Ventilator Compliance Guide
Why Lung Compliance Matters
Lung compliance describes how easily the respiratory system accepts delivered volume. A lower value means the ventilator needs more pressure to move the same tidal volume. A higher value means the lungs and chest wall expand more easily. The number helps teams follow mechanics during ventilation, but it never replaces clinical judgment.
Static and Dynamic Views
Static compliance uses plateau pressure. It reflects the lung and chest wall when airflow is paused. Dynamic compliance uses peak pressure. It includes airflow resistance, tube resistance, secretions, and bronchospasm. Comparing both values can show whether pressure is rising from stiffness or resistance. The driving pressure also matters. It is plateau pressure minus PEEP.
Practical Use
This calculator accepts tidal volume, plateau pressure, peak pressure, PEEP, rate, predicted body weight, inspiratory time, and a previous compliance value. It returns static compliance, dynamic compliance, elastance, resistive pressure, minute ventilation, normalized compliance, and a simple mechanical power estimate. These values are estimates. They depend on accurate ventilator readings and stable measurement conditions.
Measurement Tips
Measure plateau pressure during an inspiratory hold. Use the same units each time. Tidal volume should be the exhaled or delivered volume used by your local protocol. PEEP should match the measured total value when auto PEEP is present. Peak pressure can change with flow, tubing, secretions, and patient effort. Note coughs, leaks, and spontaneous breaths because they can distort pressures.
Result Review
A falling static compliance trend can suggest worsening stiffness. A large gap between peak and plateau pressure can suggest extra airway resistance. A high driving pressure should prompt careful review. The calculator includes warning notes for common patterns, but it is educational only. Always verify results with a qualified clinician, the ventilator display, and local care standards.
Limits and Safety
Compliance does not diagnose a disease by itself. It can be affected by posture, sedation, abdominal pressure, circuit setup, and patient effort. Look at oxygenation, imaging, blood gases, alarms, and the full bedside picture. Repeat measurements under similar conditions. Record the time and mode. Exported files can support audit trails, shift handover, and teaching reviews. Do not use this page to choose settings without professional supervision. Document assumptions, leaks, and measurement timing for safer comparison.