Leukemia (Blood Cancer)

 

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neumothorax. Pneumo refers to air and thorax means chest so a pneumothorax is when there's air in the chest more specifically air in the space between the lungs and the chest wall called the pleural space. The pleural space lies between the parietal pleura which is stuck to the chest wall and the visceral pleura which is stuck to the lungs. The pleural space normally contains a lubricating fluid that helps reduce friction as the lungs expand and contract pressure within the pleural space is established by two main opposing forces one is the muscle tension of the diaphragm and the chest wall which contracts and expands the thoracic cavity outwards and the other is the elastic recoil of the lungs which try to pull the lungs inward the two pull on each other creating a balance between the forces that creates a slight vacuum in the pleural space, it results in the pleural space having a pressure of minus five centimeters of water relative to a pressure of 0cm of water in both the thoracic cavity and the lungs.

           

A pneumothorax forms when the seal of the pleural space is punctured and air moves in from the outside making the pressure in the pleural space equalized to 0cm of water since the negative pleural pressure is lost the two opposing forces no longer pull on one another as a result the lungs simply pull inwards and collapse and the chest wall simply springs outwards a bit a collapsed lung limits how well it can exchange the air and can lead to a reduction in oxygen being brought into the body and a buildup of carbon dioxide in the body because it can't get released.

There are many types of pneumothorax the first is spontaneous pneumothorax which typically occurs when a bullet which is a large air pocket forms on the surface of the lung and breaks bullet form when the alveoli which are the terminal ends of the lungs where gas exchange occurs develop a tiny leak and air slowly seeps into the surrounding lung tissue, typically the alveoli heal up otherwise it would itself lead to a pneumothorax but the result is a bullet and if the bullet breaks it creates a large hole in the visceral pleura and air can go from the airway directly into the pleural space, a primary spontaneous pneumothorax is one that develops in the absence of an underlying condition most typically it's a thin tall adolescent male who's holding his breath creating a lot of internal pressure. a secondary spontaneous pneumothorax is one that develops in someone with an underlying lung disease like Marfan syndrome, cystic fibrosis, emphysema or lung cancer.

In contrast to spontaneous pneumothorax, there's also traumatic pneumothorax which is when trauma like a gunshot wound or a stab wound rips through the parietal pleura allowing air to enter from the outside directly into the pleural space, finally there's tension pneumothorax which can develop similarly to spontaneous pneumothorax or a traumatic pneumothorax with the one difference being that it creates a one-way valve for air to flow into the pleural space in other words air can enter but cannot leave because there's a flap of tissue that doesn't allow air to go the other way, over time air might build up increasing the pressure and it can start compressing the heart and lung making them less functional and it can shift large structures like the trachea.

Tension pneumothorax that's pressing on the heart is particularly dangerous because it can prevent the heart from filling up properly reducing the cardiac output the main symptoms of a pneumothorax are shortness of breath and chest pain the extra air in the pleural space also changes sound transmission in the chest so on auscultation or listening with a stethoscope normal breath sounds are reduced also when the chest is tapped or percussed the extra air in the pleural space makes the resonant sound get louder known as hyper resonance. Typically an X-ray or CT is needed for diagnosis and usually, an outline of the collapsed lung can be seen with a distinct difference between the lung tissue which is mostly black, and the air in the pleural space which is completely black if there's a tension pneumothorax an X-ray or CT might show displacement of the chest structures like the trachea away from the affected side this is called tracheal deviation often if a spontaneous pneumothorax is small and not causing any shortness of breath no treatment is required and the plural will heal over time but with a larger pneumothorax that's causing severe symptoms or with a tension pneumothorax the end needs to be removed. Typically this is done by inserting a needle or a chest tube and providing an escape route for the air.  

All right as a quick recap, a pneumothorax is when there's air in the pleural space and a loss of negative pressure that leads to lung collapse and chest wall expansion which can cause shortness of breath and chest pain. Tension pneumothorax is when there's a flap of tissue creating a one-way valve and it can allow pressure to build up over time that can press against nearby organs like the heart and potentially affect cardiac output in severe cases a needle or chest tube can be used to decompress the air in the pleural space.

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