Restrictive lung disease Flashcards
What are the two classifications of pulmonary disease?
And describe each
Restrictive disease:
Characterised by reduced expansion of lung prenchyma with decreased total lung capacity while the expiratory flow rate is near normal.
Obstructive disease:
Characterised by limitation of airflow to partial or complete obstruction at any level from tachea to respiratory bronchioles.
can be reversible or non-reversible
In restriction of air, how can expansion of the lung be impaired?
Expansion of the lung can be impaired by:
- reabsoprtion of air due to occlusion of bronchus
- compression from fluid in the pleural cavity (can be squashed by something from outside, or by build up of fluid)
- contraction due to intrinsic lung disease (may be due to fibrosis which makes the lung shrink)
What is resorption Atelectasis (Collapse)?
Resoprtion Atelectasis is the fancy word for lung collapse.
It’s caused by obstruction of conducting airway (e.g. mucus plugs, foreign bodies).
Air in parenchyma distal to obstruction is slowly reabsorbed, and a vacancy in thoracic cavity occurs, causing mediastinarl shift.
What is compression atelectasis?
Caused by compression of lung parenchyma by a solid, liquid, or gas within the pleural space.
e.g. Pneumothorax and haemothorax causing compression atelectasis
Describe how Contraction Atelectasis occurs?
Contraction atelectasis is caused by fibrosis of lung parenchyma preventing expansion. The changes can be focal or diffuse.
Fibrosis can be caused various causes: Radiation, infection, toxic injuery or systemic disease
What does restrictive disease cause?
Decreased pulmonary function secondary to decreased size of chest cavity or lungs.
And in restrictive disease there is reduction in elasticity of the lung reducing volume and capacity.
What are the two groups of causes which cause Acute respiratory distress syndrome (ARDS)?
ARDS can be caused by many conditions.
Direct injury to lung:
- Pneumonia, aspiration, pulmonary contusion (trauma), fat embolism, near-drowning, inhalation injuey, post-lung transpplant, oxygen.
Indirect lung injury
- sepsis, servere trauma with shock, cardiopulmonary bypass, acute pancreatitis, transfusion, uremia
What are the 3 phases of ARDS, and what starts this process?
Firstly it starts with diffuse alveolar damage (when damage to lung occurs), then proceeds to these phases
- Exudative phase
- Proliferative phase
- Fibrotic phase
Describe the sequence of evenths that occurs in the ARDS?
First you get a damaging stimulus, which may damage eithe the alveolar lining cells or to the alveolar capillary endothelium. This damage causes intersitial oedema, causing high protein exudation in alveoli membranes (Exudative phase).
After the exudative phase you get the proliferative phase.
There is regeneration of tyoe II alveolar lining cells, and inflammation of the intersitium (since in order to get rid of protein exudate inflammatory cells invade).
The the fibrotic phase occurs, where there is organisation leading to interstitial fibrosis. This can either be mild focal fibrosis which causes ~10% mortality from ARDS, or can be marked interstitial fibrosis causing honeycomb lung - causing death due to chronic severe respiratory impairment (~70% mortality in ARDS).
Describe features and findings of the exudative phase
In exudative phase:
- Lung is dark, red, firm
- 0-7 days
- capilary congestion
- Necrosis of alveolar Type I epithelial cells
- There is interstitial, alveolar edema, & heamorrhage
- You’ll see collections of neutrophils
- Alveolar collapse occurs (due to loss of surfactant)
- Fibrin thrombi
- Hyaline membrane lining alveolar ducts
descibe this
they are disteneded alveolar ducts with a pink hyaline membrane, with inflammatory cells in the interstitium
If a patient survives the exudative phase (intersitial oedema), what phase do they enter?
And describe this phase
If they survive the interstial oedema from the exudative phase they will enter the proliferative phase. Which occurs at around 1-3 weeks.
In the proliferative phase you get a proliferatioin of type II pneumocytes, and the macrophages remove the derbis from the protein exudate.
In the fibrotic phase there is repair with fibrosis, which thickens the alveolar walls (it can be mild focal fibrosis, or progressive fibrosis which causes honeycomb lung.
What is chronic restrictive ling disease?
Its a group of different diseases, but have similar clininical, pulmonary function test and pathological findings.
They represent 15% of non-infectious diseases of lungs. The end-stage is diffuse interstitial pulmonary fibrosis (honeycomb lung).
What are the two classifications of interstitial lung disease?
-
Granulomatous
- sarcoidosis
- hypersensitivity pneumonitis
-
Non-granulomatous
- Idiopathic pulmonary fibrosis
- disease of known etiology
What is a granuloma?
Is a group of epitheliod macrophages surrounded by lymphocytes.
(may contain giant cells)
Some granulomata show necrosis and in tuberculosis this is termed caseous (Cheese like) necrosis as seen in tuberculosis.
What is sarcoidosis?
- Multisystem disease
- Unknown etiology
- Non-caseating granuloma in many tissues and organs
- diagnosis must exclude other causes of granulomalous lung disease
Describe the histoloy of sarcoidosis
Non-caseating granuloma
Collection of epithelioid histiocytes rimmed by CD4 T-cells and fibroblasts
Giant cells
schaumann bodies
Asteroid bodies (inclusions)
What kind of disease is hypersensitivity pneumonitis? (Extrinsic allergic alveolitis)
And what are it’s causes
and it’s morphology
It’s an immune mediated disease
- It’s a type III and type IV hypersensitivity inflammatory disease, and affects the small airways mainly with a bronchocentric distribution
Causes:
- Fungal/bacterial
- Farmer lung: micropolyspora
- Humidifier lung: Actinomycetes
- Cheese washer’s lung: penicillium
- Animal product
- Pigeon breeder’s lung
- Chemicals
Morphology
- Caused by inhaled particles (not ususally visibile)
- Inflammation, edema with peribronchial distribution comprising lymphocytes and plasma cells
- Non-caseating granuloma
- Fibrosis
Pathogenesis
What can be see in this slide of idiopathic pulmonary fibrosis
Lots of spindle cells, and proliferating myofibroblasts in the interstitium
What is this?
Honey comb lung - seen in end stage of disease
