Pulmonary Function Tests

Question 1

Components of PFTs

Answer 1

1 Spirometry 
Flow volume loop / curve
Lung volumes
2 Bronchodilator (BD) response 
3 Bronchoprovocation testing (methacholine challenge)
4 Maximal respiratory pressures (Bugels)
5 Diffusion capacity

Question 2

Spirometry

Answer 2

-Necessary for the diagnosis of asthma or COPD
-Obstructive vs restrictive vs mixed
-Normal predicted values
Height
Age
Gender
Ethnicity / race

Question 3

COPD

Answer 3

• don’t have respiratory muscle weakness but have reduced MIP due to hyperinflation, low MIP relate to severity and prognosis
• FEV1/FVC will remain <.7 however the FEV1 may improve some with BD

Question 4

Diffusion capacity of lung for carbon monoxide (DLCO)

Answer 4

-measures ability of lungs to transport inhaled gas from alveoli to the pulmonary capillaries
-Cannot obtain on supplemental oxygen
-Severity:
>60% mild
40-60% moderate
<40% severe
-DLCO is affected by hemoglobin, lower if anemic.

Question 5

Contraindications to Spirometry

Answer 5

Acute phase of illness or recent illness/procedure

Question 6

Abnormal Spirometry: Obstructive

Answer 6

• Low FEV1/FVC ratio
• Severity of obstruction is quantified by degree of reduction in FEV1 (% of predicted normal value)
• FVC may be normal but can be reduced in “air trapping”
• If RV & RV/TLC both high – suggests air trapping
• Flow volume curve is “scooped out” for O(bstructive)

Question 7

Abnormal Spirometry: Restrictive

Answer 7

• Normal FEV1/FVC ratio
• Low FVC, TLC
• Flow volume curve looks like a witches hat or mountain

Question 8

GOLD Classification of COPD

Answer 8

• Gold 1: Mild- FEV1 > 80%
• Gold 2: Moderate- FEV1 50-79%
• Gold 3: Severe-FEV1 30-49%
• Gold 4: Very severe: FEV1 <30% predicted