What Is It, Causes, Signs, Symptoms, Diagnosis, Treatment, and More
Author: Anna Hernández Castillo, MD
Illustrator: Aileen Lin
What is tension pneumothorax?
Tension pneumothorax is a life-threatening condition caused by the continuous entrance and entrapment of air into the pleural space, thereby compressing 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 together during respiration. The two layers of the pleura fold onto each other, forming the pleural space. Under normal conditions, the pleural space contains a thin layer of fluid that prevents the two layers of the pleura from rubbing against each other.
When there's damage to the pleura, either due to lung disease or trauma to the chest wall, air from the outside or from the lungs can flow freely into the pleural space, but cannot leave. The accumulated air in the pleural space puts positive pressure on the lung and prevents it from expanding properly, which causes respiratory distress. As the air continues to accumulate, the trachea and other structures of the chest can be pushed away from the pneumothorax, leading to increased difficulty breathing. Additionally, the increased pressure inside the chest can compress the heart and lead to a collapse of the blood vessels that drain to the heart, in turn decreasing venous return and cardiac output. If left untreated, tension pneumothorax can rapidly progress to cardiovascular collapse, which ultimately leads to cardiac arrest.
What causes tension pneumothorax?
Traumatic tension pneumothorax
Open chest wound, like a stab wound or a gunshot
Closed trauma, like a rib fracture
High positive pressure during the inspiratory phase can force air from the lungs into the pleural space, causing a rapidly growing pneumothorax.
Rarely, a spontaneous tension pneumothorax can occur in the absence of any precipitating factors.
What are the signs and symptoms of tension pneumothorax?
Severe shortness of breath
Acute chest pain
Low blood oxygen levels
Increased heart rate
Altered mental status
In severe cases:
Blue discoloration of the skin due to decreased oxygen levels in the blood
Distended neck veins as a result of the collapsed blood vessels that should return blood to the heart
Sometimes, the air in the pleural space can leak and be trapped in nearby areas, such as the subcutaneous tissue, which is known as subcutaneous emphysema, as well as nearby cavities like the mediastinum, causing a pneumomediastinum.
How do you diagnose tension pneumothorax?
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, imaging can be performed.
More specific radiological signs for tension pneumothorax includes mediastinal and tracheal deviation away from the pneumothorax, as well as flattening of the diaphragm.
A point-of-care ultrasound can also be used to confirm the diagnosis.
How do you treat tension pneumothorax?
Tension pneumothorax is a medical emergency that requires immediate treatment.
During needle decompression, an emergency technician or trained physician will insert a large needle through the chest wall, in between the ribs, and into the pleural space. This procedure can be life-saving, especially in the prehospital setting, as transport to the hospital can delay treatment.
After needle decompression, the inserted needle is left in place until a more definitive chest tube can be placed to facilitate the relief of the remaining air. After placing the chest tube, a chest X-ray is usually obtained to check the location of the tube and the successful re-expansion of the lung.
Monitoring in a critical care unit to oversee vital signs and administer high-concentration supplemental oxygen.
Frequently Asked Questions
Pneumothorax occurs when there’s a defect in the pleura that allows air to leak into the pleural space, causing the partial or total collapse of the affected lung. The air trapped does not, however, continue accumulating, and some of the air is also able to escape during expiration. As a result, the intrapleural pressure does not keep increasing, which allows the affected lung 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 absence of an underlying lung disease) or secondary spontaneous pneumothorax (if resultant from an underlying lung disease). On the other hand, traumatic pneumothorax can result from any kind of trauma to the chest; this includes iatrogenic pneumothorax, which occurs as a complication of a medical procedure.
Both spontaneous and traumatic pneumothorax can evolve into tension pneumothorax, which is a life-threatening condition that can lead to significant respiratory distress and hemodynamic instability. In tension pneumothorax, the pleural injury acts as a one-way valve. As a result, the 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.
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Resources for research and reference
Imran, J. B. & Eastman, A. L. (2017). Pneumothorax. JAMA, 2017;318(10):974. DOI: 10.1001/jama.2017.10476
Inocencio, M., Childs, J., Chilstrom, M. L., & Berona, K. (2017). Ultrasound Findings in Tension Pneumothorax: A Case Report. The Journal of Emergency Medicine, 52(6):E217–E220. DOI: 10.1016/j.jemermed.2017.02.008
Leigh-Smith, S. & Harris, T. (2005). Tension pneumothorax—time for a re-think?. Emergency Medicine Journal, 22(1):8–16. DOI: 10.1136/emj.2003.010421
Zarogoulidis, P., Kioumis, I., Pitsiou, G., Porpodis, K., Lampaki, S., Papaiwannou, A., Katsikogiannis, N., Zaric, B., Branislav, P., Secen, N., Dryllis, G., Machairiotis, N., Rapti, A., & Zarogoulidis, K. (2014). Pneumothorax: from definition to diagnosis and treatment. Journal of Thoracic Disease, 6(Suppl 4):S372–S376. DOI: 10.3978/j.issn.2072-1439.2014.09.24