Residency · Residency · Emergency Medicine

Thoracic Trauma: Pneumothorax, Hemothorax, and Cardiac Injury

Epidemiology and Mechanisms

Overview

Thoracic injuries account for approximately 25 percent of trauma deaths. The reassuring reality is that most thoracic injuries can be managed with tube thoracostomy alone — only 10 to 15 percent require operative intervention. Blunt mechanisms include motor vehicle collisions, falls, and crush injuries, while penetrating mechanisms include gunshot wounds and stab wounds. The "lethal six" of thoracic trauma are airway obstruction, tension pneumothorax, open pneumothorax, massive hemothorax, flail chest, and cardiac tamponade.

Immediate Life Threats (Primary Survey)

The immediately life-threatening conditions that must be identified and treated during the primary survey include tension pneumothorax, open pneumothorax (sucking chest wound), massive hemothorax, cardiac tamponade, flail chest with pulmonary contusion, and airway disruption from tracheobronchial injury.

Pneumothorax in Trauma

Simple Pneumothorax

A simple pneumothorax involves air in the pleural space without mediastinal shift. Patients present with pleuritic chest pain and dyspnea. Examination reveals decreased breath sounds and hyperresonance on the affected side. On chest X-ray, a visceral pleural line is visible with absent lung markings peripherally. Ultrasound findings include absent lung sliding, absent comet tails, and the presence of a lung point, which has near 100 percent specificity.

Tension Pneumothorax

Tension pneumothorax involves progressive air accumulation that causes mediastinal shift and hemodynamic compromise. This is a clinical diagnosis, and treatment must not be delayed for imaging in the unstable patient. Classic findings include hypotension, tracheal deviation (a late and often absent sign), absent breath sounds, jugular venous distension, and tachycardia. Treatment consists of immediate needle decompression at the second intercostal space in the midclavicular line or the fourth to fifth intercostal space in the anterior axillary line, followed by tube thoracostomy. The fifth intercostal space at the anterior axillary line is increasingly preferred by many clinicians because of its higher success rate, as the chest wall is often too thick at the second intercostal space for needle decompression to reach the pleural space.

Open Pneumothorax

An open pneumothorax occurs when the wound diameter exceeds two-thirds of the tracheal diameter, allowing preferential air entry through the chest wall defect. Treatment involves a three-sided occlusive dressing (which allows air egress while preventing ingress) followed by tube thoracostomy at a separate site. Definitive management requires surgical closure of the chest wall defect.

Occult Pneumothorax

An occult pneumothorax is one detected on CT but not visible on supine chest X-ray. Management is controversial. If the patient requires positive-pressure ventilation, tube thoracostomy is generally recommended. If the patient is spontaneously breathing and hemodynamically stable, observation with serial imaging may be appropriate.

Tube Thoracostomy Technique

The tube is positioned at the fourth to fifth intercostal space, anterior to the mid-axillary line within the safe triangle. A 28 to 32 French tube is used for hemothorax and a 24 to 28 French tube for pneumothorax, though smaller tubes and pigtail catheters are increasingly used. The tube should be inserted above the rib to avoid the neurovascular bundle, which runs along the inferior margin of each rib. Placement is confirmed by fogging, drainage, chest X-ray, and resolution of clinical findings. The tube is secured with suture and connected to water seal or suction at negative 20 cm H2O.

Hemothorax

Simple Hemothorax

A simple hemothorax involves blood in the pleural space, usually from intercostal or internal mammary vessels. Chest X-ray shows blunting of the costophrenic angle, though 200 to 300 mL of blood must accumulate before it becomes visible on an upright film. Ultrasound reveals anechoic fluid above the diaphragm. Treatment is large-bore tube thoracostomy (32 to 36 French).

Massive Hemothorax

A massive hemothorax is defined as more than 1500 mL of blood drained immediately or more than 200 mL per hour for 2 to 4 consecutive hours. Indications for emergent thoracotomy include greater than 1500 mL of initial output, greater than 200 mL per hour for 2 to 4 hours, hemodynamic instability despite resuscitation, and increasing hemothorax on imaging. Sources include great vessels, hilar vessels, intercostal arteries, and the internal mammary artery. Autotransfusion of drained blood should be considered.

Retained Hemothorax

Incomplete drainage of hemothorax leads to fibrothorax and empyema. Video-assisted thoracoscopic surgery (VATS) within 3 to 7 days is indicated for retained collections. Intrapleural fibrinolytic therapy with tPA and DNase is an alternative to VATS.

