Week 5 resp Flashcards
Describe restrictive lung complaince in terms of FEV1, FVC and their ratio
Low FEV1 and LOW FVC but FEV1/FVC is normal ratio
What is the interstitum?
The connective tissue space around the airways and vessels - The space between the basement membranes of the alveolar walls
What material reduces the compliance of the lung and impaedes the elasticity of the alveoli?
Collagen
Describe the characteristics of restrictive lung disease
Reduced gas transfer
Diffusion abnormalities
Ventilation/Perfusion imbalances
small airways are affected by pathology
Is there airflow limitation in restrictive lung disease
Nope
What are the clinical presentations for restrictive lung disease
Discovery of abnormal CXR
Dyspnoea
resp failure - type 1
HF
What are 3 chronic outcomes from a parenchymal (intersitial) lung injury
Usual interstitial pneumonitis
Granulomatous responses
Other patterns
What does DAD stand for?
Diffuse alveolar damage
What is DAD associated with?
major trauma Chemical injury/toxic inhalation Circulatory shock Drugs Infection Autoimmune disease Radiation However can still be idiopathic
Describe the exudative stages of DADs
within first 7 days
Oedema and hyline membranes
- Oedema: arises immediately. vessels become massively leaky, moreso than in a normal response (typically gone by day 3)
- Hyline membranes: arise after a day, decreased to half its peak value by 7 days. Contain lots of proteins
Describe the proliferative stage of Dads
A combination of interstitial fibrosis and interstitial inflammation
What are the histological features of DADs
Protein rich oedema
Fibrin
Hyaline membranes
Denuded basement membranes
What is the most common interstitial lung disease?
Sarcoidosis
Apart from sarcoidosis what is the other granulomatous response?
Hypersensitivity pneumonitis
Describe the histopathology of sarcoidosis
Epitheloid and giant cell granulomas
necrosis/Caseation very unusual - Differentiates from TB
Little lymphoid infiltrate
Variable associated fibrosis
Describe the presentation of sarcoidosis
- Young adult: Acute arthralgia, arythema nodosum, Bilateral hilar lymphadenopathy
- Incidental Abnormal CXR: No symptoms
- SOB, cough and abnormal CXR
What is the treatment for sarcoidosis
Corticosteroids
Describe the acute presentation for hypersensitivity pneumonitis
Fever, dry cough, myalgia
Chills, 4-9 hours after Ag exposure
Crackles, tachypnoea, wheeze
Precipitating antibody
What is the chronic presentation of hypersensitivity pneuomonitis
Malaise, SOB, Cough
Low grade illness
Crackles and some wheeze
[Can lead to rep failure, gas transfer low, history important]
What type of hypersensitivity causes hypersensitivity pneuomnitis?
immune complex mediated combined Type II and Type IV hypersensitivity reaction
Hypersensitivty pneumonitis is said to cause Bronchiolitis obliterans, what does this mean?
Inflammatory obstruction of bronchioles, these bronchioles become damaged and ingflamed by chemical particles or respiratory infections. Features extensive scarring that blocks airways.
What are the casues of usual interstitial pneomonitis?
Connective tissue diseases: scleroderma and rheumatoid disease Drugs Asbestos Viruses Idiopathic/Cryptogenic reasons
Describe the interstitium of a patient with UIP
Patchy chronic inflammation
Type 2 pneumocytes hyperplasia
Smooth muscle and vascular proliferation
Proliferating fibroblastic foci
What are Proliferating Fibroblastic Foci
nodules of fibrous tissue in the walls of the alveoli, reflect the severity of the disease
What is the clinical presentation of idiopathic pul fibrosis?
Dyspnoea, cough
Basal crackles, cyanosis, clubbing
Prognosis for idiopathic pul fibrosis?
<5 years
Describe type 1 resp failure
PaO2 <8kPa (PaCO2 normal or low)
Describe type 2 resp failure
PaCO2 >6.5 kPa (PaO2 usually low)
What is the resut of alveolar hypoventilation on PACO2 and PAO2 ?
Hypoventilation increases the PACO2 and therefore decreases PaCO2
Increased PACO2 takes up space in the alveoli and therefore causes PAO2 and PaO2 to fall
How can you correct a fall in PaO2 due to hypoventilation?
Raising the FIO2
What is the commones cause of hypoxaemia clinically?
V/Q mismatch
Why is normal V/Q ration 0.8?
Normally breath 4 l/min. CO is 5 l/min so normal V/Q is 4/5 or 0.8
How can you treat hypoxaemia due to low V/Q?
Increase in FIO2
What are the pleural cases of restrictive lung disease
Pleural effusion
Pneumothorax
Pleural thickening - asbestos related pneumonia
What are the skeletal causes of restrictive lung diseases
Kyphoscoliosis
Ankylosing spondylitis
Thoracoplasty
Rib fractures- soreness
What are the muscular causes of restrictive lung disease
Amyotrophic lateral sclerosis
Obesity - sub diaphragmatic - diaphragm can’t fall properly
Pregnancy - sub diaphragmatic
What is sarcoidosis?
Multisystem granulomatosus disease of unknown cause
What is the histological hallmark of sarcoidosis
Non-cesating granuloma
What are the clinical signs of sarcoidosis
Eythrma nodosum