Idiopathic Pulmonary Fibrosis

Here’s another respiratory condition because I’m actually trying to study instead of my usual procrastination. Enjoy.


Idiopathic Pulmonary Fibrosis

Definition: a type of idiopathic interstitial pneumonia, with inflammatory cell infiltrate and pulmonary fibrosis of unknown cause. Also known as cryptogenic fibrosing alveolitis. This is the commonest cause of interstitial lung disease.

(ILD = generic term used to describe a number of conditions that primarily affect the lung parenchyma in a diffuse manner)

(Pulmonary interstitium is a collection of support tissues within the lung that includes the alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and perilymphatic tissues.)

Aetiology/ risk factors:

-unknown cause

-risk factors: family history, smoking, advanced age, male sex

-weaker risk factors: organic and inorganic dust exposure, GORD, infection, diabetes

Epidemiology: rare. UK prevalence ~ 6 in 100,000.

-Male : Female = 2 : 1

-Mean age = 67yrs

Symptoms:

-shortness of breath on exertion (gradual, progressive onset)

-dry irritating cough

-malaise

-weight loss, fatigue (common)

-arthralgia (joint pain)

-symptoms may be preceded by a viral-type illness

Signs:

-cyanosis

-bi-basal fine end-inspiratory crackles

-clubbing

-no wheeze

-signs of right heart failure in advanced stages: right ventricular heave, raised JVP, peripheral oedema

Investigations:

Blood: ABG = normal in early disease, PaO2 low on exercise, if severe- PaCO2 high

                ↑CRP

               immunoglobulins ↑ – ANA +ve (30%), rheumatoid factor +ve (10%)

Chest X-ray: usually normal at presentation. Early disease may show small lung fields and ground glass shadowing. Later, there is decreased lung volume, bilateral lower zone reticulo-nodular shadowing, signs of cor pulmonale and eventually, honeycomb lung in advanced disease

Image result for ground glass chest x ray

Ground Glass Shadowing, apparently

 

Image result for chest x ray idiopathic pulmonary fibrosis

Reticulo-nodular Shadowing in Pulmonary Fibrosis

Image result for chest x ray HONEYCOMBING

CXR Example of Honeycombing

 

 

CT: similar changes to CXR, but more sensitive, especially in early disease. Affects mainly lower zones and sub-pleural areas. Essential tool for diagnosis.

pulmonary fibrosi...

Honeycombing in Pulmonary Fibrosis

Spirometry: restrictive picture (FEV1:FVC > 75%, FEV1 and FVC decreased with preserved or increased ratio). Decreased lung volumes and lung compliance.

-↓ Transfer factor/ diffusing capacity = carbon monoxide diffusing capacity of lungs (DLCO/TLCO) corrected for alveolar volume. (Low in emphysema and interstitial lung disease = impaired gas transfer).

Bronchoalveolar lavage: may indicate activity of alveolitis: ↑lymphocytes (good prognosis) or ↑ neutrophils and eosinophils (poor prognosis). Exclude infection or malignancy.

99TCm-DTPA scan: radionuclide scanning may reflect disease activity

Lung biopsy: may be needed for diagnosis. Histological changes are referred to as usual interstitial pneumonia (UIP)

-May do an echo to look for pulmonary hypertension

Management: no curative treatment available

-Best supportive care: oxygen, smoking cessation, pulmonary rehabilitation, opiates (in terminal stages for relieving distressing breathlessness, may help cough), palliative care input and psychosocial support.

-Acute exacerbations: broad-spectrum antibiotics

-Strongly recommended that high-dose steroids are not used, except where the diagnosis of IPF is in doubt.

-According tot NICE guidelines- ‘There is no conclusive evidence to support the use of any drugs to increase the survival of people with idiopathic pulmonary fibrosis.’ Nintedanib and Pirfenidone are recommended in some circumstances and oral N-acetylcysteine is sometimes used for managing IPF (benefits uncertain), but overall, NICE doesn’t recommend drug treatments.

-Consider all patients for current clinical trials or single lung transplantation.

Complications:

-respiratory failure (type 2) causing death

-pulmonary hypertension and Cor pulmonale (right heart failure)

-increased risk of lung cancer (12%)

-pulmonary embolus

Prognosis: 50% 5yr survival rate (range 1-20yrs)

Poor prognosis, mean survival ~3 yrs.

-Good prognostic factors:

  -young, female, predominantly ground glass shadowing

References: Cheese & Onion, Rapid Medicine, NICE guidelines, BMJ Best Practice

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