Interstitial Lung Disease Flashcards
What is the interstitial space?
A potential space between alveolar cells and the capillary basement membrane, which is only apparent in disease states
What may the interstitial space contain in disease states?
Fibrous tissue, cells, or fluid
What is interstitial lung disease?
A group of diseases with a variety of causes, that all have similar pathological effects and clinical features
What is the pathophysiology of interstitial lung disease?
The development of fibrous tissue in the intersticium, producing a restrictive ventilatory defect
Why does the development of fibrous tissue in the intersticium produce a restrictive ventilatory defect?
Because it makes the lungs less compliant
Is airway resistance increased in interstitial lung disease?
No
How can the FEV1/FVC ratio be kept >70% in interstitial lung disease?
Due to increased radial traction on the airway keeping the airway open
What impairs gas exchange in interstitial lung disease?
Lengthening of the diffusion path
What is selectively affected in interstitial lung disease?
Oxygen uptake
Why is oxygen uptake selectively affected in interstitial lung disease?
As CO2 diffuses much more readily
What are the symptoms of interstitial lung disease?
- Shortness of breath
- Reduced exercise tolerance
- Dry cough
What are the signs of interstitial lung disease?
- Tachypnoea
- Tachycardia
- Reduced chest movement bilaterally
- Coarse crackles
What signs may be present in interstitial lung disease?
- Cyansosis
- Signs of right heart failure
When is clubbing seen in interstitial lung disease?
Cryptogenic fibrosing alveolitis
What are the categories of causes of interstitial lung disease?
- Occupational
- Treatment related
- Connective tissue disease
- Immunological
- Idiopathic
What are the occupational causes of interstitial lung disease?
- Abestosis
- Silicosis
- Coal workers pneumoconiosis
What are the treatment related causes of interstitial lung disease?
- Radiation
- Methotrexate
- Nitrofurantoin
- Amiodarone
- Chemotherapy
What connective tissue diseases can cause interstitial lung disease?
- Rheumatoid arthritis
- SLE
- Polymyositis
- Schleroderma
- Sjorgen’s
What are the immunological causes of interstitial lung disease?
- Sarcoidosis
- Hypersensitivity pneumonitis (EAA)
What are the idiopathic causes of interstitial lung disease?
- CFA/IPF
- UIP/NSIP
- DIP
- LIP
- RB-ILD
- COP (BOOP)
CFA- cryptogenic fibrosing alveolitis
IPF- idiopathic pulmonary fibrosis
UIP- usual interstitial pneumonia
NSIP- non-specific interstial pnuemonia
DIP- desquamative interstial pneumonia
LIP- lymphoid interstitial pnuemonia
RBILD- respiratory bronchiolitis interstiial lung disease
COP- crytogenic organising pneumonia
BOOP- bronchiolitis oblitirans organising pneuomnia
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What is fibrosing alveolitis?
A progressive inflammatory condition of an unknown cause
How common is fibrosing alveolitis?
Relatively rare, 3-5 cases per 100,000
How does the incidence of fibrosing alveolitis differ between the sexes?
It is two times more common in males
What are the histological features of fibrosing alveolitis?
Increased activated alveolar macrophages
What is the effect of increased activated alveolar macrophages in fibrosing alveolitis?
- Attract neutrophils and eosinophils
- Local lung damage
- Tissue destruction and fibrosis
Why do increased alveolar macrophages lead to local lung damage?
Due to ROS and proteases
What do patients report with fibrosing alveolitis?
Progressive shortness of breath on exercise, often with non-productive cough
Do patients with fibrosing alveolitis have finger clubbing?
Most do
What does the chest x-ray show in patients with fibrosing alveolitis?
Small lungs with micro-nodular shadowing predominating in the lower lobes, with ragged heart borders
When can fibrosing alveolitis be restrained?
In the early stages, less effective once fibrosis has developed
How can fibrosing alveolitis be restrained?
By treatment with high dose oral steroids
How is the effectiveness of treatment for fibrosing alveolitis monitored?
By repeated lung function tests
What causes extrinsic allergic alveolitis?
