2- overview of pulmonary function tests

Question 1

what is an example of an effort dependant test?

Answer 1

forced expiratory volumes/flow rates - spirometry

Question 2

what are examples of effort independent pulmonary function test?

Answer 2

• relaxed vital capacity - spirometry
• helium/N2 washout static lung volumes
• exhaled breath nitric oxide - measure breath condensate and measure NO = core test (important)
• impulse oscillometry - balancing sound waves off bronchial tree, you just breathe normally so good

Question 3

what is purpose of gas diffusion tests?

Answer 3

tells you how much oxygen transferred across alveoli, through capillary wall into blood stream and in pulmonary veins

Question 4

what are examples of gas diffusion tests?

Answer 4

• CO transfer factor = use as tracer gas (tiny amount) can look at how well gas transferred from air into blood stream
• arterial blood gases (resting) = measure how much oxygen in arterial blood
• SaO2 during exercise = can test oxygen levels during exercise to see if drops in exercise

Question 5

what is (make sure you know what they mean)
a) FEV1
b) FVC
c) FER
d) RVC

Answer 5

a) forced expiratory volume in 1s
b) forced vital capacity
c) forced expiratory ratio
d) relaxed vital capacity

Question 6

what is the difference between relaxed & forced vital capacity tell us?

Answer 6

tells us how much gas is trapped in lung

Question 7

what is a normal FEV1/FVC ratio?

Answer 7

above 0.75

Question 8

what is FEV1 and FVC level like in asthma compared to normal?

Answer 8

asthma & COPD have disproportionally reduced FEV1 and FVC compared to normal

asthma usually gets up to normal FVC but has FEV1 of something like 0.5 (lower than 0.75)

*if patients with asthma have airway remodelling (collagen laid down) then they get gas trapping so lower FVC (also FVC lowers with age)

Question 9

what is FEV1 and FVC level like in COPD compared to normal?

Answer 9

asthma & COPD have disproportionally reduced FEV1 and FVC compared to normal

COPD has lower FEV1 and FVC

Question 10

what is difference in RVC and FVC in
a) normal
b) asthma
c) COPD

Answer 10

a) FVC higher (i think?)
b) FVC and RVC are usually the same (unless airway remodelling)
c) RVC always greater than FVC (due to air trapping - they can’t just force it out)

Question 11

what is FEV1 and FVC level like in restrictive lung disease compared to normal?

Answer 11

problem is in the lungs (alveolar walls e.g. fibrotic tissues etc which shrinks lungs down so they can’t expand) so pattern is like shrunken normal pattern

= the FEV1 and the FVC are reduced in direct proportion

Question 12

what causes restrictive pulmonary disease?

Answer 12

pulmonary fibrosis, rheumatoid arthritis

Question 13

why do we make flow volume curve graph?

Answer 13

because patients understand it more than FEV1 and FVC

flow volume curve has obvious spike up and down for normal and then asthma slower on both and same as COPD

Question 14

what can be used to measure peak expiratory flow rate to put on graph?

Answer 14

use PEF monitor = best of 3 blows which gives peak flow during flow volume curve (expressed in L/min)

Question 15

in obstructive pulmonary disease:
a) is PEFR normal or decreased?
b) is FEV1 normal or decreased?
c) is FVC normal or decreased?
d) what is FEV1/FVC ratio?
e) what is FEV1 response to beta2 agonist?

Answer 15

a) decreased PEFR = peak expiratory flow rate
b) decreased FEV1 (can’t breathe out as much in 1st second)
c) FVC normal in asthma and decreased in COPD
d) ratio is less than 0.75 (75%)
e) greater than 12% for asthma but less then 12% for COPD

Question 16

in restrictive pulmonary disease:
a) is PEFR normal or decreased?
b) is FEV1 normal or decreased?
c) is FVC normal or decreased?
d) what is FEV1/FVC ratio?
e) what is FEV1 response to beta2 agonist?

Answer 16

a) increased PEFR = peak expiratory flow rate
b) decreased FEV1
c) decreased FVC
d) greater than 0.75 (75%)
e) no response to beta 2 agonist as no problem with airways

Question 17

what are bronchial challenge testing examples?

Answer 17

• exercise = asthma often induced by exercise (you can test to see how much tolerated, asthma actually gets better with exercise, it’s after that it’s worse
• methacholine/histamine/mannitol test
• allergens/chemicals = not used now

Question 18

what is the methacholine/histamine/mannitol bronchial challenge test?

Answer 18

= how to assess twitchy airways

• marker of airway hyper-responsiveness
• methacholine stimulate parasympathetic post ganglionic M3 receptors = make airways constrict
• measure bronchoconstriction using FEV1 and keep giving higher dose to see how much what concentration to produce 20% fall in FEV1

Question 19

what is exercise bronchial challenge testing?

Answer 19

• peak flow & FEV1 actually improve in exercise because in exercise lots of adrenaline produced so endogenously bronchodilated airway, it’s when stop exercising that rebound flow so it’s FEV1 measured after exercise
• also fall in SaO2 if you think someone has interstitial restrictive lung disease

Question 20

what is the test that athletes get?

Answer 20

Full cardiopulmonary exercise test (CPET) -Differentiate cardiac
vs respiratory dyspnoea

• measure heart rate vs oxygen uptake vs ventilatory rate

Question 21

what is static lung volume?

Answer 21

use nitrogen wash out to measure functional residual capacity

Question 22

what can cause decreased total lung transfer for CO in transfer test?

Answer 22

Anaemia, Emphysema, Int lung disease, Pulmonary oedema, Po emboli ,Bronchiectesis

Question 23

what is transfer factor (diffusing capacity) test?

Answer 23

• CO diffusion across alveolar-capillary barrier–aka single breath
  diffusing capacity
• TLCO (or DLCO) - total lung transfer for CO ( or Diffusing
  capacity ) : corrected for alveolar volume (KCO)

= to monitor treatment response in Int lung disease

Question 24

what is oscillometry test?

Answer 24

airway resistance = bronchial sonar, sound waves against bronchial tree and depending on frequency that bounces back, work out peripheral resistance and pulmonary resistance so can show restriction

Question 25

what is exhaled breath condensate test?

Answer 25

Fractional exhaled breath nitric oxide measured at flow of
50ml/s (FeNO) –point of care non invasive marker of T2
airway inflammation (IL13) in asthma

= Used as an adjunct to bronchial challenge to assess
asthmatic inflammation –especially when spirometry is
normal
high levels (above 35ppb) = uncontrolled asthmatic inflammation

Question 26

when is exhaled breath condensate not useful?

Answer 26

Not useful in COPD as nitric oxide suppressed by smoking