Blunt injuries to the chest

CHEST SURGERY

Blunt injuries to the chest B J Evans Philip Hornick

Thoracic trauma accounts for 25% of all trauma fatalities in the UK. Blunt injury to the chest can affect any component of the chest wall and thoracic cavity. Mortality is high because of associated multi-system injuries. The most common cause is high-speed road traffic accidents, which result in deceleration injury and compression forces.

Injuries Rib fracture is the most common injury. Flail chest – a free-floating, unstable segment of chest wall is formed when three or more consecutive ribs are fractured in two or more places. Sternal fractures are significant only when they result in blunt cardiac injuries. Tracheobronchial disruption usually occurs within 2.5 cm of the carina; right-sided bronchial injuries are slightly more common than left-sided injuries. Mainstem bronchi are injured much more frequently (80–85%) than trachea (15–27%). Pulmonary contusions may impair ventilation. Shunting and dead-space ventilation can impair oxygenation. Space-occupying lesions (e.g. pneumothoraces, haemothoraces, haemopneumothoraces) interfere with oxygenation and ventilation by compressing healthy lung parenchyma. Tension pneumothorax is particularly worrying. Direct cardiac injuries (chamber rupture) or severe injuries to great vessels (thoracic aortic disruption) frequently result in death due to immediate and devastating exsanguination or loss of function of the cardiac pump. Cardiac contusions are caused by direct traumatic myocardial damage without traumatic involvement of coronary arteries. Diaphragmatic rupture is usually due to gross abdominal compression causing large radial tears in the diaphragm. Sepsis is due to leakage of contents of the alimentary tract (oesophageal perforations)

Initial management Life-threatening emergencies after blunt trauma to the chest require accurate assessment and rapid intervention to avoid complications and death.

B J Evans is a Clinical Research Fellow in Cardiothoracic Surgery at Hammersmith Hospital, London, UK. Philip Hornick is a Senior Lecturer and Honorary Consultant in Cardiothoracic Surgery at Imperial College, London, UK.

SURGERY 23:11

409

© 2005 The Medicine Publishing Company Ltd

CHEST SURGERY

Fibreoptic or rigid bronchoscopy diagnoses possible tracheobronchial injuries. It allows for passage of an endotracheal tube under direct vision.

The main objective in the initial management is to restore normal cardiopulmonary function (by establishing an adequate airway and ventilation) and correction of hypovolaemia or low cardiac output. Obtaining a detailed clinical history is important in the assessment and should include the time and mechanism of injury, velocity and deceleration of the vehicle, and evidence of other system injury.

Definitive management Most patients with blunt trauma to the chest do not require surgery (Figure 1). Most (>80%) do not require invasive therapy or insertion of an intercostal drain as definitive management. Emergency thoracotomy is indicated for: • rapid initial massive haemorrhage (>1500 ml) after insertion of chest drain • Loss of >500 ml of blood in the first hour or >200 ml/hour in the subsequent hours • Cardiac arrest after previous cardiac activity to exclude tamponade Patients presenting without vital signs or witnessed cardiac arrest should not undergo emergency thoracotomy.

Resuscitation: the Advanced Trauma Life Support™ (ATLS™) guidelines for management of trauma must be followed, with necessary modifications to avoid additional damage. For example, endotracheal intubation in a patient with major bronchial disruption can be lethal; infusion of large volumes of fluid in a patient with underlying cardiac tamponade can lead to pump failure. Investigations Analysis of arterial blood gas measures ventilation, oxygenation and acid–base status. It guides therapeutic decisions (e.g. endotracheal intubation). Troponin I – raised concentration in serum correlates with abnormalities on ECG and signifies myocardial damage. Chest radiograph is the initial radiological investigation. Tension pneumothorax should be diagnosed clinically and decompressed before a chest radiograph is taken. ECG identifies new cardiac abnormalities; most commonly tachyarrhythmias and conduction disturbances, as well as elevation of ST segment. It also identifies underlying problems that may influence decisions regarding treatment. Focused abdominal sonography for trauma assesses intrapericardial bleeding. Spiral CT/CT aortography detects blunt injuries to the aorta and delineates the location and extent of injuries. Oesophagoscopy/contrast swallow diagnoses possible oesophageal injuries (water-soluble contrast media is used; barium is used if this is negative).

