Chapter 164. Cardiothoracic Trauma

Amongst injuries associated with blunt chest trauma are tension pneumothorax, hemothorax, and cardiac tamponade, for which bedside diagnosis and immediate intervention by the emergency provider may be lifesaving.

Initial assessment and management of airway, breathing, circulation, and disability should follow the Advanced Trauma Life Support (ATLS) primary survey guidelines. Intubate patients in respiratory distress (Table 164-1). Maintaining good oxygenation is especially important in preventing secondary injury in head-injured patients. Investigate for tension pneumothorax and cardiac tamponade during the primary survey for all patients in shock after chest trauma.

Physical examination should include assessment for tracheal deviation, unequal chest rise, abnormal breath sounds, visible trauma to the chest wall, subcutaneous emphysema (suggestive of pneumothorax), open chest wounds, and bowel sounds in the chest (suggestive of diaphragmatic injury).

In the hemodynamically unstable, polytrauma patient who requires immediate operation without CT imaging, exclude immediate threats to life with rapid bedside tests (physical examination, chest radiograph, ultrasound, and chest tube, as needed). Excessive fluid administration may worsen edema in patients with pulmonary contusions. Administer fluids judiciously with crystalloids to maintain perfusion, and use blood products early in resuscitation.

If subclavian venous cannulization is attempted, it should be done on the side of suspected injury so that an iatrogenic pneumothorax does not result in bilateral pneumothoraces. Check for a tension pneumothorax or tube displacement in any patient who suddenly decompensates while on mechanical ventilation.

A small open (sucking) chest wound can progress to a tension pneumothorax through a one-way valve effect. Cover the wound with sterile petroleum gauze taped on 3 sides to allow air to exit but not enter. Immediately insert a chest tube at another site and not through the wound.

Flail chest occurs when fracture of a section of ribs in multiple places allows instability of a section of the chest wall. Intubation and positive pressure ventilation will stabilize the flail segment, so intubate patients with respiratory compromise, along with those with evidence of shock, severe head injury, preexisting pulmonary disease, fracture of eight or more ribs, and age >65 years. Insert a chest tube to relieve an identified or suspected pneumothorax. Surgical fixation may be needed.

Rib fractures may suggest other injuries or cause morbidity in themselves. Fractures of the first and second ribs require great force, and should therefore cause high suspicion and evaluation for other major thoracic injuries including myocardial, vascular, and bronchial injuries. Multiple lower rib fractures should raise suspicion for liver or splenic injuries. Simple rib fractures are often a clinical diagnosis, with up to 50% not being seen on plain radiographs. Direct diagnostic imaging at excluding other injuries, such as pneumothorax, pulmonary contusion, and intraabdominal injury.

Even in the absence of coexisting injury, the pain of rib fractures may eventually lead to splinting, ventilatory compromise, and pneumonia. Consider intercostal nerve blocks and epidural anesthesia for pain control. Patients being discharged should generally receive NSAIDs and opioid analgesics. They should be reminded to breathe deeply or taught more formal incentive spirometry exercises. Admit patients with multiple fractures, medical comorbidities, or older age for a period of observation until they are stabilized on a regimen of pain control and pulmonary toilet to avoid complications. Attempts to stabilize the chest wall with tape or binding are no longer recommended. Assess patients with a sternal fracture for cardiac injury by ECG and cardiac monitoring.

Assume patients with subcutaneous emphysema have a pneumothorax even if not seen on the initial chest radiograph. Penetrating wounds should never be deeply probed.

Tension pneumothorax occurs when air enters the pleural space, either by escaping from damaged lung, tracheobronchial tissue, or from an open chest wound and becomes pressurized during respiration, causing respiratory and circulatory compromise. Patients may have dyspnea, tachycardia, hypotension, distended neck veins, tracheal deviation, and unequal breath sounds. Recognize and treat tension pneumothorax immediately without waiting for radiographs. Immediate needle decompression treatment involves insertion of a 14-gauge, 4.5-cm over-the-needle catheter in the second intercostal space at the midclavicular line (a shorter catheter may not reach the pleural space in many patients). A rush of air through the catheter is confirmatory. Leave the catheter in until a chest tube can be inserted, as the catheter converts the tension pneumothorax to an open pneumothorax.

