Pulm function tests- exam 3 Flashcards
(36 cards)
What does the Fowler’s test give us a measure of, and how does it work?
Anatomical deadspace; Patient inhales a normal breath from FRC of 100% O2, on expiration a nitrogen meter measures the %N2 being exhaled. The volume exhaled at the Midpoint of the transitional phase gives us a measure of anatomical deadspace
What does the Nitrogen Washout Test measure, and how does it work
even/uneven ventilation, gives us indication of how healthy/unhealthy lungs are.
Patient breathes in 100% O2, nitrogen meter measures the amount of N2 with each exhalation. Patient keeps doing this until the N2% is about 2.5% which.
If patient takes too long to reach 2.5% it shows they have unhealthy lungs
What is considered a normal Nitrogen Washout Test?
<7 minutes
What does the Expiratory Flow Curve tell us
Normal, vs Restrictive vs. Obstructive lung disease
How would the expiratory flow curve FVC of a patient with emphysema compare to normal
- lower peak expiratory flow rate
- higher lung volume
- higher RV
- lower vital capacity
- prolonged downward slope of the effort independent portion of the curve
How would the expiratory flow curve FVC of a patient with restrictive lung disease compare to normal
- lower peak expiratory flow rate
- lower lung volumes
- lower vital capacity
- lower RV
What is an example of a Fixed Flow-Volume Loop? Does it affect inspiration or expiration?
endotracheal tube
Both insp and exp. : the fixed inner lumen diameter limits the flow rate on inspiration and expiration. looks like top/bottom of the curves are chopped off
Can be intra or extrathoracic in source
What is an example of a variable intrathoracic flow-volume loop? Does it affect inspiration or expiration?
Forced expiration, emphysema, asthma
Only exists on the expiratory cycle. the increased positive pressure of forced expiration causes collapse of the small airways which limits expiration. inspiration is unaffected
What is an example of variable extrathoracic flow-volume loop? Does it affect inspiration or expiration?
Obstruction of trachea and upper airway; paralyzed vocal cords
Only affects inspiration. The low negative airway pressure causes collapse of the weak upper airway.
What does FEV1 stand for
Forced expiratory volume in 1 second,
The maximal amount of air you can get out of the lung using maximal effort in a period of 1 second
What does FVC stand for
Forced vital capacity
What does the FEV1/FVC ratio tell us
What % of vital capacity we can forcibly exhale in a period of 1 second.
What is a normal FEV1/FVC ratio
80%
What is the FEV1/FVC ratio in this image? What would it indicate?
76%
FEV1 = 3.8L
FVC= 5L
normal lungs
In obstructive lung disease FEV1/FVC is typically
Low
In restrictive lung disease FEV1/FVC is typically
Normal
FVC is low, but the FEV1/FVC ratio is the same as normal
What is the FEV1/FVC ratio in this image? What would it indicate?
83%
FEV1= ~2.5L
FVC= 3L
example of restrictive lung disease. Low FVC but Normal FEV1/FVC ratio
What is the FEV1/FVC ratio in this image? What would it indicate?
87%
FEV1= ~1.75L
FVC= 2L
example of restrictive lung disease. Low FVC but high/normal FEV1/FVC ratio
What is the FEV1/FVC ratio in this image? What would it indicate?
~43%
FEV1= 1.5L
FVC= 3.5L
example of COPD/emphysema. long expiratory time is indicative of obstructive lung disease
Normal exhalation is highly reliant on what force?
Elastic recoil
Which obstructive disease is reversible by bronchodilators
Asthma
Which obstructive disease is not responsive to bronchodilators
COPD/emphysema
Which obstructive disease is partially reversible by bronchodilators
chronic bronchitis
PFTs in asthma would look like what
(FEV1, FVC, FEV1/FVC, TLC, RV, FRC, DLCO)
- FEV1 = ↓
- FVC = ↓
- FEV1/FVC = ↓
- TLC = N or ↑
- RV = ↑
- FRC = N or ↑
- DLCO = N
