ABSTRACT
Measurement of the peak expiratory flow (PEF) is one of the most convenient, economical, and commonly performed tests in the management of asthma. The test requires the simplest of measurement equipment and is straightforward to teach and perform. The PEF is an easy test for most individuals to master but is dependent upon maximal effort, and so requires cooperation, coordination, and comprehension to produce repeatable and reliable results. The value recorded is usually the best of three efforts, each of which should be made with acceptable technique. PEF is the highest velocity of airflow that can be transiently achieved during a maximal expiration from total lung capacity. Because flow is a function of resistance, the peak flow is an excellent indicator of large airway function. Normal values for PEF are commonly read from a nomogram. Confirmation of a diagnosis of asthma hinges upon demonstration of airflow obstruction, varying over short periods of time.
