A 35 year old man presented at the emergency department with a penetrating chest injury. He was involved in an alleged assault that resulted in a screwdriver being thrust into his sternum. He had no other associated injuries. Initial assessment showed that he was haemodynamically stable with no signs of respiratory distress. The screwdriver was left in place. Chest radiographs taken in the emergency department confirmed the penetrating chest injury (fig 1).
Fig 1 Chest radiograph taken in the emergency department
(1) What can you see on this chest radiograph (fig1)? Is this an adequate view?
(2) What are the potential worries with this patient?
(3) Should the screwdriver be removed straight away?
Answers
(1) This anteroposterior chest radiograph shows a foreign body within the thoracic cavity. There is a normal cardiac shadow but no signs of pneumothorax or pleural effusion. Although this rules out various important sequelae of chest injury, it does not identify the anatomical path of the foreign body. A lateral chest radiograph taken at the same time is shown in fig 2.
Fig 2 Lateral chest radiograph
The radiograph shows the foreign body has penetrated the body of the sternum and is butting against the cardiac shadow. The pericardium and, of more concern, the right ventricle are potentially injured.
(2) Several potential complications may arise as a result of this injury:
Pleural injury—Pneumothorax (simple or tension), haemothorax, haemopneumothorax, and pulmonary contusion.
Cardiac injury—Cardiac arrhythmias, cardiac tamponade, and intracardiac injury.
Other Injuries—Diaphragmatic injury and injury to the great vessels.
(3) Removing the screwdriver at this stage could prove fatal, and measures should be taken to secure it in place to prevent further injury or unintentional displacement.
Discussion
Chest injuries are frightening to junior doctors and consultants alike and need to be carefully managed to avoid potentially life threatening complications. Chest trauma is the commonest cause of death in young adults, with 30% of all trauma cases involving considerable trauma to the chest. Chest injury accounts for 25% of all deaths related to trauma and when associated with other severe injuries has a mortality of 70-90%. Prevalence of routinely carrying knives or other weapons in children aged 16 in Great Britain is estimated to be 24%, and 19% admit to having attacked someone with the intent to cause harm. Knowing how to manage chest injuries is sadly, therefore, an urgent priority.
Chest trauma can be broadly divided into blunt and penetrating, with penetrating trauma accounting for more than a quarter of cases. Blunt chest trauma is commonly caused by steering wheels and in pedestrians hit by road vehicles, causing acceleration or deceleration and compression injuries.
Penetrating trauma can be further categorised as low, medium, and high velocity. Low velocity injuries include stabbing, such as in this case. Medium velocity injuries are caused by handguns and air powered pellet guns. High velocity injuries result from rifles and military weapons. The clinical consequences depend on the mechanism and location of injury, associated injuries, and any underlying illnesses.
Initial management
Initial management, as always in trauma, begins with stabilising the patient haemodynamically, keeping in mind that there may be other important injuries, such as cervical spine trauma. The ABCDE approach taught in the internationally recognised advanced trauma life support course should be applied in these situations. Only once the patient is stable can investigations be conducted safely to determine management.
The next step is to accurately image the site of injury to determine which structures are involved. Radiography of the chest is a mandatory first investigation at this stage, with at least two views for patients with chest trauma. Early referral to the cardiothoracic team is essential to prevent any delay in treatment, which may have a profound effect on the patient's outcome.
Complications
Specific complications must be borne in mind when treating patients with blunt or penetrating trauma to the chest, namely the "lethal six" and the "hidden six," collectively known as the deadly dozen (box).
The deadly dozen The lethal six
Airway obstruction
Tension pneumothorax
Cardiac tamponade
Massive haemothorax
Open pneumothorax
Flail chest
The hidden six
Thoracic aortic disruption
Tracheobronchial disruption
Oesophageal disruption
Myocardial contusion
Pulmonary contusion
Diaphragmatic tear
The lethal six injuries are immediately life threatening and need to be treated during the primary survey to avoid irreversible deterioration. Early recognition is paramount and treatment may include an emergency thoracotomy in an operating theatre or even in the emergency department.
An important indication for emergency thoracotomy is an immediate evacuation of 1500 ml or more of blood from the chest drain or an output of more than 200 ml/h for at least two hours. Research in a large US trauma centre shows that survival rates are higher for patients with penetrating trauma compared with patients with blunt trauma (14% v 2%) when performing thoracotomy in the emergency department.
The hidden six injuries are normally detected during the secondary survey, may require further investigation, and must be treated urgently, although they carry a lower mortality than the lethal six.
Further investigation
Initial investigations for all patients with trauma to the chest include blood tests, electrocardiography, and imaging. Laboratory blood tests that give haemoglobin and haematocrit values and arterial blood gas analysis are of some use but may be delayed until the patients are stable. Biochemistry results are useful to assess any underlying medical conditions that the patient may also have.
A variety of imaging methods are available when dealing with these patients. Radiography of the chest is an important tool to initiate and guide further investigations, with at least two views necessary for patients with trauma to the chest. Computed tomography is an excellent primary diagnostic tool and is commonly used in many types of trauma. The crucial message is that this can only be performed once the patient is stable—this means that the airway is secured, and breathing and circulation are controlled. The term "doughnut of death" is not a misnomer.
Echocardiography is an excellent tool to image the heart and the ascending and descending aorta. Studies have shown that transoesophageal echocardiography, although more invasive, gives an accurate diagnosis in a short time and is inexpensive, compared with the lower diagnostic yield using transthoracic echocardiography. Most cardiothoracic anaesthetists have the expertise to carry out this investigation.
Other investigations used include contrast studies, such as an aortogram, especially in suspected aortic injuries, although the use of multislice computed tomography with three dimensional reconstruction has reduced the use of this invasive tool. Multislice computed tomography has limitations in these injuries, such as pulsation artefact and suboptimal injection of contrast, and in these cases contrast studies are necessary. Magnetic resonance imaging gives excellent images with good detail of soft tissue but is limited in the acute setting because of the difficulty in monitoring and limited access to the patient.
A definitive management plan
Having made a diagnosis and further defined the pattern of injury in the patient, definitive management can be planned. Each organ in the chest should be considered carefully when treating the patient. Management may involve emergency surgery in a cardiothoracic unit—this may be on site or may require transfer to another hospital if feasible.
In this case, having already taken chest radiographs, this patient had transthoracic echocardiography because there was concern about intracardiac injury. This showed possible injury to the right ventricular outflow tract. This may be in the form of myocardial contusion (the hidden six) or an injury that may lead to the subsequent development of cardiac tomponade (the lethal six).
Based on this, the patient was taken to the operating theatre, anaesthetised, and transoesophageal echocardiography was carried out, with a view to carrying out surgery. This showed better anatomical detail and ruled out an intracardiac injury. With this knowledge the screwdriver could be safely removed and the wound cleaned and sutured. The patient made an uneventful recovery and was discharged the next day.
Chetan S Modi, clinical fellow in trauma, Leicester Royal Infirmary
Email: chet_modi@hotmail.com A Alani, senior house officer in trauma, New Cross Hospital, Wolverhampton Gwyn S Williams, cardiothoracic senior house officer Patrick Yiu, consultant cardiothoracic surgeon
Student BMJ 2007;15:293-336 September ISSN 0966-6494
Competing interests: None declared.
Adnet F, Lapandry C, Lapostelle F. Thoracic trauma. La Revue du Practicien 2003;53:967-74.
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