Chapter 4 – Thoracic Injury




Abstract




Chest trauma is estimated to be the primary cause of death in 25% of traumatic mortalities and a contributing factor in another 25% of deaths. Good understanding of the pathophysiology of chest trauma and timely selection of the appropriate investigations and treatment are all critical components for optimal outcome.





Chapter 4 Thoracic Injury


Demetrios Demetriades and Peep Talving



Introduction


Chest trauma is estimated to be the primary cause of death in 25% of traumatic mortalities and a contributing factor in another 25% of deaths. Good understanding of the pathophysiology of chest trauma and timely selection of the appropriate investigations and treatment are all critical components for optimal outcome.



Clinical Examination


ATLS principles should always be followed in the initial evaluation and management of the chest trauma patient.


During the primary survey, there are six life-threatening conditions that need to be identified and treated:




  1. 1. Airway obstruction



  2. 2. Tension pneumothorax



  3. 3. Open pneumothorax with a “sucking chest wound”



  4. 4. Flail chest



  5. 5. Massive hemothorax



  6. 6. Cardiac tamponade


During the secondary survey, there are an additional six potentially lethal chest injuries that should be identified and treated. The diagnosis of these conditions may need more complex and time-consuming investigations.




  1. 1. Lung contusion



  2. 2. Myocardial contusion (blunt cardiac trauma)



  3. 3. Aortic rupture



  4. 4. Diaphragmatic rupture



  5. 5. Tracheobronchial rupture



  6. 6. Esophageal injury



Investigations


History and clinical examination will determine the type and timing of investigations necessary for the safe and efficient evaluation of the chest trauma patient. In the unstable patient, therapeutic interventions such as thoracostomy tube insertion or thoracotomy may need to be initiated prior to any investigation due to imminent arrest. In all other patients, when the diagnosis is uncertain, the following investigations may be useful in chest trauma:




  1. 1. Focused assessment with sonography for trauma (FAST): FAST is an important investigation and should be immediately available in the emergency department. Emergency physicians and trauma surgeons should be trained in its use, as it allows early diagnosis of cardiac tamponade or hemoperitoneum at the bedside with high accuracy (see Chapter 25, Ultrasound in Trauma). The extended FAST (EFAST) provides additional information regarding hemo- and pneumothoraces.



  2. 2. Chest X-ray: Ideally chest X-ray should be taken during deep expiration and in the upright position, for the most accurate detection of small pneumothoraces, hemothoraces, and mediastinal abnormalities. In many cases, this is not possible because of associated hemodynamic instability, depressed level of consciousness, or concern about spinal injury. In evaluation of the chest X-ray, a systematic approach should be adopted that allows evaluation for pneumothorax, hemothorax, lung contusion, subcutaneous or mediastinal emphysema, fractures, mediastinal widening, enlarged cardiac shadow, pneumopericardium, elevated diaphragm or suspicious shadows suggestive of diaphragmatic hernia, free air under the diaphragm, and foreign bodies.



  3. 3. Electrocardiogram (EKG): EKG should be performed in all patients with severe blunt chest trauma and suspected cardiac trauma. In addition, EKG might be useful in some stable patients with suspected penetrating cardiac injuries.



  4. 4. Pericardiocentesis: This diagnostic procedure has little or no value in the evaluation of suspected cardiac trauma in a modern trauma center, as it is associated with an unacceptably high incidence of false-negative results because of clot formation in the pericardium. In addition, it is a potentially dangerous procedure because of the risk of myocardial or coronary vessel perforation, especially if performed in the absence of hemopericardium. It might have a role for temporary decompression of a tense hemopericardium in selected cases where a surgeon is not immediately available.



  5. 5. Subxiphoid pericardial window: This major invasive procedure has been used by some surgeons to diagnose cardiac tamponade. However, with the availability of EFAST, the subxiphoid window is rarely or almost never indicated. Intraoperative transdiaphragmatic window during an exploratory laparotomy, however, remains a useful diagnostic tool for the evaluation of cardiac involvement after penetrating thoracoabdominal injuries.