Specific treatment Chest wall and diaphragm Rib fractures: ribs 4–10 are most frequently involved. Presentation is with inspiratory chest pain and local bony tenderness and crepitus over the fracture site. Fractures of ribs 8–12 are associated with abdominal injuries; fractures of ribs 1–2 require excessive force and are associated with cranial, major vascular, thoracic, and abdominal injuries. Treatment of rib fractures is analgesia, including intercostal nerve blocks or thoracic epidural anaesthesia to allow for early mobilization and physiotherapy. A flail chest presents with paradoxical motion of the chest wall, dyspnoea, and tachycardia; associated pulmonary contusions are common. Endotracheal intubation and positive-pressure ventilation may be necessary for flail chest. Fluids (i.v.) are given cautiously to avoid respiratory failure (particularly in patients with pulmonary contusions).

Blunt trauma to the chest: indications for surgery

Chest wall/diaphragm

Airway/gastrointestinal tract

Immediate surgical indications

Long-term surgical indications

Traumatic thoractomy and loss of integrity of the chest wall Diaphragmatic tears

Delayed recognition of blunt injury to the diaphragm

Tracheal, major bronchial or oesophageal injury

Delayed recognition of tracheobronchial or oesophageal injury Tracheo-oesophageal fistula

Contents of gastrointestinal tract in the chest drain

Traumatic diaphragmatic hernia

Persistent thoracic duct fistula/chylothorax Pleural space

Massive air leak after insertion of a chest drain Massive haemothorax or continued high rate of blood loss via the chest drain

Chronic clotted haemothorax or fibrothorax Empyema

Lung/cardiac

Cardiac tamponade

Traumatic lung abscess

Major vessels

Radiographic confirmation of a major vessel injury An embolism into the pulmonary artery or heart

Late recognition of a injury to major vessel (development of traumatic pseudoaneurysm)

1

SURGERY 23:11

410

© 2005 The Medicine Publishing Company Ltd

CHEST SURGERY

Lung and cardiac Pulmonary contusions are caused by the transmission of external forces to the lung parenchyma, resulting in haemorrhage. Presentation is with varying degrees of respiratory difficulty and hypoxia. An overlying injury to the chest wall is usually apparent. Radiographical changes in the lung parenchyma can be delayed for 48 hours. Management is supportive, using careful fluid balance to avoid respiratory failure. Significant pulmonary shunting and dead-space ventilation may develop if a large amount of parenchyma is involved, necessitating endotracheal intubation and mechanical ventilation.

Sternal fractures: patients report pain; a sense of dyspnoea may be present. Examination reveals local tenderness, bruising, swelling or crepitus. Associated injuries (usually rib fractures) occur in 55–70% of patients. Blunt cardiac injuries are diagnosed in fewer than 20% of patients. An ECG should be done. Diaphragmatic injuries should be considered after a blow to the abdomen (e.g. seatbelt injury) leading to dyspnoea or respiratory distress. The left side is more commonly affected due to the liver protecting the right. Hypovolaemic shock may result from associated injuries (splenic or hepatic trauma). The diagnosis is usually made radiographically. With herniation of viscera into the chest, suspicion can be confirmed by passage of an nasogastric tube. Laparotomy is required because 90% of cases have associated abdominal trauma; the high mortality rate (41%) is a consequence of this.

