Thoracic trauma is the cause of 25% to 50% of all fatal injuries, making it the leading cause of death in the first 3 decades of life.^1,2 In addition, injuries to the thorax are accountable for more than 50% of deaths in children. Thoracic trauma is the third leading cause of death after neoplasms and atherosclerosis for all age groups.³

The mortality from thoracic injuries is about 10%.² Blunt thoracic trauma accounts for 96.3%, whereas penetrating injuries account for only 3.7% of cases. The most common causes are motor vehicle accidents (70%), suicides (10%), falls (8%), homicides (7%), and other (5%).

The peri- and intraoperative management of patients with thoracic injuries is a difficult task for any anaesthetist.⁴ The causes of perioperative morbidity and mortality include respiratory obstructions, respiratory arrest, and often difficult-­to-control bleeding. In most cases, those affected present with an unstable cardiopulmonary situation and have complex, life-threatening injuries. Therefore evaluation, intervention, and possibly resuscitation take place under considerable time pressure. In close cooperation between the specialist areas, abdominal or neurologic injuries must also be treated with the same urgency and with a high priority.

The thorax protects vital organs, including the heart, lungs, large vessels close to the heart, and airways. To damage these structures, considerable force is usually required. Thoracic injuries can lead to fatal bleeding, and air or blood in the pleural space or pericardium can rapidly lead to cardiovascular collapse.

The perforation of the chest is often an isolated injury, but significant blunt trauma may be associated with multiple injuries. However, blunt and perforating mechanisms lead to a common pathway of inadequate supply of oxygen to peripheral tissues and consecutive metabolic failure.

Massive pulmonary or cardiac injuries are rare, but are usually lethal if present. Less severe injuries often result in the impairment of vital organ function, but because of the functional reserve of the organs there is often time for diagnosis and therapy.

Injuries, such as pneumothorax or cardiac tamponade, combine the effects of direct heart or lung injury, which further compromises organ functions. Hemorrhages, swelling of damaged tissues because of fluid retention, or neurogenic shock from spinal cord injuries can also contribute impaired oxygen delivery to tissues.

For example, tension pneumothorax not only affects gas exchange, but also can affect the venous return to the heart. In addition to impaired cardiac function, a cardiac tamponade also reduces venous return. The direct injury to the chest or diaphragm, usually associated with severe pain, may impair both the respiratory mechanics and gas exchange.

Perioperative management therefore requires anticipation, early detection, temporary support, and conservative or surgical care for thoracic injuries.⁴

Categories of (Blunt) Thoracic Trauma

Thoracic trauma can be divided into different categories based on the injured structures. Each category can occur on its own or in combination with other injuries, each of which has different anesthesiologic implications.

• • Tracheobronchial injury/laryngeal injury
  
• • Rib fractures, flail chest
  
• • Lung contusion, pneumothorax, hemothorax
  
• • Mediastinal widening
  
• • Aortic rupture
  
• • Cardiac contusion/myocardial trauma/pericardial tamponade
  
• • Diaphragmatic rupture
  
• • Esophageal perforation/rupture

In patients with blunt thoracic trauma, one must consider additional injuries to the head, face, cervical spine, and upper and lower respiratory tract injuries. Tracheobronchial injuries are rare with a frequency of 0.8%.⁵ Unfortunately, most patients with this pattern of injuries die at the scene of the accident. In the patients who arrive at the trauma center, failure to diagnose early can lead to disastrous acute or delayed complications (Figs. 33.1 and 33.2).⁶ Cardinal symptoms are hemoptysis and/or subcutaneous emphysema. Pneumothorax and pneumomediastinum are radiologic correlates of intrathoracic tracheobronchial injuries.⁷ Impaired consciousness (Glasgow Coma Scale [GCS] <9), respiratory obstruction, or insufficient or impossible mask ventilation require immediate endotracheal intubation or the immediate establishment of surgical airways.

A tracheobronchial injury must be considered when a pneumothorax with massive air leakage cannot be drained or reduced in size with the insertion of a chest tube. The extent of the injury is confirmed by fiberoptic bronchoscopy. Control and splinting of the respiratory tract, injuries of the main bronchi, large air leaks, and/or hemoptysis is frequently established with insertion of a double-lumen tube (DLT). Regardless of the type of endotracheal tube used, placement should be carried out under direct fiberoptic visualization. The injury can be accurately diagnosed and documented by bronchoscopy to avoid further aggravation of the lesion.⁸

The need for cervical immobilization, the uncertain nil per os (NPO) status, and the trauma related disturbed gastric emptying usually necessitate a “rapid sequence induction” or, more safely, an awake intubation (direct laryngoscopy, or with fiberoptic bronchoscopy).