Inhalation of organic material triggers an allergic reaction in alveoli and bronchioles
Is extrinsic allergic alveolitis an acute or chronic condition?
Can be either
What are the characteristics of acute extrinsic allergic alveolitis?
- Sudden onset
- Rapidly progressing
Give an example of acute extrinsic allergic alveolitis
Farmer’s Lung
What is the antigen in Farmer’s Lung?
Thermophillic actinomycetes found in mouldy hay
How does Farmer’s Lung present?
- Influenza like illness 4-9 hours layer with a dry cough and breathlessness on exertion
- Fine mid and late inspiratory crackles
- May be a wheeze
Give an example of chronic extrinsic allergic alveolitis
Bird Fancier’s Lung
What causes Bird Fancier’s Lung?
Long term antigen exposure from pigeons and budgerigars
How does Bird Fancier’s lung present?
- Insidious malaise
- Dry cough and breathlessness over months and years
- Inspiratory crackles
What is meant by insidious malaise?
Feeling particularly unwell
Does finger clubbing occur with extrinsic allergic alveolitis?
No
What does a chest x-ray show in acute extrinsic allergic alveolitis?
Diffuse micro-nodular infiltrate, denser towards the hila
What does a chest x-ray show in chronic extrinsic allergic alveolitis?
May be almost normal, progressing to fibrosis in late disease
What do lung function tests show in extrinsic allergic alveolitis?
- Reduced compliance
- Reduced gas transfer
What causes asbestosis?
Inhalation of asbestos fibres
When does asbestosis often develop?
Long after the exposure
What is asbestos inhalation associated with?
- Three forms of disease
- Benign pleural plaques
- Asbestosis (pulmonary fibrosis)
- Mesothelioma
- Marked increase in lung cancer
What do asbestos fibres produce alveolitis?
When they can penetrate the alveoli
What happens once asbestos fibres have produced alveolitis?
- There is an influx of macrophages
- Alveolitis progresses to fibrosis
What does the influx of macrophages produce in alveolitis caused by asbestos?
Characteristic asbestosis bodies
What is required for a diagnosis of asbestosis?
A history of asbestos exposure
How does a patient with asbestosis present?
- Breathless on exertion
- Dry cough
- Inspiratory crackles at lung bases, which rise as the disease advances
What is the treatment for asbestosis?
None
What do lung function tests show in a patient with asbestosis?
- Small lungs
- Reduced compliance
- Impaired gas transfer
What causes sarcoidosis?
Unknown
What is sarcoidosis characterised by?
Non-caseating granulomas (non-necrotising) in multiple organs and body sites
Where is sarcoidosis most common?
In the lungs
What happens in sarcoidosis?
- Fluid is collected by lavage in the airways
- Alveoli contain lots of cells
What cells are present in large numbers in the alveoli in sarcoidosis?
Macrophages and lymphocytes
What is the epidemiology of sarcoidosis?
- More common in Afro-Caribbean and Asians than Caucasians
- Highest incidence in 30’s and 40’s
- More female cases
What can be determined from the fact that there is a difference in incidence between races?
There is a genetic predisposition
How does sarcoidosis present?
- Often asymptomatic
- Cough
- Breathlessness
How is the severity of sarcoidosis assessed?
Grading system from 0-4
What do chest x-rays show in patients with sarcoidosis?
- Miliary and nodular shadowing
- Diffuse fibrosis
What is the treatment for sarcoidosis?
Steroids
When are steroids effective in supressing sarcoidosis?
Stages 1-3
Give 4 occupational lung diseases
- Asthma
- Diffuse fibrosis
- Nodular fibrosis (e.g. pneumoconiosis)
- Alveolitis
What occupation is asthma associated with?
Lab workers
What is asthma related to being a lab worker due to exposure to?
Rat urine
What occupation is diffuse fibrosis associated with?
- Boiler/pipe laggers
- Railway/construction
What is diffuse fibrosis associated with exposure to?
Asbestos
What occupations is nodular fibrosis associated with?
- Coal Miner
- Miner
- Demolition
What is nodular fibrosis associated withe exposure to?
