The chest radiograph (CxR) may be the single most essential test for the blunt trauma victim, and its usage is recommended for all trauma patients. CxR is not invasive, low cost, easily obtainable, and can reveal a great deal of information. The CxR should be interpreted immediately and certainly prior to transfer from the trauma bay with attention to life-threatening injuries to the airway, evidence of pneumothorax, hemothorax, or blunt aortic injury.

Bedside ultrasound is increasingly used in the evaluation of blunt trauma patients. The focused assessment with sonography for trauma (FAST) exam, which examines the hepatorenal and splenorenal spaces and the pelvis, may be performed while other resuscitative interventions occur in a hypotensive patient. A FAST exam’s true utility is the assessment for intra-abdominal fluid in the hypotensive patient, where it can reliably detect 100–150 cc of fluid [17]. FAST has less utility in the normotensive patient and cannot be reliably used to detect solid or hollow viscus injuries. At most centers an evaluation for pericardial effusion is included in the FAST exam. Collapse of the right atrium by a pericardial effusion is a sensitive indicator for cardiac tamponade. Some authors have advocated an extended FAST exam as the primary diagnostic modality for hemothorax and pneumothorax [18, 19].

Computed tomography (CT) scans are often utilized in the evaluation of blunt trauma and have had increased usage over the last two decades. Driving this increased utilization is the desire to reduce missed traumatic injury thereby reducing complications from delayed diagnosis [20]. Increased utilization is seen not just during initial workup but also throughout the hospital course. This trend of high utilization of CT scanning is most pronounced in the elderly patient [21]. Plurad et al. question the clinical utility of the increased utilization of this expensive test. The majority of chest CT scans in their study were performed after an initial normal CxR, and although a number of occult pneumothoraces and hemothoraces were identified, few patients were identified who had significant injury requiring treatment [22]. Significant traumatic mechanism, abnormal CxR, or patterns of associated injuries should prompt a chest CT scan in order to diagnose injuries such as blunt aortic injury or diaphragmatic hernia.

Pulmonary contusion is the most common of the potentially lethal chest injuries and is often associated with other traumatic injuries. It is caused by trauma to the lung parenchyma typically adjacent to the site of impact; however, it may also occur in a countercoup fashion. The initial diagnosis is usually made on chest radiograph or computed tomography, but these evaluations often miss the true severity, for contusions often blossom over the first 24–36 h after injury. Although contusion occurs in 75 % of all patients with significant chest trauma, the incidence may be less in the elderly patient population with a less compliant thorax. The less compliant thorax dissipates the force of the trauma within the elderly skeleton through fractures instead of transmitting the energy to the lung parenchyma. Parenchymal injury causes ventilation-perfusion inequalities with right-to-left shunt and hypoxia, which is often exacerbated by hypoventilation secondary to splinting. If pulmonary contusion is not complicated by infection, large resuscitation, or volutrauma from mechanical ventilation, contusion resolves in 3–5 days. Pulmonary contusion is a risk factor for development of ARDS and has a significant impact on mortality across all age ranges [26–28]. Treatment of pulmonary contusion includes supportive therapy and aggressive pulmonary hygiene. There is no role for prophylactic antibiotics, steroids, or diuretics in this injury.

Pneumothorax is one of the most common sequelae of blunt chest trauma. Pneumothorax is caused by trauma disrupting the lung parenchyma or tracheobronchial structures resulting in air escaping into the thoracic space. The leak of air into the thoracic cavity results in partial or complete lung parenchymal collapse. In healthy people with intact pulmonary reserve, a partial collapse may be asymptomatic. In the elderly, who often have compromised baseline pulmonary function, tachypnea and declining systemic oxygenation can occur. Continued leak of air into the chest cavity can result in increased intrathoracic pressure that decreases cardiac venous return and causes hypotension and shock. Although classic signs of tension pneumothorax, tracheal deviation, unilateral decreased breath sounds, and jugular venous distention may not be appreciable in the trauma bay, suspicion should be high and needle decompression or tube thoracostomy should be utilized liberally in hemodynamically compromised patients.

