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    Estimated/Expected Peak Expiratory Flow (Peak Flow)

    Quantifies asthma exacerbation severity.
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    When to Use
    Pearls/Pitfalls
    Why Use

    Use in patients age 5-80 years with asthma.

    • Useful in patients who do not know their baseline peak expiratory flow rate (peak flow).

    • Comparison of a patient’s current peak flow to a known or expected personal best is only one aspect of the evaluation of a child with an acute asthma exacerbation. Other important factors such as respiratory rate, lung auscultation, mental status, and accessory respiratory muscle use must also be considered.

    • Height and sex have been the factors most strongly correlated with peak flow across multiple studies; however, other differences, including ethnicity and other factors may also play a role in affecting predicted values.

    Asthma exacerbation severity can be quantified by comparing a patient’s current peak expiratory flow rate (PEFR) to their most recent personal best value. In the absence of a known recent personal best, this calculator can be used to estimate an expected “personal best.” The difference between the predicted and actual value can therefore help the clinician determine how severe the current exacerbation is.

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    L/min

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    Next Steps
    Evidence
    Creator Insights

    Advice

    Patients with much lower actual peak flow than estimated typically require further treatment of their asthma.

    Critical Actions

    Assessment of peak flow must not delay administration of critical treatments for acute asthma exacerbations.

    Content Contributors
    Reviewed By
    • Josh Needleman, MD
    About the Creator
    Dr. John L. Hankinson
    Are you Dr. John L. Hankinson?
    Content Contributors
    Reviewed By
    • Josh Needleman, MD