Lung function tests

Question 1

what are lung funtion tests?

Answer 1

• Pulmonary function tests are non-invasve that allow us to evaluate monitor and manage
• can measure lung air flow, volumes and rates
• lung volumes and capacities

Question 2

what are the two most common PFTs

Answer 2

• PEFR -> use a peak flow meter
• Spirometery

Question 3

what is a peak flow meter

Answer 3

• maximal expiration
• blow out as hard as you can

Question 4

what is residual volume

Answer 4

after full expiration, you still have some air left in your lungs

Question 4

what is residual volume

Answer 4

after full expiration, you still have some air left in your lungs

Question 5

label this graph

Answer 5

Question 6

label this diagram

Answer 6

Question 7

what does vital capacity rely on

Answer 7

• it may be reduced due to to lungs not being fully filled in inspiration
• lungs not fully emptied on expiration
• could be both
• ## can be due to lungs being stiff eg, pulmonary lung fibrosis as a form of interstitial lung disease

Question 8

what is forced vital capacity

Answer 8

• during expiration small airways are compressed
• there is a point when no more air can be driven out the alveoli
• ## if expiratory flow is compromised much earlier in expiration then this produces an obstructuve deficit -> Chronic obstructuve lung disease

Question 9

what does it mean if FVC>0.7
and FVC<0.7

Answer 9

• FVC<0.7 =obstructive
• FVC>0.7 = restrictive

Question 10

what are some features of obstructive defect

Answer 10

• FVC nearly normal in early days but may decrease if there is ari trapping
• FEV1 is reduced
• FEV1/FEV < 0.7
• seen in asthma, COPD, bronchiastasis

Question 11

what are some features of a restrictive defect

Answer 11

• TLC is reduced
• FVC is reduced
• FEV1 is reduced proportionately
• FEV1/FVC is normal
• lung fibrosis, interstitual lung disease, myasthenia gravis

Question 12

mild obstructive flow chart

Answer 12

Question 13

moderate obstructive flow chart

Answer 13

Question 14

restrictive flow limitation

Answer 14

• vital capacity is reduced
• FEV1 is reduced
• there is an elevated FEV1 ratio due to reduced complications

Question 15

in which situaton does a bronchodialator help

Answer 15

significant improvement in asthma than in COPD

Question 16

label this

Answer 16

Question 17

what is tidal volume

Answer 17

• amount of air moving in and out of the lungs

Question 18

what is inspiratory reserve volume

Answer 18

• additional amount of air that can be inhaled after normal inspiration (how much more air we breathe in after tidal volume)

Question 19

what is expiratory reserve volume

Answer 19

additional amount if air we can expel

Question 20

what is inspiratory capacity?

Answer 20

tidal volume + inspiratory reserve volume

Question 21

what is functional residual capacity

Answer 21

expiratory reserve volume + residual volume

Question 22

vital capacity equation

Answer 22

volume exhaled after max inspiration - sum of inspiratory volume + tidal volume + expiratory reserve volume

Question 23

DLCO test

Answer 23

• diffusing capacity carbon monoxide
• lets us determinate how much oxygen travels from alevoili of lungs to blood eg diffusion
• can be decreased due o:
• emphysema - reduced surface area
• alveolar inflammation - increased thickness
• pulmonary fibrosis - increased thickness

Question 24

how do you differentate different restrictive lung diseases

Answer 24

- parenchymal lung disease -> restructive pattern and abnormal DLCO - chest wall abnormalities - normal DLCO - neuromuscular (myasthenia gravis) normal DLCO