Tension pneumothorax

This is similar to a pneumothorax, but the pressure effects are great enough to impede respiration or circulation. This is a medical emergency.

 

Pathophysiology

The defect which allows air into the pleural cavity acts as a one-way valve. Air accumulates inside the pleural cavity and cannot escape. The air in the hemithorax produces such pressure that it forces the heart to the other side and compresses the other lung. Venous return and cardiac preload to the heart are reduced.

Oxygen saturation falls. The respiratory rate and tidal volume increase to compensate. This worsens the problem.

 

Complications

• Respiratory arrest
• Hypoxia
• Obstructive shock
• Pulseless electrical activity

 

Investigations

• Chest radiograph

 

Management

• Needle thoracostomy : Insertion of a sterile needle into the pleura, between the ribs, as soon as possible. 

Classically, it is taught that this must be performed on clinical suspicion of tension pneumothorax, without waiting for a radiograph. Recently, evidence suggests that the 'tension effects'  progress more slowly than widely believed. Some ATLS courses are now recommending the radiograph before attempting the procedure.