Week 5 - RESP Flashcards
Asthma, Pneumoconioses, Acute Lung Injury
1
Q
What is the pathogenesis of acute lung injury?
A
- noxious/irritant stimulus
- necrosis of type I pneumocytes
- epithelial/endothelial injury and inflammation
- neutrophils –> inflamm. mediators and proteases
- breakdown of tissue, vasodilation and plasma protein leakage (EXUDATION)
- leaked plasma proteins deposited as protein layers which line alveolus and inhibit oxygenation (HYALINE MEMBRANE) –> diffuse alveolar damage (DAD)
- severe hypoxia, atelectasis, wet heavy lungs filled with exudate
- healing –> type II pneumocyte proliferation
2
Q
What is goodpasture syndrome?
A
- autoimmune disorder of both kidneys and lungs –> anticollagen Ab!
- diffuse alveolar hemorrhage + rapidly progressive glomerulonephritis
- rapidly progressive pulmonary and renal failure
3
Q
What are 2 important complications in newborns with respiratory distress syndrome?
A
- Retrolental Fibroplasia
2. Bronchopulmonary Dysplasia
4
Q
What is the definition of acute lung injury?
A
- rapid onset hypoxemia and alveolar damage in the absence of heart failure
- non-cardiogenic pulmonary oedema
- more severe form = Adult Respiratory Distress Syndrome (ARDS)
5
Q
What are to common etiologies of acute lung injury?
A
- pneumonia/sepsis
- shock
- gastric aspiration
6
Q
True or False?
There is clubbing in asbestosis
A
True
-there is clubbing in 50% of patients
7
Q
What do asbestos bodies cause?
A
- very severe extensive fibrosis
- they are very small fibres which are carried to the lung periphery to small bronchioles –> pleural surface –> form PLEURAL PLAQUES
- Asbestosis
- diffuse fibrosis, honeycombing, pleural thickening, pleural effusions, dyspnoea, cough
8
Q
What is sarcoidosis?
A
- granulomatous multisystem inflammation in response to an UNKNOWN antigen
- 90% pts show lung involvement (diffuse interstitial fibrosis)
9
Q
What are the clinical features of sarcoidosis?
A
- fever
- fatigue
- weight loss
- anorexia
- night sweats
- lymphadenopathy
- SOB from diffuse interstitial fibrosis
- erythema nodosum
- hypercalcemia
- nephrocalcinosis
10
Q
What is the most characteristic finding in sarcoidosis?
A
Granuloma formation
- non-caseating
- contain ASTEROID bodies in giant cells!
*asteroid bodies = star-like shaped inclusions within the giant cells of the non-caseating granulomas
11
Q
What are the 2 types of asbestos bodies?
A
- Flexible serpentine
- Stiff straight amphibole
*both cause severe damage and fibrosis
12
Q
What is the commonest type of pneumoconioses?
A
silicosis
13
Q
What are the morphologic types of pneumoconioses?
A
Inert - coal workers pneumonia
Fibrous - asbestosis, silicosis
Allergic - bird watchers lung
Neoplastic - mesothelioma -> cancer of pleural laye - common in asbestosis
14
Q
What are the 5 various grades of coal miners lung?
A
- Asymptomatic anthracosis (carbon only)
- Simple coal workers pneumonia
- Complicated coal workers pneumonia (fibrosis)
- Progressive massive fibrosis (PMF) - severely decreased pulmonary function
- Honeycomb lung –> end-stage lung (total destruction)
15
Q
What is the etiology of silicosis?
A
- inorganic sand & stone dust
- lung injury
- activated lymphocytes/macrophages
- proteases/oxidants also from neutrophils
- destruction of type I pneumocytes
- increased type II pneumocytes
- increased FGFs/fibroblasts –> FIBROSIS!
16
Q
What is the morphology of silicosis?
A
- multiple focal fibrotic nodules (with silica particles in the centre of nodules)
- carbon pigment
- surrounding irregular emphysema
- diffuse fibrosis –> honeycomb
17
Q
What are the microscopic features of idiopathic pulmonary fibrosis?
A
- irregularly thickened alveolar septum with marked fibrosis and lymphocytes/macrophages within
- marked hypertrophy of type II pneumocytes (forming clusters)
18
Q
What is heard on auscultation of idiopathic pulmonary fibrosis?
A
dry “velcro-like” inspiratory crackles
19
Q
What is the pathogenesis of restrictive lung diseases?
A
- Lung injury (inhaled agents, dusts, toxins)
- Activated lymphocytes + macrophages/neutrophils –> oxidants/proteases damage type I pneumocytes –> increased replication of type II pneumocytes
- Interstitial inflammation and fibrosis –> type II pneumocytes secrete FGFs –> fibroblasts –> FIBROSIS
- Stiff Lung!
20
Q
What are the 2 key features in sputum microscopy of asthma?
A
- Charcot-Leyden Crystals
- eosinophil basic protein
- part of eosinophil granules –> form big crystals in sputum - Curschmann Spirals
- long mucous threads with eosinophils inside
21
Q
What are the microscopic features of asbestosis?
A
- pulmonary oedema
- emphysema with asbestos bodies
22
Q
True or False?
Asbestosis typically causes pulmonary oedema
A
True
23
Q
Progressive Massive Fibrosis (PMF) is typically seen in?
A
Coal Miner’s Lung
24
Q
Fibrotic nodules on microscopy are typically seen in?
