Chest trauma: Clinical practice

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Chest trauma: Clinical practice

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A 40-year-old woman presents to the emergency department complaining of fever. Her past medical history reveals diabetes and morbid obesity. Vitals reveal a blood pressure of 80/60 mmHg, a heart rate of 140/min, a respiratory rate of 35/min, an oxygen saturation of 94% on room air, and a temperature of 40°C (104°F). Urine analysis indicate positive for UTI. Sepsis is suspected. A right internal jugular central venous catheter is placed without complication under ultrasound guidance for vascular access in preparation for administration of vasopressors. The patient’s blood pressure has improved to 100/70 mmHg with saline running through a peripheral line. A chest radiograph is obtained subsequent to placement of the central line placement. Which of the following is the best next step in management in this patient subsequent to seeing this X-ray image?

Transcript

Content Reviewers:

Rishi Desai, MD, MPH

The chest wall houses a number of vital structures in the body - the heart and the pericardium, the lungs and the pleura, the aorta, and the esophagus - all protected within the rib cage and sternum.

And trauma to the chest wall is responsible for over one-fourth of trauma deaths.

Chest trauma can be blunt, such as from motor vehicle accidents, or penetrating, such as from a stab or gunshot wound.

Chest trauma evaluation starts with the primary survey, which includes the ABCDEs: airway, breathing, circulation, disability, and exposure, and the goal is to quickly assess and treat life-threatening injuries.

It starts with checking the patency of the airway and whether the individual requires endotracheal intubation.

As for breathing, you can look, listen, and feel.

So look at the respiratory rate, oxygen saturation, and breathing pattern.

If the person is hypoxemic, a 100% oxygen non-rebreather mask should be given.

Also if there’s asymmetric breathing it could indicate a weak chest segment due to rib fractures.

Next, listen for breath sounds for signs like decreased air entry in tension pneumothorax or hemothorax, or muffled heart sounds in cardiac tamponade.

After that feel for tenderness along the chest wall, which can occur with rib fractures.

In circulation, check the blood pressure and heart rate.

If there are signs of shock it could be due to a number of causes like bleeding into the pleura or pericardium, obstruction of cardiac output in the setting of a tension pneumothorax, or inadequate cardiac output in the setting of myocardial injury.

Also, as part of circulation, it’s important to look for other sources of bleeding, to insert two large-bore intravenous lines, and to prepare for the need for blood products.

It’s specifically important to assess for signs of inadequate end-organ perfusion, such as altered mental status, decrease urine output, cool or pale skin, and a delayed capillary refill.

Bedsides ultrasound can also be used in the primary survey - and it’s called focused assessment with sonography for trauma, or the FAST exam.

When views are added to look for a pneumothorax, hemothorax, or cardiac tamponade, it’s called an extended FAST or E-FAST.

“Disability” means neurological disability, and is assessed by checking the pupils and using the Glasgow Coma Scale, or GCS.

Finally, exposure is assessed by turning the individual on their side, and assessing their back for any occult injuries.

Alright, now the secondary survey focuses on taking a history, and performing an elaborate head-to-toe examination with the goal of detecting more subtle injuries.

Now, if a life-threatening injury is recognized, then life-saving interventions are immediately performed, like a needle decompression for a tension pneumothorax, covering an open pneumothorax wound, inserting chest tubes for pneumothorax or hemothorax, or performing a pericardiocentesis for a cardiac tamponade.

Initially, a chest x-ray should also be done to help identify rib fractures, pulmonary contusions, a pneumothorax, a hemothorax, or an aortic injury.

An electrocardiogram or ECG and cardiac enzymes, should be done to help identify myocardial injury.

A CBC can help identify a baseline for bleeding since there may be a dilutional anemia that will begin hours to days after the trauma, a blood type and crossmatch for blood transfusions, and a PT, PTT, and INR.

Alright, let’s get into specific chest wall injuries, starting with rib fractures, which are the most common chest wall injuries.

Usually a rib fracture causes point tenderness over the rib along with bruising.

In fact, the pain can be really severe and it can lead to very shallow breathing.

So to help maintain good ventilation, encouraging deep breathing and good pain control is the key.

Analgesics like acetaminophen and NSAIDs are a good start.

Sometimes, opioid medications are used even though they can cause respiratory depression.

Intercostal nerve blocks are a great option for pain control.

Under the guidance of ultrasound, a local anesthetic medication like bupivacaine is injected just below the edge of the fractured rib, because that’s where the intercostal nerves run.

Complications of rib fractures include a pneumothorax, hemothorax, or a splenic or liver laceration, which are all the result of the sharp edge of a displaced rib injuring a nearby structures.

Now, if there’s inadequate pain control and ventilation the lung can collapse, and that’s called atelectasis.

Atelectasis predisposes a person to developing a post-traumatic pneumonia.

Generally speaking, individuals younger than 65 years with no comorbidities and 1 or 2 rib fractures are discharged home.

On the other hand, individuals over age 65, or those with comorbidities like COPD, or those with 3 or more rib fractures should be admitted for observation.

Alright, now if three or more adjacent ribs are each fractured in at least two locations, this creates a free-floating segment called a flail chest.

A flail chest can have paradoxical movement during respiration. In other words, the flail segment will move inwards during inspiration, and outwards during expiration, which is the opposite of the remaining normal chest.

The respiratory failure in a flail chest is not due to the mechanical issue, instead it’s directly related to injury to the underlying lung, which is called a pulmonary contusion - or a “lung bruise”.

Pulmonary contusions happen in the context of blunt chest trauma, and can be diagnosed on a chest x-ray.

