Answers

Short answers

1 Pneumomediastinum is the presence of gas in the mediastinal tissues outside the oesophagus and tracheobronchial tree.

2 This study is a water soluble contrast swallow. It is used in suspected oesophageal rupture to demonstrate a leak from the oesophagus into the mediastinum (fig 2).

View larger version (93K): [in this window] [in a new window] [PowerPoint Slide for Teaching]   Fig 2 Water soluble contrast study showing an oesophageal leak from the right side of the oesophagus (O) into the mediastinum (M) with only a small amount of contrast entering the stomach (S)

3 Boerhaave’s syndrome.

4 If the patient presents within 24 hours, direct surgical repair or insertion of an endoscopic stent is usually advocated; after this time, a conservative approach may be the better option.

Long answers
1 Pneumomediastinum
Pneumomediastinum is the presence of gas in the mediastinal tissues outside the oesophagus and tracheobronchial tree. It is associated with pneumothorax and subcutaneous emphysema, and it occurs when air is introduced into the mediastinum from an intrathoracic or extrathoracic source.¹ Pneumomediastinum may be traumatic or spontaneous.

Spontaneous pneumomediastinum occurs most commonly when alveolar pressures increase and cause terminal alveolar rupture into the lung interstitium. This occurs in acute asthma and in patients on ventilation.

Other intrathoracic causes include oesophageal rupture caused by perforating malignancy, iatrogenic injury, and Boerhaave’s syndrome.

Extrathoracic causes include perforation of a hollow intra-abdominal viscus, with air passing into the mediastinum via communications with the retroperitoneum, and sinus fractures and dental extraction via communications between the mediastinum and the neck.²

Trauma to the chest may cause oesophageal rupture, alveolar rupture, or fracture of the trachea or bronchus, thereby giving rise to a pneumomediastinum.

The presence of a pneumomediastinum, pneumothorax, and pleural effusion with a history of chest pain preceded by vomiting makes oesophageal rupture a likely diagnosis.

2 Radiological test
A contrast study of the oesophagus may detect a leak from a ruptured oesophagus into the mediastinum. In suspected perforation, water soluble contrast agents are used. Although these agents are less visible than barium, which makes it harder to detect a leak, the incidence of adverse reactions is lower (barium can precipitate mediastinal fibrosis). In 10% of cases, this study is negative. In such cases, if clinical suspicion is high, higher density "thin" barium may be used because it can detect smaller leaks.³

Single contrast studies using thin barium are useful for assessing oesophageal motility and contour as well as extrinsic causes of stenosis, which cannot be assessed by endoscopy. They may also be helpful in assessing varices in patients unable to tolerate endoscopy.

Ionic contrast agents such as gastrograffin are no longer used because aspiration can induce pulmonary oedema and chemical pneumonitis.

3 Diagnosis
Boerhaave’s syndrome is complete transmural rupture of the oesophageal wall secondary to vomiting. It accounts for around 15% of causes of oesophageal rupture, with 55% being caused by iatrogenic injury and 10% by closed chest trauma.⁴

The most common site of perforation is at the weakest point of the oesophagus, the left posterolateral wall, 2-3 cm above the gastro-oesophageal junction. It typically presents with Mackler’s triad of vomiting, sudden severe chest pain, and subcutaneous emphysema and is associated with pneumothorax and pleural effusion. Effusions occur on the left in 90% of cases.⁵ Gastric contents enter the mediastinum and pleural cavity, causing mediastinitis and empyema. Severe sepsis may ensue and lead to circulatory shock. Fluid resuscitation and rapid administration of broad spectrum antibiotics can improve the outcome.

It is most common in men aged 50-70, with the male:female ratio ranging from 2:1 to 5:1.⁶ Mortality ranges from 20% to 40%.⁵ Prognosis is influenced by the underlying physical status of the patient.

Presentation can be varied, and Boerhaave’s syndrome often mimics conditions such as pulmonary embolism, acute aortic dissection, aortic rupture, myocardial infarction, perforated peptic ulcer, and pancreatitis.⁷

Chest radiography is often the preliminary investigation and is abnormal in 90% of cases.⁸ The earliest finding is of extraluminal gas forming a radiolucent triangle behind the heart. Other findings include a pleural effusion, pneumomediastinum, subcutaneous emphysema, pneumopericardium, mediastinal widening, and an air-fluid interface level.

As described earlier, contrast studies can show a leak into the mediastinum. Computed tomography is useful in patients who are too unwell to undergo fluoroscopy or when the diagnosis is uncertain.⁹ Features include air and abscess cavities in the perioesophageal soft tissues of the mediastinum, and communication of an air filled oesophagus with an adjacent mediastinal or paramediastinal air-fluid collection. Oral administration of water soluble contrast is occasionally used to demonstrate a leak.¹⁰

4 Management
If presentation is within 24 hours, direct surgical repair is usually advocated.¹¹ After 24 hours, primary repair may be less successful, and a conservative approach may be the best option. However, successful delayed primary repair has been reported.¹²

Endoscopic placement of metallic stents to seal oesophageal perforations has shown good results when performed early after rupture in patients who are not septic.¹³ Stents are removed after healing to prevent complications such as infection or an aorto-oesophageal fistula. Chest drains can be put in place to drain pleural collections.

Conservative management is appropriate in patients with well contained perforations and minimal mediastinal and pleural contamination.⁸ Initially, patients should be given nil by mouth, with nasogastric suction, and given broad spectrum antibiotics and total parenteral nutrition.

Conclusions
This case was not typical of Boerhaave’s syndrome and it illustrates the variable clinical and radiological findings. The patient was a middle aged woman who presented with a right sided pleural effusion. Some reports have suggested that 80% of cases occur in middle aged men.⁶ Most patients present with a left sided rupture. At surgery, the patient was found to have a 13 cm tear, which is significantly longer than the average tear of 2.2 cm.⁵

Outcome
The patient underwent a partial direct repair within 24 hours and pleural drains and a feeding jejunostomy were inserted. She subsequently developed a fistulous connection between the oesophagus and the right thorax, which was closed endoscopically with clips and bioglue. She was discharged after a four month stay in hospital and remains well.

Cite this as: BMJ 2009;339:b3004