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A careful and thorough secondary survey will identify multiple non-life-threatening chest injuries. Their prompt recognition and treatment may lead to an overall reduction in morbidity and mortality.
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Pulmonary contusions are injuries of the lung parenchyma with hemorrhage and edema without associated laceration. They are the most frequent intrathoracic injuries in nonpenetrating chest trauma. They occur in approximately 30–75% of patients with significant blunt chest trauma. Pulmonary contusions typically occur at the site of impact and are often associated with other thoracic injuries such as rib fractures and flail chest, although they may occur alone. Pneumonia is the most common complication of pulmonary contusion, but their presence is a risk factor for the development of acute respiratory distress syndrome and long-term disability as well. Associated medical conditions, such as chronic obstructive pulmonary disease, increase the likelihood of complications from pulmonary contusion and should lower the threshold for early intubation.
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Pulmonary contusion is often silent during the initial trauma evaluation. Significant traumatic mechanism as well as the presence of other associated thoracic and extrathoracic injuries should raise one's suspicion for the presence of pulmonary contusion. The most important sign of pulmonary contusion is hypoxia. The degree of hypoxemia directly correlates with the size of the contusion. Large contusions will lead to significant respiratory distress. Other clinical findings suggestive of pulmonary contusion include dyspnea, hemoptysis, tachycardia, and other evidence of chest injury such as palpable rib fractures, chest wall bruising, decreased breath sounds, or crackles on pulmonary auscultation.
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Radiographic findings by CXR may range from patchy interstitial infiltrates to complete lobar opacification. CXR will initially miss a substantial number of pulmonary contusions, but as a result of ongoing hemorrhage and edema, radiographic evidence of contusion is usually apparent within 6 hours of injury. Since the size of the contusion may help predict the clinical course for the patient, thoracic CT may provide additional useful information. Animal studies suggest that CT will identify contusions in 100% of those with experimentally induced pulmonary injury; therefore, CXR should be followed by CT in the patients where suspicion for undetected injury is high and identification of the injury will alter their management.
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Early recognition and treatment of pulmonary contusion is essential to preventing long-term complications. The mainstay of treatment is supportive care and consists of the careful use of intravenous fluids so as to keep the patient euvolemic, supplemental oxygen, chest physiotherapy, and if severe, the use of mechanical ventilation with positive end-expiratory pressure.
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Most patients with radiographic evidence of pulmonary contusion or clinical findings suggestive of pulmonary contusion should be admitted for monitoring and respiratory support. Exceptions to this would include young adults with minor contustions and no underlying pulmonary disease.
Klein Y, Cohn SM, Proctor KG: Lung contusion: pathophysiology and management. Curr Opin Anaesthesiol 2002:15(1):65–68
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Miller LA: Chest wall, lung, and pleural space trauma. Radiol Clin North Am 2006;44(2):213–224, viii
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Miller PR et al: ARDS after pulmonary contusion: accurate measurement of contusion volume identifies high-risk patients. J Trauma. 2001 Aug;51(2):223–228
[PubMed: 11493778]
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It is estimated that 15–20% of patients sustaining significant thoracic trauma have some degree of cardiac involvement. Myocardial contusions are distinct areas of hemorrhage that are typically subendocardial but may extend transmurally. The right ventricle is most commonly involved due to its proximity to the sternum. Contusions of the myocardium typically produce wall motion abnormalities that may lead to conduction defects, dysrhythmias, or a decrease in cardiac output leading to cardiogenic shock.
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The clinical presentation of myocardial contusion is nonspecific. Patients are often asymptomatic but may complain of chest pain, have subtle ECG changes, or present with hypotension secondary to cardiac dysmotility. Specific standardized criteria for the diagnosis of myocardial contusion do not exist. Studies of blunt trauma patients looking for evidence of cardiac contusion have classically used one or more of the following criteria:
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ECG—A normal ECG does not exclude the possibility of myocardial contusion, but it is the best screening tool. An ECG should be obtained in all patients with significant thoracic trauma, particularly if there are concomitant injuries such as flail chest, rib fractures, or pulmonary contusion. An ECG should also be obtained in trauma patients complaining of chest pain, with unexplained hypotension, and those with a history of coronary artery disease. The most common finding by ECG in myocardial contusion is sinus tachycardia (ST) followed by nonspecific ST and T wave changes. Right bundle branch block is also commonly seen. A range of dysrhythmias and conduction disturbances may be evident however, including ST elevation, atrial fibrillation, atrial flutter, premature ventricular contractions, ventricular tachycardia, ventricular fibrillation, first-degree heart block, and right bundle branch block. While a normal ECG cannot 100% exclude the presence of a myocardial contusion, the literature suggests that very few patients with normal ECGs develop complications.
Biochemical markers—There is much debate in recent literature regarding the value of obtaining cardiac enzymes in the evaluation of the patient with potential myocardial contusion. Creatine kinase MB (CK-MB) is nonspecific for cardiac injury in the setting of trauma and is often elevated in cases of skeletal muscle, diaphragm, liver, or bowel injury. Both Troponin T and Troponin I have been shown to be very specific for cardiac injury in trauma but have poor sensitivity. Cardiac enzymes have not been shown to predict the development of complications or need for hospital admission.
