The maximum volume of air that can be expelled from the lungs during a vigorous exhalation. Its measurement is used to determine the degree of respiratory impairment in patients with obstructive lung diseases.
A metric that assesses the highest velocity at which a patient exhales (breathes out), commonly referred to as the peak expiratory flow rate (PEFR) or peak flow. This measurement is obtained using a compact handheld device known as a peak flow meter.