Spirometry Flashcards
Define FEV1
forced expiratory volume in 1 second
amount of air a person can exhale as fast as they can in 1 second
Define FVC
forced vital capacity
total amount of air a person can exhale after a full inhalation
Obstructive disease spirometry results
reduced FEV1
relatively normal FVC
FEV1/FVC ratio < 75%
Causes of obstructive disease spirometry findings
asthma
COPD
Restrictive disease spirometry results
reduced FEV1
reduced FVC
(often reduced to similar degree)
FEV1/FVC ratio normal (>75%)
Causes of restrictive disease spirometry findings
restriction of ability of lungs to expand and take air in:
- ILD
- neurological (eg. MND)
- scoliosis/chest deformity)
- obesity
Define tidal volume
the volume of air breathed in and out without conscious effort (normal breath)
Define inspiratory reserve volume
the additional volume of air that can be inhaled with maximum effort after a normal inspiration
Define functional residual capacity
volume of air remaining in lungs at the end of normal expiration
acts as a buffer against extreme changes in alveolar gas levels with each breath
RV + ERV (residual volume + expiratory reserve volume)
Define residual volume
the volume of air remaining in the lungs after maximum exhalation (the lungs can never be completely emptied)
Define inspiratory capacity
tidal volume + inspiratory reserve volume
Define expiratory reserve volume
volume of air breathed out by forced expiration over and above normal tidal volume
Define vital capacity
the total volume of air that can be exhaled after a maximum inhalation
IRV + TV + ERV
(inspiratory reserve volume + tidal volume + expiratory reserve volume)
Define total lung capacity
vital capacity + residual volume