Echocardiography—Transthoracic and transesophageal echocardiography should not be used as screening tools for myocardial contusion. They are best used in the evaluation of patients with unexplained hypotension or persistent ECG abnormalities to exclude other potential cardiac injuries such as pericardial tamponade and ventricular rupture. While both studies will identify wall motion abnormalities that are consistent with myocardial contusion, they have not been shown to predict or prevent clinical complications.
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There is no particular treatment for myocardial contusion other than to treat the potential complications as they arise. Patients should be monitored at all times. Dysrhythmias should be treated as discussed in previous chapters. There is no role for the administration of prophylactic antidysrhythmics. Patients who subsequently develop myocardial infarction should be treated as such, but thrombolytics should not be used in the trauma patient.
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Asymptomatic stable patients with normal ECGs and no evidence of other thoracic injury may be safely discharged from the emergency department. Elderly patients and those with a history of coronary artery disease, significant blunt thoracic trauma, ECG changes, or hypotension should be admitted for monitoring.
El-Chami MF, Nicholson W, Helmy T: Blunt cardiac trauma. J Emerg Med 2008;35(2):127–133
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Diaphragmatic hernias have been reported in 1–5% of patients sustaining blunt chest or abdominal trauma. They result either by direct violation of the diaphragm or significant intra-abdominal or intrathoracic pressure applied to the diaphragm resulting in its rupture. The right side is affected up to three times less than the left because it is relatively well protected by the liver. Up to 50% of these injuries are missed on the initial trauma evaluation, and their delayed presentation may not be clinically significant until herniation of abdominal contents through the diaphragm results in obstruction, incarceration, strangulation, perforation, or even death. Once a tear in the diaphragm occurs, it will not heal spontaneously, allowing for the herniation of abdominal contents into the chest cavity. Delayed presentations of blunt diaphragmatic rupture have been reported up to 50 years after the primary traumatic event.
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Patients with diaphragmatic hernias may be asymptomatic, particularly in the acute phase, or may present with symptoms of bowel obstruction. Delayed presentation is common with nonspecific respiratory or bowel complaints since early diagnosis is difficult to establish and often missed.
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CXR—The CXR is a valuable screening tool in detecting blunt diaphragmatic rupture. The initial X-ray is interpreted as normal in up to 50% of acute cases but will be abnormal in almost 100% of those with delayed presentations. Findings on an upright CXR suggestive of diaphragmatic rupture include elevation or irregularity of the diaphragmatic border, unilateral pleural thickening, obvious herniation of abdominal contents into the chest cavity, and the presence of a nasogastric tube in the chest cavity (Figure 24–4).
CT—CT scans are often used preoperatively in the hemodynamically stable patients but have had less than satisfactory results in reporting isolated diaphragmatic injuries. Right-sided lesions are often missed because the contour of the right diaphragm is difficult to discern from the contour of the liver.
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Surgical reduction of the hernia and repair of the diaphragm is mandatory in all patients with diaphragmatic rupture. Care should be taken to avoid abdominal injury when placing a chest tube in patients with concomitant hemothorax or pneumothorax.
Nursal TZ et al: Traumatic diaphragmatic hernias: a report of 26 cases. Hernia 2001;5(1):25–29
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Singh S et al: Diaphragmatic rupture presenting 50 years after the traumatic event. J Trauma 2000;49(1):156–159
[PubMed: 10912874]
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Esophageal Disruption
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Esophageal disruption or perforation is an infrequent injury sustained secondary to blunt trauma. The mechanism of injury is unclear, but most occur during high-speed motor vehicle collisions and are typically associated with other serious thoracic injuries. While their occurrence is rare, the reported mortality is more than 20% because of its resultant complications of mediastinitis, which include pericarditis, pneumonitis, empyema, and even aortic erosion.
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Esophageal injuries are difficult to diagnose. The symptoms and signs are often nonspecific and masked by other serious injuries. It should always be suspected in the patient with evidence of serious neck, thoracic, back, or abdominal injury. Patients may complain of throat pain, dysphagia, odynophagia, hoarseness, choking, chest pain, hematemesis, dyspnea, or continued neck pain despite appropriate treatment and immobilization. Neck redness, swelling, unexplained tachycardia, subcutaneous emphysema of the neck or chest, and bloody nasogastric tube contents may be found on physical examination.
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Radiologic signs on CXR suggestive of esophageal injury include pneumomediastinum, widened mediastinum, and left pleural effusion. Gastrograffin followed by barium swallow and esophagoscopy are probably the best diagnostic tools available for the detection of esophageal perforation; however, detailed exploratory surgery may be necessary for definitive diagnosis.
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Treatment of esophageal perforations depends on the location and the extent of the injury. Nonoperative management with drainage, antibiotics, and nutritional support may be appropriate for select injuries, but most require aggressive surgical management to prevent extensive spread of infection to the mediastinal and pleural cavities.
