Session 7- Lung function Tests: Spirometry, DLCO and peak flow Flashcards
what do peak flows measure
high velocity of airflow that can transiently be achieved durind a maximal expiration from total lung capactiy
what does spirometry asses
the integrated mechanical function of the lung chest wall and resp muscles and airways
FEV1
Forced expiratory volume in one second
FVC
forced vital capacity
maximal volume of air that can be expelled from a patient’s lung after maximal inspiration
IRV
erv
Inspiratory reserve volume
expiratory reserve volume
how do we calculate total lung capacity
inspiratory capacity
functional residual capacity
how do we calculate vital capacity
inspiratory reserve volume
expiratory reserve volume
tidal volume
how do we measure inspiratory capacity
inspiratory reserve volume
tidal volume
what causes an obstructive deficit on spirometrey
when the small airways are compressed this increases flow resistance to the point where no more air can b driven out of the alveoli
what is the FEV/FVC ratio in normal indiviuals
measure FVC and FEV in one second
in normal people FEV1/FVC is greater than 70%- they can blow out greater than 70% of the total amount of air they are capable of exhaling by the first second of the test
what is the FEV1/FVC ratio in an obstruction defect
FVC is nearly normal in early disease though may decrease as disease progresses if there is air trapping
FEV1 is reduced markedly and disproportionately
ratio is <0.7
what diseases show an obstrcutive deficit
COPD
Asthma
Bronchiectasis
what is the FEV1/FVC ratio in a restrictive defect
TLC is reduced
FVC is reduced
FEV1 is reduced proportionately
FEV1/FEV ratio is normal or even higher than normal >0.7
how do we measure residual volume
helium dilution test
how do we measure dead space
nitrogen washout method