  6. 6. CT and CTA: CT imaging is the most valuable investigation in blunt trauma for the evaluation of the mediastinum, aorta, thoracic spine, and suspected lung contusions. All stable blunt trauma patients with a suspicious mechanism of injury (high-speed injury, falls from height) or those with an abnormal mediastinum on chest X-ray should be evaluated by CTA for aortic rupture. CTA is highly sensitive and specific in detecting aortic rupture and has replaced aortography as the standard of care. CTA also has a definitive role in the evaluation of selected patients with penetrating chest trauma. In patients with transmediastinal gunshot wounds who are hemodynamically stable, a high-quality CTA may be useful in identifying the bullet track and in determining the need for further investigations, such as endoscopy or esophageal contrast swallow studies. If the direction of the bullet track is away from the major vessels, esophagus, and other important mediastinal structures, no further investigations are necessary. CT scan is also useful in the evaluation of persistent opacifications on chest X-ray, following the insertion of a thoracostomy tube. In these cases, a CT scan without contrast may be utilized to help distinguish between the potential differential diagnoses of atelectasis, contusion, and residual hemothorax.



  7. 7. Catheter angiography: Diagnostic angiography has largely been replaced by CTA, although it still has an important role in the evaluation of patients with shotgun injuries with multiple pellets. Therapeutic catheter angiography and placement of stent-grafts, however, play a major role in the management of traumatic thoracic aortic injuries, false aneurysms, and arteriovenous fistulas of the major thoracic inlet arteries.



  8. 8. Color flow doppler: Color flow doppler ultrasound is a good noninvasive vascular study that can reliably evaluate the subclavian and neck vessels, and it can be used in hemodynamically stable patients with thoracic inlet penetrating injuries. Its major weaknesses include operator-dependent accuracy, immediate availability, and inability to visualize the left proximal subclavian vessels, especially in obese patients.



  9. 9. Endoscopy: Esophagoscopy and bronchoscopy may be necessary for suspected aerodigestive tract injuries, usually as a result of mediastinal penetrating trauma or mediastinal emphysema on plain X-ray or CT.



  10. 10. Diagnostic laparoscopy: Diagnostic laparoscopy has a definitive role in the evaluation of the diaphragm in asymptomatic patients with left thoracoabdominal or selected right thoracoabdominal penetrating injuries. Patients that have been ruled out for hollow viscus or abdominal injury requiring an operation are evaluated by diagnostic laparoscopy with laparoscopic diaphragmatic repair if an injury is identified. Failure to recognize and repair a diaphragmatic injury may result in a diaphragmatic hernia with visceral strangulation at a later stage. Right posterior thoracoabdominal injuries do not need evaluation and repair of the diaphragm because the presence of the liver protects against herniation of intra-abdominal organs.



  11. 11. Thoracoscopy: Thoracoscopy is used in the evaluation of diaphragmatic injuries, especially in the posterior region and for the evacuation of residual hemothorax. It has the disadvantage of requiring double-lumen intubation and lung collapse, which may be technically demanding and sometimes not well tolerated by the patient, especially if there is a contralateral lung injury.



  12. 12. Troponin levels: Serial troponin measurements should be considered in suspected blunt cardiac trauma. Troponin levels do not correlate with the severity of the myocardial trauma. In addition, many patients with severe extrathoracic injuries, such as head trauma or acute kidney injury, may have elevated troponin levels.



  13. 13. Arterial blood gas (ABG): ABG monitoring should be considered in all severe chest trauma cases in order to assess severity, plan treatment, and monitor progress of treatment.



General Management


In an urban environment, there is no place for prehospital attempts to stabilize patients with severe chest trauma, and the principle of “scoop and run” should be applied. The patient should be placed on a spinal board, receive oxygen by mask, and be transferred without any delay to the nearest trauma hospital. Intravenous access should be attempted in the ambulance en route. In patients with severe respiratory distress and clinical suspicion of tension pneumothorax, a needle thoracostomy at the 4th or 5th intercostal space at the anterior axillary line may be attempted. Open sucking wounds should be covered with commercially available chest seals or a clean square gauze, taped only on three sides to avoid a tension pneumothorax. Patients with respiratory failure will need prehospital intubation or bag-valve mask ventilation en route. In the emergency department, the primary survey will determine the need and type of immediate treatment. Patients with imminent or established cardiac arrest should be managed with an emergency department resuscitative thoracotomy. Any bleeding is controlled by sutures, clamping, or manual compression. Aortic cross-clamping is performed, and cardiac massage is initiated. Transfusion with O-negative (women of child-bearing age) or O-positive blood, ACLS medications, calcium, sodium bicarbonate, and defibrillation are administered as warranted. If cardiac activity returns, the patient is transferred to the operating room for completion of the operation.


