Medicine: Restrictive lung diseases, Pulmonary hypertension and O2 therapy Flashcards
Conditions causing upper zone fibrosis
Fibrosis predominately affecting the upper zones
- hypersensitivity pneumonitis (also known as extrinsic allergic alveolitis)
- coal worker’s pneumoconiosis/progressive massive fibrosis
- silicosis
- sarcoidosis
- ankylosing spondylitis (rare)
- histiocytosis
- tuberculosis
Conditions causing lower zone fibrosis
Fibrosis predominately affecting the lower zones
- idiopathic pulmonary fibrosis
- most connective tissue disorders (except ankylosing spondylitis) e.g. SLE
- drug-induced: amiodarone, bleomycin, methotrexate
- asbestosis
Drugs that can cause lung fibrosis
- amiodarone
- cytotoxic agents: busulphan, bleomycin
- anti-rheumatoid drugs: methotrexate, sulfasalazine
- nitrofurantoin
- ergot-derived dopamine receptor agonists (bromocriptine, cabergoline, pergolide)
Pathophysiology of lung fibrosis
Injury to endothelial cells → inflammatory response (with initiation of growth factors, cytokines etc → repair (cellular re-organization and fibrin formation) → wound contraction
Pathophysiology of Interstitial Pneumonitis
•excessive extracellular
matrix deposition
•fibroblast and myofibroblast
accumulation
•between vascular and alveolar
endothelium
- disrupt normal lung structure
- “honeycomb” appearance
What can be seen in this X-ray?
- Increased interstitial markings
- Reduced lung volumes
What pattern can be seen on spirometry in Pulmonary Fibrosis?
- restrictive
- reduced FEV1 and FVC
- normal FEV1/FVC ratio
- reduced lung volumes
- reduced transfer factor
Features of Idiopathic Pulmonary Fibrosis
IPF is typically seen in patients aged 50-70 years and is twice as common in men.
Features
- progressive exertional dyspnoea
- bibasal fine end-inspiratory crepitations on auscultation
- dry cough
- clubbing
Diagnosis of idiopathic pulmonary fibrosis
- modalities
- what’s seen
- spirometry: classically a restrictive picture (FEV1 normal/decreased, FVC decreased, FEV1/FVC increased)
- impaired gas exchange: reduced transfer factor (TLCO)
- imaging: bilateral interstitial shadowing (typically small, irregular, peripheral opacities - ‘ground-glass’ - later progressing to ‘honeycombing’) may be seen on a chest x-ray but high-resolution CT scanning is the investigation of choice and required to make a diagnosis of IPF
- ANA positive in 30%, rheumatoid factor positive in 10% but this does not necessarily mean that the fibrosis is secondary to a connective tissue disease. Titres are usually low
What can be seen on imaging in idiopathic pulmonary fibrosis ?
- bilateral interstitial shadowing (typically small, irregular, peripheral opacities - ‘ground-glass’ - later progressing to ‘honeycombing’)
- may be seen on a chest x-ray but high-resolution CT scanning is the investigation of choice and required to make a diagnosis of IPF
Management of Pulmonary FIbrosis
- pulmonary rehabilitation
- very few medications have been shown to give any benefit in IPF. There is some evidence that pirfenidone (an antifibrotic agent) may be useful in selected patients
- many patients will require supplementary oxygen and eventually a lung transplant
Prognosis in Pulmonary Fibrosis
poor, average life expectancy is around 3-4 years
What’s seen on this CT?
CT scan showing advanced pulmonary fibrosis including ‘honeycombing’
What’s seen on this imaging?
Chest X-ray and CT scan
- The x-ray shows reitcular opacities predominantly in the bases
- CT demonstrates honeycombing and traction bronchiectasis
Symptoms of pulmonary hypertension
- Breathlessness
- Weakness / lethargy
- Exertional dizziness
- Syncope
- Anginal chest pain
Signs of Pulmonary hypertension
- Raised JVP with large V wave
- Right ventricular heave
- Loud P2
- Murmur of Tricuspid Regurgitation
- PSM, lower left sternal edge
- Fixed or reverse split 2nd heart sound
- Peripheral oedema
- Sometimes:
- Murmur of pulmonary regurgitation
- Pulsatile hepatomegaly
- Ascites
What’s that?
