Calc Function

    • Calcs that help predict probability of a diseaseDiagnosis
    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
    • Disease is diagnosed: prognosticate to guide treatmentPrognosis
    • Numerical inputs and outputsFormula
    • Med treatment and moreTreatment
    • Suggested protocolsAlgorithm





    Chief Complaint


    Organ System


    Patent Pending

    Static Lung Compliance (Cstat) Calculation

    Calculates pressure needed to overcome elastic resistance to ventilation.


    Launched during COVID-19 crisis.

    When to Use
    Why Use

    Pplat is measured before exhalation (end of inhalation) by using an inspiratory hold maneuver. Airflow is briefly "held", eliminating the effects of airway resistance.

    Cstat (static compliance) is static (during an inspiratory hold, where no gas flow is taking place), and should not be confused with Cdyn (dynamic compliance), calculated during gas flow.

    • Static lung compliance is change in volume for any applied pressure given.

    • Work of breathing is largely determined by lung compliance, and compliance can be important in monitoring disease progression, particularly in critical patients on mechanical ventilation in the ICU.

    • Low lung compliance suggests "stiffness" - seen in fibrotic conditions, for example.

    • High lung compliance suggests pliability - seen in conditions like emphysema, for example.

    • ARDS in particular causes decreased lung compliance by alveolar collapse and decreased surfactant activity; part of the treatment of severe ARDS involves attempting to improve lung compliance (proning, neuromuscular blockade, etc).

    cm H₂O
    cm H₂O
    Confirmed positive
    Confirmed negative


    Please fill out required fields.

    Next Steps
    Creator Insights
    Dr. Robert Marshall

    About the Creator

    Robert Marshall, MD, was a physician and researcher in the department of physiology and pharmacology at the University of Pennsylvania in Philadelphia. Dr. Marshall’s primary research is focused on the physical properties of lungs and pulmonary mechanics.

    To view Dr. Robert Marshall's publications, visit PubMed

    Are you Dr. Robert Marshall? Send us a message to review your photo and bio, and find out how to submit Creator Insights!
    MDCalc loves calculator creators – researchers who, through intelligent and often complex methods, discover tools that describe scientific facts that can then be applied in practice. These are real scientific discoveries about the nature of the human body, which can be invaluable to physicians taking care of patients.
    Content Contributors
    About the Creator
    Dr. Robert Marshall
    Are you Dr. Robert Marshall?
    Content Contributors