- Coal dust
- Silica
- Asbestos
What occupations is alveolitis associated with?
- Farmer
- Pigeon Fancier
What is alveolitis associated with exposure to?
- Fungal spores from hay
- Avian antigens
What is the x-ray appearance of fibrosing alveolitis?
- Small lungs
- Micro-nodular shadowing (lower lobes)
- Ragged heart borders
What is the x-ray appearance of acute extrinsic allergic alveolitis?
- Micro-nodular infiltrate
- Denser towards hila
What is the x-ray appearance of chronic extrinsic allergic alveolitis?
- Almost normal
- Progresses to fibrosis in late disease
What is the x-ray appearance of sarcoidosis?
- Miliary and nodular shadowing
- Diffuse fibrosis
What is the x-ray appearance of asbestosis?
- Holly leaf plaques
- Fibrosis
- Mesothelioma
What is the pleura?
A serous membrane
What does the pleura consist of?
A single layer of mesothelial cells with a thin layer of underlying connective tissue
Waht does the parietal pleura line?
The inside of each hemi thorax
What does each hemi thorax consist of?
- The bony thoracic cage
- Diaphragm
- Mediastinal surface
What does the parietal pleura become continuous with?
The visceral pleura
Where does the parietal pleura become continuous with the visceral pleura?
At the hilum of the lung
Where does the visceral pleura extend?
Between lobes of the lung into the depths of the oblique and horizonal fissures
What is the pleural cavity?
A potential space between the two layers of pleura that are continuous at the hilum
What are both layers of pleura covered with?
A common film of fluid
What produces the common film of fluid covering the layers of pleura?
The parietal surface
What is the fluid produced from the parietal surface absorbed by?
Parietal lymphatic vessels
What does the pleural fluid allow?
The two layers to slide on one another, thus in heatlh the pleura allows movement of the lung against the chest wall while breathing
What does the surface tension of the pleural fluid provide?
The cohesion that keeps the lung surface in contact with the thoracic wall
What is the result of the lung surface being in contact with the thoracic wall?
When the thorax expands in inspiration, the lung expands along with it and fills with air
Do the lungs occupy all the available space in the pleural cavity?
No, even in deep inspiration
Label this diagram
- A - Pleural cavity
- B - Collapsed lung
- C - Visceral pleura
- D - Parietal pleura
- E - Thoracic wall lined with endothoracic fascia
- F - Pheno-pleural fascia (part of endothoracic fascia)
- G - Suprapleural membrane
- H - Parts of parietal pleura
- Hi - Cervical pleura
- Hii - Mediastinal part
- Hiii - Costal part
- Hiv - Diaphragmatic part
- I - Endothoracic fascia
- J - Visceral pleura
- K - Diaphragm
- L - Mediastinum (contains heart)
- Orange - Visceral pleura
- Purple - Parietal pleura
- Blue - Costal pleura
- Green - Diaphragmatic pleura
- Red - Mediastinal pleura
- Yellow - Cervical pleura
- Solid - Fascial membrane (Suprapleural and mediastinal fascia, fibrous pericardium)
- Dashed - Endothoracic fascia
How much pleural fluid is turned over per day?
15ml, but can increase to 300ml
What produces pleural fluid?
Capillary filtration at the parietal pleura
How does capillary filtration produce pleural fluid?
Starling Forces
When does the amount of pleural fluid increase?
- When theres an increase in lung interstitial fluid
- When theres an increase in hydrostatic pressure
- When theres a increase in permeability
- When theres a decrease in oncotic pressure
What condition may cause an increase in hydrostatic pressure?
Heart failure
What conditions may cause an increase in permeability?
- Inflammation
- Sepsis
- Malignancy
What condition may cause a decrease in oncotic pressure?
Liver failure
How is pleural fluid absorbed?
Via lymphatic drainage
What can decrease the rate of lymphatic drainage of pleural fluid?
Lymphatic blockage
What can increase the rate of lymphatic drainage?
Increase in systemic venous pressure
What is a pleural effusion?
Any collection of extra fluid in the pleural space
What fluids can collect in the pleural space?
- Blood
- Chyle
- Pus
- Serous fluid
What is chyle?