Patients with severe hypotension and suspicion of cardiovascular trauma should be taken directly to the operating room with minimal investigations. All investigations are targeted at determining the location of operative incision. A FAST is very valuable in that it can rapidly evaluate the pericardial, bilateral thoracic, and peritoneal spaces.


Hemodynamically stable patients are examined carefully, and further investigations are performed as indicated. Thoracostomy tubes, analgesia, intubation, and mechanical ventilation may be necessary.


Elderly patients with multiple rib fractures or significant lung contusions, despite a normal respiratory status on initial examination, should be admitted to the ICU for close monitoring. Early, liberal endotracheal intubation and mechanical ventilation should be considered because elderly patients have limited physiologic reserves and often deteriorate rapidly and with little warning. Adequate analgesia by means of epidural or patient-controlled analgesia (PCA) is a critical component of the management of these cases, as these patients often deteriorate several hours after admission, despite apparent stability on admission.



Indications for Thoracotomy


Fewer than 5% of blunt chest trauma, approximately 15% of stab wounds, and approximately 20% of gunshot wounds require thoracotomy. The majority of patients with chest trauma can be safely managed with a thoracostomy tube and other supportive treatment. The indications for urgent thoracotomy include the following:




  • Cardiac arrest or imminent cardiac arrest



  • Evidence of significant thoracic injury with hypotension or active bleeding



  • Immediate blood loss in the thoracostomy tube of more than 1,000–1,200 ml



  • Diagnosis of esophageal or tracheobronchial injury


Semielective thoracotomy is indicated for large residual hemothoraces or persistent large air leaks when proximal airway injury is suspected.



Tips and Pitfalls




  1. 1. Elderly patients with multiple rib fractures or lung contusions may seem stable on admission, but rapid respiratory deterioration may occur a few hours later. Consider admission to the ICU for close monitoring in the event that early endotracheal intubation or mechanical ventilation is needed.



  2. 2. Patients with flail chest may seem stable on admission. Decompensation with severe respiratory failure may occur with potentially catastrophic consequences. Liberal early intubation is recommended, particularly before these patients are transferred to the radiology suite for prolonged investigations.



  3. 3. A widened mediastinum following a motor vehicle or motorcycle collision or a fall from height may be due to rupture of the thoracic aorta or to fractures of the thoracic spine or the sternum or cardiac tamponade.



  4. 4. Traumatic rupture of the thoracic aorta may not be associated with an abnormal mediastinum on chest X-ray. In high-speed deceleration trauma, all patients should be evaluated by chest CT scan to rule out aortic injuries.



  5. 5. In asymptomatic left thoracoabdominal penetrating injuries, routine laparoscopy should be performed on all asymptomatic patients. Diaphragmatic injuries are common, and CT imaging is often not a reliable diagnostic tool.



Chest Wall and Soft Tissues


Seat-belt marks on the thoracic wall are indicators of severe trauma, and 20% of these patients have significant intrathoracic injuries. These patients should have routine evaluation for lung contusion, myocardial contusion, aortic rupture, and hemopneumothorax (Figure 4.1 A–C).





Figure 4.1 A–C Chest seat-belt marks are markers of significant internal injuries and should be evaluated by CT scan, EKG, and troponin levels.