Monzon JR, Ryan B: Thoracic esophageal perforation secondary to blunt trauma. J Trauma 2000;49(6):1129–1131
[PubMed: 11843720]
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Traumatic aortic rupture is a common cause of death in blunt trauma. Injury is typically caused by rapid deceleration and shearing forces sustained in motor vehicle accidents, falls, and crush injuries and most commonly involves the descending segment of the aorta just past the origin of the left subclavian artery. More than 80% of patients die at the scene. Another 10–20% of patients with aortic disruption will die within the first hour. Rapid diagnosis and treatment is essential for limiting the mortality associated with these injuries.
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Aortic injury should be considered in all patients involved in rapid deceleration accidents such as motor vehicle collisions at speeds greater than 30 miles/h or falls from greater than 10 feet. Clinical signs and symptoms suggestive of aortic injury include chest pain, back pain, dyspnea, hoarseness, intrascapular murmur, and extremity pain caused by ischemia. Patients may be hypertensive, hypotensive, or may present with pseudocoarctation where the upper extremities are hypertensive and the lower extremities have minimal blood pressure and pulse deficits. Thirty percent of patients with traumatic aortic injury have no external signs of trauma to the chest. Other patient factors that can raise a clinician's index of suspicion for TAI include age >50, unrestrained driver, ejected passenger or pedestrians struck by a motor vehicle.
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CXR—CXR is a screening tool for blunt aortic injury and is commonly used to determine the need for further studies. Mediastinal widening more than 8 cm is the most commonly cited abnormality on CXR that leads to further workup. Other findings suggestive of aortic injury include indistinct aortic knob, left mainstem bronchus depression, tracheal deviation to the right, nasogastric tube deviation, widening of the right paratracheal stripe (>5 mm), apical capping, and obliteration of the space between the pulmonary artery and the aorta (Figure 24–5). Despite its use as a screening tool, CXRs are normal in 2–5% of patients with aortic injury.
Angiography—Angiography has historically been the gold standard for diagnosis of aortic injury but is rarely employed in clinical practice today. Angiography is expensive, time consuming, invasive, and requires a large dye load. Because the clinical indicators for blunt aortic injury are often nonspecific, a large number of negative aortograms have been performed in the past. Over the last decade, CT of the chest has been used in the evaluation of aortic injury with angiography saved for those patients with indeterminant findings by CT.
Chest CT—CT is less expensive than angiography and can be performed much more quickly. With the newer-generation scanners and the use of intravenous contrast and consistent protocols, the sensitivity and specificity for aortic injury approaches 100%, particularly when criteria for positive scans include periaortic hematoma along with direct signs of aortic injury.
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Treatment of blunt aortic injury includes pharmacologic management of blood pressure in combination with prompt surgical or endovascular repair.
Dyer DS et al: Thoracic aortic injury: How predictive is mechanism and is chest computed tomography a reliable screening tool? A prospective study of 1561 patients. J Trauma 2000;48(4):673–682
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Nagy K et al: Guidelines for the diagnosis and management of blunt aortic injury: An EAST Practice Management Guidelines Work Group. J Trauma 2000;48(6):1128–1143
[PubMed: 10866262]
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O'Conor CE: Diagnosing Traumatic rupture of the thoracic aorta in the emergency department. Emerg Med J2004;21:414–419
[PubMed: 15208221]
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Tracheobronchial Injury
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Injury to the trachea or bronchus as a result of blunt trauma is relatively uncommon but can be quite severe. Approximately 80% of patients with tracheobronchial injuries die before reaching a hospital. Tracheobronchial injuries are usually the result of motor vehicle accidents and crush injuries. Right-sided bronchial injuries occur more commonly and are typically more severe, while almost 80% occur within 2 cm of the carina. The diagnosis of tracheobronchial injury is missed in at least 25% of patients during the initial trauma evaluation.
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Failure to recognize tracheobronchial injury during the initial trauma evaluation is common. Patients may be comfortable on room air or may present in acute respiratory distress. The most common clinical symptoms and signs suggestive of injury to the trachea or bronchus are dyspnea and subcutaneous emphysema of the neck or upper thoracic region, but may also include hoarseness, hemoptysis, hypoxia, and persistent pneumothorax despite appropriate tube thoracostomy. CXR findings indicative of tracheobronchial injury include subcutaneous emphysema, pneumomediastinum, pneumothorax, and peribronchial air.
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All patients in respiratory distress with suspected tracheobronchial injury should be endotracheally intubated, preferably over a bronchoscope if time allows. Blind intubation is discouraged as it may result in the complete disruption of small tracheal lacerations. Stable patients with suspected trauma to the trachea or bronchi should undergo immediate bronchoscopy for definitive evaluation and localization of the injury followed by operative repair.
Cassada DC et al: Acute injuries of the trachea and major bronchi: importance of early diagnosis. Ann Thorac Surg 2000;69(5):1563–1567
[PubMed: 10881842]
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Kiser
AC et al: Blunt trachebronchial injuries: treatment and outcomes. Ann Thoracic Surg 2001;71(6):2059–2065
[PubMed: 11426809]
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