Transmediastinal gunshot wound

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A transmediastinal shooting wound (TMGSW) is a person's thoracic injury in which the bullet enters the mediastinum, possibly damaging some of the major structures in this area. Hemodynamic instability has been reported in approximately fifty percent of cases with death rates ranging from twenty to forty percent. Several studies have shown a marked increase in the mortality rate of survivors from transfer to the operating room rather than being treated by surgery in the ER.

Video Transmediastinal gunshot wound

Complications

Complications caused by TMGSW can range from mild to life-threatening depending on the damaged structure. It can be very deadly if the main structure is involved. Some of the possible complications caused by TMGSW are:

• damage to large blood vessels such as the vena cava, aorta, pulmonary artery
• damage to the heart muscle
• massive bleeding
• heart tamponade
• hemomediastinum
• pneumomediastinum
• neurological injury
• In many cases there is pneumothorax or hemothorax because of the proximity of the lungs to the mediastinum.

Maps Transmediastinal gunshot wound

Evaluation

Stable patient

Previously every stable patient who suffered TMGSW received extensive evaluation that included chest radiography, oesophagography, esophagoscopy, angiography, bronchoscopy, cardiac ultrasound. Grossman et al. found evidence that the bullet trajectory can be described using Computed Tomographic Scan (CT). Furthermore, other studies have shown the use of CT as a screening tool for stable patients suffering TMGSW is a reliable tool to rule out, diagnose and avoid missed injuries. For example Stassen et al. showed data from 22 stable patients screened with CT, chest x-ray and abdominal ultrasound; seven patients showed positive CT scans and required additional evaluation, and these seven patients, three required surgical management. In addition, the work of Burack et al., Who evaluated stable patients with penetrating injuries to mediastinum - this time including stab wounds - largely dependent on CT and ultrasound, showed similar results. The work of Ibirogba et al. do it too. Recent data indicate that the use of CT scans with some additional noninvasive techniques, such as ultrasound and chest xengenogram is a reliable screening tool for deciding whether the patient needs further evaluation.

Unstable patient

The criteria for defining patients as stable or unstable can have variations from institution to institution. For example, Burack et al. uses a list of 6 criteria in his paper that define an unstable hemodynamic state:

1. Traumatic cardiac arrest or near pull and EDT
2. Heart tamponade
3. Continuous third-grade ATLS stings despite fluid resuscitation (blood loss 1500-2000 mL, pulse rate greater than 120, blood pressure decreased)
4. Chest tube output over 1500 mL of blood at insertion
5. Chest tube output more than 500 mL/hr for the initial hour
6. Massive hemorax after chest tube drainage

One common criterion found in the literature is systolic blood pressure less than 100 mmHg, but this can be an over-simplification. Patients with clinical evidence of TMGSW likely to be considered unstable did not receive further evaluation and were brought to surgery immediately.

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Management

Stable

Stable patients will be evaluated with CT, ultrasound, chest x-rays as prescribed by the institutional protocol. When this initial survey was negative, patients could be observed with conservative management. In many cases, the chest tube is necessary because the lesions coexist in the pleural cavity. If possible lesions (eg, a missile track near the trachea or esophagus, or pneumomediastinum) further investigation will be followed by oesophagography, esophagoscopy, angiography, bronchoscopy required to exclude or confirm the lesion, and decide whether surgical repair is justified.

Unstable

Unstable patients are managed by mediastinal operative explorers. Patients who experience bleeding will undergo an emergency thoracotomy. This step is taken because upon their arrival in the emergency room, these patients are in critical condition so that they will not last long enough to be transferred to the operating room. The results are very bad. Burack et al. reported only 2.8 patients survival in the study. In a study by Van Waes et al., (Which included all thoracic injuries, not just transmediastinal) survival after emergency department tacacotomy was 25 percent. In other instances the unstable patient is immediately transferred to the operating room for exploration with a thoracotomy or sternotomy. Survival rates have been reported as high as 75 percent when patients were able to achieve OR.

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References

1. Degiannis E, Benn CA, Leandros E, et al. Injuries from transmediastinal shots. Surgical 2000; 128: 54-58.
2. Grossman MD, May AK, Schwab CW, et al. Determine anatomic injury with computed tomography in selected gunshot wounds. A Trauma. 1998; 45: 466-456.
3. Renz BM, Cava RA, Feliciano DV, Rozycki GS. Transmedient wound firing: a prospective study. J Trauma 2000; 48: 416 -422.
4. Richardson JD, Flint LM, Snow NJ, et al. Management of transmediastinal gunshot wounds. 1981 Surgery; 90: 671-676.

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