Rib Fractures



Fracture of the Upper (First or Second) Ribs


Fractures of the upper ribs, especially the first rib, are associated with a high incidence of subclavian and other major vascular injuries. The force required to fracture an upper rib is severe, and thus mediastinal structures, including the aorta, are at high risk with this mechanism. A CTA of the chest is indicated to evaluate for aortic and great vessel injuries. Children have a much more compliant chest wall, and thus any rib fractures are significant, although CTA of the chest in the pediatric population is not routinely indicated, given the rarity of aortic and great vessel injury after blunt trauma (see Chapter 13, Pediatric Trauma) (Figure 4.2 A,B).





Figure 4.2 A,B Chest X-ray with fractures of the upper ribs. These cases should always be evaluated for thoracic inlet vascular injuries, especially the subclavian vessels.



Fracture of Middle (Third to Eighth) Ribs


Rib fractures are diagnosed clinically (pain aggravated by breathing or coughing, or pain on anteroposterior chest compression) or radiologically. Fractures at the costochondral junction may not show on X-rays. Associated injuries include hemopneumothorax, lung contusion, cardiac trauma, and diaphragmatic tear. Pain relief is extremely important, especially in elderly patients with multiple rib fractures, in order to prevent atelectasis and pneumonia. PCA or epidural or paraspinal analgesia should be considered in multiple fractures. Selected patients with significant functional or mechanical loss after severe rib fractures may be candidates for rib fixation procedures and should be evaluated by a surgeon capable of this procedure.


Rib fractures in children are uncommon and signify severe impact to the chest wall, and there is a high incidence of underlying lung contusion (Figure 4.3 A–C).





Figure 4.3 A–C Plain radiographs of multiple mid rib fractures, with underlying lung contusion (A). Multiple rib fractures on the right side with associated clavicular fracture. Adequate analgesia with epidural or patient-controlled analgesia should be considered early, especially in elderly patients (B). 3-D reconstruction of multiple mid rib fractures and a thoracostomy tube in place (C).



Fracture of the Lower (Ninth to Twelfth) Ribs


Fractures of the lower ribs are often associated with injuries to the kidneys, liver, diaphragm, or spleen. Liberal use of abdominal CT scan should be considered. Intervention is rarely required unless a fractured segment remains impaled in the solid organ (Figure 4.4 A,B).





Figure 4.4 A,B Radiograph showing fractures of the right lower ribs (arrows;). Injuries to intra-abdominal solid organs are common and CT scan evaluation should be considered (A). Intraoperative photograph of the associated liver injury in the same patient (B).



Flail Chest


Flail chest is the result of anterior or lateral double fractures of at least three adjacent middle ribs. In most cases, there is an underlying lung contusion. Clinically, the flail segment moves paradoxically to normal chest wall motion, and the patient may be in respiratory distress. A thoracostomy tube should be considered, as it is indicated in most patients with flail chest and all patients should be monitored in an ICU setting with continuous pulse oximetry. Analgesia by means of PCA or epidural/paraspinal anesthesia should always be considered. Mechanical ventilation is often necessary for respiratory failure or imminent failure. Internal, operative fracture fixation may be useful in selected cases (Figure 4.5 A-E).





Figure 4.5 A–E Double fractures of at least three adjacent ribs are required in order to produce a flail chest (A). Chest X-rays showing multiple rib fractures, underlying lung contusion, and clinical flail chest. The diagnosis of flail chest is clinical (B, C). CT scan with 3-D reconstruction of multiple double rib fractures and clinical flail chest (D). Patient with a flail sternal segment; note the midsternal depression (E).



Hemo-Pneumothorax



Pneumothorax


A pneumothorax may be due to blunt or penetrating trauma. Small pneumothoraces are usually asymptomatic and can safely be managed without a thoracostomy tube, provided the patient does not need mechanical ventilation, prolonged, or air transportation. In these cases, any size pneumothorax should be treated with a thoracostomy tube to avoid the creation of tension pneumothorax. Large pneumothoraces may cause respiratory distress, and a tension pneumothorax can cause cardiorespiratory failure. The diagnosis of simple pneumothorax is usually made by chest X-ray or CT. An upright chest X-ray in deep expiration is the most suitable film to identify small pneumothoraces (Figure 4.6 A,B).





Figure 4.6 A,B Pneumothorax. Large right pneumothorax on chest X-ray. Arrow points to collapsed lung (A). Bilateral pneumothoraces on CT scan (arrows; B).



