Tansmediastinal gunshot wound
A transmediastinal gunshot wound (TMGSW) is a penetrating injury to a person's thorax in which a bullet enters the mediastinum possibly damaging some of the major structures contained in the anatomy of this area. It has been reported hemodynamic instability in approximately 50 percent of cases with a mortality rate ranging from 20 to 40 percent. Some studies have showed marked difference in the mortality rate in the patients that survived transfer to operating room vs being treated surgically in the ER.
Complications caused by a TMGSW can range from mild to life-threatening depending on which structures are damaged. It can be rapidly lethal if a major structure is involved. Some of the possible complications caused by a TMGSW are:
- damage to great vessels (vena cava, aorta, pulmonary arteries)
- damage to heart muscle
- massive hemorrhage
- cardiac tamponade
- neurologic injury
- In many cases there is pneumothorax/hemothorax due to proximity of lungs to mediatinum.
Previously every stable patient that suffered a TMGSW received extensive evaluation that
included chest radiography, oesophagography, esophagoscopy, angiography, bronchoscopy, cardiac ultrasound. Grossman et al. showed evidence that the trajectory of the bullet can be delineated with the use of Computed Tomographic Scan. Subsequently other studies have demonstrated that the use of CT as a screening tool for stable patients who suffered TMGSW is a reliable tool for ruling out, diagnosing and avoiding missed injuries. For example Stassen et al. showed data of 22 stable patients who were screened with CT, chest x ray and abdominal ultrasound; seven patients showed a positive CT scan and required additional evaluation and of these seven patients, three required surgical management. Additionally the work of Burack et al. in which their evaluation of stable patients with penetrating injuries to mediastinum (this time including stab wounds) relied mostly CT and Ultrasound showed similar results as did the work of Ibirogba et al. Recent data suggests that the use of CT scan with some additional noninvasive techniques as ultrasound and chest roentgenogram are reliable screening tools to decide if patients need further evaluation.
The criteria to define a patient as stable or unstable could have variations from institution to institution. For example Burack et al. used a list of 6 criteria in his paper that defined an unstable hemodinamic state:
- Traumatic cardiac arrest or near arrest and an EDT
- Cardiac tamponade
- Persistent ATLS class III shock despite fluid resuscitation (blood loss 1500–2000 mL, pulse rate greater than 120, blood pressure decreased)
- Chest Tube output greater than 1500 mL of blood on insertion
- Chest Tube output greater than 500 mL/hour for the initial hour
- Massive hemothorax after chest tube drainage
One common criteria found in literature is a sustained systolic blood pressure of less than 100 mmHg but keep in mind this could be oversimplified. Patients with clinical evidence of possible TMGSW that are considered unstable receive no further evaluation and are taken to surgery immediately.
Stable patients will be evaluated with CT, ultrasound, chest x ray as the institution's protocol specifies it. When this initial survey is negative patient can be observed with conservative management. In many cases chest tubes are required due to concomitant lesions in the pleural cavity. If possible lesions are found (for example, missile track near trachea or esophagus, pneumomediastinum) further investigation will follow with oesophagography, esophagoscopy, angiography, bronchoscopy as needed to rule out or confirm such lesion and decide if surgical repair is warranted.
Unstable patients are managed by operative exploration of mediastinum. Moribund patients will go through an Emergency department thoracotomy. This measure is taken because at the arrival in the emergency room, this patients are in such critical condition that would not survive long enough to be transferred to an operating room. Outcome is very poor. Burack et al. reported only 2.8 survival of this patients in his study. In Van Waes et al. study (which included all thoracic penetrating injuries, not only transmediastinal) survival after emergency department thoracotomy was 25 percent. In other circumstances the unstable patient is immediately transferred to the operating room for exploration by thoracotomy or sternotomy. Survival rate has been reported as high as 75 percent when the patient is able to reach the OR.
- Burack, J., K. Emad, A. Sawas, et al. Triage and Outcome of Patients with Mediastinal Penetrating Trauma. Annals of Thoracic Surgery 2007; 83: 377-382.
- Degiannis E, Benn CA, Leandros E, et al. Transmediastinal gunshot injuries. Surgery 2000; 128:54–58.
- Grossman MD, May AK, Schwab CW, et al. Determining anatomic injury with computed tomography in selected torso gunshot wounds. J Trauma. 1998;45:466–456.
- Ibirogba, Sheriff, Andrew J. Nicol, and Pradeep H. Navsaria. "Screening helical computed tomographic scanning in haemodynamic stable patients with transmediastinal gunshot wounds. Injury, Int. J. Care Injured 2007;38: 48-52.
- Renz BM, Cava RA, Feliciano DV, Rozycki GS. Transmediastnal gunshot wounds: a prospective study. J Trauma 2000; 48:416 –422.
- Richardson JD, Flint LM, Snow NJ, et al. Management of transmediastinal gunshot wounds. Surgery 1981;90:671–676.
- Stassen, Nicole A., James K. Lukan, David A. Spain, et al. "Re-evaluation of diagnostic procedures for transmediastinal gunshot wounds." the journal of trauma, injury, infection and critical care 2002;53: 635-638.
- Van Waes OJ., Van Riet PA., Van Lieshout EM., Hartoq DD. Immediate thoracotomy for penetrating injuries: ten years' experience at a Dutch level I trauma center.Eur J Trauma Emerg Surgery 2012 Oct;38(5):543-551