Introduction
Pneumothorax is one of the more common injuries seen in trauma patients. Its treatment is simple and straightforward; however a clinician must first be able to recognize it. Failure to do so may result in the development of a tension pneumothorax; and rapidly deteriorate into a life threatening emergency. In this article we will look at simple pneumothorax and tension pneumothorax and review their management and treatment.

Definition
Pneumothorax refers to an accumulation or collection of air in the pleural space resulting in a partial or complete collapse of the affected lung. Most often the lung tissue is actually lacerated resulting in an air leak. This is referred to as a simple pneumothorax.

An open pneumothorax or "sucking chest wound" occurs when an opening in the chest wall (usually from a penetrating object) allows air to move through the chest wall instead of the trachea. The wound usually has to be at least 2/3 the size of the trachea for this to occur. Air may move in and out via the wound or a one way valve effect can occur thus trapping the air inside the thoracic cavity.

A hemothorax is free blood in the pleural space that results from bleeding lung tissue or blood vessel injury. A hemothorax may result in both hypoxia and shock.

A tension pneumothorax is created when the air within the pleural space cannot escape and completely collapses the affected lung. As this pocket of air increases the lung collapses further, and the mediastinum and its contents are displaced to the opposite side. For a simple pneumothorax to progress to a tension pneumothorax a "one way valve" must exist ie: air is not allowed to escape but increase in volume within the pleural space. This volume of trapped air increases with each ventilation thus rapidly filling the affected hemithorax. This air is under "tension" and cannot escape due to the one way valve effect. The mediastinum shifts to the unaffected side causing compression or torsion of the great vessels and inadequate ventilation of the unaffected lung. The patient may present with dyspnea and rapidly progress to cardiovascular collapse/arrest.

Tension pneumothorax is a life threatening emergency and lethal if not recognized and definitively treated.
 

Etiology
The most common etiologies are related to trauma
 

• Trauma (blunt or penetrating) - Involves disruption of the pleura and often is associated with rib fractures (rib fractures not necessary for tension pneumothorax to occur)
   
• Barotrauma secondary to positive-pressure ventilation, especially when using high amounts of positive end-expiratory pressure (PEEP)
   
• Central line placement, usually subclavian or internal jugular
   
• Conversion of simple pneumothorax to tension pneumothorax
   
• Unsuccessful attempts to convert an open pneumothorax to a simple pneumothorax in which the occlusive dressing functions as a 1-way valve
   

Assessment Strategy
The following assessment focuses on recognition of pneumothorax/tension pneumothorax.
 

1. Look at the patient. Do they appear in distress? Sick or not sick? Are they dying in front of your eyes? Do they appear short of breath? (if you have to ask they are probably not that short of breath)
2. Observe their thorax for any abnormalities (abrasions, wounds, ecchymosis, etc) Do they have symmetrical chest wall movement? Don't forget their back!
3. Auscultate breath sounds. Listen at the midaxillary line just below the axilla, the apices and if possible the patient's back. Do you hear equal bilateral breath sounds? If not are they diminished? On what side?
4. Palpate the patient's thorax. Feel for subcutaneous emphysema, tenderness, or other abnormalities. If possible percuss the patient's chest (not always practical or feasible in the prehospital environment)
 

Pertinent Assessment Findings
 

• Shortness of breath/dyspnea/air hunger
   
• Chest pain
   
• Open wounds/ecchymosis/abrasions/contusions/SQ air
   
• Tachycardia/Falling oxygen saturations
   
• Hyperessonance on the affected side
   
• Diminished/absent breath sounds on the affected side

Premorbid/Late Findings
 

• Altered mental status
   
• Hypotension/Tachycardia
   
• Cyanosis
   
• Deviated trachea to the contralateral side
   
• Distended neck veins (may or may not be present)

Conditions that may mimic Pneumothorax/Tension Pneumothorax
 

• Pulmonary Contusion-diminished breath sounds, dyspnea, hypoxia
   
• Multiple Rib Fractures- diminished breath sounds, dyspnea, chest pain
   
• Post Pnuemonectomy-diminished breath sounds

Your assessment needs to be rapid, but thorough and conducted with a high index of suspicion. The intubated/ventilated patient

General Treatment
As with everything in emergency medicine we begin and end with the ABC's. Securing the patients ABC's is paramount. Approach all patients with the same assessment/treatment strategy. All patients with suspected or actual pneumothoraces should be given 100% oxygen via non-rebreather mask. The following patients should be considered candidates for intubation:
 

• GCS <8/Inability to protect their airway
   
• Hypoxia, respiratory distress, dyspnea, hypoventilation
   
• Multisystem instability (hemodynamically unstable/hypoxic/altered mental status)
   

During your assessment/treatment phase of airway/breathing a suspected tension pneumothorax would be addressed (more on this later). After securing the airway and breathing, initiate (2) large bore IV's and continue on with the standard trauma treatment algorithm.

