The<unk>  <unk> , also called<unk>  rate <unk> R), is a person's maximum speed of expiration, as measured with a peak<unk>  meter, a small, hand-held device used to monitor a person's ability to breathe out air. It measures the airflow through the bronchi and thus the degree of obstruction in the airways.<unk>  is typically measured in units of liters per minute (L/min).
Peak expiratory flow
Peak inspiratory pressure
Tidal volume
Lung compliance
Ventilatory threshold
FEV1/FVC ratio
Functional residual capacity
Lung volumes