap

• High peak with a normal plateau means a resistance problem. Think bronchospasm, secretions, a kinked or bitten endotracheal tube, or a mucus plug.
• High peak AND high plateau means a compliance problem. Think worsening ARDS, pulmonary edema, pneumothorax, atelectasis, or abdominal distension pressing on the lungs.

This single distinction turns a vague high-pressure alarm into a focused differential at the bedside.

The Bottom Line

Peak pressure reflects resistance plus compliance; plateau pressure, measured with an inspiratory hold, reflects compliance alone. When the peak climbs, compare it with the plateau: a widening gap points to the airway, while both rising together points to the lung or chest wall. For deeper, evidence-based ventilation guidance, explore more from the Interprofessional Critical Care Network.