By Jim Sideras
Tension pneumothorax is a life-threatening condition that can occur with chest trauma and is more likely to happen with trauma involving an opening in the chest wall. Recognizing and treating it quickly is important. This is particularly true for combat and SWAT team medics who are working in tactical environments and may often encounter thoracic trauma. The military has collected vast amounts of data regarding tension pneumothorax and subsequent treatment. In the combat setting, tension pneumothorax is the second leading cause of death, and often it is preventable.
With time, more and more information is becoming available that will likely improve survival for patients in the urban prehospital setting. This article will discuss the injury process that often leads to a tension pneumothorax as well as prehospital treatment. Any open chest wound has a high probability of developing a tension pneumothorax. The medical provider needs to be keenly aware of the signs, symptoms, and treatment of a tension pneumothorax. This article is not intended to replace actual training.
A pneumothorax means air in the chest cavity. This occurs when air, either from the lungs or outside the body, enters the pleural space that is normally occupied by the lung. It is called a "closed pneumothorax" when the chest wall is intact. With an intact chest wall, a pneumothorax can be caused by several things, but the most frequently encountered cause is from trauma resulting in a rib fracture that punctures a lung, releasing air into the pleural space. The signs and symptoms for a closed pneumothorax are chest pain, tachypnea, and dyspnea. Normally, a closed pneumothorax is not a life-threatening condition unless it progresses into a tension pneumothorax, which will be discussed later.
An "open pneumothorax" occurs when there is an opening in the chest wall, which can be the result of penetrating trauma such as a gunshot wound or stabbing. This opening allows air to move from the outside of the body, through the opening in the chest wall, and directly into the pleural space. The larger the hole, or holes, in the chest wall, the greater the amount of air that can enter the pleural space.
Remember, the opening can also be on the patient's back in the case of an entry or exit wound. The provider needs to check both the front, back, and sides of the patient for penetrating trauma. Additionally, if the patient is wearing body armor, it is important to check for atypical entry and exit sites that may occur from deflections due to the armor. The signs and symptoms are similar to a closed pneumothorax with the addition of sucking or gurgling sounds that may occur over the opening.
A tension pneumothorax occurs when the patient cannot compensate, and several events begin to occur that can lead to death. As air fills the pleural space on inspiration through the opening with an open pneumothorax, the wound can act as a one-way valve and not allow the air to exit. This leads to a cascading effect on the patient.
As more air enters the pleural space, the pressure in the space increases and begins to collapse the lung on the injured side. As the injured lung collapses, there is less air that can be exchanged for perfusion in the lung. Once the lung has collapsed, pressure begins to compress the heart, shifting the mediastinum toward the uninjured lung. This triad of a collapsing lung, shift in the mediastinum, and rebreathing is the beginning of a rapid deterioration of a patient's ability to maintain oxygenation.
As this continues, the compression of the vena cava reduces cardiac blood flow to the heart and decreasing cardiac output. This leads to difficulty breathing, and tachycardia. A noticeable shift in the trachea will be evident. This entire process leads to a life-threatening condition known as a "tension pneumothorax." The patient in this condition will die if treatment is not provided.
For an open pneumothorax, treatment requires sealing the open wound with an occlusive dressing. This is often taught by using Vaseline gauze and securing the gauze to the patient's chest with tape. However, this can be a difficult process in the field depending on the size of the wound, the patient's condition, and the area the dressing is applied.
Often the area is hairy, bloody, and dirty, which can be factors in keeping the occlusive dressing intact. There are dressings that are manufactured specifically for chest wounds. These dressings have an aggressive and very sticky adhesive, which ensures a secure seal to the chest. Some of these dressings are available in larger sizes to fit a greater amount of surface area and others have a one-valve, with the idea that trapped air can vent from the pleural space. Commercial dressings for open chest trauma have been used with great success by both military and tactical medics, and should be part of a medic's standard supply.
With an open chest wound that is covered, the patient may often still deteriorate and have a tension pneumothorax. This happens when air is leaking from a damaged lung continuing to fill the pleural space with air that cannot escape. When the patient's condition is deteriorating, some paramedic programs teach that it may be possible to lift the dressing from the wound allowing trapped air to escape, or even gently spread the wound to help air escape. The wound is then resealed after such a procedure.
