Diffuse crushing of the chest (e.g. by a trench col-lapse) will cause transient venous engorgement and petechial haemorrhages over the upper chest and face. There may also be subconjunctival haemor-rhages. Maximal barotrauma occurs in the presence of airway obstruction.
The prognosis is good if the patient is rescued promptly. If crushing is not quickly relieved, hypoxia is severe with lung contusion and alveolar collapse.
Some patients may initially appear deceptively well.
Pulmonary oedema gradually develops and gas exchange is impaired – a form of adult respiratory distress syndrome.
Tx
Oxygen is given in high concentration and the patient admitted for intensive care. Steroids are of no benefit. If there is associated bronchospasm in the early stages nebulised salbutamol will be useful.Injury to the heart
Damage may be inflicted by a gunshot, a stabbing or blunt decelerating forces. Contrary to popular belief, these injuries may not be instantly fatal and may remain undetected in the patient who is slowly dying from ‘multiple injuries’. The paucity of specific signs may frustrate early and precise diagnosis.
Stab wounds anywhere between the midclavicular lines, from the lower third of the neck to the epigas-trium, have the potential to involve mediastinal structures. Beware of small entry wounds, especially in the back.
Laceration of the thick left ventricular wall may not be as catastrophic as damage to less muscular struc-tures. Pump failure may occur because of valve damage, hypovolaemia or tamponade.
Haemopericardium may produce a life-threatening cardiac tamponade at any time, with high venous pressure, muffled heart sounds and falling BP (Beck’s triad). There may be distended neck veins. Classically, the systolic BP is lower during inspiration (pulsus paradoxus). Tamponade may also cause a paradoxi-cal rise in venous pressure during inspiration (Kuss-maul’s sign). Profound shock and IPPV may invalidate these signs.
Blunt injuries are more common. Most minor con-tusions probably resolve without detection. At the other extreme, fatal dysrhythmias may not be associ-ated with structural damage post mortem. A few patients, in between, present with symptoms and signs typical of myocardial ischaemia, including ECG changes.
Box 6.3 Needle aspiration of the pericardium (pericardiocentesis) The subxiphisternal approach is recommended (→ Figure 6.3) although parasternal and apical approaches have also been described.
Ideally, the procedure should be performed under ultrasonic (e.g. echocardiographic) guidance.
• Consider the need for sedation or general anaesthesia
• Position the patient with a 30° head-up tilt
• Monitor the patient’s SaO2 and ECG
• Clean and anaesthetise the subxiphoid area with 2% lidocaine, if time allows
• Make a 5-mm incision through the skin, just below a point midway between the tip of the xiphoid process and the left costal margin (→ Figure 6.3)
• Attach a 20-mL syringe to a three-way tap and a long 16 G over-the-needle catheter (or use a central venous Seldinger-type set)
• Enter the skin through the 5-mm incision (→ Figure 6.3), just below and to the left of the xiphochondral junction, at a 30–45° angle to the skin
• Carefully advance the needle, aiming for the tip of the left scapula. Contact with the pericardium will occur at about 6–8 cm.
Watch the ECG – ventricular ectopics suggest myocardial irritation whereas QRS or ST changes may indicate actual entry into the ventricular muscle. If these ECG changes are seen, the needle should be withdrawn and repositioned
• Once fluid is reached (i.e. the needle has entered the pericardial sac), remove the needle and aspirate blood or straw-coloured fluid down the cannula. Removal of as little as 15 mL blood may result in a dramatic clinical improvement. Large amounts of blood suggest that the ventricle has been entered
• After aspiration remove the syringe, leaving the cannula in situ with a closed three-way tap attached
• Secure the cannula to the skin. If the symptoms recur, aspiration can then be repeated
• Obtain an ECG and CXR and arrange definitive care
Figure 6.3 The site of entry for percutaneous pericardiocentesis.
Surface marking of pericardium Position of skin incision Direction of advancement of needle
Figure 6.4 ECG of a 16-year-old driver involved in a road traffic accident. The CT scan showed a mediastinal haematoma and a small aortic tear.
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Direct damage to coronary arteries is rare but septal rupture, damage to papillary muscle and chordae tendineae, and tears of the atria or right ventricle do occur. Rupture of the sturdy left ventricle is rare.
It is useful to distinguish between cardiac contu-sion and concuscontu-sion. The latter is defined as the occurrence of a dysrhythmia without ECG or bio-chemical evidence of muscle necrosis. Most of these dysrhythmias are transient, but sudden death has been reported after relatively minor blows to the sternum.
Tx
• Give a high concentration of oxygen
• Obtain IV access
• Consider aspiration of the pericardium (→ Box 6.3 and Figure 6.3)
• In dire cases of penetrating injury consider emer-gency thoracotomy (→ below)
• Seek cardiothoracic advice
• Perform routine blood tests and cross-match blood
• Obtain an ECG (→ Figure 6.4).
In less urgent cases the problem is always the initial paucity of physical signs. Admit the patient to a high-dependency area and monitor carefully.
Emergency thoracotomy may be life saving after stab wounds, but is rarely helpful after gunshot wounds, and never after blunt trauma. The criteria for this operation are defined in Box 6.4 and the
technique is described in Box 6.5. Some possible intrathoracic procedures are listed in Box 6.6.
