Pathology of obstructive lung disease

Question 1

What is Chronic Obstructive Pulmonary disease? (COPD)

Answer 1

Chronic bronchitis and emphysema occurring together

Question 2

What is FEV1?

Answer 2

FEV1 is the Forced Expiratory Volume of air exiting the lung in the first second of this exercise.
Usually about 70-80% of FVC
Normally about 3.5-4 L

Question 3

What is FVC?

Answer 3

FVC is the Final Total amount or air expired
Normal FVC is 5 L

Question 4

What is the normal ratio of FEV1:FVC?

Answer 4

0.7-0.8

Question 5

Give the negative characteristics of obstructive lung disease?

Answer 5

-there is airflow limitation
- peak expiratory flow rate is reduced
-FEV1 is reduced
-FVC may be reduced
-FEV1 is less than 70% of FVC

Question 6

What are the two mechanisms of reduction of the luminal cross-sectional area of the airways?

Answer 6

type 1 hypersensitivity in lungs- orchestrated by the granulation of mast cells in our airways.
Degranulation of mast cells releases lots and lots of different chemical factors which orchestrates an inflammatory response in the airways.
De granulation of mast cells also releases substances which cause smooth muscle to contract either very quickly or sometimes very slowly.
Cross sectional area of that airway will reduce and that will cause airflow limitation.

The evolution of that inflammatory response with lots of lots of inflammatory cells and perhaps fluid and oedema causes swelling of the bronchial mucosa.
This also reduces the cross sectional luminal area of the airways that are affected.

Question 7

Why is bronchial asthma considered to be reversible?

Answer 7

bronchial smooth muscle contraction and inflammation can both be modified by drugs

Question 8

What are the factors of COPD?

Answer 8

• common factor is irritation (inhalation of substances that cause irritation to the airway)
  tobacco smoking
  atmospheric pollution
  dust
  -effect of age and susceptibilty
  -more common in men as men tend to smoke more

Question 9

What is the rare cause of emphysema that is an enzyme deficiency?

Answer 9

Alpha-1-antiprotease (antitripsin) deficiency

Question 10

How is chronic bronchitis defined clinically?

Answer 10

Cough productive of sputum most days over a period of three consecutive months for two or more consecutive years

Question 11

What is chronic bronchitis clinically confused for?

Answer 11

chronic bronchial asthma

Question 12

What is an infective exacerbation of chronic bronchitis?

Answer 12

when sputum turns mucopurulent -turns yellow or green (acute infective exacerbation)

Question 13

What is complicated bronchitis?

Answer 13

When FEV1 begins to fall

Question 14

Describe the morphological changes in the large airways in chronic bronchitis?

Answer 14

-mucous gland hyperplasia
-goblet cell hyperplasia
-inflammation and fibrosis is a minor component

Question 15

Describe the morphological changes in the small airways in chronic bronchitis?

Answer 15

-goblet cells appear
-inflammation and fibrosis in long standing disease

Question 16

How is emphysema defined?

Answer 16

Increase beyond the normal in the size of airspaces distal to the terminal bronchiole arising either from dilatation or from destruction of their walls and without obvious fibrosis

Question 17

Describe centriacinar emphysema?

Answer 17

the loss of the alveolar tissue occurs in the middle of the acinus

Question 18

Where does centricacinar emphysema predominantly occur?

Answer 18

in apical parts of the upper and lower lobes

Question 19

Describe panacinar emphysema?

Answer 19

predominantly occurs in the basal parts of the lung and it’s a complete wipe out
-all of the alveolar walls in the affected acinus are wiped out

Question 20

Describe periacinar emphysema?

Answer 20

when emphysema develops at the edges of the acini and not in middle
-aini against pleura get spaces underneath the pleura
-associated with smoking and genetics (tall young people)
-if “blebs” pop and leak- get a pneumothorax

Question 21

How do patients with chronic bronchitis and emphysema find it easier to breathe?

Answer 21

find it easier to breathe in and out by retaining a lot of air in their lungs and therefore develop hyper inflation

Question 22

Describe the pathogenesis of emphysema?

Answer 22

• smoking
• protease - antiprotease imbalance
  ageing
  alpha -1 -antitrypsin deficiency

Question 23

What are anti proteases for?

Answer 23

to protect our lungs against the effect pf our inflammatory cell proteases
-when balance is maintained the elastin and the other structural proteins in the lung tissue are safe

Question 24

What happens if you have alpha 1 antitrypsin deficiency?

Answer 24

don’t have the anti-proteases and may have severe emphysema

Question 25

Why would smoking contribute?

Answer 25

various compounds in tobacco smoke which negate the function of the anti proteases. Increase proteases and inflammatory cells - tissue destruction.

Question 26

Do patients with COPD get drugs to make them feel better?

Answer 26

the contracting of the small airways muscle and inflammation may be reversed

cant reverse fibrosis or emphysema (likely contributes most to airflow limitation by loss of alveolar tissue that surrounds terminal and respiratory bronchioles)

Question 27

What is hypoxia?

Answer 27

a reduction in the concentration of oxygen in the alveoli distal to that obstruction

Question 28

What are the causes of hypoxaemia in COPD?

Answer 28

airway obstruction - poor ventilation of alveoli
reduced respiratory drive - IMPORTANT
loss of alveolar surface area
shunt - only during severe acute infection

Question 28

Describe physiological pulmonary arteriolar vasoconstriction?

Answer 28

blood vessels carrying blood to areas of lung that are hypoxic constrict and therefore limit the amount of blood that goes to the well less oxygenated area of the lung

Question 29

What is pulmonary hypertension a result of?

Answer 29

Pulmonary vasoconstriction
Pulmonary arterioles
-muscle hypertrophy and intimal fibrosis
if lost aveolar tissues -Loss of capillary bed
Secondary polycythaemia – increased blood viscosity- heart trying to pump more viscous blood through fewer blood vessels that are narrower than normal
Bronchopulmonary arterial anastamoses

Question 29

What happens if you’re globally hypoxic and when all of your pulmonary arterials constrict?

Answer 29

nowhere for blood to go and more stress put on RHS of heart and RHS suffers badly.
Pulmonary hypertension

Question 30

What is hypoxic cor pulmonale?

Answer 30

heart disease because of a lung disease thats causing hypoxia

Question 30

Why is pulmonary artery pressure lower than pressure in aorta?

Answer 30

vascular resistance in lungs is very low, much lower than systemic vascular resistance. Therefore pulmonary artery pressure is much lower than the pressure in the aorta because you don’t in normal situation as much pressure to make the blood flow through your lungs.

Question 30

What happens to patients with longstanding hypoxic cor pulmonale?

Answer 30

the strain RHS of heart causes muscle bunk in right ventricle to increase and eventually it fails