Cardiac Injury

Blunt Cardiac Injury (Myocardial Contusion)

Blunt cardiac injury ranges in severity from minor contusion to free wall rupture. The right ventricle is most commonly affected because of its anterior position. Screening is performed with an ECG — if the ECG and troponin are both normal, clinically significant blunt cardiac injury is unlikely. Concerning ECG findings include new arrhythmias, ST changes, and new right bundle branch block. Troponin elevation without ECG changes is of uncertain significance. Echocardiography is indicated for hemodynamically significant blunt cardiac injury to evaluate for wall motion abnormalities, decreased ejection fraction, and valvular injury. Patients who are hemodynamically stable with a normal ECG require no additional workup. Management involves monitoring for dysrhythmias (24 hours if the ECG is abnormal) and treating as any other cause of cardiac dysfunction.

Cardiac Tamponade

In cardiac tamponade, blood accumulates in the pericardial space and compresses the cardiac chambers. Beck's triad — hypotension, muffled heart sounds, and jugular venous distension — is present in only 10 to 40 percent of cases. Pulsus paradoxus (a drop in systolic blood pressure greater than 10 mmHg with inspiration) may be present. FAST or bedside echocardiography reveals pericardial effusion with right ventricular diastolic collapse, which is the most specific finding. Emergent pericardiocentesis is performed via a subxiphoid approach under ultrasound guidance, and aspiration of as little as 15 to 20 mL can produce immediate hemodynamic improvement. Definitive management is operative repair via median sternotomy or thoracotomy.

Penetrating Cardiac Injury

The cardiac "box" — bordered by the clavicles, nipples, and xiphoid — defines the zone where wounds carry a high risk of cardiac injury. Stab wounds to the heart are more survivable than gunshot wounds because the pericardium may seal, allowing tamponade physiology to develop rather than immediate exsanguination. ED thoracotomy is indicated for penetrating trauma with loss of vital signs in the ED or en route (within 15 minutes of CPR). The steps include a left anterolateral thoracotomy, opening the pericardium anterior to the phrenic nerve, evacuating the clot, repairing the cardiac wound (with staples, suture, or a Foley catheter), and cross-clamping the aorta if needed.

Flail Chest and Pulmonary Contusion

Flail Chest

Flail chest occurs when three or more consecutive ribs are fractured in two or more places, creating a free-floating segment that moves paradoxically during respiration (inward with inspiration). The underlying pulmonary contusion, not the mechanical flail, is the primary cause of respiratory failure. Management focuses on aggressive pain control (epidural, intercostal nerve block, and multimodal analgesia), pulmonary toilet, and avoidance of intubation when possible. When intubation is needed, positive-pressure ventilation provides internal pneumatic stabilization. Surgical rib fixation with plating for severe flail segments is gaining evidence, with studies showing improved outcomes and shorter ventilator days.

Pulmonary Contusion

Pulmonary contusion involves hemorrhage and edema within the lung parenchyma from blunt force. Chest X-ray shows patchy alveolar opacities that may be delayed 4 to 6 hours, while CT is more sensitive for early detection. Management is supportive: oxygen, pain control, and judicious fluid resuscitation (avoiding over-resuscitation). Most contusions resolve within 3 to 7 days. Contusion involving more than 20 percent of lung volume is predictive of the need for mechanical ventilation.

Other Thoracic Injuries

Aortic Injury (Traumatic Aortic Disruption)

Traumatic aortic injury most commonly occurs at the aortic isthmus, at the site of the ligamentum arteriosum, from high-speed deceleration mechanisms. Chest X-ray findings suggestive of aortic injury include a widened mediastinum (greater than 8 cm), loss of the aortic knob contour, a left apical cap, and deviation of the nasogastric tube or trachea to the right. CT angiography is the diagnostic study of choice. Management involves blood pressure control (targeting heart rate below 80 and SBP below 100 mmHg) and emergent vascular surgery or endovascular repair (TEVAR).

Tracheobronchial Injury

Tracheobronchial injury is rare but life-threatening. It should be suspected when there is massive subcutaneous emphysema, a persistent air leak despite chest tube placement, pneumomediastinum, or failure of the lung to re-expand. Diagnosis is made by bronchoscopy, and management requires operative repair.

Esophageal Injury

Esophageal injury usually results from penetrating trauma and is rare in blunt mechanisms. A missed esophageal injury leads to mediastinitis with high mortality. It should be suspected when there is a left pneumothorax or hemothorax without rib fracture, pneumomediastinum, or particulate matter in chest tube drainage. Diagnosis is made by CT esophagography or esophagoscopy.

