Resp. Misc. 5 - Overview of Lung Function Tests

Question 1

What are the 3 main categories of pulmonary function tests?

Answer 1

Effort dependent tests
Effort independent tests
Gas diffusion tests

Question 2

What are 2 effort dependent pulmonary function tests?

Answer 2

Peak Expiratory Flow (peak flow metre)
Spirometry (forced expiatory volumes)
*these are the most important in clinical practice

Question 3

what does the flow rate =

Answer 3

Volume / time

Question 4

What are 5 effort independent tests?

Answer 4

Relaxed vital capacity (spirometry)Helium/ N2 washout stati lung volumesWhole body plethysmographyImpulse oscillometryExhaled breath nitric oxide*these are the most important in clinical practice

Question 5

What are 3 gas diffusion tests?

Answer 5

CO transfer testsArterial blood gases (resting)SaO2 during exercise*these are the most important in clinical practice

Question 6

What is the name for the following ratio:FEV1/FVC?

Answer 6

Forced expiratory ratio (FER)

Question 7

What does RVC stand for?

Answer 7

Relaxed vital capacity

Question 8

What is the difference between static and dynamic lung volumes?

Answer 8

Static = not concerned with rate at which they are inspirited or exhaledDynamic = dependent on the rate (FVC)

Question 9

How many times do the airways divide?

Answer 9

23 times

Question 10

In terms of spirometry, where is air trapping suggested?

Answer 10

When there is a major difference between the relaxed vital capacity and the forced vital capacity

Question 11

Do people with asthma or COPD normally have a full forced vital capacity?

Answer 11

FVC is normally preserved in asthmatics although it is normally lowered in COPD (due to remodelling)

Question 12

Is the reduced FVC in COPD patients usually proportionate to the reduced FEV1?

Answer 12

No meaning the ratio is still lowered where as in restrictive conditions both are reduced proportionally meaning the ratio is usually normal

Question 13

if you plot the expiatory flow rate against the forced expiatory volume (from TLC to RV), what is the shape for:-normal?-volume dependent airway closure e.g. asthma, chronic bronchitis-pressure dependent airway closure e.g. emphysema

Answer 13

Normal = comes to a peak and decreases Volume = comes to less f a peak and decreases in a curve instead of a straight linePressure = comes to a much lesser peak and decreases suddenly

Question 14

What test produces the flow-volume curve?

Answer 14

Spirometry (have to take gradients from some line)

Question 15

What values can be extracted from the flow-volume curve?

Answer 15

Peak expiatory flow rate (PEFR)Forced expiatory flow rate (FEFR) at a % of FVC

Question 16

What are the units of the peak expiatory flow rate?

Answer 16

L/min

Question 17

Apart from spirometry, what other instrument can be used to measure the peak flow rate?

Answer 17

Simple linear peak flow meter

Question 18

What is the peak expiatory flow rate?

Answer 18

The person’s maximum speed of expiration

Question 19

PEFR in obstructive disease?Restrictive?

Answer 19

DecreasedNormal

Question 20

FEV1 in patients with obstructive disease?Restrictive?

Answer 20

DecreasedDecreased

Question 21

FVC in patients with obstructive disease?Restrictive?

Answer 21

Normal in asthmatic and decreased with COPDDecreased

Question 22

FEV1/FVC ratio in obstructive?Restrictive?

Answer 22

Less than 75%Greater than 75%

Question 23

Fev1 response to B2-agonist in asthmatics?COPD?Restrictive?

Answer 23

greater than 15%less than 15%No response

Question 24

3 main types of triggers used in bronchial challenge testing?

Answer 24

ExerciseMetacholine/ histamine/ mannitol Allergens/ chemicals

Question 25

What is a reaction of the airways to metacholine/ histamine/ mannitol a marker of?What is measured during this?

Answer 25

Airway hyper-responsiveness markerConcentration to produce 20% decrease in FEV1

Question 26

Why do asthmatic patients not get wheezy in general until after exercise?

Answer 26

Adrenaline causing bronchodilation

Question 27

What is cardiopulmonary exercise testing used to differentiate between?What does it involve?

Answer 27

To differentiate between cardiac and respiratory dyspnoeaMeasuring heart rate, oxygen uptake and ventilatory rate during exercise

Question 28

What happens to SaO2 during exercise in interstitial lung disease?

Answer 28

It drops (used to monitor treatment response)

Question 29

What happens to the functional residual capacity in COPD?

Answer 29

It increases in expense of Inspiratory capacity

Question 30

What does CO diffuse across?

Answer 30

Alveolar capillary barrier

Question 31

What is the total lung transfer for CO (TLCO)/ (interchangeable with DLCO)?

Answer 31

The total lung transfer for CO (corrected for alveolar volume (KCO)) - very sensitive measure of gas diffusion = implies integrity of alveolar-arterial vascular bed (anythings that impairs the bed will give a reduction in TLCO)

Question 32

What can reduce TLCO? (6)

Answer 32

AnaemiaEmphysemainterstitial lung diseasePulmonary oedemaPEbronchiecstasis

Question 33

How is airway resistance measured?

Answer 33

Either by whole body plethysmography or more commonly/ easily with impulse oscillometry

Question 34

What does impulse oscillometry measure?

Answer 34

Airway resistance during quiet tidal beathing at different resonant frequencies to give total resistance and central resistance and hence peripheral airway resistance

Question 35

When is impulse oscilometry particularly useful?

Answer 35

In patients (i.e. kids) where it is easier to breathe at tidal volume than doing forced expiatory manoeuvre

Question 36

what is exhaled breath condensate?

Answer 36

Exhaled breath nitric oxide measured at a flow of 50ml/s

Question 37

What does is exhaled breath condensate a non invasive marker of?

Answer 37

Eosinophilic airway inflammation in asthma

Question 38

Why is exhaled breath condensate not useful in COPD?

Answer 38

NO suppressed by smoking

Question 39

What does high levels of exhaled NO (>35ppb) reflect?

Answer 39

Uncontrolled asthmatic inflamation

Question 40

What 2 tests are used to assess asthmatic inflammation especially when spirometry is normal?

Answer 40

Bronchial challengeExhaled breath condensate