The cough was productive of clear sputum and the shortness of breath on exercise had been progressive over a period of months. Further questioning established that Susan had not experienced fever, weight loss, chest pain or haemoptysis.
Susan had stopped smoking over 20 years ago. She had spent the majority of her working life on a farm that would have allowed exposure to mineral dusts and inhaled organic material.
Susan did not keep pets, had been on no recent foreign travel, and there was no previous history of asthma or other lung disease. She was taking meloxicam and co-dydramol for her osteoarthritis.
Susan was breathless on entering the consulting room.
Fine inspiratory crackles were heard throughout her lung fields, most marked at the bases with good lung expansion. She was well perfused with no suggestion of clubbing, and normotensive. Her pulse was 84 beats per minute, with normal heart sounds and no ankle swelling of note. Her peak flow reading was 340L/min.
Making the diagnosis
Susan may have developed late-onset asthma or perhaps COPD, with congestive cardiac failure as another diagnostic possibility. However examination features did not support these ideas.
Inspiratory crackles rather than expiratory wheeze argued against obstructive airway disease and the widespread nature of the crackles and lack of peripheral oedema were not in keeping with cardiac failure. The diffuse nature of the inspiratory crackles was consistent with interstitial lung disease.
A set of baseline bloods revealed an elevated ESR but no anaemia and Susan's chest X-ray was suggestive of pulmonary fibrosis.
Susan was referred to the respiratory physicians. A restrictive pattern was demonstrated on spirometry and a CT scan of the lungs confirmed diffuse interstitial disease although no clear underlying cause was found.
Monitoring over the following year showed a clear decline in lung function with a corresponding worsening of breathlessness on exertion. The respiratory consultant recommended immunosuppressant therapy and Susan was initiated on high-dosage prednisolone with subsequent introduction of azathioprine as a steroid-sparing agent.
Unfortunately she reacted adversely to the azathioprine with significant disturbance of LFTs necessitating withdrawal of this treatment. Susan is maintained on a lower dosage of prednisolone with alendronate cover.
Idiopathic pulmonary fibrosis most commonly presents in late middle age with progressive breathlessness and may have its origin in autoimmune disease.
Spirometric findings are of a restrictive picture with reduced lung volume. If sufficiently advanced the diffuse lung fibrosis is evident as ground-glass shadowing on the chest X-ray and CT scan. Ultimately, progression to a honeycomb lung may occur.
In considering possible causes of pulmonary fibrosis (see box) it is obviously important to review past medical, occupational and drug histories and to establish any previous exposure to smoking, industrial dusts, organic matter and irradiation.
In advanced disease the patient may progress to respiratory failure with cyanosis and pulmonary hypertension.
Initial treatment is with prednisolone and steroid-sparing agents such as azathioprine and cyclophosphamide may be used.
Ultimately the patient may become oxygen dependent and in suitable cases lung transplantation can be considered.
- Dr Morris is a GP in Shrewsbury, Shropshire