Supine chest radiograph is a relatively insensitive screening tool (52%) for pneumothorax and for hemothoraces of <200 mL. Up to 1000 mL may appear as only diffuse haziness. Lung collapse from intubation of a mainstem bronchus can have a similar appearance. If the patient can safely sit up, upright and expiratory views can increase sensitivity. Ultrasound has been shown to have good sensitivity for pneumothorax. Using a high-frequency linear probe, signs of pneumothorax include loss of the sliding pleura sign. A hemothorax will show fluid in the dependent portion of the chest. CT scan is highly sensitive for both of these conditions. A small stab wound may develop into a delayed pneumothorax, so a repeat chest radiograph at 4 to 6 hours after initial presentation is prudent.

Treat a small pneumothorax with inpatient observation; insertion of a chest tube may not be necessary. For a larger pneumothorax without suspicion of hemopneumothorax, insert a 24-to-28F (8.0 to 9.3 mm) chest tube. If blood is suspected in the chest, insert a 32-to-40F (10.7 to 13.4 mm) chest tube. Patients with pneumothoraces of any size and those with subcutaneous emphysema (requiring presumption of an occult pneumothorax) who will be intubated or who will be transported by air should have a chest tube inserted, as positive pressure ventilation and decreased barometric pressure can cause expansion of trapped air to convert into a tension pneumothorax. Never clamp a chest tube, but always place on water seal when taken off suction. See Table 164-2 for causes of the lung not to fully reinflate after chest tube placement.

Treat a hemothorax with tube thoracostomy. Indications for surgery include an immediate return of 1 L of blood or ongoing bleeding of 150 to 200 mL/h for 2 to 4 hours. Consider using a heparinized autotransfusion device.

Pulmonary contusions are direct injuries to the lung parenchyma without laceration. Hypoxia ensues since contused lung tissue is compromised by bleeding and edema. Seventy percent of pulmonary contusions are not immediately visible on initial chest radiograph, but may appear as patchy opacities. CT scan is much more sensitive. Radiographic findings of fat embolism and aspiration pneumonia usually appear as patchy opacities 12 to 24 hours after injury, while pulmonary contusions appear within the first 6 hours. Initial management should include pain control to prevent hypoventilation, avoidance of unnecessary fluid infusion to prevent pulmonary edema, and strict pulmonary toilet. A trial of positive pressure ventilation by mask is reasonable in a patient with normal mental status who requires limited respiratory support. Patients with involvement of >25% of lung tissue will likely require intubation, but should not be intubated obligatorily. If intubated, use positive end expiratory pressure. Use diuretics if the patient is thought to have volume overload. Steroids are not recommended.

Major deceleration injuries can result in injuries to the trachea and large airways, usually within 2 cm of the carina or at the origin of lobar bronchi. Dyspnea, hemoptysis, subcutaneous emphysema in the neck, a crunching sound with the cardiac cycle (Hamman sign), and a massive continued air leak through a chest tube suggest tracheobronchial injury. Mediastinal air, large pneumothorax, and a round appearance of the endotracheal tube balloon on plain radiograph or CT also suggest tracheobronchial injuries.

Coughing, heavy breathing (such as seen in drug inhalation), or exertion can rupture alveoli and release air into the mediastinum. In the absence of major trauma, treat this type of pneumomediastinum expectantly once pneumothorax has been excluded.

All penetrating injuries from the level of the nipples to the umbilicus have the potential to injure the diaphragm. Small lacerations can be asymptomatic and then progress to the rupture of abdominal contents into the chest weeks to months later. The diagnosis is obvious if imaging shows herniation of abdominal contents into the chest or coiling of a gastric tube within the chest. Subtle abnormalities may also be seen on chest radiograph, CT, or upper GI series with contrast. Laparotomy or laparoscopy remain the gold standards to exclude diaphragmatic injuries. All diaphragmatic lacerations require surgical repair.

The right ventricle is the most commonly injured portion of the heart because of its large anterior exposure. Recognition of cardiac tamponade by the emergency provider is critical because cardiac tamponade can potentially be temporized in the ED by pericardiocentesis prior to definitive operative management. Accumulation of blood in the pericardial space compresses the heart, which prevents filling during diastole. Beck's triad of hypotension, distended neck veins, and muffled heart tones may be seen. Confirm the diagnosis by bedside ultrasound. Pericardiocentesis is technically difficult and may result in laceration of a coronary artery, injury to the myocardium, or inability to withdraw blood. Therefore, it should only be attempted for a patient in shock with confirmed cardiac tamponade, in which case it may be lifesaving. Stable patients should have a pericardial window or thoracotomy performed in the operating room.

Patients with penetrating chest injuries with signs of life in the field but who subsequently and suddenly become pulseless may be candidates for ED thoracotomy. Relieving cardiac tamponade, cross clamping the descending aorta, or repairing a myocardial laceration may be lifesaving.