Plexiform lesion
- associated with pulmonary hypertension (thickening of a pulmonary arteriolar wall)
Difference between primary vs secondary pulmonary hypertension
Primary
- elevated pulmonary artery pressure
- no cause identified
- greatest number of cases in women aged 21-40
Secondary
- due to another pathology
- cardiac disease
- congenital heart defects
- intracardiac left to right shunts such as ASD (atrial septal defect)
- heart valve problems such as mitral stenosis
- lung disease
- COPD
- pulmonary fibrosis
What can be seen on ECG in a patient with Pulmonary Hypertension?
ECG (may be normal)
- right atrial enlargement
- right axis deviation
- right ventricular hypertrophy
- ST depression and T-wave inversion in the anterior leads
- RBBB
What can be seen on CXR in a patient with pulmonary hypertension?
- CXR
- elevated cardiac apex
- enlarged right atrium
- prominent pulmonary outflow tract
- enlarged pulmonary arteries
- pruning of peripheral pulmonary vessels
What can be seen on pulmonary function tests in a patient with pulmonary hypertension?
Pulmonary Function Tests
- Reduced transfer factor
- Evidence of a secondary (pulmonary) cause
What’s seen on Echocardiogram in Pulmonary Hypertension ?
Echocardiogram
- mean pulmonary artery pressure (PAP) > 25 mmHg at rest or 30 mm Hg with exercise
- most echo reports will give systolic PAP
- systolic PAP 40 mmHg implies mean PAP > 25 mmHg (i.e. pulmonary hypertension)
- dilated Pulmonary Artery
- dilated Right Atrium
- bulging of septum into the LV cavity causing diastolic dysfunction
- presence of at least a trivial tricuspid regurgitant jet
- May also show a cause for the pulmonary hypertension
Investigations for Pulmonary hypertension
- CXR
- ECHO
- ECG
- pulmonary function tests
- Right heart catheter
- measure pulmonary artery pressure directly
- determine pulmonary vasoreactivity
Also consider:
- CTPA (chronic thromboembolic disease, lung disease)
- autoimmune screen
- exercise test
- pulmonary angiography
- B-natriuretic peptide
- overnight oximetry
Management of Primary Pulmonary Hypertension
- Anticoagulation
- If CTEPH or idiopathic PAH (IPAH)
- Role in other causes of pulmonary hypertension unclear
- Diuretics
- Oxygen
•Specific medical therapies (IPAH)
IPAH:
- Prostanoids such as iloprost (IV, subcutaneous or nebulised )
- Endothelin receptor antagonists (such as bosentan- oral )
- Phosphodiesterase-5 inhibitors (such as sildenafil -oral)
Indications for long term oxygen therapy (LTOT) in a patient with COPD, interstitial lung disease or CF
- Stable COPD, Interstitial Lung Disease or Cystic Fibrosis
- PaO2 ≤ 7.3 kPa at rest
- PaO2 ≤ 8 kPa if peripheral oedema, polycythaemia (haematocrit ≥55%) or pulmonary hypertension
Indication for LTOT in patient with pulmonary hypertension
PaO2 ≤ 8 kPa
What and how to assess inpatient we consider LTOT for?
Assess patients if any of the following:
- very severe airflow obstruction (FEV1 < 30% predicted). Assessment should be ‘considered’ for patients with severe airflow obstruction (FEV1 30-49% predicted)
- cyanosis
- polycythaemia
- peripheral oedema
- raised jugular venous pressure
- oxygen saturations less than or equal to 92% on room air
Assessment is done by measuring arterial blood gases on 2 occasions at least 3 weeks apart in patients with stable COPD on optimal management.
How many hours day oxygen should be used in a patient with LTOT?
At least 15 h a day
What groups of patients would have O2 sats target of 88-92%?
88-92% for those patients at risk of hypercapnic respiratory failure
- moderate/severe COPD
- chest wall or spinal deformity (e.g. kyphoscoliosis)
- neuromuscular disease
- obesity
- cystic fibrosis
Colours of venturi masks and % of oxygen they deliver
