Chest trauma
Pneumothorax
Closed
Rupture of the pleura forms a valve through which air is forced on coughing into the pleural space which cannot escape.
Needle decompression if tension then
Chest drain.
Open
If >0.75 diameter of trachea air preferentially enters through chest wall defect.
3 sided dressing or
Seal and see if exacerbated.
Chest drain if tension.
IPPV will stop the wound sucking.
Flail chest
Defined as at least two fractures per rib, in at least two adjacent ribs (producing a floating segment).
This leaves a section of chest wall that moves paradoxically and does not contribute to lung expansion.
The force required to cause this injury also leads to pulmonary contusion, impairing gas exchange further in these patients.
Clinical features:
Respiratory distress, hypoxia, and the paradoxical movement of the flail segment are diagnostic.
CT demonstrates the bony injuries and the extent of the pulmonary contusions.
Treatment
Large segments require tracheal intubation and application of positive-pressure ventilation.
The mainstays of treatment are high-flow humidified oxygen and good analgesia with intravenous patient-controlled analgesia or a thoracic epidural.
Many patients require a chest drain for the associated haemo-thorax or pneumothorax.
Massive haemothorax
>1500mls in hemithorax
Venous bleeding will occur at pressures exceeding 50mmHg. Would therefore require at least this intrathoracic pressure to tamponade bleeding.
The hemithorax can accommodate the whole of the circulating volume.
In massive haemothorax, the primary problem is breathing (B) and then circulation (C). Therefore need to re-expand lung and optimise oxygenation rather than circulation
Chest drain clamping
Traditionally taught to clamp chest drains when transferring patients to prevent back flow of water trap into chest.
Additionally, taught to clamp chest drains prior to removal so that a check CXR could localise any residual small leaks.
Current BTS guidelines
A bubbling chest tube should never be clamped.
A chest tube which is not bubbling should not usually be clamped.
If a chest tube for pneumothorax is clamped, this should be under the supervision of a respiratory physician or thoracic surgeon, the patient should be managed in a specialist ward with experienced nursing staff, and the patient should not leave the ward environment.
If a patient with a clamped drain becomes breathless or develops subcutaneous emphysema, the drain must be immediately unclamped and medical advice sought.
High risk of clamp being forgotten if utilised for transfer.
Risk of tension pneumothorax developing if ventilated.
Keep duration of water trap above patient to a minimum.
Any siphoning of fluid can be drained away later.
Cardiac tamponade
50 ml of blood in the pericardial sac compresses the heart and great vessels leading to reduced venous filling and reduced cardiac output.
Diastolic collapse of the right atrium and ventricle on echocardiography has been shown, in animal and human studies, to be a sensitive and specific indicator of raised pericardial pressure and leads to the haemodynamic compromise seen in the patient.
Clinical features:
‘Beck’s’ triad of muffled heart sounds, hypotension and raised central venous pressure is described, but in the resuscitation room with a hypovolaemic patient these signs are unreliable.
Hypotension in patients with significant chest trauma should warrant further investigation with an echocardiogram.
Investigations and treatment:
Echocardiogram shows the effusion and can be used to guide pericardiocentesis.
Re-accumulation of fluid should prompt referral to a cardiothoracic surgeon, who will consider forming a pericardial window.
Thoracotomy is the treatment of choice for cardiac arrest in the presence of penetrating cardiac trauma.
Aortic injury
Rapid deceleration causing vertical shear force or hyperextension of the neck leads to movement of the heart against the fixed thoracic aorta.
The range of injuries include:
- Minor haematoma or small intimal flap (benign course)
- Pseudoaneurysms (more insidious)
- Complete rupture (75–90% mortality); most of these patients die at the scene of the incident but 8–13% die in the resuscitation room.
Supraclavicular or neck haematomas
5% of patients have different blood pressures in each arm
Carotid or subclavian bruits
Reduced peripheral pulses
Neurological signs if dissection has affected the cerebral vessels
Haemorrhagic shock from aortic injuries alone is rare and other sources of blood loss should be sought.
Investigations:
CXR
Widened mediastinum, blurring of aortic knob, enlargement of paratracheal stripe, pleural cap and left pleural effusions.
A mediastinal abnormality is 90–95% sensitive but only 5–10% specific, with a positive predictive value of 10–15%.
Spiral CT has excellent predictive value but an aortogram is the gold standard.
Transoesophageal echocardiography is poor for detecting abnormalities in the descending aorta.
Treatment:
Without operative repair, 30% of survivors die within 24 hours and 50% within 1 week.
Preoperatively the aim should be to reduce shear stress on the intima by avoiding hypertension – systolic <120
Pulmonary contusion
Blunt injury to lung parenchyma → blood and oedema fluid filling the alveolar space → loss of normal lung structure and function.
This results in impaired gas exchange, increased pulmonary vascular resistance and reduced lung compliance.
50% of patients with significant pulmonary contusions develop acute respiratory distress syndrome.
Clinical features
Respiratory distress
Hypoxia
Pain from overlying rib fractures.
Investigations:
CXRs often underestimate the size of the injury as the extent is not apparent until 24–48 hours later.
CT is sensitive for the identification of pulmonary contusions, though they may not all be clinically relevant.
Treatment
Supportive with supplemental oxygen and analgesia for the chest wall injury.
If hypoxaemia is developing, there is good evidence to use NIV; if this fails, intubation and IPPV will be required.
Historically, patients with these injuries have had fluid restricted in an attempt to reduce the leak into the alveolar space. Now fluid treatment is aimed at keeping the patient euvolaemic.