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Flashcards in Interpretation of Lung Function Deck (32)
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1

What are the values of lung function dependent on

- Age
- height
- sex
- BMI
- ethinic origin

2

What are the 4 main lung function tests

- Spirometry
- PEF
- Lung volume
- Gas exchange

3

What does spirometry measure

Spirometry measures the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled

4

What are the two measurements that spirometry measures

- forced vital capacity (FVC)
- Forced expiratory volume in one second (FEV1)

5

what is forced expiratory volume in one second

This is the amount of air you can blow out within one second.
- With normal lungs and airways you can normally blow out most of the air from your lungs within one second.

6

What is forced vital capacity

The total amount of air that you blow out in one breath.

7

what is the ratio in spriometry

FEV1 divided by FVC (FEV1/FVC).
- Of the total amount of air that you can blow out in one breath, this is the proportion that you can blow out in one second.

8

spirometry is more

reproducible than PEF

9

What airways does spirometry mostly detect changes in

- Mostly detects changes in the smaller airways

10

What is PEF

- Maximal rate that a person can exhale during a short maximal expiratory effort after a full inspriation

11

What is PEF useful for detecting

- detecting changes or trends in a patients asthama control

12

What type of airways does PEF detect changes in

- detects changes mostly in the larger airways

13

PEF has significant

testing variability

14

what is the differences in spirometry in obstructive and restrictive lung disorders

Obestructive
- FEV1 is lowered by a greater proprotion than the FVC
- FVC is lowered
- FEV1/FVC is lowered

restrictive
- FEV1 is lowered
- FVC is lowered
- FEV1/FVC is raised or normal

15

What is the normal FEV1/FVC ratio

when the ratio is 0.7 or 70% or above

16

If the FEV1/FVC falls below 0.7 what type of lung disease is this

Obstructive

17

Name some obstructive disorders

- asthma
- COPD
- endobronchial tumour
- foreign body

18

Name some restrictive disorders

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

19

define tidal volume

- volume of air breathed in and out in each breath at rest

20

How do you wokr out inspriatory capaicty

IRV + TV

21

How do you work out vital capacity

IRV + TV + ERV

22

How do you work out total lung capacity

IRV + TV + ERV + RV

23

How do you work out functional residual capacity

ERV + RV

24

Why can you not measure residual volume on spirometry

- RV cannot be expired
- Since RV is the volume left in the lungs after a maximal expiration, it cannot be measured by simple spirometry. Similarly, the capacities containing RV (i.e. FRC & TLC) cannot be measured directly with a spirometer

25

How do you measure residual volume

- use a tracer gas (helium) which mixed with the air in the lung but does not diffuse out the lung
- the volume is then determined by the amount that this tracer gas is diluted as it mixes with the air in the lungs

26

How do you measure oxygen transfer

O2 transfer is measured indirectly using CO
- CO has a higher affinity than oxygen

27

What happens to the flow volume loop in obstruction

- loop moves to the left

28

What happens to the flow volume loop in restrictive

- loop moves to the right

29

What happens to the flow volume loop in extrathroacic tracheal obstruction

- inspriatory loop is flattend but the expriatory loop is normal

30

What happens to the flow volume loop in intrathroacic large airway obstruction

- expiratory loop is flattend but the inspiratory loop is normal