These are some important definitions to understand Respiratory function tests .
We will explain Tidal Volume, Residual Volume (RV), Inspiratory reserve volume (IRV), Expiratory reserve volume (ERV), Vital capacity (VC), Forced vital capacity (FVC), Maximum breathing capacity, Forced expiratory volume in 1 second (FEV1) and Total lung capacity (TLC) .
• Tidal Volume :
it is the volume of air in one breath during normal quiet breathing.
• Residual Volume (RV) :
it is the volume of gas present within lung after a maximal expiration = 1200 ml.
• Inspiratory reserve volume (IRV) :
it is the additional volume of air that can be inspired above the tidal volume = 3 L.
• Vital capacity (VC) :
it is the volume of air expired after the maximal inspiration = 4600 ml.
• Forced vital capacity (FVC):
is the same as VC, except that the inhalation is performed as rapidly and forcefully as possible.
• Maximum breathing capacity = volume of air expired after the deepest
inspiration/minute.
• Forced expiratory volume in 1 second (FEV1) :
The volume of air forcefully expired in the first second after a deep breath .
• In the first second --> most of vital capacity is expired, about 80% = FEV1
if decreased = obstructive airway disease.
• Total lung capacity (TLC) :
is the volume of gas in the lungs after a maximal inspiration, it equals the sum of the four lung volumes.
We will explain Tidal Volume, Residual Volume (RV), Inspiratory reserve volume (IRV), Expiratory reserve volume (ERV), Vital capacity (VC), Forced vital capacity (FVC), Maximum breathing capacity, Forced expiratory volume in 1 second (FEV1) and Total lung capacity (TLC) .
• Tidal Volume :
it is the volume of air in one breath during normal quiet breathing.
• Residual Volume (RV) :
it is the volume of gas present within lung after a maximal expiration = 1200 ml.
• Inspiratory reserve volume (IRV) :
it is the additional volume of air that can be inspired above the tidal volume = 3 L.
• Expiratory reserve volume (ERV) :
it is the volume of air that can be forcefully expired after a normal expiration.• Vital capacity (VC) :
it is the volume of air expired after the maximal inspiration = 4600 ml.
• Forced vital capacity (FVC):
is the same as VC, except that the inhalation is performed as rapidly and forcefully as possible.
• Maximum breathing capacity = volume of air expired after the deepest
inspiration/minute.
• Forced expiratory volume in 1 second (FEV1) :
The volume of air forcefully expired in the first second after a deep breath .
• In the first second --> most of vital capacity is expired, about 80% = FEV1
if decreased = obstructive airway disease.
• Total lung capacity (TLC) :
is the volume of gas in the lungs after a maximal inspiration, it equals the sum of the four lung volumes.