A 23-year-old man is brought to the emergency department after a motor vehicle collision. The patient was found unresponsive at the scene and intubated by the paramedics, who also administered 2 L of normal saline. He was the unrestrained driver. Upon arrival, blood pressure is 72/54 mm Hg, and pulse is 120/min. The patient responds to strong vocal and tactile stimuli by opening his eyes. Pupils are equal and reactive to light. Neck veins are distended. There are multiple bruises involving the anterior chest and upper abdomen. Chest x-ray reveals a small, left-sided pleural effusion and normal cardiac contours. Which of the following is the most likely diagnosis?

Question

A 23-year-old man is brought to the emergency department after a motor vehicle collision.  The patient was found unresponsive at the scene and intubated by the paramedics, who also administered 2 L of normal saline.  He was the unrestrained driver.  Upon arrival, blood pressure is 72/54 mm Hg, and pulse is 120/min.  The patient responds to strong vocal and tactile stimuli by opening his eyes.  Pupils are equal and reactive to light.  Neck veins are distended.  There are multiple bruises involving the anterior chest and upper abdomen.  Chest x-ray reveals a small, left-sided pleural effusion and normal cardiac contours.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec25c8_d833_4c5c_bc81_23a74bb7344b_MD0003_00 This patient with refractory hypotension, tachycardia, and jugular venous distension likely has acute cardiac tamponade (due to blunt cardiac injury from the collision). Cardiac tamponade is classified as acute or subacute based on the rate and volume of pericardial fluid accumulation. Subacute tamponade typically develops from chronic processes that cause the slow accumulation of pericardial fluid (eg, malignancy, renal failure), giving the pericardium time to progressively stretch. The pericardium may accommodate 1-2 L of fluid before intrapericardial pressure rises and compromises cardiac function. This large quantity of pericardial fluid causes the classic globular cardiac silhouette on x-ray. globular cardiac silhouette In contrast, acute tamponade occurs due to rapid fluid accumulation (eg, accumulation of blood due to blunt cardiac injury in this patient). Because the stiff pericardium does not have time to adapt, a small amount of pericardial fluid (eg, 100-200 mL) can dramatically increase intrapericardial pressure without causing cardiomegaly on x-ray (typically seen with >200 mL). Therefore, acute tamponade is associated with normal cardiac contours, as in this patient. On physical examination, patients may have hypotension with elevated jugular venous pressure (obstructive shock due to the pericardial fluid preventing adequate cardiac contraction) as well as muffled heart sounds (Beck triad, only seen in a minority of patients). This patient's small, left-sided pleural effusion may be due to blood leaking from the pericardium (eg, through a small tear) or a concomitant injury (eg, lacerated lung parenchyma). (Choice A) Aortic rupture is often immediately fatal. In rare instances, aortic rupture with bleeding into the left pleural space that has been contained (eg, by a hematoma) can present with left-sided pleural effusion and hypotension. However, it would cause hypovolemic (rather than obstructive) hypotension with flat (rather than distended) neck veins. (Choice B) Traumatic bronchial rupture (air leaking from the tracheobronchial tree into the pleural space) can cause hypotension and jugular venous distension. However, this typically occurs with massive extrapulmonary air leakage, which would be associated with tension pneumothorax, pneumomediastinum, and subcutaneous emphysema (not seen on this patient's x-ray). (Choice D) Esophageal rupture can allow efflux of gastrointestinal contents into the pleural space (causing pleural effusion) and mediastinum (causing mediastinitis, a systemic inflammatory response, and vasodilatory hypotension). However, flat (rather than distended) neck veins would be expected due to peripheral vasodilation. (Choice E) Lung contusion that injures the lung parenchyma and visceral pleura can bleed into the pleural space, causing left-sided pleural effusion. However, lung contusion with bleeding sufficient to cause hypotension (from hypovolemia) would be associated with flat (rather than distended) neck veins. Educational objective: Acute cardiac tamponade is due to rapid accumulation of a small amount of fluid within a stiff pericardium, causing a sudden rise in intrapericardial pressure. Unlike subacute tamponade, the cardiac silhouette can be normal on chest x-ray. References: Blunt cardiac trauma: a review of the current knowledge and management. (http://www.ncbi.nlm.nih.gov/pubmed/25069684) Blunt cardiac trauma review. (http://www.ncbi.nlm.nih.gov/pubmed/29173678)

A 23-Year-Old Man Is Brought to the Emergency Department After