Tension Pneumothorax · What Is It, Causes, Signs, Symptoms, Diagnosis, Treatment, and More

Tension pneumothorax is a life-threatening condition caused by the continuous entrance and entrapment of air into the pleural space, resulting in compression of the lungs, heart, blood vessels, and other structures in the chest. The pleura is a double-layered membrane that lines the inner part of the chest wall and the surface of the lungs, allowing them to move and slide over each other during respiration. The two layers of the pleura fold onto each other, forming the pleural space. Under normal conditions, the pleural space contains a lubricating fluid that prevents the two layers of the pleura from rubbing against each other.  

When the pleura is damaged, either due to lung disease or chest wall trauma, air can flow freely into the pleural space from the outside environment or the lungs but is unable to escape. The accumulated air in the pleural space exerts positive pressure on the lung and prevents it from expanding properly, resulting in respiratory distress. As the air continues to accumulate, it pushes away the trachea and other structures of the chest, leading to increased difficulty breathing. Additionally, the increased intrathoracic pressure can compress the blood vessels returning blood to the heart and the heart itself, decreasing venous return and cardiac output. If left untreated, tension pneumothorax can rapidly progress to cardiovascular collapse, which can ultimately lead to cardiac arrest. 

Pneumothorax occurs when a defect in the pleura allows air to leak into the pleural space, causing partial or total collapse of the affected lung. In this case, however, the trapped air does not continue to accumulate and is in part able to escape during expiration. As a result, intrapleural pressure does not keep increasing, and the affected lung is allowed to partially expand and fill with oxygen during inspiration.  

Depending on the cause, pneumothorax can be classified as spontaneous or traumatic. Spontaneous or simple pneumothorax can be further subdivided into primary spontaneous pneumothorax, in the absence of an underlying lung disease, or secondary spontaneous pneumothorax, if an underlying lung disease is present. On the other hand, traumatic pneumothorax can result from any kind of chest trauma, including iatrogenic pneumothorax, which occurs as a complication of a medical procedure.  

Both spontaneous and traumatic pneumothorax can evolve into tension pneumothorax, which is life-threatening and can lead to significant respiratory distress and hemodynamic instability. In tension pneumothorax, the pleural injury acts as a one-way valve through which air can enter the pleural space during inspiration but is unable to escape during expiration. With each inhalation, more air gets trapped inside the chest, leaving less space for the lungs to expand.  

Individuals with tension pneumothorax may present severe shortness of breath, shallow breathing, and acute chest pain, along with low blood oxygen levels, increased heart rate, low blood pressure, and altered mental status.  

Upon physical examination, common findings include tracheal deviation away from the affected side, decreased or absent breath sounds upon lung auscultation, hyperresonance at chest percussion, and asymmetrical chest expansion due to the collapsed lung. In severe cases, individuals can present blue skin discoloration due to decreased blood oxygen levels, and distended neck veins as a result of the impaired venous return to the heart.  

Sometimes, the air can leak from the pleural space and get trapped in surrounding areas, such as the subcutaneous tissue, causing subcutaneous emphysema, and nearby cavities like the mediastinum, causing pneumomediastinum.  

Diagnosis of tension pneumothorax should be suspected in individuals with respiratory distress, tracheal deviation, distended neck veins, low blood pressure, and decreased or absent breath sounds upon lung auscultation.  

A strong clinical suspicion of tension pneumothorax is enough to initiate emergency treatment, which should not be delayed by any imaging studies. Once the individual has been successfully treated, a chest X-ray can be performed. Radiological signs of pneumothorax include increased transparency or radiolucency of the affected side, increased rib separation, and partial or total collapse of the affected lung. Radiological signs more specific for tension pneumothorax include mediastinal and tracheal deviation away from the affected side, as well as flattening of the diaphragm. A point-of-care ultrasound is an alternative strategy that can be used to confirm the diagnosis.  

Tension pneumothorax is a medical emergency that requires treatment with needle decompression of the chest, also known as needle thoracostomy, to allow trapped air to leave the pleural space. During needle decompression, an emergency technician or trained physician inserts a large needle through the chest wall, between the ribs, and into the pleural space. This procedure can be lifesaving, especially in the prehospital setting, as transport to the hospital can delay treatment.  

Individuals with a tension pneumothorax should be transferred to a critical care unit for continuous monitoring of their vital signs and administration of high-concentration supplemental oxygen. After needle decompression, the inserted needle is left in place until a more definitive chest tube can be inserted to evacuate the remaining air. After placing the chest tube, a chest X-ray is usually obtained to check its location position and confirm the successful re-expansion of the lung.