Thoracic trauma

Many of the surgically treatable conditions of the lung are treated at specialist thoracic centres and the only exposure to thoracic surgery that most surgeons have is dealing with thoracic trauma. The approach to treatment must be methodical and exact because the signs, particularly in the presence of other injury, may easily be missed. The guidelines produced by the American College of Surgeons Advanced Trauma Life Support (ATLS®) Group provide a thorough and unambiguous approach to trauma. The general principles of resuscitation and need for priorities are extensively discussed and will not be repeated here. However, the specific aspects of trauma management related to the thorax will be covered. Thoracic trauma is responsible for over 70 per cent of all deaths following road traffic accidents. Blunt trauma to the chest in isolation is fatal in 10 per cent of cases, rising to 30 per cent if other injuries are present. An increasing number of penetrating thoracic wounds is also seen from domestic and civil violence, with a mortality rate of 3 per cent for simple stabbing to 15 per cent for gunshot wounds.

Initial management

Early deaths after thoracic trauma are caused by hypoxemia, hypovolaemia and tamponade. The first steps in treating these patients should be to diagnose and treat these problems as early as possible because they may be readily corrected. Young patients have a large physiological reserve and serious injury may be overlooked until this reserve is used up; then the situation is critical and may be irretrievable. The best approach is to maintain a high index of suspicion and suspect the worst if life-threatening conditions are to be anticipated and treated. Early consultation with a regional thoracic centre is advised in cases of doubt. In an emergency it is essential that experienced help is summoned immediately.

The basic principles of resuscitation are securing the airway and restoring the circulating volume. Blood and secretions are removed from the oropharynx by suction. If the patient is unable to maintain his or her airway then an oropharyngeal airway followed by tracheal intubation (once a cervical spine injury is excluded) may be necessary.

A thorough inspection of the chest wall includes noting the frequency and pattern of breathing, external evidence of trauma and structural defects of the thorax. Palpation will detect surgical emphysema, paradoxical movement and a stove-in chest. Auscultation and percussion should reveal the existence of a pneumothorax (there is decreased movement on the affected side with a hyperresonant percussion note, reduced breath sounds in the axilla and shift of the trachea to the opposite side) which requires emergency drainage (see Pneumothorax for a more detailed appraisal and see Chest drainage for advice on technique of drain insertion).

Once the patient has been stabilised then radiographs of the chest should be taken and further treatment decided on the basis of the patient’s condition and the radiographic result. It

is rarely necessary to perform a thoracotomy in the resuscita­tion room but, in the case of tamponade from a penetrating injury, it might be life saving. However, the fact is that, even in experienced hands, the yield in terms of survival in this group of patients is very small. If there is profound hypoten­sion as a result of cardiac tamponade, needle aspiration of the pericardium is life saving and may hold the situation long enough for more controlled surgery to be performed.

The components of chest injury in blunt trauma

Any combination of structures may be involved in varying degrees of severity. If the skeletal injuries are severe, underlying parenchymal injuries are likely to be in proportion; however, in young flexible chests, or those restrained by seat belts, there may be little external evidence of the severity of internal damage.

Chest wall

Localised rib fracture due to direct trauma. A simple rib fracture may be serious in elderly people or in those with chronic lung disease who have little pulmonary reserve. Uncomplicated fractures require sufficient analgesia to encourage a normal respiratory pattern and effective coughing. Oral analgesia may suffice but intercostal nerve blockade with local anaesthesia may be very helpful. Chest strapping or bed rest is no longer advised and early ambulation with vigorous physiotherapy (and oral antibiotics if necessary) is encouraged. A chest radiograph is always taken to exclude an underlying pneumothorax. It is useful to confirm the skeletal injuries but routine chest radiography may miss rib fractures. However, once a pneumothorax and major skeletal injuries are excluded, the management is the same — the local control of chest pain.

Major chest wall trauma. Flail chest (Fig. 47.1). This occurs when several adjacent ribs are fractured in two places either on one side of the chest or either side of the sternum. The flail segment moves paradoxically, that is, inwards during inspiration and outwards during expiration, thereby reducing effective gas exchange. The net result is poor oxygenation from injury to the underlying lung parenchyma and paradoxical movement of the flail segment. The underlying lung injury with loss of alveolar function may result in deoxygenated blood passing into the systemic circulation. This creates a right-to-left shunt and prevents full saturation of arterial blood. In the absence of any other injuries and, if the segment is small and not embarrassing respiration, the patient may be nursed on a high-dependency unit with regular blood gas analysis and good analgesia until the flail segment stabilises. In the more severe case, endotracheal intubation is required with positive pressure ventilation for up to 3 weeks, until the fractures become less mobile. Thoracotomy with fracture fixation is occasionally appropriate if there is an underlying lung injury to be treated at the same time. An anterior flail segment with the sternum moving paradoxically with respiration can be stabilised by internal fixation but operative management is not usual for either.

