Lecture 13- Pulmonary lung function tests

Question 1

PFTs are tests that measure

Answer 1

• Lung volumes
• Rate of airflow
• Gas exchange (alveolar-vascular membrane)

Question 2

PFTs used to

Answer 2

• diagnose patients with resp symptoms
• establish severity and progression of lung disease
• assess treatment response
• monitor patients on meds with lung toxicity

Question 3

• Instruments used

Answer 3

• peak flow meter
• spirometry
• diffusing capacity of CO (DLCO)- provides info about alveolar-capillary membrane diffusing capacity

Question 4

define peak expiratory flow

Answer 4

Maximum airflow rate attained during forced expiration (PEFR)

Question 5

normal peak PEFR

Answer 5

• Normal >80% of predicted average based on
  
  • Ethnicity
  • Height
  • Gender
  • Age

Question 6

what is used to measure PEFR

Answer 6

peak flow meter

Question 7

baseline PEFR measured when

Answer 7

when pt is asymptomatic

Question 8

• PEFR Useful in monitoring people with

Answer 8

asthma

Question 9

Spirometry

Answer 9

• Used to measure some lung volumes
• Calculates airflow as volumes are measured over time
• Reports those values
• Also produces graphical representations

Question 10

graph which can be produced by spirometry

Answer 10

Question 11

Which values will spirometry give

Answer 11

• Tidal volume
• Inspiratory reserve volume
• Expiratory reserve volume
• Inspiratory capacity
• Forced expiratory volume in 1 second (FEV1)
• Forced vital capacity (FCV)
• FEV1/FVC

Question 12

• Tidal volume

Answer 12

• Breathing quietly
• How much air you breathe in and out of the lungs

Question 13

• Inspiratory reserve volume

Answer 13

Extra air inspired above and beyond normal inspiration (tidal volume)

Question 14

• Expiratory reserve volume

Answer 14

Extra air expired above and beyond normal expiration

Question 15

• Residual volume
  *

Answer 15

• Air left in lungs after expiratory reserve volume
  
  • Spirometry cant measure this- can only measure air that can be blown or sucked into tube

Question 16

• Functional reserve volume

Answer 16

= expiratory reserve volume + residual volume

• Also cant measure this using spirometry
• Represents the balance between lung inner elastic recoil and chest wall outer elastic recoil
• Volume of air left when the forces are equally balanced

Question 17

• Inspiratory capacity

Answer 17

Amount of air I can breathe in (tidal volume) + inspiratory reserve volume

Question 18

• Vital capacity

Answer 18

Amount of air breathe out after maximum inspiration

Question 19

• Total lung capacity

Answer 19

• • Vital capacity + residual volume
    
    • Spirometry cant give this

Question 20

• Forced expiratory volume in 1 second (FEV1)

Answer 20

- maximum volume of can be forcefully expired within 1 second after maximal inspiration

Question 21

• Forced vital capacity (FCV)

Answer 21

• total amount of air exhaled after maximal inspiration during entire FEV test – occurs over 6 seconds

Question 22

• FEV1/FVC r

Answer 22

• epresents proportion of patients forced vital capacity that they are able to expire in first second of forced expiration
  
  • FEV1:FVC <70% (0.7) obstructive airway disease

Question 23

volume time plot

Answer 23

shows FEV1 and FVC graphically

• characteristic shape
• Healthy plot
  • FEV1 = 4l
  • FVC= 5l

Question 24

Flow volume loops (spirotmetry doesn’t measure these)

Answer 24

• Volume of air present in lungs at transition maximum inspiration expiration = total lung capacity
• Volume of air present in lungs transition expiration to inspiration= residual volume (RV)

Question 25

example of obstructive lung disease

Answer 25

COPD and asthma

Question 26

volume time plot and flow voluem loops in obstructive diease

Answer 26

**Volume time plot** * Asthma/COPD – full line * FEV1 is less than normal person * FEV1= 1.5 in asthma/COPD / FEV1= 4 in normal peron * therefore FEV1/FVC ratio \<70% * FCV will be pretty normal- jsut takes longer to get to maxinal value **Flow volume loop** * We are looking at the shape * Full line = obstructive lung disease (COPD/Asthma) * Peak flow rate less (peak flow meter can also measure this) * **Coving/notching** on expiration * Peak flow rate falls quicker * Marked obstruction of flow during expiration * Not much difference on expiration

