Flashcards in PFTs Deck (37):
When is a PFT indicated?
anyone presenting with dyspnea, SOB, cough, pre-operative evaluation, disability
How is spirometry performed?
patient is sitting and after tidal volume, max inspiration and max expiration are performed 3 times and then average is taken
What is functional residual capacity?
volume of air left after normal expiration (obese decreases this)
Slow expiration is key in spirometry evaluation of which patients?
those with obstructive disease
Pulmonary function peaks at what age?
25 (secular trend of decline- 25-30cc decline/year)
T or F. The initial part of expiration is EFFORT dependent
T. The terminal portion is not and is driven by elastic recoil of the lung
When is a post-bronchodilator response considered positive?
An increase of at least 200ml (AND 12%) in FEV1 or 15% from basal FEV1
What is an MVV?
Maximal volume ventilation= max inhale and exhale as many times as possible in 12 seconds (needed before lung resection)
What is a normal MVV?
What MVV is needed for pneumonectomy?
greater than 55%
What MVV is needed for lobeectomy?
greater than 45%
A low MVV suggests what?
What part of lung function can not be measured with spirometry?
What lung parameter is very important int he evaluation of hypoxemia in the ICU?
FEV1/FVC is reduced in what type of disease?
FVC is reduced in obstructive or restrictive?
FEV1 is reduced in obstructive or restrictive?
What things reduce TLC?
-disease of the thorax or inspiratory muscles
-loss of alveoli
What things reduce VC?
-fatigue or poor effort
Why does dynamic hyperinflation occur in obstructive disease?
Not being able to get out all the air causes "stacking"
In restrictive diseases, compliance is decreased
T. Harder to inhale, easier to exhale
How does compliance change in asthma patients?
it doesn't even though its obstructive (no destruction of tissue) BUT FEV1/FVC still decreases
How does compliance change in emphysema patients?
Flow velocities during exhalation are higher in which type of lung disease?
Flow volume loops are also used to evaluate what?
upper-airway obstruction (carina and up)
What is the difference between extra-thoracic and intra-thoracic?
extra- suprasternal notch up
intra-carina up to suprasternal notch
What part of the flow-volume loop is flattened in extra-thoracic disease?
What part of the flow-volume loop is flattened in intra-thoracic disease?
What is a fixed Upper airway obstruction?
where you see flattening of both the inspiratory and expiratory portions of the flow-volume curve
What is lung diffusion capacity defined as?
rate at which gas enters the blood divided by the driving pressure of the gas (PA-Pa)
How is DLCO measured?
SINGLE breath (requires inhaled VC of greater than 1 L and 10 of breath holding)
Change is DLCO 7% per gram of Hb
What is a normal DLCO?
What things can increase DLCO?
putting blood/Hb in the lungs (e.g. CHF, pulmonary hemorrhage)
What are the uses of DLCO?
-differentiate between asthma and COPD, or interstitial and chest wall disease
- diagnose pulmonary vascular disease
What things would show normal PFT and low DLCO?
pulmonary emboli or HTN