If this does not relieve the trapped air, the next step is a thoracic decompression, often called needle thoracostomy or needle compression. This involves using a needle catheter to release the trapped air in the pleural space. If the patient has either a closed or open tension pneumothorax, then the need for a needle decompression is required to save the patient.
A needle decompression involves inserting a large bore needle in the second intercostal space, at the midclavicular line. Once this is done, there should be an audible release as the trapped air, and as the tension is released the patient should begin to improve.
It is important to have the proper equipment on hand to successfully perform a needle decompression. The latest data suggest that the optimal needle for use in treatment of a tension pneumothorax in adult patients is a 3.25 inch 14 gauge (or larger diameter) needle. However, currently taught practices may be ineffective in the successful treatment of a tension pneumothorax. These practices use a 1.75 to 2 inch, 14 to 16 gauge needle for chest decompression. However, recent studies are proving that this needle length will not provide the optimum care for patients with a tension pneumothorax.
A study published in Prehospital Emergency Care used CT scans to measure the thickness of the chest wall. These measurements determined that using a 1.75 inch needle catheter for chest decompression would result in a failure rate of 50 percent basis on body composition tested.
A similar study published in the Journal of Trauma found that the use of the commonly taught practice of using a 2 inch catheter resulted in a failure rate of just over 35 percent of the population.
A study in Military Medicine found that a needle length 3.25 inches successfully reached the pleural space in 99 percent of the persons in their study. Keep in mind that needle length is critical to releasing trapped air, and often patients are larger in size than in the past.
Research from the US Army Institute of Surgical Research has also focused on the treatment of tension pneumothorax. Studies have determined that chest decompression with a 14 gauge needle is as successful as a chest tube in relieving a tension pneumothorax and therapeutic benefits can continue for as long a four hours.
If using a needle catheter with a flash chamber, you should ensure that the chamber is removed. There are specially manufactured needles designed just for a tension pneumothorax. These are prepackaged 3.25 inch 14 gauge needles that do not have flash chambers. The removal of the chamber ensures that in a high-stress situation, the provider will not have to remember to remove it. It has been reported that often the provider will forget to remove the flash chamber, and this will cause the procedure to fail.
Method for needle decompression
A needle decompression should only be performed if the patient has a tension pneumothorax. When inserting the needle, it should be inserted at a 90 degree angle to the chest wall. This is a critical point as this will position the needle straight into the pleural space. If any other angle is used, there may be a chance of hitting other structures in the area such as major blood vessels or even the heart.
The following are steps to perform a chest decompression. However, you should follow your own protocols.
- Ensure patient is oxygenated if possible
- Select proper site
a. Affected side at the second intercostal space and along the mid-clavicular line
b. Note: Draw an imaginary line from the nipple up to the clavicle. The needle should not be closer to the middle of the chest than this line
- Clean site with alcohol or povidine solution
- Prepare needle; if it has a leur-lock or flash chamber, it will need to be removed
- Insert the needle into the second intercostal space at a 90 degree angle to the chest, just over the third rib.
Note: There are blood vessels running along the bottom of the ribs. Ensure the needle is closer to the top margin of the lower rib in the intercostal space. This will prevent these vessels from being damaged.
- Listen for a rush of exiting air from the needle
- Remove the needle and leave the catheter in place, properly disposing of the needle
- Secure the catheter in place with tape. Some suggest covering the end of the catheter, but this will depend on the situation
- Ensure the tension has been relieved and the patient's condition improves. If there is no improvement, the procedure will need to be repeated with another needle placed adjacent to the first needle
- Monitor, then reassess the patient
A tension pneumothorax is a life-threatening situation. It may present with either a closed or open chest injury. The medical provider needs to be keenly aware that there is a high probability of a tension pneumothorax if the patient has an open trauma to the chest wall. Good assessment skills, proper equipment, and the training to effectively relieve a tension pneumothorax are vital to save patients from this critical condition.
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