Differential Diagnosis of Chest Trauma
When managing patients with potential chest injuries, it sometimes can be a challenge to differentiate between tension pneumothorax, massive hemothorax, and pericardial tamponade. In EMS environments the differences between these injuries can seem subtle and convoluted. This article examines differentiation of these injuries. Real-life case studies will help readers focus on physical signs that eliminate some of the grey area when trying to distinguish between them.
Case Study #1
You are called to the scene of a vehicle crash on a local highway. Upon arrival you find one vehicle with major front-end damage where it collided with a bridge abutment at high speed. Your patient is a 23-year-old male who was unrestrained and complains of chest pain, difficulty breathing, and dizziness.
Physical assessment reveals:
- Skin: cool, pale, and diaphoretic;
- Head: contusion above left eye;
- Neck: external jugular veins appear distended;
- Spine: negative to palpation;
- Chest: contusion to sternum;
- Lung sounds: diminished on left side;
- Abdomen, pelvis, back, and upper and lower extremities: all negative to palpation;
- Vital signs:
- BP: 92/54;
- Pulse: 120 and regular but weaker at the wrist compared to the neck;
- Respirations: 30, shallow and regular.
Case Study #2
You are called to the scene of a vehicle crash on a local highway. Upon arrival you find one vehicle with major front-end damage where it collided with a bridge abutment at high speed. Your patient is a 19-year-old male who was unrestrained and complains of chest pain, difficulty breathing, and dizziness.
Physical assessment reveals:
- Skin: cool, pale, and diaphoretic;
- Head: 2–3-cm laceration above the left eye with minimal bleeding;
- Neck: external jugular veins appear distended;
- Spine: negative to palpation;
- Chest: contusion to sternum;
- Lung sounds: equal bilaterally;
- Abdomen, pelvis, back, and upper and lower extremities: all negative to palpation;
- Vital signs:
- BP: 98/50;
- Pulse: 120 and regular but weaker at the wrist compared to the neck;
- Respirations: 30, shallow and regular.
Case Study #3
You are called to the scene of a vehicle crash on a local highway. Upon arrival you find two vehicles with major front-end damage where they collided at high speed. Your patient is a 31-year-old male who was restrained and complains of chest pain, difficulty breathing, and dizziness.
Physical assessment reveals:
- Skin: cool, pale, and diaphoretic;
- Head: contusion in center of forehead;
- Neck: external jugular veins appear flat;
- Spine: Negative to palpation;
- Chest: contusion to sternum;
- Lung sounds: diminished on left side;
- Abdomen, pelvis, back, and upper and lower extremities: all negative to palpation;
- Vital signs:
- BP: 90/62;
- Pulse: 120 and regular but weaker at the wrist compared to the neck;
- Respirations: 30, shallow and regular.
Based upon these presentations, what condition do you believe each patient is suffering from?
Differentiating Between Chest Trauma
At superficial glance the mechanism of injury and circumstances associated with these cases are similar. The sustained injuries for each of these patients are also similar. Here is the differential diagnosis for each of these cases:
- Patient #1 suffered a tension pneumothorax.
- Patient #2 suffered a pericardial tamponade.
- Patient #3 suffered a massive hemothorax.
Regardless how challenged you were in differentiating between these injuries, let’s attempt to simplify the differential assessment. Although these injuries can present with a myriad of signs and symptoms, the EMS provider should focus primarily on the patient’s neck and lung sounds. The reason for focusing on these areas is that the pathophysiology associated with each of these injuries uniquely affects pressure within the jugular veins and how the lungs expand.
Table 1 illustrates the physiologic differences. Notice each of these chest injuries presents with a unique combination of neck vein appearance and lung sounds. Let’s look at why these physiologic differences occur.
Tension Pneumothorax
Tension pneumothorax is caused by pressure accumulating within one side of the thorax. This results in one lung collapsing on the affected side and placing pressure on the mediastinum, which compromises blood flow. The collapsed lung causes diminished breath sounds because the lung is collapsed and no longer expanding. Pressure on the mediastinum creates back pressure on the heart, causing jugular vein distention (JVD). Without relief of this pressure via thoracic needle decompression, the patient’s condition will continue to deteriorate.