First rib fracture. Fracture of the first rib should alert the clinician to a potentially serious chest injury. This rib is well protected and requires a considerable force to fracture and associated injuries to the great vessels, abdomen, head and neck are common. The mortality rate associated with a frac­ture of the first rib exceeds 30 per cent. Similar suspicions are raised when fractures of the sternum and scapula are seen. Fractures of the lower ribs may involve underlying abdominal viscera (spleen on the left and liver on the right). Intercostal artery bleeding may still be severe, resulting in haemothorax.

Fractures of the sternum (Fig. 47.2). This injury is now seen as a result of deceleration on to seat belts. Steering wheel injuries are now much less common. The injury is very painful even in the mild case where only the external plate of the sternum is fractured. However, there is a real risk of underlying myocardial damage and the patient should be observed in hospital with constant electrocardiogram (ECG) monitoring, analgesia and serial cardiac enzymes. Rupture of the aorta and associated cervical spine injuries also need to be excluded. Most cases need no specific treatment but paradoxical movement or instability of the chest may need more active management. It should be remembered that sternal fracture may occur during closed cardiac massage.

Vertebrae. The thoracic spine may be injured as one com­ponent of multiple injury or in isolation. It is more usual for the cervical spine to be injured and this must be excluded before any manipulations or movements take place. Damage to the thoracic spine is likely to be associated with injuries to other thoracic viscera. The assessment and treatment of spinal injury are discussed in Chapter 33. However, the thoracic spine injury is a reminder that, in patients where the chest injury predominates, a quick screening neurological examination confirming the integrity of the nerve supply to the lower limbs should be performed and documented.

Pleura. If the visceral pleura is breached (most commonly by a rib fracture) pneumothorax follows. Generation of posi­tive pressure in the airways by coughing, straining, groaning or positive pressure ventilation will result in tension pneumo­thorax. The pleural space may also fill with blood as a result of injury anywhere in its vicinity. Remember that an erect chest radiograph is the only sure way to confirm or exclude the diagnosis of pneumothorax and should be obtained if at all possible. Early management of tension pneumothorax is life saving. Good management of the pleural space pre-empts many later complications from clotted haemothorax, constriction of the lung and empyema. The diagnosis and management of a simple pneumothorax are discussed in detail later, but in the trauma situation it is imperative to consider tension pneumothorax and haemothorax.

Traumatic pneumothorax. Blunt trauma to the chest wall may result in a lung laceration from a rib fracture. All trau­matic pneumothoraces require drainage through an under­water seal drain because of the possibility that they may become a tension pneumothorax with mediastinal shift and circulatory collapse. There is decreased air entry on the affected side and the trachea may be pushed over to the opposite side. There is an increased percussion note and reduced breath sounds. If a tension pneumothorax is suspected on clinical grounds, treatment is necessary before radiographs can be taken. A wide-bore needle introduced into the affected hemithorax will release any air under tension and is life saving. A wide-bore intercostal rube is introduced laterally and directed to the apex of the pleural cavity. A second drain may be introduced basally to drain blood. Chest drain insertion. Insertion of a chest drain is indicated when there is air or fluid in the pleural cavity (Fig. 47.3). The site of insertion is in the triangle of safety which is defined as the anterior border of the latissimus dorsi, the posterior border of the pectoralis major and the superior border of the fifth rib. The area chosen is infiltrated with local anaesthetic and an incision is made in the skin and subcutaneous tissues, sufficient to admit a finger easily. The intercostal muscles are separated with artery forceps and the pleura is punctured. The intercostal drainage tube is inserted with the stylette withdrawn; so as not to damage the underlying lung tissue. A large-bore tube is used for the drainage of blood and fluids, whereas a smaller-bore tube may be used for the removal of air.

Traumatic haemothorax. Drainage is essential because re­expansion of the lacerated lung compresses the torn vessels and reduces further blood loss. Drainage will also allow the mediastinal structures to return to the midline and relieve compression of the contralateral lung. If left, a dense fibro­thorax will result, with the possibility of an added empyema. The procedure is similar to drainage for pneumothorax but a wide-bore rube (>28 Fr) is required and a basal drain is sometimes necessary. Continuing blood loss in excess of 200 ml/hour may require urgent thoracotomy within the first few hours.

