restrictive lung disease Flashcards
define restrictive lung disease
decrease in total lung capacity (FVC + residual volume – max volume in lungs)
what are the 2 categories of restrictive lung disease?
intrinsic
extrinsic
what are intrinsic lung diseases?
Affecting the lung parenchyma – driven by inflammation that leads to lung scarring
what are extrinsic lung diseases?
Affecting the pleura, chest wall or neuromuscular apparatus
what % of interstitial lung diseases are of known origin? name some causes
35% of ILDs are DPLD of known cause e.g. pneumoconiosis e.g. asbestosis
what % of ILDs are idiopathic?
65%
name the major ILDs?
IPF, Sarcoidosis, pneumoconiosis
what is the aetiology of IPF?
unknown
what are risk factors for IPF?
smoking, environmental exposures, chronic viral infections, abnormal acid reflux and family history of the disease
how does IPF affect the lungs?
Results in scarring/honeycombing in lung –> restricts breathing and oxygen exchange
how can repetitive microinjuries damage the epithelium in IPF?
causes o Epithelial cell senescence o Epithelial apoptosis o Epithelial proliferation o Epithelial activation o Epithelial-mesenchymal transition
what is the proposed pathology of IPF?
- environmental factors lead to repetitive microinjuries
- Repetitive microinjuries can also cause the release of chemicals e.g. growth factors, developmental signals, cytokines, chemokines etc. fibroblast migration and proliferation + differentiation to myofibroblasts and ECM accumulation
• Fibroblast proliferation leads to scarring – form plaques which reduce ability of lungs to expand
what alveolar damage occurs in IPF?
- IPF results in traction bronchiectasis (dilation of the bronchi)
- Alveolar remodelling
- Parenchymal fibrosis
what are the symptoms of IPF?
- Dry cough
- Exertional dyspnea
- Clubbing
- Breathlessness
how do you diagnose IPF?
• Medical history + symptoms • Physical examination with stethoscope • Lung function tests - DLCO/TLCO - high resolution CT histology
what should you hear with a stethoscope in IPF?
Should hear; fine, high-pitched bibasilar inspiratory crackles (Velcro-like sounds)
what is the lung test for IPF?
DLCO/TLCO
how is CO different to O2?
greater affinity for Hb than oxygen
how does DLCO work?
• CO is inhaled at a particularly low concentration – measuring quantity of carbon monoxide (CO) transferred per minute from alveolar gas to red blood cells (mL/min/mm Hg)
what are the units for the DLCO test?
o mL of CO transferred per minute for each mm Hg of pressure difference across the total available functioning lung gas exchange surface
what is the equation for DLCO?
DLCO = Lung surface area available for gas exchange (Va) X rate of capillary blood CO uptake (Kco)
what would affect your uptake ability in the DLCO test?
If you have fibrotic plaque and injury to the epithelial cell then your uptake ability is impaired
what should a normal result be in the DLCO test?
• Anyone with DLCO >75% is considered normal – less than that implies restrictive lung disease
what are the concerns with DLCO?
falsely reduced in individuals who fail to inspire to TLC + significant variation
what does a CT show in IPF?
High resolution CT: reticular changes associated with traction bronchiectasis and honeycombing
what is the treatment goal for IPF?
• Treatment goal is to improve symptoms + survival, preserve lung function and reduce adverse effects
what are the 3 main drugs used for IPF treatment?
Pirfenidone, Nintedanib, Antacid therapy
what type of drug is pirfenidone?
anti-fibrotic agent
what effect does pirfenidone have?
- ↓Physiological deterioration
* ↑Progression-free survival
what are the adverse effects of pirfenidone?
GI, photosensitivity, anorexia, skin rash & liver toxicity
what type of drug is nintedanib?
tyrosine kinase inhibitor
what effect does nintedanib have?
decreased FVC decline
what are the adverse effects of nintedanib?
diarrhoea, weight loss & liver toxicity
what are the adverse effects of antacid therapy?
Infection, cognitive function & MI
what are the non-pharmacotherapy treatments for IPF?
- Pulmonary rehab: increases physical and psychological, increases walk distance and increases quality of life
- Long term oxygen: patients with hypoxemia at rest
- Short burst oxygen therapy: exertional hypoxemia
- Lung transplant: moderate-severe disease
what is sarcoidosis?
Acute + self-limiting inflammatory disease - immune system goes into overdrive
• Cause immune cells to clump together to form granulomas
what part of the body does sarcoidosis affect?
Can affect almost any organ in the body – 90% of times it affects the lungs
what is the cause of sarcoidosis?
cause isnt known
what group of people does sarcoidosis affect?
- Can affect people of any age but 70% of patients are 20 to 40
- More common in African Americans and people of Northern European descent
what organs does sarcoidosis affect and what symptoms does this cause?
- Eye – dry eyes and blurry vision
- Lymph nodes – enlarged
- Lungs – hacking cough, coughing up blood
- Heart – complications
- Liver and spleen – enlargement
- Joints – pain, arthritis, swelling of the knees
- Skin – rashes, lupus pernio, erythema nodosum, skin lesions on the back, subcutaneous nodules
what is the proposed pathology of sarcoidosis?
- Aetiology unknown
- Antigen phagocytosed by APC
- APC present to T cells by HLA class 2 molecules
- Formation of sarcoid granuloma
how do you diagnose sarcoidosis?
- Clinicoradiographic data:
- Bilateral hilar adenopathy on the chest radiograph
- Lofgren syndrome (erythema nodosum skin rash + bilateral hilar adenopathy on chest radiograph +/- fever and arthritis)
