A rare case of congenital diaphragmatic defect presenting with clinical signs of an acute tension pneumothorax is described. The clinical findings were eventually attributable to a herniation of abdominal contents into the chest (Bochdalek hernia). Attempted decompression of the chest by needle thoracocentesis and subsequent introduction of a chest drain caused gastric perforation, requiring repair at laparotomy. It is suggested that if needle thoracocentesis does not result in immediate clinical improvement, or if there is abdominal pain, a portable chest radiograph should be performed before tube thoracostomy to exclude Bochdalek hernia. All emergency department staff should be taught to recognise the radiological appearance of a Bochdalek hernia.
- tension pneumothorax
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Diaphragmatic hernias through the foramen of Bochdalek were first described in 1848 and result from the failure of fusion of the lateral (costal) with the posterior (crural) components of the diaphragm. It occurs in one in every 2500 live births and is more common on the left.
A 43 year old, previously fit man presented to accident and emergency complaining of severe abdominal pain and shortness of breath.
Examination revealed a tachypnoea of 34 breath/min, pulse rate of 137 beat/min, and a blood pressure of 117/85. His oxygen saturation was maintained at 94%. Chest expansion was equal bilaterally with a central trachea but decreased breath sounds on the left. The abdomen was soft to palpation, but tender in the left upper quadrant.
A diagnosis of simple pneumothorax was made and a portable chest radiograph performed.
Shortly afterwards, the patient became hypotensive (blood pressure of 105/65 mm Hg), cyanosed and sweaty, with a respiratory rate of 40 breath/min and pulse rate of 140 beat/min. The chest appeared hyper-expanded on the left, with decreased breath sounds and reduced movements on that side. The trachea was deviated to the right.
The chest radiograph (see fig 1) revealed a large radiolucent area in the left hemithorax. The appearance was thought to confirm the diagnosis of tension pneumothorax.
Needle thoracostomy was performed in the second intercostal space anteriorly and a hiss of escaping air was noted.
A chest drain was introduced and air was seen to bubble through an underwater drain. There was an improvement in pulse and respiratory rate and an increase in oxygen saturation to 95%.
Within a few minutes, the chest tube had stopped draining air and the patient deteriorated again. The tube was replaced, but still no air drained.
On further analysis of the chest radiograph, herniation of abdominal contents into the left hemithorax was diagnosed. The chest drain was removed and the patient prepared for theatre. Operative findings included a large Bochdalek hernia posterolaterally with herniation of stomach, transverse colon, and spleen in to the chest. There was a large perforation in the gastric fundus, presumably caused by the insertion of a chest drain.
The abdominal organs were replaced and the gastric fundus oversewn. The diaphragmatic defect was repaired. The patient made a full recovery.
Tension pneumothorax is a life threatening condition. It should be treated by immediate decompression by needle thoracocentesis followed by tube thoracostomy.5 The diagnosis is a clinical one and treatment should not be delayed by chest radiography.
In this case the clinical signs, while being consistent with a tension pneumothorax, were caused by herniation of a gas filled stomach into the left hemithorax. Chest radiography before chest decompression revealed the gastrothorax, but was misinterpreted. Subsequent needle thoracostomy resulted in a slight improvement, presumably because of decompression of the stomach. The radiograph (fig 1) showed lung markings in the left upper zone, separated from the large lucent area by a curved radio-opaque line representing the stomach wall. These changes are not consistent with a diagnosis of tension pneumothorax, in which the peripheries of the lung field will be devoid of lung marking and the lung margin should be visible.
Herniation of abdominal contents should have been diagnosed and a nasogastric tube passed to decompress the stomach. Laparotomy and diaphragmatic repair should then have been carried out without the need to repair the stomach perforation.
Differentiating tension pneumothorax from bowel herniation may not be straightforward. In one study of 26 children,2 16 patients (62%) were misdiagnosed clinically and radiologically. In another case report3 a 29 month old child presented with acute respiratory failure. Chest radiography showed a gastrothorax, which (as in this case) was misinterpreted as a tension pneumothorax and the stomach perforated by tube thoracostomy.
In conclusion, patients presenting with the signs of tension pneumothorax should have immediate decompression by needle thoracocentesis. In the presence of abdominal pain, or a failure to improve significantly after needle decompression, a portable chest radiograph should be performed before tube thoracostomy to exclude Bochdalek hernia. All emergency department staff should be taught to recognise the radiological appearance of a Bochdalek hernia.
Conflicts of interest: none declared.
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