But the thing is, the chest x-ray may not show any changes until 6 hours after the injury. This makes sense, because you’d expect the same delay in the appearance of a skin bruise.

So the classic presentation of a pulmonary contusion is someone who was initially oxygenating well, but then began to deteriorate over time.

In a pulmonary contusion, a chest x-ray typically shows patchy opacities representing pulmonary edema and hemorrhage.

Now a chest CT is more sensitive and can pick up signs of a pulmonary contusion earlier, so it’s usually preferred for that reason.

Management of a flail chest and pulmonary contusion includes pain control, as well as oxygenation and ventilation with non-invasive positive pressure ventilation, or if necessary, endotracheal intubation.

Also, it’s important to avoid giving IV fluids, because that can exacerbate the pulmonary edema. If IV fluids are needed, sometimes they’re given along with a diuretic like furosemide.

Finally, it’s unclear if surgical fixation of the fractured ribs provides any additional benefit.

A pneumothorax is a collection of air in the pleural space.

A tension pneumothorax occurs when the injured pleura forms a one-way valve, allowing air to go in, but not go out. This means that with every breath, the pneumothorax gets bigger and bigger.

Individuals present with chest pain, shortness of breath, and hypoxia, and examination reveals decreased air entry on auscultation and hyperresonance on percussion.

Now, in cases of a tension pneumothorax, it can compress the right atrium of the heart and the vena cavae, decreasing venous return. This results in decreased cardiac output manifesting as hypotension, altered mental status and an elevation of the jugular venous pressure, and this is typical of obstructive shock.

Additionally, in a tension pneumothorax, the mediastinum and trachea may be shifted to the contralateral side.

A tension pneumothorax is a clinical diagnosis, meaning that if it’s suspected, it’s a medical emergency that must be immediately treated by inserting a needle in the 2nd or 3rd intercostal space at the midclavicular line, decompressing the pneumothorax.

Following decompression, a chest tube is inserted in the 4th or 5th intercostal space along the anterior axillary line.

An open pneumothorax, also called a “sucking chest wound” is a pneumothorax that communicates with atmospheric air due to an open chest wound.

An open pneumothorax occurs if the chest wound is greater than two-thirds the diameter of the trachea, because atmospheric air likes to take the path of least resistance, preferring the open wound over the trachea.

One key difference between an open pneumothorax and a tension pneumothorax is the absence of obstructive shock. This is because air is not being trapped in the pleural space, instead it’s free to go in and out of the chest. So, pressure does not build up, and the surrounding structures aren’t compressed.

Initial management of an open pneumothorax is applying dressing over the wound, and then taping it from 3 sides, leaving one side open. This creates a unique valve mechanism that allows air to go out, but does not allow air in.

Eventually, a chest tube needs to be inserted, and the wound needs to be repaired.

Next up is a hemothorax which is a collection of blood in the pleural space. Individuals have shortness of breath, hypoxia, decreased air entry on auscultation and dullness on percussion.

Because the pleural cavity can accommodate large amounts of blood, the major concern in hemothorax is hemorrhagic shock.

The diagnosis is made with an upright chest x-ray, because a supine chest x-ray may miss a smaller hemothorax.

The chest x-ray shows a concave opacity blunting the costophrenic angle, which is the angle between the pleura covering the ribs and the pleura covering the diaphragm.

The FAST exam may also help with the diagnosis of a hemothorax.

Although a hemothorax usually originates from injury to the lung parenchyma or the intercostal vessels, it’s important to consider an intra-abdominal source of bleeding that may have leaked through an injured diaphragm.

The FAST exam or a CT scan of the abdomen can usually detect an intra-abdominal source, and if there is one, then the individual is taken to the operating room to control the bleeding.

Treatment of a hemothorax consists of inserting a chest tube, and restoring the circulating blood volume.

If the amount of blood drained from the chest tube is more than 1500 milliliters in a day, or if the rate of bleeding is more than 200 milliliters per hour for 2 to 4 hours, or the individual decompensates after initial stabilization, then a surgical thoracotomy should be done. This involves surgically opening the chest to identify and stop the bleeding.

A unique intervention to restore blood volume is autotransfusion. This means taking the hemothorax blood from the chest tube, and giving it back to the individual intravenously. This eliminates the risk of transfusion reactions, because it’s their blood.

Okay, cardiac injury can be blunt or penetrating.

Blunt cardiac injuries include myocardial concussion, contusion, or rupture, and coronary vessel injury.

A myocardial concussion, also called commotio cordis, is a rare form of cardiac injury that manifests as sudden collapse of the individual due to a life-threatening arrhythmia like asystole, ventricular fibrillation, or cardiac arrest. This is thought to occur when the blow to the chest happens just before the T-wave; a period of electrical vulnerability. In other words, bad timing.

Treatment should follow the advanced cardiac life support, or ACLS protocols, including cardiopulmonary resuscitation, or CPR, and if necessary, defibrillation.

A myocardial contusion is a “heart bruise”. Because of its anterior and retrosternal location, the right ventricle is most commonly injured.

The signs and symptoms of a myocardial contusion depend on the extent of injury, but commonly include chest pain, arrhythmias, hypotension, and even cardiogenic shock.

Now, in the context of chest trauma, hypotension and arrhythmias should be initially presumed to be from hemorrhage, rather than a cardiogenic cause, because bleeding is so much more common.

Now, an ECG should be done on all individuals with chest trauma to help identify any resulting arrhythmias; with sinus tachycardia being the most common, conduction blockade, or ischemia.

Additionally, troponin levels are obtained as a marker of cardiac myocyte injury.