Chest trauma - Clinical Tree

Essentials

1
Initial management priorities are oxygenation, ventilatory support if required, pleural and pericardial decompression when indicated, circulatory support, adequate analgesia and early imaging to identify evolving and potentially life-threatening injuries.
2
Less than 10% of blunt chest trauma patients require thoracic surgery.
3
Supine chest radiographs do not reliably exclude haemothorax, pneumothorax, aortic transection, diaphragmatic disruption, cardiac tamponade or rib, sternal, thoracic spine and scapula fractures.
4
Multislice computed tomography with intravenous contrast is the ‘gold standard’ screening and diagnostic tool for thoracic injuries. Sonography may demonstrate haemothorax, pneumothorax, pulmonary contusion, cardiac tamponade and diaphragmatic injury.
5
Aseptic percutaneous digital identification of the pleural space is the essential first step for pleural decompression. Drainage and insertion of a chest tube is a secondary priority. Needle thoracocentesis is an unreliable means of decompressing the chest of an unstable patient.
6
Pleural decompression and chest tube insertion during resuscitation has a low complication rate.
7
There is a clear role for resuscitative thoracotomy in shocked patients with sonographic evidence of cardiac tamponade.
8
Non-invasive ventilation may avoid complications of mechanical ventilation in select patients with flail chest and pulmonary contusion.

Introduction

Incidence

Thoracic trauma is responsible for 25% of all trauma deaths and contributes to a further 25%. In Australasia and the United Kingdom, 90% to 95% of chest trauma is secondary to blunt injury.

Principles of initial management

The initial management priorities are oxygenation, ventilatory support if required, pleural and pericardial decompression when indicated, circulatory support, adequate analgesia and early imaging to diagnose evolving and potentially life-threatening injuries. The majority of chest trauma patients may be managed non-operatively. Less than 10% of blunt thoracic trauma patients will require thoracotomy; the remainder require supportive care, including pleural decompression and drainage.

Supportive care—in particular resuscitation—is often suboptimal. Delayed or inadequate ventilatory resuscitation, inadequate shock management, insufficient monitoring of arterial blood gases, delay or failure to perform pleural decompression and drainage and delays in definitive diagnostic imaging remain identifiable problems that contribute to preventable morbidity and mortality.

Thoracic injuries evolve. Life-threatening injuries—including flail chest, pulmonary contusion, thoracic aortic transection, pneumothorax, haemothorax, pericardial tamponade, respiratory insufficiency secondary to rib fractures and ruptured hemidiaphragm—may not be apparent on initial presentation. These diagnoses must be pursued and actively excluded. Supine chest radiographs do not reliably exclude these injuries. Multi-slice computed tomography (CT) with contrast is the ‘gold standard’ screening and diagnostic test for patients at high risk of potential life-threatening injuries. However, life-saving procedures should be performed first ( Table 3.6.1 ). Ultrasound screening provides early identification of cardiac tamponade and haemothorax.

Table 3.6.1

Actions prior to computed tomography

Situation	Response
Pneumothorax or haemothorax on initial supine chest x-ray	Decompress pleural space and insert chest drain on affected side
Spontaneously breathing patient with unilateral decreased air entry and normal chest x-ray, oxygenation and haemodynamic status	Await computed tomography
Intubated and ventilated patient with unilateral decreased air entry and normal chest x-ray but with hypoxia or hypotension	Decompress pleural space and insert chest drain on affected side, then reassess
Intubated and ventilated patient with hypotension or hypoxia (no other apparent cause)	Decompress pleural spaces bilaterally and then insert chest drains

Oxygen

Hypoxia may be absent at the initial reception and resuscitation of a patient with chest trauma yet may develop as injuries evolve. Supplemental oxygen may be required for mild desaturation, with the FiO ₂ titrated to the clinical response. A higher FiO ₂ may be achieved using positive airway pressure and invasive ventilation (continuous positive airway pressure [CPAP], expiratory positive airway pressure [EPAP]).

Increasing the normal inspiratory/expiratory (I/E) ratio may be beneficial in mechanically ventilated patients with severe hypoxia. The outcome benefits of independent lung ventilation, inhaled nitric oxide, prone position, partial liquid ventilation and extracorporeal membrane oxygenation in the initial resuscitation setting are unproven.

Support of pulmonary function

Pain, fatigue from increased work of breathing, disruption of lung mechanics and side effects of opiate analgesia may cause hypoventilation. The elderly as well as other patients with pre-existing poor chest wall compliance are particularly at risk of hypoventilation in the setting of chest wall injury.

Non-invasive ventilation

Patients with pulmonary contusions and high oxygen requirements do not necessarily require intubation but may be safely managed with non-invasive ventilation (NIV). By avoiding mechanical ventilation, mortality from nosocomial infection is significantly reduced.

Mechanical ventilation

Contraindications to NIV in the trauma patient include the need for full spinal precautions, depressed conscious state and facial injury. Patients with pulmonary contusion and poor lung compliance require ventilation with low tidal volumes and low inspiratory pressures. This reduces barotrauma, secondary lung injury and mortality.

Fluid resuscitation

There is evidence that ‘permissive hypotension’ prior to surgical control of blood loss may improve survival in hypotensive penetrating torso injury. It may also reduce blood product requirements, coagulopathy and early postoperative mortality. It is unclear whether these findings translate equally to hypotensive blunt trauma. Once haemorrhage has been controlled, fluid therapy to maximize cardiac output and oxygen delivery may reduce trauma mortality.

Conservative fluid resuscitation has been recommended to minimize extravascular lung water in patients with pulmonary contusion. However, under-resuscitation and tissue hypoperfusion may compound organ dysfunction and secondary lung injury. The early use of invasive monitoring to guide fluid replacement may be required.

Analgesia

Adequate analgesia reduces hypoventilation secondary to pain and facilitates coughing and chest physiotherapy. It reduces complications of atelectasis, consolidation and respiratory failure and improves pulmonary function. Oral analgesia is often sufficient for single rib fractures. Parenteral narcotic analgesia, intercostal nerve block or thoracic epidural analgesia is usually required for multiple rib fractures. Intercostal nerve block involves a number of injections to treat multiple rib fractures, which limits its usefulness compared with other techniques. Advanced regional nerve blocks such as epidural, paravertebral or intercostal nerve blocks are technically challenging and carry a higher risk of complications. The serratus anterior plane block, a fascial plane block distant from neurovascular bundles and pleural space, is an alternative.

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