A
Silicosis
25
What are gross and microscopic features of respiratory distress syndrome? (infants)
Gross:
-purple, congested, wet, heavy, airless lungs (airless due to lack of surfactant)
Micro:
- collapsed, inflamed alveoli
- hyaline membrane of plasma proteins lining alveoli with necrotic cells
*total dysfunction --> severe hypoxemia
26
What is the etiology of respiratory distress syndrome?
- prematurity (<28wks) = MOST COMMON
| - maternal diabetes, maternal sedation, trauma
27
What is the pathogenesis of respiratory distress syndrome?
- immature lung
- decreased surfactant (as type II pneumocytes have not fully developed)
- when child takes first breath, there is no surfactant to increase compliance/decrease surface tension --> atelectasis as alveoli cannot stay open
- inflammation results --> exudation
*similar to ARDS but this is in a newborn (HMD)
28
What is respiratory distress syndrome?
Hyaline Membrane Disease of new born (HMD)
29
What is DAD/Acute Lung injury referred to as when it is severe? and how does healing occur?
ARDS --> Adult Respiratory Distress Syndrome
*Healing by type II pneuomocyte proliferation
30
True or False?
| normal/near normal FEV1/FVC ratio is a typical feature of obstructive pulmonary disease COPD
False
| -restrictive (but decreased TLC)
31
True or False?
| sarcoidosis is more common in smokers
False
| -smoking may give protection
32
True or False?
| Carbon alone does not cause damage in coal miner's lung
True
- acanthrosis + silicosis = coal workers pneumonia
- associated SILICA causes fibrosis
- carbon alone causes blackening of lung tissue but is usually asymptomatic --> "asymptomatic acanthrocis"
33
What is the etiology of pneumoconioses?
```
Due to inhaled dusts
-inorganic (mineral) or organic
Reaction may be:
-inert
-fibrous
-allergic
-neoplastic
*depending on type of dust
```
34
What is idiopathic pulmonary fibrosis also referred to as?
Usual Interstitial Pneumonia (UIP)
35
What size particles cause most damage to alveoli?
1-5microns
- <1 micron = easily removed
- >5 microns = too large to reach/deposited in terminal alveoli
*carbon, SILICA, asbestos --> commonest particles
36
Compare type I and type II pneumocytes
Type I:
- larger, squamous cells --> make up most of alveolar wall
- involved in gas exchange
- susceptible to toxic insults and CANNOT replace itself
Type II:
- cuboidal type cells occur more diffusely
- secrete surfactant and FGFs --> fibrosis
- CAN replicate itself and will replace damaged type I pneumocytes
37
What is an example of an extrinsic disorder causing restrictive lung disease?
- kyphosis
- scoliosis
- gross obesity
38
True or False?
| Expiration on a respiratory flow curve occurs over a longer duration in restrictive lung disorders
False
-restrictive lung disorders = lung cannot expand --> therefore decreased compliance --> expiration occurs over a SHORTER duration
*whereas obstructive disorders --> expiration occurs over a longer duration
39
What is the definition of restrictive lung disorders?
- decreased expansion of lung due to diffuse fibrosis ("stiff lung" --> decreased lung compliance)
- decreased FEV1/FVC --> therefore FEV1:FVC ratio is roughly normal (but TLC id decreased)
40
What is status asthmaticus?
- persisting, severe exacerbation of an asthmatic attack with NO response to therapy --> excess mucous plugging major bronchi
- severe hypoxia, hypercapnia, and acidosis --> may be FATAL
- hyperinflation of lungs --> bronchi constricted so air retained in alveoli
41
What is the only difference in microscopy between asthma and chronic bronchitis?
Very similar microscopy
| -except, plenty of eosinophils in asthma and in chronic bronchitis = increase neutrophils
42
What are gross and microscopic features of asthma?
Gross:
- inflamed, thick bronchi
- mucous plugs
Micro:
- excess mucous (with eosinophils in mucous)
- goblet cell hyperplasia
- inflammation with eosinophilia
- smooth muscle cell hyperplasia
- mucous gland hyperplasia
- increased capillaries/vasodilation
43
What is the hygiene hypothesis?
- proposes that childhood exposure to germs and certain infections helps immune system to develop
- teaches body to differentiate harmless substances from harmful substances that trigger asthma
- exposure to certain germs 'teaches' immune system NOT to overreact (hypersensitivity)
44
What is the pathogenesis of asthma?
- Th2 lymphocyte stimulation via dendritic cell with allergen attached
- IL-4 release --> B cells for IgE secretion --> attach to mast cells
- IL-5 release recruits eosinophils which release chemical mediators and granules
- IL-13 causes mucous production
- mast cells --> histamine release, etc
- inflammation + episodic bronchospasm --> from exposure to irritants (caused by mast cell secretions)
45
What do allergens stimulate in acute vs. chronic allergic reactions?
```
Acute = Mast cells
Chronic = Dendritic cells --> Th2 cells
```
46
Which inflammatory cells are predominantly present in asthma?
eosinophils
47
What are asthma triggers and in which types of asthma do they occur?
- infections
- smoke
- fumes
- stress
- exercise
*ALL types
48
What are the types of asthma?
Atopic *COMMONEST
-allergen, early age, FHx.
Non-atopic
-no allergen, adult, no FHX., usually due to reaction to pollutants/viral infection
Other
- drug-induced (aspirin)
- occupational
49
What is the commonest type of asthma?
Atopic
- allergen (hypersensitivity to environmental allergen)
- early age (childhood)
- FHX. (either autoimmune or hypersensitivity disorders)
50
What is the key difference between asthma and COPD?
```
COPD = permanent/irreversible due to scarring
Asthma = intermittent bronchospasm + reversible (no scarring)
```
