Complications Flail chest

Crush injuries of the chest, in which the whole ster- num is loosened by fractured ribs on either side or several ribs are fractured in two places, result in the condition of flail chest (Figure 10.1). On inspiration,

The chest and lungs

Learning objectives

✓ To have a knowledge of the types of chest injury and their management.

✓ To have a knowledge of lung cancer and its management; this is particularly important as it is the most common cause of cancer death in the UK.

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The chest and lungs

the flail part of the chest wall becomes indrawn by the negative intrathoracic pressure, as it is no longer in structural continuity with the bony thoracic cage.

Similarly, in expiration the flail part of the chest is pushed out while the rest of the bony cage becomes contracted. This is termed paradoxical movement.

The patient becomes grossly hypoxic due to failure of adequate expansion of the affected side and also because of shunting of deoxygenated air from the lung on the side of the fracture into the opposite side. The pendulum movements of the mediastinum also produce cardiovascular embarrassment so that the patient can become rapidly and progressively shocked.

Pneumothorax

If a bony spicule penetrates the lung, air escapes into the pleural cavity and will result in a pneumothorax.

A tension pneumothorax (Figure 10.2) results if the pleural tear is valvular, allowing air to be sucked into the pleural cavity at each inspiration but preventing air returning to the bronchi on expiration. A tension pneumothorax produces rapidly increasing dysp- noea; the trachea and the apex beat are displaced away from the side of the pneumothorax; and, on the left side, cardiac dullness may be absent. The chest on

the affected side gives a tympanitic percussion note with bulging of the intercostal spaces.

Subcutaneous emphysema (surgical emphysema)

When a fractured rib tears the overlying soft tissue and allows air from the pneumothorax to enter the subcutaneous tissues, subcutaneous emphysema will result. The skin over the trunk, neck and sometimes face gives a peculiar crackling feel to the examining fingers (crepitation) and, in severe cases, the face and neck may become grossly swollen. The alternative name, surgical emphysema, is misleading as it is rare- ly caused by surgeons. Although distressing, subcu- taneous emphysema almost never causes any harm.

Sucking wound of the chest

A pneumothorax will also result from a penetrating wound of the chest wall produced, for example, by a knife stab or gunshot wound. The lips of the wound may also have a valvular effect so that air is sucked into the cavity at each inspiration but cannot escape on expiration, thus resulting in another variety of ten- sion pneumothorax, which has been vividly named a sucking wound of the chest.

Flail segment sucked in Air shunted

from one lung to the other on inspiration

Air movement within lungs Inspiration

Expiration

Figure 10.1 Flail chest. On inspiration, the detached segment of the chest wall is sucked inwards, producing paradoxical movement, and inhaled air shunts back and forth between lungs.

The chest and lungs

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Apex beat displaced medially Hyper-resonant percussion note over pneumothorax;

no breath sounds Trachea

deviated away

Air sucked into pleural cavity on inspiration

Figure 10.2 Tension pneumothorax produced by a valvular tear in the lung. Air is sucked into the pleural cavity on inspiration and cannot escape on expiration.

Haemothorax

A haemothorax often accompanies a chest injury and may be associated with a pneumothorax (hae- mopneumothorax). The bleeding is usually from an intercostal artery in the lacerated chest wall or from underlying contused lung, but on occasions may re- sult from injury to the heart or a great vessel.

Traumatic asphyxia

With severe crush injuries of the chest, the sudden sharp rise in venous pressure produces extensive bruising and petechial haemorrhages over the head, neck and trunk. There are often subconjunctival haemorrhages and nasal bleeding. Any area of the skin that has been subjected to compression at the time of injury (e.g. from a tight collar, braces or spec- tacles) is protected and these areas remain mapped out on the body as strips of normal skin, giving a char- acteristic appearance to the patient.

Other visceral injury

It is important to remember that penetrating wounds of the chest may also injure the underlying dia- phragm and thence the abdominal viscera. Thus, it is not uncommon for a knife or bullet wound of the left chest to penetrate the spleen or, on the right side,

to damage the liver – incorrect placement of a chest drain may do the same.

Treatment

The priorities in the management of chest injuries are as follows.

