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Ann Thorac Surg 2007;83:377-382
© 2007 The Society of Thoracic Surgeons
a Department of Surgery, Kings County Hospital Center, and State University of New York–Downstate, Brooklyn, New York
b Department of Radiology, Kings County Hospital Center, and State University of New York–Downstate, Brooklyn, New York
Accepted for publication May 18, 2006.
* Address correspondence to Dr Burack, Department of Surgery, Box 40, State University of New York–Downstate, 450 Clarkson Ave, Brooklyn, NY 11203. (Email: jburack{at}downstate.edu).
Presented at the Forty-second Annual Meeting of The Society of Thoracic Surgeons, Chicago, IL, Jan 30–Feb 1, 2006.
| General thoracic surgery:
The Annals of Thoracic Surgery CME Program is located online at http://cme.ctsnetjournals.org. To take the CME activity related to this article, you must have either an STS member or an individual non-member subscription to the journal.
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Abstract |
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METHODS: Unstable patients underwent emergent operative intervention, and stable patients underwent chest roentgenogram, transthoracic echocardiography (TTE), and CTA. Further testing (angiogram, bronchoscopy, esophagoscopy, esophagogram) was done only if one of these studies revealed evidence of a trajectory in the vicinity of major vasculature or viscera.
RESULTS: Between 1997 and 2003, 207 patients had MPT. Seventy-two (35%) were unstable (45 gun shot wounds, 27 stab wounds) and 19 died in the emergency department. Fifty-three had emergent intervention and 32 survived. Work-up was done on 135 stable patients (65%) consisting of 46 gunshot wounds and 89 stab wounds, of which 5 had a positive TTE result and underwent a repair of a cardiac injury. CTA evaluation was normal in almost 80% of patients, who subsequently did not require further evaluation or treatment. In the stable patients, endoscopy or esophagography confirmed one tracheal injury and no esophageal injury. In the entire group, 10 patients (7%) had occult injury, and there were no deaths or missed injuries.
CONCLUSIONS: In cases of MPT, unstable patients require surgery, and in stable patients, TTE and chest CTA are effective screening tools. Patients with a negative TTE and CTA results can be observed and may not require further testing or endoscopy, whereas patients with positive TTE or CTA results require further assessment to exclude occult injury.
Approximately 150,000 people die each year in the United States as a result of trauma, and 25% of the deaths can be directly related to thoracic injury [1]. Almost all patients with thoracic trauma are treated conservatively with a successful outcome. Most patients survive as a result of a prompt resuscitation, efficient diagnostic testing, and simple therapeutic maneuvers. In a contemporary multicenter experience, urgent operative treatment was required in only 0.5% of blunt and 2.8% of penetrating thoracic injuries [2, 3].
In contrast are those patients with penetrating injury to the mediastinum, a group of patients who have a substantial operative intervention rate and mortality. Historically, a gunshot injury traversing the mediastinum precipitates hemodynamic instability related to a thoracic vascular injury in approximately 50% of patients and has an operative mortality rate of 20% to 40% [4–6].
Certainly, the lethal nature of the injury is related to the high concentration of major vascular and visceral structures that reside within the mediastinum, and in many instances, it is implausible that a transmediastinal penetrating injury has avoided a major structure. Indeed, another distinct subgroup of patients present with stable vital signs and mediastinal penetrating trauma (MPT), who typically require diagnostic evaluation, followed by observation alone. The essential clinical task is to efficiently triage the unstable patients to the operating room and correctly diagnose and operate on only those stable patients who harbor potentially lethal injuries.
The evolution of imaging techniques in ultrasound and computed tomography (CT) have been assets in the rapid and accurate diagnosis of injury and have gradually replaced the cumbersome invasive evaluation of mediastinal injury by pericardial drainage, endoscopy, and routine angiography [4–9]. The purpose of the present study was to assess the reliability and the efficacy of transthoracic echocardiography (TTE) and CT angiography (CTA) in the diagnostic workup of patients with MPT and to determine whether the use of these diagnostic tests diminished the reliance on invasive investigative procedures. To record the lethal nature of all types of penetrating mediastinal trauma, injuries from stab wounds and gunshot wounds were both examined. Furthermore, a precise scheme for the classification of MPT was developed to clarify and organize the clinical presentation and outcome of these injuries.
