4- overview of restrictive lung disease Flashcards
what is restrictive lung disease?
group of lung disorders characterised by reduced lung volume and impaired expansion of lung volume. can be intrinsic or extrinsic (depending on what cause is)
- disease of lung itself
what is common type of intrinsic restrictive lung disease?
interstitial lung disease (ILD)
what is ILD?
interstitial lung disease = big spectrum group of lung diseases characterized by inflammation and scarring (fibrotic) of the lung’s interstitial tissue, which surrounds the air sacs (alveoli) and small blood vessels
what is common cause of ILD?
idiopathic pulmonary fibrosis (IPF) = characterised by irreversible fibrolytic and causes shrinkage of lung through scarring which can also prevent exchange
what are components of ILD diagnosis?
history, examination, pulmonary function tests and radiological assessment
what are important sub types of interstitial lung disease, ILD (which is a type of intrinsic restrictive lung disease)?
IPF = idiopathic pulmonary fibrosis
COP = cryptogenic organising pneumonia (associated with things like rheumatoid arthritis)
NSIP = inflammatory type ILD which can happen seperately but commonly associated with connective tissue diseases
RB-ILD = respiratory bronchiolitis interstitial lung disease = seen exclusively in smokers (common inflammatory ILD)
what should you think about when granulomatous?
think sarcoidosis, HP, TB
granulomatous ILDs = associated with sarcoidosis and hypersensitive pneumonitis
what is restrictive pattern on pulmonary function test?
- decreased FEV1 & FVC, but normal/increased ratio (70% is normal)
- decreased DLCO = a test to measure efficiency of gas exchange, patient inhales very small amount of carbon monoxide (<80% predicted is abnormal = worse efficiency)
why is gas exchange impaired in ILD (interstitial lung disease)?
impaired alveolar walls = impaired gas exchange
*more advanced stages = physical effect on FVC, means decreased PaO2 and normal PaCO2 (type 1 respiratory disease)
what can affect diffusion capacity (DLCO)?
- anaemia
- emphysema (alveolar damage)
- ILD’s
- pulmonary oedema
- large volume pulmonary embolisms →can affect blood flow
why is it helpful to monitor DLCO?
to monitor treatment response in ILD (more sensitive than FVC)
what are extrinsic problems that can result in restriction?
- obesity e.g. can also cause sleep apnoea, diaphragmatic palsy
- neuromuscular disorders e.g. motor neuron disease or myasthenia gravis
- pleural diseases e.g. Diffuse pleural thickening; mesothelioma; large pleural effusions
what is pathophysiology of restrictive hypoventilation?
Hypoventilation means impaired alveolar ventilation which means a rise in paCO2 and reduced paO2
how does neuromuscular conditions help cause restrictive hypoventilation?
reduces power of muscles involved in respiration
how does obesity/kyphoscoliosis cause restrictive hypoventilation?
by reducing chest wall compliance
what is obstructive sleep apnoea?
sleep disorder characterised by repetitive episodes of partial or complete obstruction of upper airway during sleep
what is obesity hypoventilation syndrome?
condition characterized by obesity and chronic hypoventilation during wakefulness, leading to elevated levels of carbon dioxide (hypercapnia) and decreased levels of oxygen (hypoxemia) in the blood
what are clinical features of restrictive lung disease?
- finger clubbing - growth in nail bed due to hypoxia
- obese; kyphosis; scoliosis
- fibrotic crepitations = characteristic sound like velcro, persistent basal crepitation think about ILD or bronchiectasis
- clinical signs of pleural effusions or ascites
- cyanosis
what are symptoms of CO2 retaining?
flushed skin, bounding pulse, rapid breathing, premature heart beats, muscle twitches, flapping tremor
what is asbestosis?
pulmonary fibrosis caused by asbestos
what are investigations for restrictive lung disease?
- measure with PFT’s (to check for type 1 resp failure), can do exercise desaturation
- chest x-ray
- blood test - can pick up pigeon serum IgG, this causes reaction if gets into lung i think? serum precipitants done with hypersensitivity
what is non-pharmacological treatment of ILD?
- weight management
- smoking cessation
- remove trigger e.g. drug, bird etc
what is medical therapy treatment for ILD?
- anti-inflammatory /immunosuppressive drugs (steroids 1st line, usually prednisolone +/- rituximab etc)
- antifibrotic drugs (pirfenidone or nintedanib) = only 2 of these type
- Treat neuromuscular disease (Pyridostigmine in MG)
what is treatment for restrictive lung disease?
= mostly obesity related lung diseases
- CPAP (continuous positive airways pressure) - mostly for obstructive sleep apnoea progresses, enough but also need NIV a lot. not used in ILD
- Non-invasive ventilation (NIV) = ventilatory support for neuromuscular weakness; kyphoscoliosis
