lung conditions and function tests

Question 1

name 4 lung pathologies that affect diffusion

Answer 1

emphysema, fibrotic lung disease, pulmonary oedema, asthma

Question 2

what effect does emphysema have on alveoli?

Answer 2

reduces surface area for gas exchange

alveoli can be seen by the naked eye

Question 3

what effect does emphysema have on compliance and elasticity?

Answer 3

high compliance because of loss of resistance

lost elasticity because elastic fibres break down

Question 4

what effect does fibrotic lung disease have on alveoli?

Answer 4

thickened alveolar membrane slows gas exchange

fibrous tissue visible in x-ray

Question 5

what effect does fibrotic lung disease have on compliance and expansion?

Answer 5

loss of compliance which decreases ventilation

fibres resist expansion

Question 6

what effect does pulmonary oedema have on alveoli?

Answer 6

larger spaces between alveoli seen in histology

separates alveoli from capillary

Question 7

what effect does pulmonary oedema have on diffusion and O2?

Answer 7

fluid in interstitial space increases diffusion distance which separates alveoli from capillaries
impacts O2 because it doesn’t dissolve in water

Question 8

what effect does asthma have on diffusion?

Answer 8

asthma affects the airways rather than the alveoli so has little direct effect on diffusion, has impact on PAO2 and PACO2 which subsequently limits diffusion

Question 9

what are the basic characteristics of obstructive and restrictive lung diseases?

Answer 9

obstructive- obstruction of air flow, especially on expiration (asthma,COPD, bronchitis, emphysema)
restrictive- restriction of lung expansion (fibrosis, infant respiratory distress syndrome, oedema, pneumothorax)

Question 10

how can spirometry be used to identify abnormal lung function?

Answer 10

by either static or dynamic measurements
static- only volume exhaled is considered
dynamic- time taken to exhale a certain volume

Question 11

what can spirometry measure?

Answer 11

tidal volume, inspiratory reserve, expiratory reserve, inspiratory capacity and vital capacity

Question 12

what is meant by FEV1 and what is the normal volume in a fit, healthy, adult male?

Answer 12

forced expiratory volume in 1 second

4L

Question 13

what is meant by FVC and what is the normal volume for a fit, healthy, adult male?

Answer 13

forced vital capacity

5L

Question 14

what effect do obstructive diseases have on the FEV1:FVC ratio?

Answer 14

impact on air flow is greater than the impact on lung capacity so the FEV1:FVC ratio is significantly reduced

Question 15

what effect do restrictive diseases have on FEV1:FVC ratio?

Answer 15

both FEV1 and FVC reduce in proportion and the ratio remains normal or may even increase

Question 16

do obstructive or restrictive diseases increase the work of expiration?

Answer 16

Obstructive diseases increase the work of expiration

Question 17

do obstructive or restrictive diseases increase the work of inspiration?

Answer 17

Restrictive diseases increase the work of inspiration

Question 18

what’s the normal ratio of FEV1/FVC?

Answer 18

80%

Question 19

what’s the ratio of FEV1/FVC in obstructive disease?

Answer 19

42%
FEV1- 1.3
FVC- 3.1

Question 20

what is the ratio of FEV1/FVC in restrictive disease?

Answer 20

90%
FEV1- 2.8
FVC- 3.1

Question 21

why is the FEV1/FVC ratio higher in restrictive disease than obstructive disease?

Answer 21

air flow is not affected because there’s not problem with getting air out but the total amount of air expired is restricted