• Airway control. This may involve the passage of an endotracheal tube, particularly where a head injury co-exists with chest trauma. Aspiration of vomit is prevented by passing a nasogastric tube to empty the stomach.

• Breathing. Ensure the patient is breathing and maintaining adequate oxygenation. A saturation monitor should be employed and intubation and ventilation considered when the oxygen saturation is below 80% or Pco₂ above 7.3 kPa (55 mmHg).

• Sucking wounds. These should be closed. In an emergency, a dressing pad should be applied over the hole and secured in place.

• Lung expansion. This should be achieved by insertion of an intercostal drain with underwater drainage.

• Stop bleeding. Small haemothoraces, which do not interfere with expansion of the lung, require only observation, but a large haemothorax should be drained, again with underwater seal as for a pneumothorax (Figure 10.3). Continued bleeding is an indication for an exploratory thoracotomy.

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The chest and lungs

Simple rib fracture

• Pain relief may be achieved by analgesics, par- ticularly non-steroidal anti-inflammatory drugs (NSAIDs), by the injection of local anaesthetic in the paravertebral region to block the intercostal nerves or by a thoracic epidural block, which can be maintained by means of an infusion into an in- dwelling plastic catheter.

• Vigorous physiotherapy is administered to en- courage deep breathing.

• Strapping of the chest wall inhibits thoracic move- ment and encourages pulmonary collapse; it should be avoided.

Flail chest

• Support the flail segment in an emergency by means of a firm pad held by strapping. This stops the paradoxical movement and air shunting.

• Good pain control, with paravertebral or even epi- dural blocks, and avoidance of fluid overload and antibiotics are keys to successful management and avoiding ventilation.

• Rib fixation, for which there are now a range of specialist devices, has an increasing role, particu- larly where there is displacement.

• Endotracheal intubation and positive pressure ventilation on admission to hospital will stop the paradoxical movement, as the chest wall now moves as a single functional unit. The treatment is continued for about 10 days until fixation of the chest wall occurs.

Pneumothorax

A traumatic pneumothorax requires insertion of a chest drain, in contrast to a spontaneous pneumo- thorax, which may resolve without intervention.

Tension pneumothorax

Urgent emergency treatment is required by inserting an intercostal tube drain.

A chest drain is inserted into the pleural cav- ity via an intercostal space, the fifth space being preferred. After cutting through the overlying skin in the midaxillary line, the remaining insertion is done by blunt dissection into the pleural cavity, at which point the drain is inserted and connected to an underwater seal. When the pressure in the pleu- ral space is increased on expiration, the air escapes through the water but air cannot enter the chest at inspiration as this is prevented by the water seal.

Underwater seal below level of chest

Underwater seal prevents air being sucked in

Figure 10.3 Underwater seal chest drain in the treatment of a pneumothorax. Air escapes from the pleural cavity on expiration but cannot be sucked back through the water seal on inspiration (as shown here).

The water bottle is placed below the level of the chest to ensure fluid does not reflux into the thoracic cavity.

The chest and lungs

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This essential safety valve has been a most important step in the development of safe thoracic surgery (see Figure 10.3).

Re-expansion of the lung is assisted by attaching the drain to low-pressure suction.

A bronchopleural fistula, due to rupture of a bron- chus into the pleural space, should be suspected if the pneumothorax persists, or if the lung remains col- lapsed despite suction on the drain bottle, and there is a large ‘air leak’. It may require a thoracotomy to repair.

Penetrating wounds of the chest

Immediate application of a dressing is required in order to prevent suction of air into the pleural space.

Minor cases require only wound toilet with an un- derwater intercostal drain to allow escape of any ac- cumulated blood or air in the pleural space. Wounds demand exploration if there is continuing blood loss or evidence of diaphragmatic damage. All significant penetrating wounds should be investigated with CT scan.

Cardiac tamponade

This is suspected in any penetrating injury anteriorly between the midaxillary lines. It is characterized by a rise in venous pressure and a fall in arterial pressure.

The heart sounds are distant and the cardiac shadow enlarged on chest X-ray. Urgent echocardiography is the definitive investigation, either identifying the problem or, more commonly, excluding tamponade as a cause of shock and diverting attention elsewhere.

If present, treatment is emergency surgical explora- tion; the pericardium is opened, the blood is evacu- ated and the cardiac laceration sutured.