Pericardial Tamponade
Pericardial tamponade is caused by blood and/or fluid accumulating within the pericardial sac. This results in the heart being compressed, which compromises blood flow. The compressed heart creates back pressure, resulting in JVD. Breath sounds will be equal because the lungs are not affected by this injury. The EMS provider may buy some time by initiating aggressive fluid resuscitation,1 but the patient ultimately requires a pericardial centesis to remove the excess blood/fluid.
Massive Hemothorax
Massive hemothorax is caused by blood accumulation of 1,500 cc or more within one side the thoracic cavity.2 This results in one lung being compressed and causes diminished breath sounds because the lung is no longer expanding. The neck veins will present flat because a large amount of blood has hemorrhaged and is no longer within the veins. Due to the large amount of blood loss, the patient may present with signs of shock.
Summary
Patients suffering from these major chest injuries obviously require rapid transport to a trauma facility. By integrating the findings of neck veins and lung sounds, the EMS provider will be more effective at developing a differential diagnosis. This will assist in determining which therapies may be most beneficial for their patient’s prehospital course of care.
References
1. Williams C, Soutter L. Pericardial tamponade; diagnosis and treatment. AMA Arch Intern Med, 1954 Oct; 94(4): 571–84.
2. Chang SW, Ryu KM, Ryu KW. Delayed massive hemothorax requiring surgery after blunt thoracic trauma of a 5-year period: complicating rib fracture with sharp edge associated with diaphragm injury. Clin Exp Emerg Med, 2018 Mar; 5(1): 60–65.
Table 1: Differences in Neck Veins and Lung Sounds
Tension pneumothorax
- Neck veins: distended
- Lung sounds: unequal
Pericardial tamponade
- Neck veins: distended
- Lung sounds: equal
Massive hemothorax
- Neck veins: flat
- Lung sounds: unequal
Bob Matoba is lead instructor for the St. Anthony Paramedic Academy in Lakewood, Colo. He has been involved in EMS for more than 37 years.
Sidebar: Chest Trauma—What Else Might It Be?
Chest trauma remains one of the most common and potentially lethal forms of injury given the vital organs of the chest cavity and potential for rapid decompensation. Early intervention is necessary to increase survivability from severe chest/chest wall injuries. This is true for both blunt and penetrating mechanisms of injury.
As an example, recent research in identifying causes of preventable death after civilian public mass shootings found that preventable death rates are high and deaths are most commonly due to nonhemorrhaging chest wounds, such as tension pneumothorax.1 This article highlights the importance of early recognition and treatment of chest injuries in the prehospital setting.
Chest trauma is most frequently classified by mechanism: blunt or penetrating. High-energy blunt injuries include high-speed motor vehicle collisions, assaults, and ground-level falls in elderly patients, while penetrating injuries most commonly result from gunshot wounds and stabbings. A high index of suspicion for injury to the heart and lungs is necessary when evaluating these patients. Initially they may only complain of chest pain or have focal tenderness, but their symptoms can rapidly progress to shortness of breath, tachycardia, hypotension, and complete cardiovascular collapse.
The differential diagnosis for causes of immediate life-threatening injuries in thoracic trauma includes pneumothorax (open or closed), hemothorax, and rib fractures with/without flail segments. Blunt chest trauma can also cause damage to the heart by causing rupture of the cardiac chambers, most commonly the right atrium, resulting in tamponade physiology or potentially lethal arrhythmias, a condition called commotio cordis. Early identification and treatment of these injury patterns is essential for preventing rapid decompensation.
A pneumothorax and hemothorax occur when air or blood collects between the lung and chest wall. Early signs can be decreased breath sounds on the affected side and decreased oxygen saturation. A pneumothorax may quickly progress to a tension pneumothorax when intrathoracic pressure compresses the veins of the chest, decreasing blood return to the heart and therefore reducing cardiac output and blood pressure. Address this immediately with a temporizing needle decompression.