Lymph with fats in it
What is a pleural effusion with blood called?
Hemothorax
What is a pleural effusion with chyle called?
Chylothorax
What is a pleural effusion with pus called?
Empyema
What is a pleural effusion with serous fluid called?
Simple effusion
What are simple pleural effusions characterised by?
Protein content
What do transudates have?
Low protein content
What is the protein content of transudates?
<30g/L
What do exudates have?
High protein content
What is the protein content of exudates?
>30g/L
What can cause transudates?
- Increased hydrostatic pressure
- Decreased capillary oncotic pressure
- Increased capillary pressure
What condition can cause increased hydrostatic pressure?
Cardiac failure
What conditions can cause decreased capillary oncotic pressure?
- Hypoalbuminaemia
- Nephrotic syndrome
What condition can cause increased capillary permeability?
Sepsis
What can cause exudates?
- Neoplasms
- Infection
- Immune disease
- Abdominal disease
What neoplasms can cause exudates?
- Cancer involving pleural surface
- Secondary’s from breast, lung, ovarian, GI, lymphoma
- Primary tumour of pleura
Give two infections that can cause exudates
- Pneumonia
- TB
What immune diseases can cause exudates?
Connective tissue diseases
Give two examples of connective tissue immune diseases that can cause exudates
- RA
- SLE
Give 3 abdominal diseases that can cause exudates
- Pancreatitis
- Ascites
- Subphrenic abscess
How does pancreatitis cause exudates?
Diaphragmatic inflammation
How does ascites cause exudates?
When it transverses the diaphragm
What is pleurisy, or pleuritis?
Inflammation of the pleura
What are the symptoms of pleurisy?
- Sharp pain on inspiration
- Pain worse on coughing, sneezing, laughing, etc.
- Patients take small breaths, and hold affected side of chest
- Pain on shoulder on the same side
- Pleural rub
Why does pleurisy produce pain in the shoulder on the same side?
Because of involvement of the diaphragmatic pleura
What is meant by pleural rub?
A creaking noise heard through a stethoscope with respiratory movements
What are the causes of pleurisy?
- Infection
- Autoimmune
Lung cancer - Pneumothorax
- Pulmonary embolism
What is the most common cause of pleurisy?
Infection
What infections can cause pleurisy?
- TB
- Pneumonia
What autoimmune conditions can cause pleurisy?
- SLE
- RA
What may lead to pleural fibrosis?
Unabsorbed pleural effusion
What is the effect of pleural fibrosis?
- A small degree of thickening has no effects
- Wide spread fibrosis restricts expansion, with a measurable reduction in lung volumes and compliance
Are secondary deposits of tumours uncommon in the pleura?
No
What is the most common primary tumour of the pleura?
Malignany mesothelioma
What is true of almost all victims of malignant mesothelioma?
They were exposed to asbestos 20-40 years before
What are the early symptoms of malignant mesothelioma?
Those of a pleural effusion, but with a duller pain
What are the signs of a malignant mesothelioma?
That of a large pleural effusion
What are the types of chest wall abnormalities?
- Deformation of the ribs, sternum, and thoracic spine
- Acquired abnormalities
Give two examples of sternal abnormalities
- Pectus Carcinatum
- Pectus excavatum
What do sternal abnormalities produce?
Cosmetic deformities, rarely produce functional impairment
What may scoliosis and kyphosis produce?
Significant functional impairment of the thoracic cage
How can chest wall abnormalities be acquired?
- Trauma producing broken ribs
- Surgery for TB
What may trauma producing broken ribs cause?
Possible pneumothorax
What is the purpose of surgery for TB?
Designed to collapse their lung
Who may have had surgery for TB?
Old patients
How may the muscles involved in breathing be affected?
- By generalised muscular diseases
- Neurological diseases
What generalised muscular disease can affect the muscles involved in breathing?
Muscular dystrophy
What neurological diseases can affect the muscles involved in breathing?
- Motor neurone disease
- Polio
What does weakness of muscles involved in breathing produce?
Respiratory failure with lower resistance to respiratory tract infections because of poor clearance of secretions