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Patients and Methods |
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Under the direction of a dedicated, trauma surgeon, a team of surgical residents evaluated each patient with penetrating trauma. An unstable hemodynamic state was determined by the supervising trauma surgeon within the first hour of admission and was defined by using standard bedside criteria (Table 1). All other patients were deemed stable. Dependent on vital signs, unstable patients underwent an abbreviated evaluation, followed by surgical exploration in the operating room. Some patients, without signs of life on admission or shortly thereafter, were pronounced dead in the emergency department (ED). Other patients, in extremis or traumatic cardiac arrest, underwent an ED thoracotomy (EDT). Stable patients were managed prospectively by preexisting management algorithms (Fig 1) [8]. The data were collected retrospectively by medical records review and database analysis.
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In the radiology suite, patients had continuous monitoring of oxygen saturation, electrocardiogram, and arterial blood pressure by noninvasive or catheter technique. For the purposes of this study, a CTA was considered positive if the tract of the injury was "in proximity" to vital mediastinal vascular or visceral structures or if a substantial collection of air or blood was "in proximity" to the tract. Indications for endoscopy were determined by individual clinical circumstance, and in particular, if a pneumomediastinum or a posterior mediastinal tract was identified, patients underwent additional endoscopic evaluation. Additional patients, those with a hematoma or a missile tract near major vasculature, were triaged to formal angiography.
Patients were generally observed either on the regular ward or in the surgical intensive care unit for 48 hours. Routine follow-up was done at an interval of 5 to 7 days in the outpatient clinic.
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2 analysis, was associated with significant risk of both instability and death. In the entire population of 207 patients, 72 patients (35%) were unstable. Within the cohort of unstable patients, 19 patients (26%) with confirmed MPT died shortly after admission to the ED, without any intervention. An EDT was done in 13 patients (18%), with 2 survivors (2.8%), both of whom had sustained a cardiac injury. Excluding the patients who died shortly after presentation, 16 patients had cardiac injuries, and 11 of these patients were unstable; 12 patients in this group survived. Forty patients underwent formal operative exploration, either by thoracotomy or sternotomy, with pulmonary and great vessel injury being the most common injuries.
There were no "negative" explorations and no apparent missed injuries. Intraoperative endoscopy was liberally applied in patients with pneumomediastinum or with an injury to the posterior mediastinum. In the unstable group of patients, there were two injuries to the esophagus, which were successfully repaired, and none to the trachea. In the entire group of unstable patients, 32 survived for an overall survival rate of 44%. The survival rate increased to 75% in those patients who survived to transfer to the operating room.
The results of the stable patients, who were triaged by diagnostic algorithm, were recorded (Fig 3.) After the initial echocardiogram, 5 patients (3.7%) were transferred to the operating room for successful repair of a cardiac injury. The remaining stable patients underwent a CTA evaluation, which was unremarkable in almost 80%. None of the patients became unstable during the course of the diagnostic work-up or required emergent transfer to the operating room.
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Comment |
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In the operating room, the culprit was invariably an injury to the heart, the great vessels, or the pulmonary hilum. The overall mortality rate in the entire unstable group was 55%, with an 85% mortality rate in the moribund patients who underwent an EDT. The operative mortality was 25% for patients who survived long enough to transfer to the operating room. This is similar to the results in several small series of transmediastinal gunshot wounds, where the operative mortality for unstable patients was 20% to 36% [4–6].
Selective management of transmediastinal gunshot wounds was first proposed in 1981 by Richardson and colleagues [4] and has become the standard for the current management of stable patients. In a recent prospective study of transmediastinal gunshot wounds, all ED patients with an admission systolic blood pressure of more than 100 mm Hg and no obvious bleeding safely underwent a complete diagnostic evaluation [5]. No patients in the current series decompensated during the diagnostic phase and no deaths were recorded in the entire group of stable patients. Additionally, after the diagnostic angiogram, several patients with vascular injury underwent percutaneous interventions with coil embolization or placement of an endovascular stent [11].
Only 7% of stable patients in the current study required intervention for injury. In several recent small clinical series of transmediastinal gunshot wounds, the surgical exploration rate in stable patients was 8% to 31% [6–8, 12]. Uniform survival in a stable patient after a transmediastinal gunshot wound has been repeatedly observed [7, 8]. Other reports have noted an occasional death in a patient who becomes unstable in angiography and in patients with a failed esophageal repair or those with late multiorgan failure and sepsis [6, 12].
Injuries to the trachea and the esophagus are rare: only three cases were observed in the entire cohort, for an incidence rate of 1.4%. In several other series of mediastinal gunshot wounds, the rate of injury to the trachea and the esophagus was quite variable, ranging from 0% to 33% [4–8, 12]. Regardless of the variability of the incidence, the disastrous consequences of a missed hollow viscus injury will continue to mandate the use of traditional bronchoscopy, esophagoscopy, or contrast esophagography in those patients where there is a clinical suspicion related to "proximity of the injury" or pneumomediastinum. Flexible endoscopy, particularly in the agitated or intubated patient or contrast esophagraphy in the awake and cooperative patient can accurately diagnose esophageal injury [13]. Flexible bronchoscopy similarly provides direct visualization and is highly accurate in the diagnosis of airway injury [14].