Diaphragmatic Injury

Diaphragmatic injury is more commonly diagnosed on the left because the liver protects the right hemidiaphragm. Blunt trauma produces large radial tears, while penetrating trauma causes small perforations that may not manifest immediately. Chest X-ray findings include an elevated hemidiaphragm, a gastric bubble in the chest, or a nasogastric tube in the chest. CT sensitivity is moderate, and surgical exploration is definitive. All diaphragmatic injuries require operative repair because they do not heal spontaneously.

ED Thoracotomy

Indications

ED thoracotomy is indicated for penetrating trauma with witnessed cardiac arrest or loss of vital signs with signs of life within 15 minutes. For blunt trauma with witnessed cardiac arrest, survival is extremely poor (less than 2 percent), and many consider this futile, though institutional variation exists. The goals of ED thoracotomy are to relieve tamponade, control hemorrhage, perform open cardiac massage, and cross-clamp the aorta.

Technique Summary

The procedure begins with a left anterolateral thoracotomy at the fifth intercostal space, which can be extended across the sternum (clamshell) if needed for right-sided injuries. The pericardium is opened longitudinally, anterior to the phrenic nerve. Clot is evacuated, cardiac wounds are identified and repaired, and the descending aorta is cross-clamped if needed for blood pressure augmentation. Internal cardiac massage is performed.

Outcomes

Outcomes depend heavily on the mechanism and injury pattern. Penetrating thoracic trauma with tamponade has the best outcomes, with survival up to 35 percent. Penetrating trauma without tamponade has approximately 10 to 15 percent survival. Blunt trauma carries less than 2 percent survival with near-uniformly poor outcomes.

<image>An anatomical diagram of the chest wall showing the "safe triangle" for tube thoracostomy insertion. The triangle is bordered by the anterior border of the latissimus dorsi, the lateral border of the pectoralis major, and a horizontal line at the level of the nipple (5th intercostal space). The diagram shows the correct insertion point at the 4th-5th intercostal space in the mid-axillary line, with a cross-section inset showing the neurovascular bundle running along the inferior margin of each rib, illustrating why the tube should be inserted just above the rib.</image>

<image>A four-panel illustration of ED thoracotomy technique. Panel 1: Left anterolateral thoracotomy incision from sternum to posterior axillary line at the 5th intercostal space. Panel 2: Rib spreader inserted with the pericardium exposed, showing the incision line anterior and parallel to the phrenic nerve. Panel 3: Pericardium opened with evacuation of blood clot and exposure of the heart, showing a right ventricular laceration being repaired with horizontal mattress sutures. Panel 4: Cross-clamping of the descending thoracic aorta to augment coronary and cerebral perfusion.</image>

<image>A bedside ultrasound image set showing cardiac tamponade. Image 1: Subxiphoid view demonstrating a large pericardial effusion with right ventricular diastolic collapse (arrow indicating the collapsed RV free wall). Image 2: A corresponding M-mode tracing showing the cyclical collapse pattern. Image 3: An apical four-chamber view in a normal patient for comparison, with no pericardial fluid.</image>

Clinical Pearls

Tension pneumothorax is a clinical diagnosis, and treatment must not be delayed for imaging in the unstable patient. The fifth intercostal space at the anterior axillary line is increasingly preferred over the second intercostal space at the midclavicular line for needle decompression because of lower failure rates related to chest wall thickness. In massive hemothorax, both the initial output and the ongoing rate matter — more than 1500 mL initially or more than 200 mL per hour for 2 to 4 hours indicates the need for surgery. The underlying pulmonary contusion, not the mechanical flail, causes respiratory failure in flail chest. A normal ECG plus a normal troponin effectively rules out clinically significant blunt cardiac injury. ED thoracotomy for penetrating trauma with tamponade has the best survival outcomes, while blunt cardiac arrest has near-zero survival. All diaphragmatic injuries require surgical repair because they will not heal spontaneously and will herniate over time.

References

• Mowery NT, et al. Practice management guidelines for management of hemothorax and occult pneumothorax. J Trauma. 2011;70:510-518.
• Burlew CC, et al. Western Trauma Association critical decisions in trauma: resuscitative thoracotomy. J Trauma Acute Care Surg. 2012;73:1359-1363.
• Clancy K, et al. Screening for blunt cardiac injury: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma. 2012;73:S301-S306.
• Kasotakis G, et al. Operative fixation of rib fractures after blunt trauma: a practice management guideline from the EAST. J Trauma Acute Care Surg. 2017;82:618-626.
• Seamon MJ, et al. An evidence-based approach to patient selection for emergency department thoracotomy. J Trauma. 2015;79:159-173.

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