Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.
Definition of Peak expiratory flow
Medically reviewed by Dr. Otari Nergadze, Neurosurgeon | Updated: January 2026
Peak expiratory flow: Abbreviated PEF. The maximum airflow during a forced expiration beginning with the lungs fully inflated. The PEF is reduced in proportion to the severity of the airway obstruction, as in asthma and COPD (chronic obstructive pulmonary disease).
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