Session 2 - Lung Diseases

Question 1

What is interstitial lung disease and give an example

Answer 1

Stiff lungs due to fibrotic tissue in interstitial space (between alveolar cells and capillary basement membrane)

Many causes

End result tissue injury and fibrosis

Question 2

What effects does fibrotic tissue in the interstium have on the lungs ( pathophysiology )

Answer 2

Lungs stuff , hard to expand since collagen less stretchy than elastin, lung compliance reduced

Elastic recoil incr ( both elastin and collagen fibres returning to original size , collagen not stretchy )

Small lungs due to incr elastic recoil

Reduced chest expansion on examination

Causes restrictive type of vent defect

Question 3

Why are the airways normal in interstitial lung disease and what’s it called

Answer 3

Fibrous tissue exert outward pull ( radial traction ) on small bronchioles keep airways open

Question 4

Why in interstitial disease would oxygen values decrease but co2 normal

Answer 4

Thickening of alveolar walls increases the distance o2 has to diffuse from alveolar air to blood

But the effect on diffusion of o2 is greater than that on Co2 which is more soluble

Question 5

What are symptoms and signs of interstitial disease

Answer 5

Shortness of breath, reduced exercise tolerance, dry cough

Signs : incr resp rate , tachycardia

Question 6

Many causes but all have same result (sometimes not even known cause) for interstitial lung disease

Answer 6

Do not need to know list of causes

Question 7

What is respiratory distress syndrome

Answer 7

Occur in newborns (another stiff lung disorder(

Deficiency of surfactant in babies less than 32 weeks

Question 8

Describe what happens in RDS

Answer 8

Without surfactant the ST in alveoli is high making lungs harder to expand so some alveoli collapse and no gas exchange occur

Stiff lungs so low compliance

More effort to breathe resulting in impaired ventilation

Question 9

Signs of RDS

Answer 9

Grunting
Cyanosis
Intercostal recession on inspiration

Question 10

Treatment of RDS

Answer 10

Surfactant replacement and o2 with assistant ventilation

Question 11

What is emphysema and what does it cause

Answer 11

Loss of elastin and breakdown of alveolar walls

causes incr lung compliance and narrowing of small air ways

Question 12

What is the main cause of emphysema and why

Answer 12

COPD - caused by smoking which breaks down elastin fibres in alveolar walls

Question 13

Pathophysiology (due to loss of elastin , opp of lung fibrosis)

Answer 13

Lungs EASY to expand as there is LESS elastin so compliance incr

Elastic recoil reduced which cause lungs to be hyper inflated at rest

Barrel chest due to hyper inflation

Small airways narrow due to loss of elastin exerting outward force (radial traction) on small bronchioles

Obstructive type of defect

Question 14

Symptoms of emphysema

Answer 14

Shortness of breath and reduced exercise tolerance

Question 15

What is one main lung function test

Answer 15

Spirometry

Question 16

What is asthma and what triggers it

What happens (pathophysiology)

Answer 16

Chronic inflam process which can be triggered by allergies

Airway narrowing due to bronchial smooth muscle contraction

Thickening of airway walls by mucosal oedema and excess mucus production can partially block lumen

Question 17

Describe what a pneumothorax is

Answer 17

Air enters pleural space, loss of pleural seal along with lung collapse

At rest, the neg pressure is slightly less than atmospheric creating pleural seal to keep lungs adhered to chest wall but when opening created air will flow into pleural cavity down pressure gradient until pressure in pleural sanity reaches atmospheric

Breaks pleural seal which disrupts elastic recoil causing lung to collapse toward hilum cuz neg pressure and chest wall outward recoil cannot counteract it

Question 18

What are others causes of lung collapse (atelectasis)

Answer 18

• incomplete expansion of lungs

- collapse of previously inflated lung producing areas of airless parenchyma

Question 19

What are the main types of acquired atelectasis (lung collapse)

Answer 19

• compression occur when fluid or air acculturate in pleural cavity
• resorption from complete airway obstruction cuz overtime air is resorbed from alveoli which collapse (bronchial carcinoma)

Question 20

When the term lung collapse is used on its own what is it referring to

Answer 20

Resorption atelectasis secondary to airway obstruction ( lung tumour etc )

Question 21

What is hypoventilation

Answer 21

Poor expansion of thoracic cavity or lungs

Cause : resp uncle weakness , thoracic wall defects can cause this and resp failure , stiff lungs , severe airway constriction

Question 22

What is required for normal ventilation

Answer 22

Neurones from resp center in brain to reach resp muscles via spinal nerves

Expansion of thoracic cavity and lungs

Normal bony thorax