Lung Function Tests / Spirometry - Summary Notes

Function Tests
Full of
set
Lung lung function tests include:1. Spirometry 2. Lung Volumes 3. Gas Transfer


Restrictive:diseases that reduce lung volumes, resulting in reduced vital capacity.
·
caused by changes in lung compliance.
e.g. CF. Sarcoidosis, Pulmonary edema, MSK.
Obesity,
·




Both FEV1 and FVC are
proportionally reduced, FEV1:FVC ratio preserved.
-




-All
lung volumes reduced.


Obstructive:diseases that increase airway resistance, resulting in reduced FEV1: FVC ratio 0.8.=




caused by changes in airway diameter.
·




·

e.g.Asthma, COPD, Bronchitis, Bronchiectasis, CF.
FLOW-VOLUME
LOO9
Both FEV1 and FVC are reduced,
-




butFEV1 proportionally more so.




N
-vC/ERU reduced, RV/FRC/TLC increased.



spirometry i
·
most common evaluation of lung function, as it is quantitative.
measures 3 variables: Flow, Volume and Time.


VC, FVC, FEV1, PEFR.
·

measures
·


Spirometry cannot measure any lung volumes that include Residual volume (like FRC and TLC),
as it cannot be expired and therefore measured.


FEV1-Forced Expiration Volume in 1 second. PEFR- Peak Expiratory Flow Rate.
·
FEV1: FVC ratio can distinguish between ·
Restrictive Disease reduced peak flow, and
-




Restrictive and Obstructive Diseases. scooped descending limb.
out
·
Normal 80% of FVC
=
Obstructive Disease reduced peak flow, and
-




Restrictive Disease 80% of FVC
=


Steeper descending limb.
Obstructive Disease =
80% of FVC
=




(FEV1:FVC ratio =
0.8)
=




varying FEV1<12%/200m) reversible = -

Asthma

Reversibility: FEV1 12%/200m) irreversible
varying COPD
= -




Spirometry Reversibility Test used to differentiate Asthma/COPD obstructive disease
-


-




baseline FEV1 is compared to FEV1after salbutamol, in order to assess reversibility.
·




Obstruction:


Wheeze extrathoracic obstruction
Inspiratory
=




e.g. mass effectfrom quitre, tumour.


Wheeze intrathoracic obstruction
Expiratory
=




e.g. obstructive disease, foreign body.