Lung parenchyma

Lung contusion. The underlying lung is often injured in moderate-to-severe blunt thoracic trauma and the area of contusion may be extensive. This usually resolves but lacerations with persistent air leak may require exploration by thoracotomy. It is important to prevent infection of the underlying lung by early mobilisation (if the patient’s condition permits), prophylactic antibiotics, suction drainage and physiotherapy. The importance of a good-quality posteroanterior erect chest radiograph following any trauma to the lung cannot be overemphasised (Fig. 47.4).

Major airways

Injuries to major bronchi are infrequently seen as the patient rarely survives the insult leading to major airway disruption. There is usually a combination of surgical emphysema, haemoptysis and pneumothorax. Chest drainage in spite of the addition of suction fails to reinflate the lung and a persistent air leak may be present. Injury to the trachea requires considerable force and consequently less than a quarter of patients survive to reach hospital. The injury may be from direct trauma or the result of high intratracheal pressure against a closed glottis. There is hoarseness, dyspnoea and surgical emphysema. The exact pattern of signs will depend on the site of the injury and whether or not the pleura has been breached. The treatment is exploration and repair if possible. Resection of lung should be avoided as a surprising degree of recovery may occur.

Diaphragm

Diaphragmatic rupture. The mechanism for diaphragmatic rupture is high-speed blunt abdominal trauma with a closed glottis. The sudden rise in intra-abdominal pressure breaches the weakest part of the abdominal wall, namely the diaphragm. This occurs much more commonly on the left hemidiaphragm (the right is protected by the liver). Colon and stomach may herniate into the thorax, displacing the lung. Bowel sounds may be heard in the chest and the chest radiograph may reveal bowel gas in the lung fields. A contrast study will confirm the diagnosis. Occasionally, the injury is overlooked and the patient presents some time later with a diaphragmatic hernia. Cases presenting acutely should be explored by thoracotomy not only to repair the diaphragm and prevent respiratory embarrassment, but to exclude injury to an underlying abdominal viscus such as the spleen. Penetrating injuries below the level of the eighth rib may penetrate the diaphragm and injure an underlying abdominal viscus.

Oesophageal injury

The oesophagus is rarely injured in blunt trauma. The management of penetrating trauma to the oesophagus is discussed in Chapter 50.

Cardiac injury

Major injuries to the heart and great vessels from blunt trauma are frequently fatal and the patient rarely survives long enough to reach hospital. The injuries that are encountered in the accident and emergency department are the following.

Myocardial contusion. This must be suspected when the sternum is fractured, although the true incidence is not known. Myocardial damage from trauma will give an ECG pattern similar to myocardial infarction and enzyme changes may occur. In severe trauma there may be arrhythmias and signs of heart failure. Patients with ECG changes and enzyme rises even in the absence of any problems should be nursed in a high-dependence area with full monitoring and resuscitation equipment available. There is no specific treatment in the uncomplicated case but the risk of fatal arrhythmia diminishes after 48 hours or until the enzymes have returned to normal and any ECG changes have resolved. Occlusion of the coronary arteries progressing to discrete, localised myocardial infarction has been documented.

Chamber rupture and valve blow-out. This is well described and is thought to occur if the ventricle is

compressed just before systole at the point of maximal diastolic filling. Chamber rupture is likely to be fatal and those that do survive are likely to have an atrial rupture. Rupture of the mitral or tricuspid valve may not be immediately apparent, but a loud pansystolic murmur should arouse suspicion. Surgical treatment usually results in dramatic improvement in these patients.