There is ongoing debate regarding the best location to perform a needle decompression, with some sources recommending placing a 5-cm angiocatheter in the second intercostal space in the midclavicular line and other sources recommending placing the needle in the fifth intercostal space at the anterior axillary line.2 When one evaluates studies on this question, the most common conclusion is location does not matter.3
“Finger thoracostomy,” where an incision is made in the chest wall to relieve intrathoracic pressure, is much more effective that needle thoracostomy but rarely allowed in prehospital protocols. A massive hemothorax can result in exsanguination and may need to be addressed surgically. Treatment in this case involves decompression of the chest to prevent a tension hemothorax, blood pressure support with fluids (and transfusion if that is available), and rapid transport to a trauma center.
A flail chest is defined as three or more rib fractures in two or more places. This disruption in the integrity of the chest wall inhibits adequate expansion during respiration. These injuries indicate a high-energy mechanism that should prompt further evaluation.
A flail chest is almost always associated with an underlying pulmonary contusion. This bruising of the lung remains the most common potentially lethal chest injury. While paradoxical chest wall movement suggesting a flail chest injury may be seen in physical exam, a pulmonary contusion is often symptomatic initially. These patients are at very high risk for development of pneumonia and typically require prolonged periods of mechanical ventilation.4 Also important, given the ongoing inflammation in the lungs, is that these patients should have minimal fluid resuscitation, as this can worsen the contusion and pulmonary congestion.
Rib fractures are associated with extreme pain and inability to take deep breaths. Mortality after rib fractures increases with the number of rib fractures along with patient age.5,6 Treatment of rib fractures requires a multidisciplinary approach, with an early focus on ensuring adequate pain control. A multimodal pain regimen centered on non-narcotic medications and including acetaminophen and NSAIDs, nerve blocks, and minimal use of narcotics allows for early mobilization and chest physiotherapy.7 In cases of refractory pain or ongoing paradoxical movement of the chest, surgical fixation of rib fractures has been shown to lower mortality rates.8
Any type of blunt chest trauma, such as seen in unrestrained drivers who slam their chests into steering wheels, should prompt further assessment for a blunt cardiac injury (BCI).9 This can alter the electrical conduction system of the heart. While BCI is mostly asymptomatic, patients may present with a resting sinus tachycardia but also ventricular dysrhythmias that can be fatal. For this reason, patients with BCI require cardiac monitoring and warrant transfer to a trauma center.
In high-impact trauma it is possible to rupture a chamber of the heart, most commonly the right atrium. This rupture leads to the rapid accumulation of blood around the heart. Even small amounts of blood can cause circulatory collapse. Beck’s triad of hypotension, distended neck veins, and muffled heart sounds is rarely seen in clinical practice. Most often one finds refractory hypotension alone—the treatment of which is fluids and rapid transport to a trauma center. If available, point-of-care ultrasound to evaluate the pericardium can allow one to diagnose tamponade. Although there has been discussion around the utility of pericardiocentesis in this setting, the simple point is that as long as there is ongoing bleeding from a chamber rupture, the only way to stabilize the patient is rapid access to the operating room for repair of the heart.
Commotio cordis is a rare event and results from a high-energy blunt mechanism of injury (e.g., a baseball hitting the chest) if the force is imparted during the T-wave of the EKG cardiac cycle. This is akin to performing a nonsynchronized cardioversion and applying energy during the T-wave. The patient can develop torsades de pointes with sudden cardiac collapse. Such a condition is easily identified on a cardiac monitor, and treatment is based on ACLS algorithms for the rhythm present. Transport to a trauma center is needed for ongoing monitoring of the heart.
References
1. Smith ER, Sarani B, Shapiro G, et al. Incidence and Cause of Potentially Preventable Death After Civilian Public Mass Shooting in the U.S. J Am Coll Surg, 2019 Sep; 229(3): 244–51.
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