Injuries to the great vessels
Immediate survival depends on the formation of an acute false aneurysm. Stab wounds may inflict injury at any site, but the more common deceleration injury usually produces a lesion at the level of the aortic isthmus. The intima and media rupture, but the adventitia and adjacent mediastinal structures may provide a sufficiently strong sheath to contain the arterial pressure for a few hours, or indeed many years.
Box 6.6 Procedures after an emergency thoracotomy
• Pericardotomy to relieve tamponade
• Open cardiac massage
• Internal defibrillation (up to 10 J energy)
• Cardiac haemostasis
(An 18 G French Foley catheter may be inserted through a wound in the heart and the balloon inflated inside. Gentle traction on the distal catheter then achieves temporary haemostasis. If the catheter is connected to an IV infusion, fluids and drugs can be given by the intracardiac route.)
• Clamping of major lacerations of the lung
• Cross-clamping of the descending aorta to optimise cerebral circulation and reduce major abdominal blood loss
The expanding haematoma may occlude the origin of one or more of the vessels arising from the aortic arch. Blood pressure and pulse may differ in the two arms. Pain radiating to the back is more common than precordial pain.
These injuries can be overlooked, even at thora-cotomy. The history is important. Most are associated with injuries elsewhere after high-speed road traffic accidents or falls.
Investigations: A plain CXR may show haemorrhage into the mediastinum and other indirect signs of blood vessel injury:
• Widened mediastinum (mediastinum/chest width
>25%; may be obscured by lung injury and not present in 10% of cases)
• Trachea (or nasogastric tube) displaced to the right
• Left main-stem bronchus depressed
• Aortic knuckle absent
• Left apical pleural cap (the left paraspinal line is displaced laterally and extends up and over the apex of the left lung)
• Broad right paratracheal stripe
• Separation of calcium deposits in the aortic wall
• Other signs of severe chest trauma (rib fractures, pulmonary contusion, haemopneumothorax, rup-tured diaphragm).
On an AP (portable) film the mediastinum always appears to be widened. Other benign causes of a widened mediastinum are as follows:
Box 6.4 Criteria for thoracotomy in the emergency department
• History of penetrating trauma
• Signs of life in the field
• Short transport time to hospital (up to 15 min)
• Agonal vital signs or electromechanical dissociation (EMD; for <5 min)
• Cardiopulmonary resuscitation in progress if pulseless (for <5 min)
Patients with asystole or ventricular fibrillation will not benefit from thoracotomy
Box 6.5 Technique of thoracotomy in the emergency department
1 Intubate and ventilate the patient
2 Start the incision in the fourth left intercostal space, 2 cm to the left of the sternum (the internal mammary artery runs within 2 cm of the sternal border)
3 Extend the incision along the upper border of the rib as far as the anterior axillary or even the midaxillary line (the intercostal vessels and nerve run behind lower rib border) 4 Incise the pleura and sweep the area with a
gloved finger
5 Insert a rib spreader and crank it open to allow visualisation of the thoracic cavity
6 Open the pericardium transversely parallel to and above the phrenic nerve, without damaging surface vessels on the heart
• Examine the abdomen, noting areas of tenderness, guarding and lacerations, clothing imprints and grazes. Listen for bowel sounds.
• Consider early analgesia.
Fluid loss into the abdomen is usually underestimated.
Intravenous analgesia is unlikely to mask significant signs in the abdomen. On the contrary, it usually makes the following procedures much easier to perform.
• Log-roll the patient and examine the back and perineum.
• Consider performing a rectal examination (noting injuries, sphincter tone, presence of blood, the wall and contents, and prostate gland).
• Obtain details of the incident, past medical history, medication and time of last food and drink.
• Insert a urinary catheter if there is no urethral injury (→ p. 84).
• Consider passing a large-bore nasogastric tube if there is no basal skull fracture (→ p. 43).
Closed abdominal injuries may easily be overlooked especially when they are less painful than injuries elsewhere and not immediately associated with signs of hypovolaemic shock.
• Give antibiotics if gut perforation suspected.
• Obtain surgical advice early on. There are three possible courses of action:
1 Obvious injury → immediate operation 2 Apparently stable → admission and observation 3 Equivocal signs or impaired level of consciousness
→ repeated / further assessment in ED.
Methods of assessment → below.
Methods of assessment of intra-abdominal damage
Diagnostic peritoneal lavage: DPL is decreasingly used where sophisticated imaging is available. It
• Supine as opposed to upright film
• Rotated positioning of the patient
• X-ray beam directed cranially (lordotic view)
• Short distance between the film and the X-ray source
• Poor inspiratory effort.
High-resolution CT (HRCT) provides much more information, especially with contrast angiography, and is the definitive investigation once the diag-nosis is suspected. Transoesophageal ultrasonogra-phy and arch aortograultrasonogra-phy may also be useful in some circumstances.
ECGs in thoracic trauma are usually unremarkable although they may sometimes show dramatic changes (→ Figure 6.4).
Tx
The role of the ED is to:• have a high index of suspicion
• begin fluid replacement (but beware of overload)
• refer urgently for specialist care.