Question 27

main feature of obstrucitve lung disease

Answer 27

* **OBstrUtive** * **O=** harder to breath **OUT** * **B=** PFTs **BELOW** normal value * **U= UPPER value (numerator) reduced)**

Question 28

Obstructive disease and FEV1

Answer 28

will bedecreased by more than 70% - how much FEV1 decreased below normal provides ifno about disease severity

Question 29

COPD and FVC

Answer 29

FVC initially normla, will decrease in severe disease

Question 30

asthma and FVC

Answer 30

FVC typically decreased- small airways close prematurely

Question 31

key diagnostic finding for obstructive lung disease

Answer 31

FEV1:FVC \<0.7

Question 32

Obstructive kung disease and TLC (total lung capcity) and FRC (functional residual capacity)

Answer 32

if there is air trapping because iof small airway collapse- TLC and FRC will be increased because of increased residual volume (RV)--\> air lef tin the lungs after breathing out

Question 33

how to determine if the obstructive lugn disease is asthma or COPD

Answer 33

PT given bronchodilator after baseline spirometry is taken and the values are compared * FEV1 12% or greater after bronchodilator – asthma * Not greater after bronchodilator in COPD * COPD is irreversible lung disease (minimal response to Beta agonists inhalers) * some people will have some degree of revrsibility through inhalers- most wont

Question 34

examples of restrictive lung disease

Answer 34

ILD and myasthenia gravis (chest wall weaker in MG)

Question 35

**Restrictive lung disease also known as**

Answer 35

* stiff lungs

Question 36

in restictive lung disease stiff lungs means

Answer 36

* hard to expand- hard to inspire (breathe in) * return to original volume very quickly (very elastic)

Question 37

why are lungs stiff in restrictive lung disease

Answer 37

inbalance between lung elastic recoil and chest elastic recoil

Question 38

volume time plot and flow volume loop for restrcitve lung disease

Answer 38

**Volume time plot** * **FEV1 can be normal- will typically be reduced though** * Amount of air that can be removed in 1s- if you have smaller amount of air in lungs- going to be less air to blow out * Not that they cant get it out quickly * **FVC markedly decreased** * Less air in lungs to begin with due to stiffness of lungs reducing the amount of air in the lungs to start with **Flow volume loop** * Shape is the same as healthy lung * Total volume being moved in/out of lungs markedly decreased

Question 39

**DLCO- not part of ...................- part of PFTs**

Answer 39

spirometry

Question 40

DLCO stands for

Answer 40

* Diffusing capacity carbon monoxide * Determines how much oxygen travels from alveoli of lungs to bloodstream i.e. diffusion

Question 41

PFT results restrictive lung disease

Answer 41

* normal/increased FEV/FVC ration (both may be reduced, but FVC is most markedly reduced) * TLC and FRC will be reduced to reduced lung capacity

Question 42

DLCO can provide info on

Answer 42

* Can provide info about alveolar-capillary membrane * Can be decreased in many conditions including

Question 43

in which conditions may DLCO be reduced

Answer 43

* Emphysema – decreased SA * Alveolar inflammation- increased thickness due to pus * Pulmonary fibrosis – increased thickness * These conditions would have normal spirometry or chest x-ray

Question 44

**So what does an abnormal DLCO with normal chest x-ray and spirometry suggest?**

Answer 44

Suggests problem with vascular part of membrane * **Idiopathic pulmonary arterial hypertension** * Pulmonary arterial become thickened- impaired diffusion * Drugs that supress appetite can cause this- don’t know why * **Chronic thrombo-embolic disease of lungs** * Need other tests to confirm

Question 45

volume time plot for different disease state

Answer 45

Question 46

flow volume loops in different disease states

Answer 46

Question 47

**How do you differentiate different restrictive lung disease**

Answer 47

**By looking at the DLCO**

Question 48

DLCO in myasthenia gravis (RLD)

Answer 48

* Restrictive pattern on spirometer * DLCO will be normal (problem with the lung parenchyma (muscle) not the alveolar capillary barrier

Question 49

* **ILD and DLCO**

Answer 49

* Restrictive pattern on spirometry * Abnormal DLCO- thickening of barrier between alveoli and capillaries

Question 50

Summaery table comparing obstructive and restrictive PFTS

Answer 50