What is the difference between static and dynamic compliance?

Static compliance (Cstat = Vt / (Pplat − PEEP)) is measured during an end-inspiratory pause, eliminating airway resistance effects, and reflects true lung and chest wall elasticity. Dynamic compliance (Cdyn = Vt / (PIP − PEEP)) is calculated using peak inspiratory pressure and includes airway resistance. Cstat decreases in parenchymal disease (ARDS, pulmonary edema); Cdyn is additionally reduced by bronchospasm or secretion accumulation.

What compliance values suggest ARDS or lung injury?

Normal respiratory system compliance is approximately 60–100 mL/cmH2O in spontaneously breathing adults. Cstat <40 mL/cmH2O suggests significant lung injury or restriction. In severe ARDS, compliance may fall below 20 mL/cmH2O (sometimes called 'baby lung' physiology), reflecting the small fraction of aerated lung available for ventilation and underscoring the importance of low tidal volume strategy.

Respiratory Compliance (Cstat/Cdyn)

Calculate static and dynamic respiratory system compliance to assess lung mechanics, guide tidal volume selection, and monitor response to prone positioning or PEEP optimization.

Use the full interactive calculator below, or

Related Calculators

Driving Pressure

Medical

PEEP Optimization

Medical

Respiratory Compliance

Medical

Respiratory Compliance (Cstat/Cdyn)

Related Calculators

Frequently Asked Questions

What is the difference between static and dynamic compliance?

What compliance values suggest ARDS or lung injury?