Tension pneumothorax

A tension pneumothorax is a life-threatening condition that results from a progressive deterioration and worsening of a simple pneumothorax, associated with the formation of a one-way valve at the point of rupture.cite web | date = March 22 2005 | url = http://www.trauma.org/thoracic/CHESTtension.html | title = Chest Trauma Pneumothorax - Tension | publisher = Trauma.org | accessdate = September 7 | accessyear = 2006]

Upon inspiration, when the pressure inside the chest and pleural cavity falls as a result of the respiratory muscles increasing chest dimensions, air is sucked in through this one way valve, into the pleural space. Because exhalation is a passive process, there is an insignificant amount of pressure created to force the air back out of the pleural cavity. This condition over time results in a gradual accumulation of air to the degree that it begins to put pressure on the mediastinum, compressing the heart and decreasing cardiac output due to the reduced amount of diastolic filling of the ventricles, and also putting pressure against the trachea, deviating it from the midline. Because of the increased thoracic pressure, venous return to the heart is decreased, causing a backup of blood into the venous system, as is evidence by distended jugular veins.

igns and symptoms

*Decreased or absent breath sounds on the affected side
*Jugular venous distension (late sign)
*Tracheal deviation towards unaffected side (late sign)
*Hyperesonance on percussion
*Unequal chest rise
*Dyspnea
*Tachypnea
*Tachycardia
*Hypotension
* Hypoxia
*Pale, cool, clammy skin
*Subcutaneous emphysema
*CyanosisSigns and symptoms associated with a tension pneumothorax can be difficult to assess in the tactical setting. The Committee on Tactical Combat Casualty Care (CoTCCC) recognizes these difficulties and recommends that diagnosis of a tension pneumothorax in the tactical setting maintain a more realistic approach for the area of operation (AO). Considerations should be made based on the possible conditions encountered ie, no/low light, high noise volume,cover and concealment considerations, hostile forces,limited diagnostic equipment, etc. That being said, in the tactical setting a tension pneumothorax should be suspected in the presence of torso trauma and progressive respiratory distress.

Differentiation

A tension pneumothorax is a condition whose signs and symptoms resemble very closely those of a condition called pericardial tamponade. A chest x-ray will distinguish the two. On physical exam, the differentiating factors are listed in the table at right. The sign that occurs in pericardial tamponade in which the pulse is affected by breathing is called pulsus paradoxus, or simply paradoxical pulse.

Treatment

Initial treatment involves the insertion of a large bore cannula or needle into the second intercostal space on the mid-clavicular line (known as "needle thoracostomy", or more commonly, "needle decompression"), thereby releasing the pressure in the pleural cavity and converting the tension pneumothorax to a simple pneumothorax, which is then treated at the earliest opportunity by inserting a chest tube.

Tension pneumothorax represents a medical emergency which cannot often accommodate the time spent waiting for the capture and interpretation of a chest radiograph. Consequently, the decision to proceed with needle decompression must be made clinically (i.e., "at the bedside") by observing the acute presentation and reviewing relevant history. There is some debate on the topic of needle thoracostomy. There are risks associated with the process such as lung laceration, especially if no tension pneumothorax condition is present, and that relieved tension may reaccumulate undetected if the needle thoracostomy becomes dislodged. There is also the possibility that the cannula will not reach the pleural cavity due to a thick chest wall, especially in overweight individuals. Traditionally needle decompression has been attempted using a 4.5cm (2") to 5cm catheter. However,previous studies have shown a failure rate of up to 40% using this technique.Based on the clinical findings and failure rates, it is recommended that a 3.25" 14 gauge needle should be used in order to address the issue of the needle not reaching the pleural space.cite journal |author=Zengerink I, Brink PR, Laupland KB, Raber EL, Zygun D, Kortbeek JB |title=Needle thoracostomy in the treatment of a tension pneumothorax in trauma patients: what size needle? |journal=J Trauma |volume=64 |issue=1 |pages=111–4 |year=2008 |month=January |pmid=18188107 |doi=10.1097/01.ta.0000239241.59283.03 |url=http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?an=00005373-200801000-00017 |accessdate=2008-08-09] cite journal |author=Cullinane DC, Morris JA, Bass JG, Rutherford EJ |title=Needle thoracostomy may not be indicated in the trauma patient |journal=Injury |volume=32 |issue=10 |pages=749–52 |year=2001 |month=December |pmid=11754880 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0020-1383(01)00082-1 |accessdate=2008-08-09] cite journal |author=Britten S, Palmer SH, Snow TM |title=Needle thoracocentesis in tension pneumothorax: insufficient cannula length and potential failure |journal=Injury |volume=27 |issue=5 |pages=321–2 |year=1996 |month=June |pmid=8763284 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/0020138396000071 |accessdate=2008-08-09]

References