Reliance on CT scanning during the diagnostic workup of trauma has revealed a significant rate of occult pneumothoraces. These small pneumothoraces, not visible on plain film, may be observed clinically. Positive pressure ventilation is not a contraindication for observation of an occult pneumothorax, though it is critical that the diagnosis of occult pneumothorax is passed between care teams during sign-outs and hand-offs. Progression of these pneumothoraces and the need for chest tube placement is required in less than 10 % of patients. In hospitalized patients daily chest radiographs should be utilized to follow progression. Visible pneumothorax on CxR, which is a sign of continued air leak, should prompt the placement of a chest tube [29, 30].

All hemothoraces visible on plain chest radiograph should be drained by tube thoracostomy. In elderly patients with a history of trauma, the practice of ascribing a pleural fluid collection to their underlying cardiac or pulmonary condition and not placing a chest tube should be discouraged. The majority of hemothoraces following blunt trauma are easily treated by drainage and re-expansion of the lung. If bleeding continues, underlying factors such as coagulopathy, acidosis, and hypothermia should all be sought and addressed. Particular attention should be paid to the elderly on various forms of anticoagulation. Initial chest tube output of >1,500 mL and ongoing bleeding (>200 mL × 4 h) indicate injury to structures such as diaphragm, intercostal artery, or cardiac injury and requires thoracotomy. Retained hemothorax, occurring in roughly 10 % of hemothoraces, is a complication of misplaced or inadequate chest tube drainage. The blood of retained hemothorax may provide a nidus for infection that results in empyema and should be evacuated completely either by further tube thoracostomies or operative intervention – video-assisted thoracoscopy (VATS) or open thoracotomy. A retained hemothorax significantly increases the risk of formation of an empyema [31]. VATS is not contraindicated even in the very elderly (although one-lung ventilation is required) and should be utilized for posttraumatic hemothorax [32]. Open thoracotomy is indicated in ongoing bleeding, persistent large-clotted hemothorax refractory to tube thoracostomy and VATS, empyema, or need for definitive repair of injury.

Empyema is a significant complication following chest trauma, occurring in 4–5 % patients who have a traumatic hemothorax. Empyemas can be caused by multiple sources: bronchopleural fistula, parapneumonic effusion, pulmonary abscess, retained hemothorax, esophageal injury, or diaphragmatic hernia with contamination from abdominal contents. CxR is generally not useful in diagnosing an empyema because it cannot differentiate between fluid, contusion, or atelectasis. A chest CT with IV contrast is a valuable diagnostic test since it may identify a rim-enhancing lesion or visualize a loculated collection. Antibiotic therapy is an important component of treatment, but source control through drainage and/or decortication is most important.

Blunt tracheobronchial injury occurs in less than 1 % of trauma patients presenting to trauma centers, though it is a common cause of prehospital mortality with these patients dying of asphyxia. While significant disruption of the tracheal/bronchial tree can present in a dramatic manner with massive subcutaneous air and continuous air leaks from chest tubes, minor injuries are often missed initially and present late with a median time to diagnosis of 6 months [33, 34]. Shear force to the intrathoracic trachea occurs at the fixed points of the carina and cricoid and most tracheobronchial injuries occur within 2.5 cm of the carina. Injury confined to the mediastinal space presents as pneumomediastinum. Injuries into the pleural space present as a pneumothorax, which may cause a persistent large air leak after tube thoracostomy. Pneumomediastinum, persistent subcutaneous emphysema without other etiology, or persistent large air leak should prompt a rigid or flexible bronchoscopy looking for a tracheobronchial injury. Minor injuries, such as mucosa injuries only and injuries in the membranous portion of the airway, can often be managed nonoperatively [35]. Even if these injuries require delayed operative intervention, good outcome can be obtained [34]. Increased age is associated with increased mortality for tracheobronchial injuries [35]. Massive, continuous air leaks or massive subcutaneous emphysema poses a significant treatment challenge. Careful fiber-optic-assisted intubation below the level of the injury can stabilize patients with injuries near the cricoid. Patients with lower injuries can be very difficult to ventilate, oxygenate, or to keep their lung expanded. In this situation, the chest tube should be removed from suction to water seal in order to decrease air leak, potentially increase tidal volumes, and provide a window to stabilize the patient prior to operative repair. Upper airway injuries can be approached surgically through a collar incision, and injuries to the carina and main stem bronchi are best approached through a right thoracotomy incision. For injuries to the left main stem bronchus greater than 1 cm away from the carina, a left thoracotomy incision may be the best approach.