Introduction
Even for those of us who deal with blunt trauma on a daily basis, a report from the field that a high speed collision has occurred with a victim who has sustained a "steering wheel injury" raises our overall level of concern. The management of thoracic trauma, with its attendant potential for life threatening injury, if approached from the standpoint of providing an airway, assuring adequate ventilation and controlling hemodynamics falls within the realm of all anesthesiologists.[1]

Airway
When evaluating the airway in a patient with blunt thoracic trauma, one must look for associated injuries to the head, face, cervical spine and injuries to the upper and lower airway. Low level of consciousness, airway obstruction or disruption, and inability to oxygenate the patient by mask indicate the need for tracheal intubation. Blood in the airway, recent food intake, and trauma itself with decreased gastric emptying, mandate an approach which minimizes the potential for aspiration of gastric contents. Awake techniques with direct visualization, i.e. fiberoptic or direct laryngoscopy, or rapid sequence induction with cervical immobilization may be appropriate depending on the clinical scenario and level of skill of the anesthesiologist.

Breathing
A careful physical assessment of the ventilatory function of the thoracic trauma victim should include inspection for respiratory rate, presence of paradoxical motion of the chest wall, or obvious chest wounds. Palpation of the chest should seek pain, crepitus or subcutaneous emphysema as clues to underlying pathology. The auscultation of the lung fields may detect a pneumothorax or hemothorax before a chest xray may be performed, as well as assessing the adequacy of air entry. Percussion although theoretically of use in differentiating between pneumo and hemothorax may be practically difficult in the atmosphere surrounding a typical resuscitation bay.

Circulation
Since hypotension in thoracic trauma is usually associated with hypovolemia it should be aggressively treated initially with volume expansion with crystalloids while other possible etiologies, i.e. pneumothorax, cardiac tamponade and blunt cardiac injury are assessed. The presence of arrhythmia should raise suspicion of blunt cardiac injury.[2, 3]. Hypertension may dramatically worsen bleeding in thoracic trauma and may dislodge thrombus which is containing a major vessel disruption and therefore should be treated. Two large bore peripheral IV's are a minimum for resuscitation and a central access is usually needed both for therapy and monitoring.

Laboratory values
The usual laboratory tests, complete blood count, electrolytes, glucose, BUN, creatinine, urinalysis, ECG, and blood type and crossmatch should be obtained.

CXR
The chest xray is of paramount importance in thoracic trauma and only attention to life threatening problems should delay obtaining it.[4]. Systematic review of the radiograph may reveal both suspected and unsuspected pathology. The bony thorax including ribs, clavicles, scapulae, and vertebrae, should be examined for fracture. Soft tissues should be evaluated for emphysema or opacification. The lung fields may likewise demonstrate pneumothorax, hemothorax, consolidation suggestive of lung contusion. Radiographic abnormalities of the mediastinum, particularly pneumomediastinum, widening of the mediastinum, or shift of the mediastinum suggest airway rupture, aortic disruption, and tension pneumothorax respectively. Finally assessment of the cardiac silhouette may aid in the diagnosis of blunt myocardial injury including tamponade.

Other radiology
In addition to the lateral cervical spine and pelvis films which are generally obtained for every blunt trauma victim, several imaging examinations are of particular interest in the work up of thoracic trauma. The echocardiogram, either precordial or transesophageal, is useful in evaluating for pericardial fluid, valve and wall motion, and the presence and extent of aortic disruption. Computerized tomography of the chest may reveal aortic disruption and pneumothorax not readily apparent on plain chest xray. Finally, arteriography is used to precisely locate vascular injury.[4, 5]

Rib Fractures
Rib fractures should be taken in context. Their presense indicate a need for examining the underlying lung for contusion, laceration, hemo or pneumothorax. Multiple or anterior and posterior rib fractures may cause a flail segment. Fracture of the relatively protected first through third ribs indicates severe impact and mandates careful search for associated injury.

Pulmonary Contusion
Pulmonary contusion frequently manefests itself as hypoxemia. the goals for treatment are oxygentherapy, positive pressure either with a CPAP mask or by intubation and mechanical ventilation with PEEP. Splinting from the pain associated with rib fractures requires adequate pain management, i.e.parenteral narcotics, interpleural local anesthetics, or epidural narcotics/local anesthetics. The contused lung is prone to capillary leak and therefore careful fluid management is indicated.[6]

Pneumothorax
A high index of suspicion for the presence of a pneumothorax must be maintained in all blunt trauma victims. Auscultation may be difficult in the ER. Other signs of tension pneumothorax, tracheal deviation, hypotension, hypoxemia should trigger chest decompression prior to CXR. If the patient is stable an xray may preceed the thoracostomy. Patients with multiple rib fractures may harbor a subclinical pneumothrax and may require "prophylactic" thoracostomy prior to OR.[1]

Hemothorax
Up to 40% of the blood volume can be accomodated in one hemothorax. 1500 ml of initial blood output in chest tube drainage is an indication for thoracotomy as a large vessle or cardiac rupture may be present.[1] Bronchial injury Blunt injury to the lower airways is usually caused by deceleration or compression injury. These injuries typically present as either a pneumothorax which doesn't resolve or a persistent air leak with tube thoracostomy. While rare, (0.4% of 515 patients in one study[7]) tracheal or bronchial injury poses management issues for the anestheiologist. Fiberoptic evaluation of the airway may serve as a guide for intubation as well as aid in the location of injury for surgical correction. Lung isolation procedures are frequently employed during repair.[8]

Widened Mediastinum
A widened mediastinum on chest xray in the blunt trauma victim is usually associated with aortic injury. Several technical factors of the AP portable films taken in the emergency setting, i.e. supine position, expiratory film, and the magnification effect of a short beam distance, may make the mediastinum appear widened. Loss of the aortic knob contour, shift of the esophagus (nasogastric tube) to the right and an apical cap in addition to mediastinal widening indicate need for further workup.[4, 5]

Aortic Injury
80-90% of patients with thoracic aortic rupture die in the pre-hospital setting. Those who survive to to reach the hospital may have minimal symptoms. The chest film may give the first suggestion of injury. The rupture is usually at the isthmus just distal to the left subclavian artery. Control of blood pressure is critical to avoid further dissection. Emergent surgery with poor hemodynamic stabilization has high mortality.[5, 9]

Blunt Cardiac Injury
Blunt trauma to the heart covers the spectrum of myocardial concussion,contusion to myocardial rupture. The right atrium and ventricle are the most frequently injured chambers because of their anterior positioning in the chest, followed by left atrium and left ventricle. Survival from one chamber rupture is about 40% . Two chamber rupture has uniform mortality. Once again echocardiaography is extremely useful in the diagnosis of this injury.[11]

Myocardial Contusion
Patients with suspected myocardial contusion are no longer routinely subjected to prolonged observation in a monitored setting. If the ECG and echocardiogram are normal the patient may go home after 12 hours if no other injuries are present. Young patients rarely have cardiac related complications even when cardiac contusion is diagnosed. The best test for diagnosis remains controversial. The ECG is unreliable unless ST elevation is present. CPK MB isoenzymes may be nondiagnostic. Cardiac troponin I which may be more specific for myocardial damge has not been adequately evaluated. Echocardiography is useful for detecting wall motion abnormalities, pericardial effusions and in combination with abnormal CPK MB may predict complications. Radionuclide angiography may also be predictive of complication. Thallium scanning can detect areas of decreased perfusion, but cannot differentiate an acute from preexisting lesion[3, 12]