Aorta

Aortic transection (Fig. 47.5). This is usually the result of a major deceleration injury (road traffic accident or a fall from a height) and the patient often has other injuries. However, only about 15 per cent of patients with aortic transection survive long enough to reach hospital. Of these, two-thirds would die of late rupture within 14 days and the remainder would be at risk from rupture of a developing chronic false aneurysm. The site is remarkably consistent (Fig. 47.5a), presumably the anatomy of the aorta determining the site of rupture. The vessel is relatively fixed at the site of the ligamentum arteriosum, just distal to the left subclavian artery, and from there down is tethered to the vertebral column by intercostal arteries and mediastinal pleura. The shear forces from a sudden impact disrupt the intima and media, resulting in retraction. If the intima is not breached, the patient may be stable but the development of a left-sided pleural effusion is an ominous sign. Transection of the aorta must be suspected in all high-speed deceleration incidents. The clinical signs may be masked by concurrent injury but include intrascapular pain, a murmur, hoarseness and radiofemoral delay of the arterial pulse. The condition may be completely asymptomatic. A good-quality posteroanterior chest radiograph showing widening of the mediastinum is very suspicious. Portable chest radiographs taken from the front (anteroposterior) always magnify the mediastinal shadow and cause uncertainty. Aortography is the diagnostic investigation and should be available at most hospitals. Computerised tomography (CT) maybe unhelpful and misleading because transections have little length and intimal lesions are missed on 1-cm slices (in marked contrast to aortic dissection where CT is a valuable investigation). Once the diagnosis is made the treatment is urgent exploration via a left thoracotomy through the fourth intercostal space. Control above and below the transection is vital and the aorta is repaired by direct suture or interposition graft (Fig.47.6). There is a risk of paraplegia (15 per cent) with this procedure and this should be specifically mentioned to the patient and the relatives before surgery. A heparin-bonded shunt (Gott) to maintain lower body perfusion may reduce the risk of paraplegia. Cardiopulmonary bypass is unsafe because systemic heparinisation is required in an already multiply injured patient.

  Management of blunt chest trauma

  Most chest injuries where the heart is not injured are managed conservatively with underwater seal drainage if necessary, and oxygen and physiotherapy to help the patient to expectorate while the underlying lung parenchyma heals. In about 10 per cent of cases a thoracotomy is required. The indications for thoracotomy following blunt thoracic trauma are the following:

  50—1000 ml of blood at the time of initial drainage is common and may need no further action, but greater volumes, especially if the blood is fresh, require intervention;

continued brisk bleeding (>100 mI/15 minutes) from the intercostal drains indicates a serious breach of the lung parenchyma and urgent exploration is required;

    continued bleeding of >200 ml/hour for 3 or more hours may require thoracotomy under controlled conditions;

  rupture of the bronchus, aorta, oesophagus or diaphragm;

  cardiac tamponade (if needle aspiration is unsuccessful).

All explorations following trauma should have double-lumen tube endotracheal intubation to facilitate surgery on the injured side and to protect the undamaged lung.

If transfer is undertaken, the patient must be stabilised before the journey. All lines must be secured and ECG monitoring available. Chest drains must not be clamped during transfer and a medically qualified person should accompany the patient.

Penetrating injury

In some aspects, penetrating thoracic injury is simpler to deal with than blunt trauma because the wound is visible and the structures at risk can be quickly assessed. A defect in the chest wall through to the pleura is a ‘sucking wound’. The underlying lung collapses and air moves in and out of the thorax with each breath. Emergency treatment involves sealing the wound and intercostal drainage. Definitive treatment may then follow. It is important to establish the path or track of bullet and stab wounds in the chest as there may be damage to the heart, great vessels, and the diaphragm and abdominal viscera in addition to the lung injury.

They are bringing him down,

He looks at me wanly.

The bandages are brown,

Brown with mud, red only —But how deep a red in the breast of the shirt,

Deepening red too, as each whistling breath

Is drawn with the suck of a slow filling squirt

While waxen cheeks waste to the pallor of death. From

Bullet wounds create a cavitating defect in the tissues that they pass through. The tissue damage may be very extensive with high-velocity missiles, and entry and exit wounds should be noted. Lung tissue is more compliant than the bone and muscles that comprise the limbs, and enthusiastic resec­tion along the track can be avoided in most cases. Tetanus prophylaxis and high-dose antibiotics (to cover anaerobic organisms) should be given. Bullets lodged in the lung do not require removal if they are not causing any problems.

Penetrating wound of the heart

This is usually the result of a stabbing or shooting incident, but can also be iatrogenic from central line placement, cardiac catheterisation and endomyocardial biopsy. Cardiac tamponade may occur rapidly even with small amounts of blood in the pericardium and the condition is recognised by low blood pressure, tachycardia, a high central venous pres­sure, pulsus paradoxus and faint heart sound (Fig. 47.7). Emergency treatment includes aspiration of the pericardium by advancing a wide-bore needle to the left of the xiphisternum towards the heart. This may hold the situation until surgical repair is performed. The heart is exposed via a median sternotomy with incision of the pericardium in the midline. For the more generally trained surgeon or those without the necessary equipment to saw the sternum, a left anterior thoracotomy may be preferred. The pericardial cavity is evacuated and the cardiac defect repaired using buttressed sutures. Bullets in cardiac chambers should be removed under cardiopulmonary bypass.

