Chapter 14: Observations
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Peak flow
Definition
Peak expiratory flow (PEF) is the highest flow achieved on forced expiration from a position of maximum lung inflation expressed in litres per minute (L/min) (Hill and Winter [82]). PEF is a simple test of lung function, commonly used to help detect and monitor moderate and severe respiratory disease. It is particularly useful in the diagnosis and monitoring of patients with asthma to assess the degree of airway obstruction, the severity of an asthma attack and response to treatment (Dakin et al. [50], NICE [137]).
