RESP - Diffuse lung disease

Question 1

What distinguishes diffuse lung disease from other lung disease patterns?

Answer 1

Diffuse diseases generally involve either or both of the alveoli or the interstitium (which includes the pulmonary vasculature)

Question 2

(3) Categories of lung disease

Answer 2

• airway disease
• diffuse lung diseases
• pulmonary vascular diseases

Question 3

Describe airway disease

• examples
• pathogenesis
• Px

Answer 3

eg asthma, COPD, bronchiectasis

inflamed, narrow airways, active mucous glands locally damaged dilated airway

Px: wheeze, cough, sputum, dyspnoea cough, large volumes of sputum

Question 4

Describe diffuse lung diseases

• examples
• pathogenesis
• Px

Answer 4

Eg pulmonary oedema, pulm fibrosis, lung injury by drugs fumes etc

Diffuse oedema, inflammation , fibrosis involving alveoli and/or interstiium

Px: cough, dyspnoea (wheeze unusual)

Question 5

Describe pulmonary vascular diseases

• examples
• pathogenesis
• Px

Answer 5

Eg pulmonary embolus, pulmonary hypertension

Narrowing or obstruction of pulm arteries, capillaries or veins

Px: dyspnoea, pleuritic pain , haemoptysis

Question 6

What kinds of processes cause a diffuse lung pattern?

Answer 6

Acute: water, inflammation, blood. Due to serious impairment of V/Q these patients are usually hypoxic

Subacute or chronic: “interstitial diseases” usually presenting over months to years

Question 7

Discuss some causes of interstitial lung diseases

Answer 7

• Idiopathic Pulmonary Fibrosis
• Sarcoidosis
• Occupational Asbestosis, other pneumoconiosis
• Extrinsic Allergic Alveolitis: Bird Fanciers Lung, Farmers Lung
• Drugs: eg Methotrexate, Amiodarone, Bleomycin
  Busulphan, Cyclophosphamide, Nitrofurantoin
• Radiotherapy
• Pulmonary Fibrosis associated with connective tissue disease: Systemic sclerosis (Scleroderma), Diffuse>Ltd cutaneous, Rheumatoid Arthritis, Systemic lupus erythematosis, Polymyositis, anti-Jo 1 +ve
• Vasculitis eg Microscopic pulmonary vasculitis, Wegeners associated with pulm haemorrhage

Question 8

Ix of interstitial lung disease

Answer 8

• Respiratory function tests
• High resolution CT of chest (“HRCT”)
• Blood tests – to screen for systemic illness and connective tissue disease
• Echocardiogram – LV dysfunction, pulmonary HTN
• Lung biopsy – not required in all cases

Question 9

What does reduced CO diffusion capacity indicate?

Answer 9

impaired gas exchange

Question 10

What are the (4) basic interstitial lung patterns?

Answer 10

• linear
• reticular: mesh like appearance. lines in all directions
• nodular: discrete opacities
• reticulonodular: combination of reticular + nodular

Question 11

Mrs S. is 69 - at a GP visit she mentions that she is quite breathless when walking her dog, especially on inclines. She has had to cut back her walking route bit by bit over the last 12 months, and has given up over the last month When pressed she thinks that she might have been a little breathless even 3 years ago. The dyspnoea doesn’t vary from day to day. Cough has become annoying in the last 6 months and she produces some sticky jelly like clear sputum She is otherwise well

Taking nitrofurantoin daily since 2001 & has RA like symptoms.

Worked as a secretary.

DDx?

Answer 11

Interstitial lung disease (idiopathic pulmonary fibrosis most likely associated with nitrofurantoin & RA)

Question 12

Mx of interstitial lung disease

Answer 12

• O2
• generally does not respond to immunosuppression
• N-acetylcysteine (anti-oxidant)
• lung transplantation for advanced disease
• mean survival of 3 to 5 yr after diagnosis

If young & fit: lung transplant
If not: chronic Mx.

May use supplementary O2 +/0 prednisolone. Bronchodilators are not effective unless individuals say so.

a poor evidence base for treatment of established fibrosis with medications such as steroids and immunosuppressive therapy.

Recommend specialist referral.