restrictive (interstitial) lung diseases Flashcards
what is the interstitium of the lung?
The connective tissue space
around the airways and vessels and the space between the basement membranes of the alveolar walls
are interstitial lung diseases usually unilateral or bilateral?
bilateral
is pulmonary oedema a restrictive lung disease?
no, however it does cause restriction
what happens to the interstitium in restrictive lung diseases?
it becomes thicker so the capillaries and pneumocytes no longer as close together. This is causes buy a build up of a substance in the interstitium, usually fibrous tissue.
what happens to compliance in restrictive lung disease?
it is reduced
what happens to FEV1 in restrictive lung disease?
it is reduced
what happens to FVC in restrictive lung disease?
it is reduced
what happens to the FEV1/FVC ratio in restrictive lung disease?
it remains nomal
what happens to gas transfer in restrictive lung disease?
it is decreased
why is gas transfer reduced in restrictive lung diseases?
the distance between alveoli and capillaries is increased as there is increases tissue in the interstitium
why is there a V/Q imbalance in restrictive lung diseases?
the disease can sometimes cause small airways to be constricted
when can a restrictive lung disease present?
when there is an abnormal discovery on a CXR.
dyspnoea that gets worse (SOB exertion –> SOB rest)
type 1 resp. failure
heart failure
why do sufferers of restrictive lung disease experience type 1 respiratory failure?
it is much easier for carbon dioxide to diffuse across the thickened alveolar walls than it is for oxygen.
what does an interstitial lung disease look like on a CXR?
lung extends <10 ribs
more lung markings because increased tissue
what is diffuse avleolar damage associated with?
Major trauma Chemical injury / toxic inhalation Circulatory shock Drugs Infection Auto(immune) disease Radiation idiopathic
what is the evolution of DADS?
oedema–> Hyaline membranes –>interstitial inflammation —> interstitial fibrosis
what are the histological features of DADS?
protein rich oedema fibrin hyaline membranes denuded basement membranes epithelial proliferation fibroblast proliferation scarring-interstitium and airspaces
what is sarcoisosis?
a multisystem granulomatous disoder of unknown aetiology
what is the histopathology of sarcoidosis?
-epitheloid and giant cell ganulomas
-no necrosis
-little lymphoid infiltration
variable associated fibrosis
is DADS an acute of chronic response?
acute
what causes the protein rich oedema in DADS?
damage to the capillary walls in the lung (probably by neutophils) which causes the massive leakage of fluid and proreins
is DADS a serious condition?
yes, sufferers usually end up in ITU
what sets DADS apart from pneumonia histologically?
the alveoli in DADS are not filled with debris like in pneumonia
what sets sarcoidosis apart from infections histologically?
the absence of tissue necrosis
what are the presentations of sarcoidosis?
1. -acute arthralgia (joint pain) -erythema nodosum (red bumps and patches on the skin) -bilateral hilar lymphadenopathy 2. incidental abnormal CXR w/ no symptoms 3. SOB, cough and abnormal CXR
is treatment required for sarcoidosis?
most resolve themselves after 2 years but those that don’t should be given corticosteroids
what is used to diagnose sarcoidosis?
- clinical findings
- image findings
- serum Ca++ and ACE ( angiotensin converting enzyme)
- biopsy
what are the antigens for hypersensitivity pneumonitis?
mostly antigens of plant or animal origin:
- Thermophilic actinomycetes
- Bird / Animal proteins - faeces, bloom
- Fungi - Aspergillus spp
some chemicals
what is the acute presentation of hypersensitivity pneumonitis?
Fever, dry cough, myalgia,
Chills 4-9 hours after Ag exposure
Crackles, tachyopnoea, wheeze
Precipitating antibody
what is the chronic presentation of hypersensitivity pneumonitis?
- Insidious
- Malaise, SOB, cough
- Low grade illness
- Crackles and some wheeze
what is hypersensitivity pneumonitis mediated by?
Type III and Type IV Hypersensitivity reaction
what is the main histological presentation of hypersensitivity pneumonitis?
soft centriacinar epithelioid granulomata
what zone of the lung does hypersensitivity pneumonitis primarly affect?
upper zone
why is hypersensitivity pneumonitis more likely to occur in central acinar areas?
this is the area where airflow changes from laminar to diffusion
where may UIP be seen?
- connective tissue diseases
- in drug reaction
- in post infection
- in industrial exposure
which connective tissue diseases can cause UIP?
scleroderma and rheumatoid disease
what is the most common form of UIP?
cryptogenic or idiopathic
what is another name for idiopathic UIP?
idiopathic pulmonary fibrosis
what is another name for cryptogenic UIP?
cryptogenic fibrosing alveolititis
what are the histopathological features of UIP?
-patchy interstitial chronic inflammation
-type II pneumocyte hyperplasia
-smooth muscle and vascular proliferation
evidence of old and recent injury as well as a spatial variation in injury
-proliferating fibroblastic foci
what is temporal heterogeneity in UIP?
injury in the lungs occuring at different times
what is spatial heterogeneity in UIP?
injury in lungs in different areas
who does idiopathic pulmonary fibrosis normally affect?
elderly >50 and M>F
what are the clinical signs of idiopathic pulmonary fibrosis?
dyspnoea, cough, basal crackles, cyanosis, clubbing
what is the prognosis of idiopathic pulmonary fibrosis?
most die within 5 years
what treatments are available for idiopathic pulmonary fibrosis?
steroidal therapy,
anti-angiogenesis treatment, (largely uneffective though)
what is the appearance of idiopathic pulmonary fibrosis on a chest x-ray?
basal/posterior diffuse infiltrates, cysts, appears like ground glass
which of the chronic responses is most likely to lead to end-stage honeycomb lung?
UIP
which of the chronic responses is least likely to lead to end-stage honeycomb lung?
granulomatous response
what are the three chronic responses to parenchymal (interstitial) lung injury?
- usual interstitial pneumonitis
- granulomatous response
- other patterns (non specific interstitial pneumonitis)
what are the granulomatous responses to parenchymal lung injury?
- sarcoidosis
- hypersensitivity pneumonitis
why do diseases caused by inhaled particulates often start at the respiratory bronchioles?
this is where bulk flow airflow becomes diffusion
what are the four abnormal states associated hypoxaemia?
- alveolar hypoventilation
- shunt
- ventilation/ perfusion imbalance
- diffusion impairment