Specific Treatment
 

Simple Pneumothorax/Hemothorax
Treatment is supportive in nature with emphasis on reassessment for deterioration. Monitor the patient's oxygenation status closely.

Open Pneumothorax
Treatment is straightforward and should be supportive. Observe the wound closely. Look for bubbles and feel for subcutaneous emphysema (SQ air) around the wound. The wound should be covered with a dressing that is occlusive and non-porous. The dressing should be taped on three sides thus allowing air to escape from the pleural cavity but not reenter. There are many different "field expedient" ways to manufacture such a dressing using plastic wrapping, tape, etc. However, a few commercial devices such as the Asherman Chest Seal are available on the market. They are prepackaged and ready to go. The Asherman device works particularly well. It is used in both military and civilian applications with good results.

Tension Pnuemothorax
Making the diagnosis is much harder than the treatment. The treatment hinges on getting the air that is under tension out of the pleural cavity. This is best accomplished via tube thoracostomy (chest tube) but a needle thoracostomy is faster and more expedient.
The goal of needle throacostomy is to introduce a needle into the pleural cavity thus relieving the trapped air. The needle will temporarily halt the rising intrathoracic pressure and stop the impingement on the pulmonary and cardiovascular function.
 

Indications for Chest Needle Decompression/Needle Thoracostomy
Diminished/Absent breath Sounds with any of the following:
 

• Significant dyspnea/shortness of breath
   
• Falling/Low oxygen saturations <90%
   
• Altered mental status
   
• Signs/Symptoms of shock (tachycardia, hypotension)

Chest Needle Decompression/The Procedure
 

1. Gather Equipment-A large (14 gauge or larger) angiocath works well. It is imperative that you use at least a 2-2 ¼" needle. For the procedure to be effective you must be able to puncture into the pleural cavity. Some patients may have a thick (2-3cm) chest wall. You must use a needle with an adequate length. There are several commercial devices on the market that are specifically designed for needle thoracostomy. Most include a flutter valve or one-way valve device on them. These valves act to allow air to escape but not reenter the pleural cavity. A finger cut from a latex glove or a condom works also. Using a flutter valve on the needle is not as imperative as using a long enough needle. The likelihood of enough air reentering via the needle to really effect the patient is small.
    
2. Identify Landmarks-You may use the 2nd intracostal (ICS) space at the midclavicular line or the 5th-6th ICS at the midaxillary line to perform the procedure. Take care to note the proper site and landmarks. The 5th ICS is roughly the nipple line. Pick your site and clean the area with alcohol or betadine.
    
3. Insertion-Insert the needle on the superior aspect of the rib. Remember that a nerve, vein and artery run on the inferior aspect. You may puncture the skin holding the needle perpendicularly. If you hit a rib "tunnel" slightly to puncture over the superior aspect. As the needle enters the pleural space you should hear a hiss or rush of air as the air under tension is released. Secure the needle or device to the chest wall and if available attach a flutter valve. Anticipate placement of a chest tube as soon as qualified personnel and equipment are available.
    
4. Follow-up-Continue to monitor the patient for dyspnea, or return/worsening of symptoms. If the patient deteriorates further consider repeating the procedure at another site. The in situ needle or device could have clotted off.

Conclusion
Simplex pneumothorax is relatively common in trauma patients however, tension pneumothorax is even less common but much more deadly. Being able to quickly recognize the clinical picture and having an aggressive patient care protocol in place for managing tension pneumothorax is of the utmost importance. Rarely are there such deleterious conditions in the trauma patient that can be definitively treated and reversed.

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References
1. American College of Surgeons, ATLS Student Manual, 7th Edition
2. Bjerke, H. Scott, Tension Pneumothorax, EMedicine Journal Jan 2002
3. Sheehy, Sue, Emergency Nursing: Principles and Practice, 4th edition 1998

About the Author: Kevin High has been a RN for 16 years and an EMT for 13 years. He has an extensive background in EMS, Emergency Nursing, and Air Medical Transport. Kevin's EMS background includes working as an ALS provider for two 911 agencies in Tennessee and also as an adjunct faculty member for local EMS education programs. Kevin has been a flight nurse at Vanderbilt LifeFlight for nine years. Kevin lectures and teaches on a local, state and national level and he has authored over 10 articles that have appeared in journals such as Journal of Emergency Nursing, EMS Magazine, Air Med, Air Medical Journal, and Emergency Medicine.