Case history
An 84-year-old gentleman was referred to the chest clinic with low oxygen saturations on pulse oximetry. He reported breathlessness and wheeze since his retirement as a surveyor 16 years previously. His exercise tolerance was 350 m. He had pre-existing diagnoses of chronic obstructive pulmonary disease and hypertension. He had no avian or occupational exposures, a minimal smoking history while in his teens and had not smoked since, and no history of transient ischaemic attack or cerebrovascular accident.
On examination, he was comfortable with no respiratory distress but had slight peripheral cyanosis and oxygen saturations of 89% on room air. Auscultation of his chest revealed increased vocal fremitus and crackles over the right lower lobe with occasional wheeze.
The patient was investigated using lung function testing, capillary blood gas sampling, a chest radiograph and thoracic computed tomography (CT). His haemoglobin at presentation was 16.1 g·dL−1.
Investigations
Lung function
The results of the lung function investigations performed as shown in table 1. Supine and erect spirometry demonstrated oxygen saturations of 93% when lying down and 86% on sitting. There was no significant reversibility to 2.5 mg nebulised salbutamol.
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A capillary blood gas taken on air at rest showed an oxygen tension (PO2) of 8.0 kPa (normal 12.0–15.0 kPa), a carbon dioxide tension (PCO2) of 4.4 kPa (normal 4.5–6.1 kPa) and pH of 7.44 (normal 7.36–7.42).
CT
CT images are shown in figure 1.
a) Axial and b) coronal CT slice.
Task 1
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What is seen on the initial CT scan (fig. 1).
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What conditions can be associated with this?
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Can you interpret the lung function results (table 1)?
Answer 1
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There is a 2-cm vascular abnormality in the right lower lobe consistent with a pulmonary arteriovenous malformation (PAVM).
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PAVMs are most commonly seen with hereditary haemorrhagic telangiectasia (>90%) and post-cardiac …
