PATHOPHYS: PFTs Flashcards
What are some indications for PFTs?
- Symptoms (dyspnea, cough)
- Pre-Operative Evaluation
- Occupational exposure
- Evaluate therapeutic response
What is the “lung age”?
way that you can “coach” patients and explain the results of PFTs
What are the common PFTs that are run together?
Spirometry MVV Lung volumes DLCO ABG
What dimesions are measured with PFTs?
Volume
Flow
Pressure
What should you do when you look at a spirometry reading?
- Check test quality
- Check vital capacity
- Look at FEV1/FVC (should be around 80%)
ON TEST
What factors impact vital capacity?
Sex
Age (negative correlation)
Height (positive correlation)
NOT WEIGHT!!!!
ON TEST
What is considered to be a positive post-bronchodilator response?
200 ccs and 12% of vital capacity
OR
15% from basal FEV1
ON TEST
What is MVV?
Maximal voluntary ventilation: gross predictor of the strength of the lung
What should your MMV be?
40 times FEV1
What makes up the vital capacity?
Tidal volume + IRV + ERV
TEST
What makes up the functional residual capacity?
Expiratory reserve volume + Residual volume
TEST
True or False: both restrictive and restrictive lung disorders have low FVCs.
TRUE
How do you define an obstructive ventilatory defect?
FEV1/FVC ratio below 70%
ON TEST
What lung volume cannot be measured by spirometry?
Residual volume
How do you measure TLC?
Spirometry + Body plethysmograph (gold standard)
ON TEST
What type of diseases decrease TLC?
Disease of thorax, inspiratory muscles, pleural diseases, and loss of functioning alveoli
What type of diseases decrease VC?
- Chest pain (too much pain to have maximum inspiratory effort)
- Fatigue
- Poor effort
What is dynamic hyperinflation?
People with obstructive airway diseases air-trap in the chest due to destruction of septi between alveoli which increases the residual volume! When a patient with COPD exercises, the hyperinflation gets worse (stacking of air with each inspiration).
ON TEST
What capacity is decreased due to static hyperinflation?
Inspiratory capacity
What is compliance?
change of volume over change in pressure
What is the compliance of a restrictive disease?
LOW (takes a lot of pressure to change a little volume)
ON TEST (know curves)
What is the compliance of an obstructive disease?
HIGH (takes a little pressure to make a large volume change)
ON TEST (know curves)
A normal slow vital capacity excludes what type of disorder?
a restrictive disorder
What is commonly seen in COPD patients?
concominant restriction
