Case 19: Stridor and facial swelling
Monday, May 16th, 2011Author: Dr Tanya Hall
A 31 year old gentleman with known SLE is seen in the resuscitation area. He is tachycardic and hypotenisve. On examination you note that he is dyspnoeic and has stridor, his face is swollen and his neck veins are distended. He is on renal replacement therapy for renal failure secondary to his SLE.
His CXR is below:
1. What is the diagnosis?
Click to see the answerThis is SVC obstruction. He presented with the classical signs of dyspnoea and stridor (due to tracheal oedema). His mother told us that his breathlessness had been getting progressively worse over the previous 3 weeks. There was also jugular venous distension and facial swelling. On the CXR we can see a widened mediastinum with greater opacity on the right hand side. Other symptoms which can occur include chest pain, hoarse voice, haemoptysis and dysphagia. Examination findings may also include dilated veins across the neck, arms and chest wall, cyanosis, and confusion due to cerebral oedema. If collaterals have had time to develop dilated veins may be seen on the abdominal wall.
2. Why is this prone to obstruction
Click to see the answerThe SVC is a relatively thin-walled structure with a low intravascular pressure. It is surrounded by rigid structures, such as the trachea, aorta, pulmonary artery, peri-hilar and paratracheal lymph nodes. This combination means that it is a somewhat easy structure to compress.
Compression of the thin walls causes obstruction to flow. This results in increased venous pressure, with subsequent oedema and distention of those veins draining into the SVC, such as the external and internal jugular veins and their tributaries. If the SVC is obstructed blood will return to the heart via collateral systems including the azygous venous system, the internal mammary venous system and the long thoracic system.
Basic cross-section of mediastinum showing the structures surrounding the SVtC
3. In this patient what is the likely cause of the diagnosis?
Click to see the answerIn this patient with SLE , it is possible that massive mediastinal lymphadenopathy was the cause of the obstruction. SVC obstruction has also been reported as a complication of repeated central venous cannulation. However, the majority of cases of SVC obstruction are caused by malignancy, the most common being bronchogenic carcinoma, with small cell carcinoma being the most common aetiology within this group.