In the current report, 15% of the unstable patients had a penetrating cardiac injury, and patients explored in the ED had a survival of 18%, and patients who were able to transfer to the operating room had a survival of 71%. In stable patients, a significant echocardiographic pericardial effusion was detected in 4%, which led to intervention and successful repair in each instance. An echocardiogram is advantageous owing to the portability of the ultrasound equipment and the rapidity of the exam. The diagnosis of a traumatic pericardial effusion can be made by the visualization of an echolucent region between the heart and pericardium, and right ventricular diastolic collapse will confirm tamponade [9]. If a skilled sonographer is present, ultrasound imaging appears to be as accurate as the traditional subxiphoid pericardial window in making the diagnosis of effusion, with an accuracy, sensitivity, and specificity that exceeds 95% [9, 15]. A combination of aggressive operative intervention in the unstable patient and ultrasound evaluation of the stable patient provided an overall survival of 40% in the 30 patients with known cardiac injury, which is similar to the results in a large recent series of penetrating cardiac trauma [16].
The diagnostic evaluation of the stable patient in the current study rested on two primary diagnostic tests—CT scans and ultrasound imaging—with the limited, selective use of angiography, endoscopy, and esophagography. The current diagnostic algorithm has replaced the traditional invasive evaluation because it is safe, efficient, and cost-effective [8]. The ever-increasing accuracy of imaging techniques has expedited the transition from reliance on invasive diagnostic tests to rapid noninvasive evaluation. Pericardial drainage and endoscopy are being replaced by trauma-specific roentgenograms and ultrasound protocols.
The current series was based on the results from a single-detector CT scan, which has been eclipsed by the current multidetector CT scans that provide exquisite anatomic detail, three-dimensional reconstructions, and potentially, vascular imaging similar to a traditional angiogram. In a recent series of stable patients with mediastinal gunshot wounds, 67% of patients had a satisfactory imaging of the missile tract with a multidetector CT scan, thus avoiding all other diagnostic testing, including echocardiography [7]. In the future, the evaluation of many stable penetrating trauma victims may be reduced to a solitary evaluation with rapid multidetector CT scan [17].
It is well established that a gunshot wound remains the most significant risk factor for both hemodynamic instability and death when compared with all types of penetrating trauma [16]. This observation was confirmed in the current series. Stab wound injury to the mediastinum is also responsible for substantial operative intervention and mortality rates, however, and the study of MPT should include both injury mechanisms, which will reflect the current trend in clinical trauma research to classify injury by either blunt or penetrating mechanism [2, 3, 10].
Various definitions of mediastinal penetrating trauma have been proposed, but the several common anatomic trajectories have yet to be classified [4, 5, 7, 8]. None of the previous definitions have described a penetrating injury that traverses the base of the neck, the thoracic inlet, and ultimately enters the mediastinum or pleural space (M1). Although not as lethal as any of the other subtypes of mediastinal wounds in the current series, this trajectory was responsible for a relatively high incidence of hemodynamic instability and operative intervention. Vascular injury in the region of the thoracic inlet, with rapid hemorrhage into the free pleural cavity, is the probable mechanism.
Further prospective observations on the individual behavior of the various subtypes of injury may help with clinical decision-making and triage in the future. In summary, accurate triage of the unstable patient, along with a classification system of injury trajectory, combined with modern diagnostic evaluation of the stable patient who may be harboring an occult injury, will continue to improve the management and outcomes of patients with penetrating mediastinal trauma.
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DR BURACK: To answer your first question, in this series the echoes were done by the cardiology fellows, who were for some reason always available to come in the middle of the night. I guess they like this sort of thing. It was done in conjunction with the trauma attending surgeon. I think that in the literature, the FAST exam is the established evaluation that is being done for pericardial effusion in the setting of trauma, and actually we’re making a transition now from cardiology fellows to the FAST exam being done by the surgeons. Also, your comments about the helical CT, in the future it may be just a helical CT, particularly the new 64-slice CTs, which can document a pericardial effusion probably better than an ultrasound exam, and in our next prospective series we may eliminate the echocardiogram and it just may be a CAT scan.
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  K. Mattox Invited commentary Ann. Thorac. Surg., February 1, 2007; 83(2): 382 - 382. [Full Text] [PDF]
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