Pulmonary Function Tests

Question 1

in spirometry of an asthmatic: FEV1 is _____

Answer 1

reduced

Question 2

in spirometry of an asthmatic: FVC is ______

Answer 2

preserved

Question 3

only situation in which FVC is reduced is when ______

Answer 3

the patient has COPD

An exception is when asthma has remodelled the airways, causing FVC to decrease

Question 4

Expiratory flow rate is from TLC to RV. What are the units?

Answer 4

L/s (litres per second)

Question 5

PEFR is _____ in obstructive, and _____ in restrictive

Answer 5

reduced, normal

Question 6

FEV1 is _____ in obstructive, and _____ in restrictive

Answer 6

reduced, reduced

Question 7

FVC is _____ in obstructive, and _____ in restrictive

Answer 7

normal in asthma and reduced in COPD, reduced

Question 8

FEV1/ FVC ratio is _____ in obstructive, and _____ in restrictive

Answer 8

reduced, normal (sometimes high)

Question 9

FEV1 response to B2-agonist is ______ in obstructive, and ______ in restrictive

Answer 9

> 15% in asthma and <15% in COPD, no response

Question 10

bronchial challenge testing

Answer 10

using a marker of airway hyper-responsiveness (e.g. histamine). Finding the concentration required to produce a 20% drop in FEV1. Or using allergens/ chemicals to diagnose occupational asthma

Question 11

exercise testing

Answer 11

for asthmatics: they will have decreased FEV1 and decreased PEFR post-exercise.
In Interstitial Lung disease: there is decreased SaO2 during exercise

Question 12

static lung volumes

Answer 12

these are effort independent tests e.g. helium dilution/ N2 washout to find the functional residual capacity.

Question 13

Transfer factor (Diffusing Capacity)

Answer 13

CO’s diffusion across alveolar-capillary barrier (AKA single breath diffusing capacity).
TLCO (total lung transfer for CO) is decreased in anaemia (not enough Hb), emphysema (not enough lung tissue - holes), Interstitial lung disease (fibrotic), pulmonary oedema (fluid), pulmonary emboli, bronchiectesis

Question 14

how is airway resistance measured?

Answer 14

whole body plethymography, or (more easily) by impulse oscillometry

Question 15

why is exhaled breath condensate measured?

Answer 15

Exhaled breath NO is a non-invasive marker of eosinophilic airway inflammation in asthma. This is not useful in COPD (NO is supressed by smoking). High NO levels reflect uncontrolled asthmatic inflammation