Interpretation of Lung Function Testing

Question 1

Reasons for lung function tests

Answer 1

Spirometry
PEF
Lung volume
Gas Exchange

Question 2

What are values dependent upon?

Answer 2

Age
Sex
Height
BMI
Ethnicity

Question 3

What doe spirometry measure?

Answer 3

Volume and/or speed/flow of air that can be inhaled and exhaled

Question 4

Most common used measurements in spirometry

Answer 4

FEV1
FVC
FEV1/FVC

Question 5

Define FEV1

Answer 5

Forced Expiratory Volume in one 1 second
Amount of ait you can blow out within 1 second
Normal lungs and airways mean you can blow out most of air from lungs

Question 6

Define FVC

Answer 6

Total amount of air you can blow out in one breath

Question 7

Define FEV1/FVC

Answer 7

Of the total amount of air than you can blow out in 1 breath, this is the proportion that you can blow out in 1 second

Question 8

Why is spirometry better than PEF?

Answer 8

More reproducible
Detects changes in smaller airways vs. larger in PEF
PEF more variable

Question 9

What is PEF?

Answer 9

Maximal rate that a person can exhale during maximum short expiratory effort after full inspiration

Question 10

What is PEF useful for?

Answer 10

Detecting change or trends in asthma control

Question 11

Obstructive Spirometry Result

Answer 11

FEV1 reduced
FVC same
FEV1/FVC reduced

Question 12

Restrictive Spirometry Result

Answer 12

FEV1 reduced
FVC Reduced
FEV1/FVC normal or increased

Question 13

Obstructive Diseases

Answer 13

Asthma
COPD
Endobronchial tumour
Foreign body

Question 14

Restrictive diseases

Answer 14

PAINT
P - pleural
A - alveolar
I - interstitial
N - neuromuscular
T - thoracic cage

Question 15

Define RV

Answer 15

Volume left in lungs after max expiration

Question 16

What are lung volumes

Answer 16

Measurements which cannot be measured by simple spirometry as contain RV which cannot be expired

Question 17

How to measure RV?

Answer 17

Use tracer gas (helium) to mix with air in lung but doesn’t diffuse out
Check amount that tracer gas has diluted as it mixes with air to determine volume

Question 18

How to measure gas transfer?

Answer 18

Indirectly measure oxygen transfer using CO
TLCO
TLCO/VA = KCO (measure of how good each alveoli is at gas transfer)

Question 19

2 loops in Flow Volume Loop

Answer 19

Larger = Maximal Flow Volume Loop
Smaller = Exercise Tidal Flow Volume Loop

Question 20

VT, EELV, EILV, ERV, IRV, IC on flow volume loop?

Answer 20

VT = tidal volume 
EELV = end expiratory lung volume
EILV = end inspiratory lung volume
ERV = expiratory reserve volume
IRV = inspiratory reserve volume
IC = inspiratory capacity

Question 21

What does an asthma flow volume loop look like?

Answer 21

Notched
Volume dependent
Reduced FEV1

Question 22

What does severe emphysema look like on a flow volume loop?

Answer 22

Bigger notch than asthma
L shape
FEV1 even less
Pressure dependent

Question 23

What does tracheal stenosis look like on a flow volume loop?

Answer 23

Rigid obstruction
Reduced width/volume
Box shape
Lost notch pattern

Question 24

Difference between extrathoracic tracheal obstruction and intrathoracic large airway obstruction on a flow volume loop?

Answer 24

Extra = flow mostly above 0, insp flat, exp normal
Intra = flow mostly below 0, exp flat, insp normal

Question 25

Normal FEV1 and FVC

Normal FEV1/FVC ratio

Answer 25

80-120%

Ratio = 70%