Tension Pneumothorax


In tension pneumothorax, air leaks into the pleural cavity with no escape route, due to a one-way valve effect. It is a life-threatening condition because of severe cardiorespiratory failure. The patient may appear panicky and have dyspnea, cyanosis, tachycardia, hypotension, and distended neck veins. The trachea may be shifted to the opposite side, there are no breath sounds, and there is hyperresonance on percussion in the affected hemithorax. Immediate life-saving intervention is needle decompression of the chest, followed by formal thoracostomy tube insertion. The mere suspicion of a tension pneumothorax is an absolute indication for a needle decompression whenever a thoracostomy tube cannot be inserted immediately (prehospital, austere environments, areas outside the emergency department or operative room). A thoracostomy tube should be subsequently inserted as soon as possible (Figure 4.7 AG).






Figure 4.7 A–G Illustration showing mechanism of tension pneumothorax (A). Chest X-rays showing a large tension pneumothorax on the left side, mediastinal shift to the opposite side, and downward displacement of the left hemidiaphragm. Arrows point to tension pneumothorax. (B). CT scan showing tension pneumothorax (arrow) with severe deviation of the heart to the right (C). Photograph showing a thoracostomy needle in place, below the middle of the clavicle (D). Bilateral needle thoracostomies placed prehospital. The catheter on the right side is not in deep enough and is likely outside the pleural cavity. (E). CT scan shows that the thoracostomy needle is located in the subcutaneous tissues, outside the pleural cavity (F). CT scan shows intrapulmonary hematoma secondary to a misplaced needle thoracostomy (G).


Figure 4.7 A–H


Hemothorax


A hemothorax can be due to blunt or penetrating trauma. Large hemothoraces may present with hypovolemia or dyspnea, but small hemothoraces can be asymptomatic. On physical examination, the breath sounds are diminished, there is dullness on percussion, and the affected hemithorax moves poorly. A chest X-ray, preferably in the upright position, may confirm the diagnosis, although many times it cannot distinguish between a hemothorax and intrapulmonary hematoma, contusion, or atelectasis. A supine chest X-ray may miss small hemothoraces. Thoracic ultrasound is a useful investigation in experienced hands, as it can reliably identify hemothorax and distinguish between this diagnosis from atelectasis, pneumonia, and contusion.


Significant hemothoraces can be treated via a thoracostomy tube, inserted at the fourth or fifth intercostal space, in the midaxillary line. A thoracotomy should be considered if the initial thoracostomy tube output exceeds 1,000–1,200 ml of blood or if the patient is hemodynamically unstable. Significant residual hemothorax following thoracostomy tube insertion should be evaluated by means of CT scan and evacuated within three to five days at the latest. Barring contraindications, thrombolytic agents such as tissue plasminogen activator (tPA) or urokinase delivered through the chest tube have resulted in high success rates of evacuation in retained hemothorax as a first line of treatment. In cases selected for operative approach, a video-assisted thoracoscopy (VATS) within three to five days, a maximum of seven days, of diagnosis or a small anterolateral thoracotomy as a last resort should be performed. Delayed evacuation is difficult because of clot organization and inflammation, and it often requires a thoracotomy with decortication.


An undrained significant hemothorax is associated with an increased risk of empyema and may cause respiratory compromise due to fibrosis (Figure 4.8 AD).





Figure 4.8 A–D Hemothorax. Chest X-ray with extensive opacification of the left hemithorax due to massive hemothorax with mediastinal shift to the opposite side and retained fragments of a missile (A). Gunshot wound to the left chest with suspected “residual hemothorax” on chest X-ray (left) two days after injury. Residual hemothorax is confirmed by CT scan (right) (B). Thoracoscopic evacuation of the residual hemothorax (C). The procedure should be performed within the first five days of injury, before organization of the clot and fibrin encapsulation of the lung. Photograph of material removed during decortication for persistent residual hemothorax and lung entrapment, a few weeks after injury (D). Delayed evacuation of a clotted hemothorax is difficult and requires thoracotomy and decortication.

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Apr 22, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 4 – Thoracic Injury
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