Peripheral lung disease

Question 1

list the 3 major types of lung disease

Answer 1

asthma -> increased airway resistance (obstructive)

COPD-> emphysema changes lung compliance and also affects airway resistance (obstructive)

fibrosis-> decreased lung compliance (restrictive)

Question 2

what is the pathology of asthma?

Answer 2

• chronic airway inflammation
• increased airway responsiveness
• bronchoconstriction –> increased R
• airway obstruction -> airway obstruction
• inflammation and infiltration of alveolar walls by immune cells
• effective airway diameter reduced (mucus plug)

Question 3

what can the pathology asthma lead to?

Answer 3

• decreased alveolar VE –>hypoventilation -> decreased PA02 and increased PACo2
• decreased PPG for diffusion of 02 and Co2 –> hypoxia (decreased pa02) and hypercapnia (increased paco2)

Question 4

what do lung function tests on patients with asthma reveal?

Answer 4

• reduced FEV1/FVC ratio to 0.25%
• PEFR reduced
• bad asthma shows a decreased ratio with continued testing

Question 5

list some relievers for asthma treatment

Answer 5

• these are bronchodilators leading to an acute reduction in resistance
• b2 agonists -> salbutamol and salmeterol

theophyllines-> aminophylline

• anti-muscarinics -> ipatropium bromide

Question 6

list some preventers for asthma treatment

Answer 6

• anti-inflammatory steroids -> chronic reduction In inflammation
• steroids -> counteract airway inflammation -> beclomethasone and prednisolone
• leukotriene receptor antagonists -> block actions of bronchoconstriction -> montelukast

Question 7

what is the pathology of COPD?

Answer 7

• Alveolar destruction (emphysema) -loss of elastic recoil and airway radial traction + reduced SA for diffusion
• Airway obstruction (increasing R)
• Air trapping (air gets stuck in the lungs)–> hyperinflation (barrel chest) and inflammation of airways due to reoccurrence of pathogens in the trapped air
• Trapped air becomes hypoxic /hypercapnic
• Elastic recoil of lung tissue keeps airways open
• COPD–> loss of elastic recoil leads to collapse of airways and increased airway resistance

Question 8

how can COPD be diagnosed via a lung function test?

Answer 8

• Reduced PEFR–> loss of elastic recoil main determinant of expiration
• Reduced FEV1 <80% predicated
• FEV1:FVC <70% predicated

Classification of COPD severity based on FEV1

• Mild -> 50%-80% predicated
• Moderate -> 30-49% predicted
• Severe -> <30% predicated

Question 9

what Is the pathology of fibrosis?

Answer 9

• Environmental factors, systemic diseases, drug side effects which affect alveoli and lung interstitium–>increase fibroblast proliferation
• Diseases include:
• Idiopathic pulmonary fibrosis
• Idiopathic interstitial pneumonias
• Connective tissue disease (eg rheumatoid disease, systemic sclerosis)
• Extrinsic allergic alveolitis
Sarcodosi

Question 10

what are the symptoms of fibrosis ?

Answer 10

• Dyspnoea (breathlessness)
• Dry cough
• Lung crackles
• Hypoxaemia with hypercapnia

Question 11

what would be viewed under a histological examination?

Answer 11

• increased fibroblast proliferation
• increased secretion of elastin and collagen
• Fibrocollagenous thickening of alveoli
• Decreased lung compliance
• Increased thickness of diffusion barrier

Question 12

what would the results of a lung function test show in a patient with fibrosis ?

Answer 12

• reduced TLC
• reduced VC
• no change in FEV1/ FVC ratio
• FVC only smaller due to less air in lungs not due to increased resistance of airways