Forced Vital Capacity is the volume of air that can forcibly be exhaled after full inspiration and is measured in litres.
FEV1 vs FVC (FEV1/FVC ratio)
This measurement determines the ratio of air the patient is able to expel in 1 second compared to their total lung capacity.
Peak Expiratory Flow [PEF]
The peak expiratory flow, also called peak expiratory flow rate, is a person’s maximum speed of expiration and is measured in litres per minute.
Forced Expiratory Volume in 1 Sec. [FEV1]
Forced Expiratory Volume measures how much air (measured in litres) a person can exhale in one second during a forced breath.
Forced Expiratory Flow 25-75% or 25-50%
Forced Expiratory Flow is the measurement of the speed of air coming out of the patients lungs in the middle portion of a forced expiration.
Tidal volume is the volume of air that is transported in and out of the lungs during a normal breath (when the breathing is not forced).