Collapsed 3

Respiratory System


Diagnosis and reasoning

This patient has presented with severe respiratory distress; examination reveals reduced chest expansion and breath sounds in the left-hemithorax in association with tracheal deviation towards the contralateral side, i.e. features suggestive of a pneumothorax.


Even more ominously, note that he is tachycardic, with a borderline blood pressure and markedly elevated jugular venous pressure. This is a tension pneumothorax until proven otherwise.


Prompt decompression via a large bore needle should be performed immediately; this should not be delayed pending investigations. This will convert the tension pneumothorax into a more benign open pneumothorax.


Subsequently, air should be evacuated until the patient is no longer compromised; a chest drain should be inserted later.


Note that thrombolysis is a management option in pulmonary embolism, while antibiotics are not indicated here.

Discussion

Tension pneumothorax is an immediately life-threatening emergency which mandates rapid clinical diagnosis and treatment.


The condition develops when a one-way valve is created between the lung and pleural space; this results in progressive accumulation of air in the pleural cavity during each respiratory cycle, with a progressive increase in intrathoracic pressure.


The intrathoracic pressure eventually increases to a point where mediastinal structures are displaced, interfering with venous return to the heart, and resulting in cardiovascular collapse and shock.


Trauma is the commonest cause of tension pneumothorax, although the condition may also occur spontaneously. In the intensive care setting, patients who are ventilated (incorrectly) are at increased risk .


Given the necessity of rapid action, the diagnosis of tension pneumothorax relies on clinical features.


Classical symptoms include dyspnea, chest pain, anxiety and very rarely, acute epigastric pain; important signs includ

e hyper-resonance and absent breath sounds on the affected hemithorax and tracheal deviation towards the opposite side; associated tachycardia and jugular venous distention is also common.


However, it is essential to appreciate that these signs and symptoms may be muted or even absent in some patients (especially in the early stages); thus, the diagnosis should be considered in all patients who present with acute respiratory compromise.


If tension pneumothorax is suspected, management should not be delayed pending radiological confirmation. Chest x-rays should only be obtained once the patient's immediate respiratory distress has been alleviated and he or she is stable.


In the rare eventuality that a chest x-ray is obtained safely, findings may include ipsilateral lung collapse at the hilum, increased thoracic volume, tracheal and mediastinal deviation towards the contralateral side, widened intercostal spaces on the affected side, and ipsilateral flattening of the heart border. If the left hemithorax is affected, the left hemidiaphragm may be depressed; note that the liver prevents this occurrence on the right side.


The most urgent goal in the management is to alleviate the increased intrapleural pressure.


This is most quickly accomplished by performing thoracocentesis using a large bore needle (14 gauge) in the midclavicular line of the 2nd intercostal space; when performed, there should be an audible release of the trapped air, and the patient should begin to improve as the tension is released.


Once the pleural space has been evacuated, a tube thoracostomy may be performed.


Note that in certain patients, thoracocentesis alone may not result in sufficient decompression; in such cases, an urgent tube thoracostomy is mandated.

Take home messages

1. Tension pneumothorax can rapidly become lethal - rapid clinical diagnosis is key to averting death.

2. Tension pneumothorax should be considered in all patients presenting with acute severe respiratory distress, as the 'classical' signs and symptoms may be muted or even absent in some patients.

3. Prompt decompression via a large bore needle should be performed immediately; this should never be delayed pending investigations.

References

  1. Thorax 2003;58:ii39-ii52 doi:10.1136/thorax.58.suppl_2.ii39, BTS guidelines for the management of spontaneous pneumothorax, M Henry, T Arnold, J Harvey.
  2. Emerg Med J 2005;22:8-16 doi:10.1136/emj.2003.010421,Review Tension pneumothorax— time for a re-think?, S Leigh-Smith, T Harris.
  3. Chest. 2001 Feb;119(2):590-602, Management of spontaneous pneumothorax: an American College of Chest Physicians Delphi consensus statement,Baumann MH, Strange C, Heffner JE, Light R, Kirby TJ, Klein J, Luketich JD, Panacek EA, Sahn SA; AACP Pneumothorax Consensus Group.
  4. J Emerg Med. 2009 Apr;36(3):242-5. Epub 2007 Aug 29, Tension pneumothorax managed without immediate needle decompression, Chan SS.