Blunt cardiac injury can lead to death from damage to cardiac structures, coronary artery injury and thrombosis, and contusion of the myocardium resulting in impaired contractility and arrhythmias. If a patient with myocardial rupture survives to ED arrival, a “splashing mill wheel” murmur may be heard. Confirm the diagnosis by echocardiogram and treat with emergency thoracotomy. ECG changes consistent with ischemia suggest coronary artery dissection or thrombosis, which are evaluated and treated by cardiac catheterization and stenting. A direct blow to the chest such as when a young athlete is struck by a hard ball can induce ventricular fibrillation cardiac arrest even without myocardial injury (commotio cordis).

A patient with cardiac injury may present with chest pain, tachycardia unexplained by hemorrhage, and arrhythmias. Bedside echocardiogram by the emergency provider should be performed as a first screen for cardiac tamponade and grossly impaired contractility. Patients with hypotension not explained by another cause, arrhythmias, and impaired contractility should undergo further evaluation by formal echocardiography and cardiac enzymes, with transesophageal echocardiogram being three times more sensitive than transthoracic echocardiogram for blunt myocardial injury. Give anti-arrhythmic and inotropic medications according to advanced cardiac life support (ACLS) algorithms. Indications for admission include abnormalities on echocardiogram, ECG, or cardiac enzymes. Discharge patients with normal vital signs, normal initial ECG, no underlying cardiac disease, and age <55 years after 4 to 6 hours of normal cardiac monitoring.

Patients with pericardial inflammation syndrome may develop chest pain, fever, and a friction rub 2 to 4 weeks after cardiac trauma or surgery. ECG may show the diffuse ST-segment elevation of pericarditis. Pericardial and pleural effusions may be seen on echocardiography and chest radiograph, respectively. Treatment is with nonsteroidal anti-inflammatory medications, such as indomethacin 25 to 50 milligrams every 6 hours.

Trauma to the major thoracic vessels is often lethal, with 90% of those sustaining blunt aortic injury dying at the scene. The most common site of blunt aortic injury is at the proximal descending aorta between the left subclavian artery and the ligamentum arteriosum. Injury to the subclavian and innominate arteries can be related to shoulder belts, fractures of the first and second ribs, and proximal clavicle. Clinical findings may include unequal bilateral blood pressures, diminished lower extremity pulses, and new murmurs. Descending aortic injuries may cause paraplegia, mesenteric ischemia, anuria, and lower extremity ischemia if they affect flow to the relevant arteries. Table 164-3 shows radiographic findings of thoracic aortic injury, although a normal chest radiograph does not exclude major vascular injury. All patients with a mechanism highly concerning for great vessel injury should undergo CT angiogram with IV contrast. Conventional aortography is still used in some cases to assess injuries and guide operative planning. Transesophageal echocardiogram is useful for diagnosing aortic intimal lesions, but is contraindicated in airway compromise or suspected cervical spinal injury.

With gunshot wounds, a discrepancy between the number of presumed entrance and exit wounds and bullets seen on imaging should make the provider consider entry into a vessel with embolization to another part of the body. A fuzzy appearance of a projectile on plain radiograph suggests an intravascular missile vibrating with pulsatile blood flow.

Indications for immediate operation for vascular injury are hemodynamic instability, radiographic evidence of a rapidly expanding hematoma, or large chest tube output. Patients with other injuries, advanced age, or uncontrolled medical comorbidities may require stabilization before definitive operative or intravascular repair. Control hypertension in order to decrease shear stress on the vessel wall by titration of narcotic pain medications and sedatives. A short-acting β-blocker, such as esmolol 50 to 300 micrograms/kilogram/min infusion, may be titrated to a systolic blood pressure of 100 to 120 mm Hg and a heart rate above 60 beats/min. If bradycardia prevents further dosing of a β-blocker, infuse an arterial dilator such as sodium nitroprusside 0.25 to 10 micrograms/kilogram/min IV.

Penetrating, and occasionally blunt, trauma may cause injury to the thoracic esophagus. If suspected, evaluate the patient by esophagram with water-soluble contrast, which is less likely to cause mediastinitis. A negative study with water-soluble contrast should be followed by the use of barium contrast, which has a higher sensitivity for injury. Flexible esophagoscopy is an alternative modality for assessing injury. Delayed diagnosis of esophageal injury has a high mortality if mediastinitis ensues. Injuries to the area of the left proximal subclavian vein may result in chylothorax, which usually is discovered as a delayed right-sided pleural effusion. Initial treatment is with chest tube drainage.