Given that I learn so much from the posts of other members, I thought I would try to contribute by posting a quick tutorial on a basic medical topic that everyone on the battlefield should know about. I tried to write this for someone with little or no medical training.
Tension Pneumothorax (T.P.)
Why is it important?
-Studies during Vietnam showed that 33% of preventable deaths on the battlefield were caused by tension pneumothorax. The simple insertion of a needle into the chest could possibly have prevented a lot of these deaths.
What is it?
-The term pneumothorax is defined as air or gas in the pleural space. The pleural is a membrane that coats your chest wall and the outermost layer of your lung. The pleural space is located between these two layers. In a normal person there is only a small amount of pleural fluid located in the pleural space. Both pleural layers are held together in place by a film of pleural fluid, like two glass microscope slides that are wetted and stuck together. This causes the chest wall and lung to move together. The pleural space is considered a potential space because in a normal person this space is almost nonexistent, but in disease states this area can fill with air or fluid and increase greatly in size. The figure 1 below shows a simple pneumothorax with the gray area representing the pleural space filled with air.
A tension pneumothorax (T.P.) is a type of pneumothorax where there is progressive accumulation of air in the plural space under pressure. It is usually caused by a ball/valve mechanism where air can enter the pleural space but it can not exit. When a T.P. occurs the pressure in the pleural space causes both lungs and the blood supply to the heart and lungs to become compressed. This essentially causes your heart and lungs not to function properly. A T.P. can cause death in minutes. Because of this it is a true emergency.
Causes:
-A tension pneumothorax can result after either blunt injury to the chest or any penetrating injury such as a gun shot or stab wound.
Clinical signs and symptoms:
-Patients with T.P. quickly become acutely ill. They will develop difficulty breathing (respiratory distress/dyspnea), their heart rate will go up (tachycardia) and their blood pressure will drop below normal (hypotension). There is a wide variety in the clinical presentation, but the hallmarks are tachycardia, neck veins that become dilated, and no breath sounds (heard through a stethoscope) on the same side of the chest as the pneumothorax. The Tactical Combat Casualty Care (TCCC) report by Dr. Butler recommends that “progressive, sever respiratory distress in the setting of unilateral blunt or penetration chest trauma on the battle field should result in the presumed diagnosis of tension pneumothorax, and that side of the chest should be decompressed with a needle.”
Treatment:
-The immediate treatment for a tension pneumothorax is a needle thoracostomy. This means inserting a large needle (16 or 18 gauge) into the space between the 2nd and 3rd rib directly above the nipple on the side that the pneumothorax is located. The needle should be inserted just above the superior aspect of the 3rd rib because there are blood vessels located on the inferior aspect of each rib. In figure 2 site A is the location where a needle thoracostomy should be performed.
Figure 3 shoes the use of a needle to puncture the pleura and establish the presence of blood or air in the pleural space. This not only is diagnostic but also may be a temporary therapeutic maneuver in a tension pneumothrax.
Because the air in the pneumothorax is under pressure when the needle is inserted into the pneumothorax air will move from the pleural space through the needle and into the external environment causing a rush of air to be heard. What this does is relieve the pressure in the pleural space resulting in restored heart and lung function. Needle decompression is only a temporizing measure (pressure can re-accumulate after needle decompression); the definitive treatment for a pneumothorax is a chest tube and negative suction. Again this is just an overview and there is much more to learn about the subject, but I hope it is helpful.
Figure 1: Figure taken from Marx: Rosen's Emergency Medicine: Concepts and Clinical Practice, 5th ed.
Figure 2: Figure taken from
http://www.hcmc.org/manualHCMC/Proce...tomy_tube.htm.
Figure 3: Redrawn from Richards. V.: Tube thoracostomy. J. Fam. Pract. 6:631. 1978.)
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