Pulmonary Function Tests - Lung Volumes Flashcards
Tidal Volume
normal breathing
Inspiratory reserve volume
how much additional can you breath in on top of what you normally breath for normal breath
Expiratory reserve volume
after normal breathing out, how much more you can force out
Residual volume
volume that remains in lungs even after everything you can forcibly breath out
Total lung capacity
total amount our lungs can hold
Inspiratory capacity
inspiratory reserve volume + tidal volume
Vital capacity
inspiratory capacity + expiratory reserve volume
Functional residual capacity
expiratory reserve volume + residual volume
Total lung capacity and COPD
Patients with COPD have higher total lung capacity
Total lung capacity and restrictive disease
patients with restrictive disease will have a lower total lung capacity
What does spirometry measure
expiratory volume and flow rates
needs to be reproducible (3x); variation in 0.2 L indicates they are not giving same effort each time
patient is sitting normally w clip on their nose — blow out as hard and fast as they can
measure what they can blow out forcibly in 1 second and stop it at 6 seconds (FEV1/FEV6) or (FEV1/FVC)
best way to measure residual volume
body plethysmography
Ventilation (what spirometry measures)
bulk flow of air movement in and out of the lungs
Provocation tests
Methacholine
Histamine “challenges”
Less than 70% for FEV1
obstruction
FEV1
amount of air you can forcibly exhale in 1 second after max inhalation
FCV
amount of air you can forcible exhale after max inhalation
FEV1/FVC ratio
how much air you can forcibly exhale in 1 second compared to the total amount that you can forcibly exhale
How to measure DLCO
measure CO through a mask –> full inspiration –> hold for 10 seconds –> expire maximally –> measure CO again
Why should CO not be expired
Hgb has a high affinity for CO
causes of decreased perfusion leading to decreased DLCO
CHF due to systolic HF (right)
Pulmonary artery hypertension
PE
anemia
causes of decreased surface area leading to decreased DLCO
intrinsic restrictive disease (pulmonary fibrosis, bronchiolitis obliterans, emphysema
Causes of high DLCO
exercise
hemorrhage
erythrocytosis
blood transfusion
One instance in which you should do body plethysmography
obesity
One instance in which you should do body plethysmography
obesity
Bronchodilation test with SABA
increase 12% or 0.2L = reversible obstruction = asthma
no significant increase = fixed obstruction = COPD
Methacholine muscarinic provocation test
(provokes asthma)
20% decrease in FEV1 = hyperreactivity = asthma
no/minimal change = fixed obstruction = COPD