Injuries to the Larynx

Blunt injuries to the larynx are rare^2,9 at about 0.3%,^2,10 its estimated incidence varying between 1:5000 and 1:137,000 trauma patients.^1–5,7,11 However, recent data suggest that its incidence may be higher than previously reported and fractures of the laryngeal skeleton may be diagnosed in almost 1% of all neck-trauma patients imaged with multidetector computed tomography (CT) in the emergency setting.⁸ Prompt management is paramount to avoid patient death or long-term impairment of breathing, swallowing, and speaking. Classic signs of laryngeal injury are:

• • hoarseness
  
• • subcutaneous neck emphysema
  
• • hemoptysis

Injuries to the respiratory system must be excluded at the initial presentation of the patient (e.g., trauma bay). Even in the absence of airway and breathing problems and lack of further obvious respiratory injuries. The inspection and examination of the upper respiratory tract by endoscopy and/or CT is necessary to determine the degree of occult injury and to make a prognosis as to whether airway obstruction in the further course can be anticipated.⁹

Patients with laryngeal injuries may seemingly present with normal respiratory findings, but and can develop life-threatening obstruction of the upper respiratory tract within a very short period of time. Early tracheal intubation should be considered dependent on the laryngoscopic finding. In addition, early tracheostomy should be considered in all patients with respiratory injury.^12,13

Rib Fracture

The most common blunt thoracic injury in both adults and children with 67.3% incidence are rib fractures.^2,11,14 Often rib fractures are associated with other injuries, such as ­thoracic instability (flail chest), lung contusion, and pneumothorax. Pronounced pain can lead to shallow breathing and thus results in secondary atelectasis formation and secretion retention.¹⁵ Perioperative pain management is therefore of eminent importance.¹⁶

In awake patients, a rib fracture can be easily detected clinically. However, preoperative thoracic x-ray imaging is not only used to detect the fracture, but also to detect associated injuries, such as pneumothorax, hemothorax, or lung contusion, as these need preferential treatment.

The greatest perioperative risk (besides the risk of bleeding) is the injury of the pleura by bone fragments, which may lead to the formation of a tension pneumothorax during the transition from spontaneous breathing to mechanical positive pressure ventilation. The placement of a chest tube before the induction of general anesthesia seems warranted (Fig. 33.3).

Thoracic Instability

Thoracic instability occurs when several adjacent ribs (rib series fracture) are affected, creating a mobile segment of the thoracic wall. During spontaneous inspiration, the segment moves paradoxically in the opposite direction of the uninjured thoracic wall (Figs. 33.4 and 33.5). An unstable thorax is therefore a purely clinical diagnosis that can only be made during spontaneous breathing and affects 23.1% of patients with blunt thoracic trauma in the operating room.² Because of the high elasticity of the ribs in childhood, the incidence in pediatric patients is extremely low¹⁴ and is an indicator of excessive force.

Thoracic instability is usually associated with a contusion of adjacent lung structures. Shallow breathing and accompanying pulmonary contusion lead to increased work of breathing, an increase in intrapulmonary shunt volume, and hypoxemia. Anesthetic management primarily includes pain control and intermittent overpressure ventilation.¹⁷ The criteria for endotracheal intubation and mechanical ventilation are:¹⁸

• • arterial partial pressure of oxygen (PaO2) under 70 mm Hg under supplemental oxygen (reservoir)
  
• • PaCO2 over 50 mm Hg
  
• • Respiratory rate over 35 breaths per minute
  
• • Vital capacity under 15 mL/kg
  
• • Negative inspiratory strength less than 20 cm H₂O

A contusion of the lungs often becomes apparent as hypoxemia. The frequency in adult patients in emergency surgery is 65%.² The therapy consists of supplemental oxygen and the application of positive airway pressure, either with the help of a continuous positive airway pressure (CPAP) mask or by intubation and mechanical ventilation with positive end-expiratory pressure (PEEP).