Cardiac injuries range from contusion associated with transient arrhythmias to rupture of the valve mechanisms, interventricular septum or myocardium. Patients can be asymptomatic or have signs and symptoms (chest pain, cardiac tamponade, cardiovascular collapse). Treatment for contusion is conservative and includes anti-arrhythmic therapy. Tamponade requires rapid pericardiocentesis or creation of a subxiphoid window. Patients with cardiac rupture rarely survive to hospital. Treatment is immediate surgical repair of the cardiac chamber. Unstable patients may benefit from insertion of an intra-aortic counterpulsation balloon pump.

Airway and gastrointestinal tract Tracheal and bronchial injuries (fractures, lacerations, disruptions) are often devastating and usually caused by severe rapid deceleration or compressive forces applied directly to the trachea. Patients are in respiratory distress, typically with stridor. Other signs include pneumothorax and subcutaneous emphysema. Establishment of an airway may require flexible bronchoscopy to guide endotracheal intubation.

Major vessels Blunt injuries to the thoracic aorta and major arteries occur after rapid deceleration and production of shear forces. Many of these patients die from vessel rupture and exsanguination. Occasionally, tamponade of the haemorrhage occurs within the mediastinum and peri-aortic tissues and patients survive. There may be differential blood pressure in the upper extremity or loss of pulses, but often the diagnosis is proved radiologically. The chest radiograph reveals a widened mediastinum, depression of the left main bronchus, trachea or oesophagus, and loss of the aortic knuckle. Confirmation is by contrast CT. The management of these injuries is evolving, using endovascular stents to repair aortic injuries. Often, urgent surgery is done to repair the defect. Proximal pulmonary arterial injuries are relatively easy to repair when in an anterior location; posterior injuries often require cardiopulmonary bypass. Pulmonary hilar injuries present the possibility of rapid exsanguination and should be treated with pneumonectomy.

Oesophageal injuries are rare because the posterior mediastinum provides protection. They usually result from a forceful blow to the epigastrium, with distal oesophageal rupture and spillage of gastrointestinal contents into the chest (usually on the left side). Associated injuries to other organs are common. Symptoms include upper abdominal and thoracic pain that is disproportionate to examination findings. Signs include cardiorespiratory compromise and subcutaneous emphysema. Surgery is indicated. Delayed presentation may result in systemic sepsis that will require supportive measures. Pleural space Pneumothorax is usually caused by a fractured rib penetrating the lung parenchyma; many patients also have associated haemorrhage. Rapid diagnosis and treatment of a tension pneumothorax is necessary because it can progress to cardiovascular collapse caused by mediastinal shift reducing venous return to the heart. Immediate therapy includes decompression of the affected hemithorax by needle thoracostomy using a large-bore needle (14–16 F) inserted through the second intercostal space in the mid-clavicular line, followed by a chest drain. Persistent collapse of the lung with a massive air leak may be due to bronchial injury.

Blunt injuries of the superior vena cava and major thoracic veins: isolated injuries of the major veins of the thorax are rare. Management is urgent surgical repair. Injured subclavian or azygous veins can be ligated if repair is difficult. Injuries of the thoracic inferior or superior vena cava may require cardiopulmonary bypass.

Prognosis The prognosis for most patients reaching hospital with blunt trauma to the chest is excellent. The most important determinant of outcome is significant associated injuries. Some injuries (e.g. rupture of cardiac chamber, thoracic aortic rupture, injuries to the venae cavae, delayed recognition of oesophageal rupture) are associated with high morbidity and mortality. 

Haemothorax caused by bleeding from the chest wall, lung parenchyma or major thoracic vessel manifests with the varying degrees of haemodynamic instability. Multiple chest drains may be required and output is monitored closely; indications for surgery are based on the initial and cumulative drainage (Figure 1). Large, clotted haemothoraces require surgical evacuation to allow full expansion of the lung and to prevent complications (e.g. fibrothorax, empyema). Thoracoscopic approaches have been used successfully.

SURGERY 23:11

411

© 2005 The Medicine Publishing Company Ltd