How to do a thoracotomy

All surgeons dealing with trauma victims should be able to perform a thoracotomy if required. The standard route into the thoracic cavity is through a posterolateral thoracotomy. The incision is used for access to:

the lung and major bronchi;

  the thoracic aorta (aneurysm resection, repair of transec­tion, coarctation repair and ligation of patent ductus arteriosus);

the oesophagus (resection and repair);

the posterior mediastinum (for mediastinal mass resection).

Following induction of anaesthesia, a preoperative rigid bronchoscopy is performed, especially if a resection for cancer is contemplated. A double-lumen tube is used to control the lungs separately, if desired. Ventilation may be maintained by ventilating one lung while the other is collapsed to facilitate surgery. However, remember that they were devised to protect the underlying lung from pus and blood, and to stay under the anaesthetist’s control. The patient is turned on to the unaffected side in the lateral position (Fig. 47.8). The lower leg is flexed at the hip and the knee with a pillow between the legs. Table supports are used to maintain the position and additional strapping is used at the hips for stability. The upper arm is supported by a bracket in a position of 900 flexion. The lower arm is flexed and positioned by the head. It is important for the surgeon to be completely satisfied with the position of the patient at this stage.

The incision is made from 1 to 2 cm inferolateral to the nipple in men and the inframammary fold in women. The incision extends along 1—2 cm below the tip of the scapula and extends posteriorly and superiorly between the medial border of the scapula and the spine. The incision is deepened through the subcutaneous tissues until the latissimus dorsi is met. This muscle is divided with coagulating diathermy taking care over haemostasis. The line of division is the same as for the skin. A plane of dissection is developed by hand under the scapula and serratus anterior. The ribs can be counted down from the highest palpable rib (which is usually the second) and the sixth rib periosteum is scored with the diathermy near its upper border. A periosteal elevator is used to lift the periosteum off the superior border of the rib. This reveals the pleura which may be entered by blunt dissection. A rib spreader is inserted between the ribs and opened gently to prevent fracture. Exposure may be facilitated by dividing the rib at the costal angle or by dividing the costotransverse ligament. Routine resection of a rib is an uncommon practice. The anaesthetist is now able to deflate the affected lung to allow a better view of the intrathoracic structures. In an emergency thoracotomy for penetrating wounds of the heart, a more anterior approach is used and no specialised supporting equipment is required (Fig. 47.9).

Large-calibre (28—32 Fr) intercostal drains are usually inserted at the end of the procedure. it is common practice to site them through the seventh or eighth intercostal space anterior to the midaxillary line so that the patient does not lie on them. For chronic management, such as closed drainage of empyema, the drains are tunnelled to come out more anteriorly for easier management. Traditionally, the more anteriorly sited drain goes to the apex and the posteriorly placed drain goes to the lung base. A rib approximator is used to realign the ribs and the stripped periosteum and intercostal muscle is sutured to the intercostal muscle below the stripped rib using a continuous absorbable suture. A nonabsorbable suture may be used to maintain the closure if healing is likely to be compromised. The fascia and muscle layer are closed in layers using an absorbable suture (Fig. 47.10). Skin closure is a matter of personal preference.

Analgesia is an important aspect of postoperative care and the process may be started intraoperatively by infiltrating the intercostal nerves in the region of the incision with a long­acting local anaesthetic. Various strategies have been developed to deliver analgesics postoperatively to facilitate a normal breathing pattern.

Postoperative care

Lung function is rarely assessed before urgent thoracotomy for trauma but it is a vital part of the patient’s preoperative work-up before elective thoracotomy. A description of lung function testing is given in Appendix 2 at the end of this chapter. These patients have limited respiratory reserve following lung resection, so infection and fluid overload are to be avoided. Chest drains placed at the time of surgery drain blood collections and cope with air leaks if present. Once the air leaks have settled and any remaining lung is re­expanded, the drains are removed. Mobilisation, breathing exercises and regular physiotherapy are begun as soon as the patient’s condition permits.

Postoperative pain

It is important to deal with post-thoracotomy pain effectively so that a normal breathing pattern and gas exchange are achieved in the early postoperative period. Patient-controlled analgesia is an important development but still requires regular nursing and anaesthetic supervision. Internally placed catheters delivering local anaesthetic into the wound and beneath the pleura may also be effective. Long-term post­thoracotomy pain can be avoided by careful attention to detail during the operation. Sources of avoidable chronic pain include rib fracture and entrapment of intercostal nerves during wound closure. Trauma accounts for most of the emergency workload of the thoracic surgeon but other situations are encountered that demand prompt investigation and treatment.