T4 - Restrictive lung disease Flashcards
what is restriction defined by?
decrease in lung volume which prevents the lung expanding
by what three mechanisms can normal interstitial structures be altered?
fluid accumulation, inflammation and fibrosis
what is the defining feature of RLD?
reduced residual volume
give three examples of interstitial lung disease and what do these affect?
pneumoconioses, hypersensitive pneumonitis and idiopathic pulmonary fibrosis
- affects alveolar filing processes
what does interstitial lung disease result in?
pulmonary oedema, haemorrhage, infection and cancer
what happens to the intrarlobular septa in ILD and what does this cause?
septa become thick and this causes a diffusion limitation
where are intralobular septa found?
surrounding the alveoli
where are interlobular septa found and what is within them?
found outlining the secondary lobules and lymphatics and veins are found within then
when can interlobular septa be visualised on CT?
only when thickened
exposure to what two things found in the environment causes hypersensitivity pneumonitis?
mould and bird proteins
give three types of pneumoconioses
coal miners lung, silicosis, asbestosis
how is interstitial lung disease categorised?
by cause
what are four causes of ILD?
inorganic exposure (asbestos, dust, silica), organic exposure (bird, hay, mould, mycobacteria), smoking or connective tissue disease (RA)
what do problems associated with coal miners lung start and how long do they last?
begin as soon as you inhale the dust and last forever
what does coal miners lung result in?
massive fibrosis and inflammation due to dust particles being engulfed by MPs and laying down of tough non elastic collagen
what is created with MPs destroy dust particles from coal and what can this progress to?
fibrotic ring around it which can progress to massive fibrosis
does exposure to asbestos mean you will get disease?
no
what are two markers of significant asbestos exposure on imaging?
pleural plaques and honeycomb cysts (fine lines on CT)
how does mesothelioma form?
asbestos is taken up by dendritic ells and deposited in the pleural space (which is lined with mesothelial cells) that can undergo malignant transformation
what are three characteristics of silica and dust exposure in the lung?
1) nodular disease
2) tissue pulled into the lungs so they can’t expand
3) massive fibrosis
what type of septa are inflammed in hypersensitive pneumonitis?
intralobular septa (become thick)
what forms when mould or bird dust are inhaled?
body sees it as infection and forms a granuloma in small terminal bronchioles
what can a granuloma transform to and how is it seen on imaging?
can transform to a scar and will be seen as shadows or lobules on imaging
what age range is idiopathic pulmonary fibrosis seen in?
elderly
where is idiopathic pulmonary fibrosis seen and how is it characterised?
- seen in lower and peripheral aspects of lung
- characterised by honeycomb cysts which are seen as holes on CT
what cell types are present in abundance in idiopathic pulmonary fibrosis and what does this cause?
lots of fibroblasts therefore lots of collagen deposited causing lungs to be rigid
what does alveolar collapse cause?
atelectasis
what are the two types of atelectasis and what are they associated with?
1) resorptive - associated with endobronchial obstruction causing decrease in alveolar size and eventual collapse
2) compressive - due to pleural processes or a lung mass
what is pleural effusion?
abnormal fluid collection between two layers of pleura
can pleural effusion usually be detected on radiology?
no
how is pleural effusion characterised in relation to influx and efflux of fluid?
influx > efflux due to a capillary leak and liquid from the visceral pleura leaks into the intersititum
what causes pleural effusion?
congestive HF, liver disease w portal hypertension, low albumin due to nephrotic syndrome, infection eg TB, parasites, malignancy, chylothorax (high lymph in the pleura)
what four things may a patient with pleural effusion present with?
dyspnoea, dull percussion at lung base, hazy CXR, may have collapse (atelectasis)
what are the two types of pleural effusion
transudative and exudative
what characterises transudative pleural effusion?
problems in normal fluid balance due to fluid leakage
which type of pleural effusion is usually due to a primary non pleural process and probably doesn’t need to be drained?
transudative
what characterises exudative pleural effusion?
problems with the pleura itself
what type of pleural effusion is due to primary pleural disease and needs to be drained?
exudative
how can an exudative pleural effusion be drained?
by needle aspiration or thoracotomy (chest tube)
what are the seven mechanisms of exudative effusions?
1) uncomplicated parapneumonic
2) complicated parapneumonic
3) empyema
4) cancer
5) chylothorax
6) blood in pleural space
7) pleurisy
what characterises an uncomplicated parapneumonic exudative effusion?
- lots of inflammatory cells but NO bacteria
- altered capillary permeability
what characterises a complicated parapneumonic exudative effusion?
- lots of inflammatory cells WITH bacteria
- no pus
- needs draining
what can a complicated parapneumonic exudative effusion result in if not drained?
pleural rind formation that needs to be surgically drained
what characterises empyema?
- frank pus
- needs draining with a chest tube
how can cancer cause an exudative pleural effusion?
if tumour cells move into the pleural space via the lymphatics
what is a chylothorax?
retrograde spillage of lymphatic material into the pleura
what is a common cause of chylothorax?
thoracic duct injury (cut by mistake in surgery)
what can cause blood in the pleural space?
penetrating trauma
how is haemothorax defined in relation to haematocrit?
haematocrit is at least 50% of that of normal blood in the pleural space
what is pleurisy and what causes it?
- sterile process of inflammatory cells and fluid that accumulate in the pleural space
- autoimmune causes
what are the two main things to diagnose exudative pleural effusion?
- lights criteria
- compare pleural levels to serum levels eg protein, LDH
what things are analysed in fluid studies of pleura?
- protein and LDH
- pH/glucose
- cytopathology for malignancy
- cell counts with a WBC differential
- microbial stain and culture
- cholesterol and Tis for thoracic duct spillage
what is a pneumothorax?
air collection in the pleural space due to alveolar rupture
what are the two types of pneumothorax?
spontaneous or traumatic
what are four causes of traumatic pneumothorax?
- procedural
- penetrating trauma
- rib fracture
- baro trauma
what can cause chest wall disease?
generative spinal disease such as MND and polio