Lung contusion causes a significant disturbance of vascular integrity through intraparenchymal and alveolar hemorrhage, which results in reduced pulmonary compliance and increased shunt fraction.¹⁹ Intraalveolar hemorrhage can result in severe acute respiratory distress syndrome (ARDS) by inducing profound inflammation and causing severe bronchiolitis. Because of inconclusive clinical signs, the diagnosis is usually made radiologically, presenting as diffuse, nonsegmental lung consolidation on the anteroposterior thoracic x-ray image.

Hemorrhage in the tracheobronchial tree can be observed in about 10% of patients. An important measure in the therapy of bleeding is frequent endotracheal suction via the endotracheal tube. In about 33% of patients with respiratory hemorrhage, lung isolation with DLT to prevent blood spillage is required.² Alternative treatment methods, such as diuretics and corticosteroid application, have not shown benefits.¹⁸ PEEP ventilation improves hypoxemia, but not the underlying contusion.¹⁹

The treatment of rib fractures requires a sufficient treatment of pain (parenteral analgesics, interpleural anesthetics, or epidural/regional anesthesia). The affected lung is susceptible to the formation of a capillary leak; therefore careful fluid management is indicated.²⁰ Intraalveolar hemorrhage resulting from severe pulmonary parenchymal trauma caused aspiration pneumonitis intraoperatively that resulted in severe ARDS following surgical stabilization of rib fractures (SSRF). Risk factors for this include lateral decubitus position, early SSRF (within 5 days of injury), and the use of a single lumen tube during the procedure. Care should be taken in performing SSRF in patients with significant traumatic lung parenchymal injury, and intraoperative lung isolation should be exercised in these patients (Fig. 33.6).²¹

Pneumothorax

Blunt thoracic trauma should always lead to suspicion of a pneumothorax. In adults, the incidence of a pneumothorax in emergency interventions is 30%.²

Possible causes include alveolar rupture with perivascular spread of air to the hilus and the connection of the distal airways to the pleural space.²² Under general anesthesia, with positive pressure ventilation, a viable risk that a simple pneumothorax will result in a life-threatening tension pneumothorax exists (Fig. 33.7). The increase in pressure in the pleural space on the one hand leads to hypoventilation and hypoxemia, and on the other hand, the venous return is reduced by kinking of the pulmonary veins and the vena cava and results in a pronounced hypotension. If untreated promptly, this may lead to cardiac arrest.

Diagnosis of pneumothorax under general anesthesia is difficult. Controlled mechanical ventilation and ambient noise make it difficult to diagnose by auscultation.²² Frequently, pneumothorax is only suspected when symptoms, such as hypotension, tachycardia, increased airway pressure, increased jugular venous pressure, and trachea deviation, occur.

The suspicion alone calls for the placement of a thoracic drain to prevent a lethal complication. Patients with multiple rib fractures may have a subclinical pneumothorax, and therefore prophylactic thoracic drainage should be performed.²³

With lung ultrasound, it is possible to accurately rule in or rule out pneumothorax at the bedside in almost all clinical scenarios.^24,25 Alternatively, if the patient is clinically stable, a thoracic x-ray can secure the diagnosis preoperatively.

Hemothorax

The frequency of hemothorax in adult patients following thoracic trauma is 26%.¹⁰ Bleeding can be minimal or massive, as a hemithorax can hold up to 30% to 40% of the total blood volume. This massive bleeding (Fig. 33.8) is usually caused by a laceration of the heart or of the large vessels in proximity to the heart.²³ A massive hemothorax is defined as a collection of more than 1500 mL of free blood in the pleural space, which inevitably results in hypovolemic shock. The mediastinal shift leads to further cardiovascular depression and ultimately to cardiovascular collapse. Clinical diagnosis in the operating room is difficult, yet symptoms, such as missing or attenuated breath sound, as well as contralateral tracheal displacement should always raise suspicion of the presence of hemothorax. The diagnosis is confirmed by ultrasound at the bedside or by an x-ray with shading of the entire hemithorax. Placement of a large diameter thoracic drainage is the therapy of choice.²⁶ This makes it possible to improve ventilation and control thoracic blood loss. Intraoperatively, the patient is best managed with a DLT and one-lung ventilation if necessary.²⁷

Mediastinal Widening

The widening of the mediastinum in an x-ray image after blunt thoracic trauma is often associated with thoracic aortic injury. However, because of the vulnerability of ­thoracic x-ray diagnostics to artifacts, the diagnosis should be secured by a CT examination. The loss of aortic contour, the displacement of the esophagus to the right, and a mediastinal widening are corresponding radiologic signs.^28,29