Shortness of breath, also known as dyspnea, is a common reason for patients to visit the Emergency Department.  Dyspnea is often caused by a pulmonary or cardiovascular condition, but it is important to remember that dyspnea can be due to endocrine conditions, toxicologic conditions, neurologic conditions, hematologic conditions, musculoskeletal conditions, and psychiatric conditions. 

The initial approach to all patients with shortness of breath involves the primary survey, or “ABCs” (Airway, Breathing, Circulation).  This first involves checking the patient for a patent airway.  A simple method to assess the airway is to ask the patient to speak and listen for the voice.  A muffled voice, the presence of stridor, hematemesis, or a lethargic patient are clues that a patent airway may not be present.  Problems with the airway, such as an obstructing foreign body, inflammation (i.e., epiglottitis, anaphylactic shock), or vocal cord dysfunction can certainly cause shortness of breath.  Endotracheal intubation may need to be performed before moving forward.  Breathing is assessed by evaluating the function of the lungs.  Steps include looking at how the patient is breathing (fast or slow), measurement of an SpO2 level, and auscultation of both lungs for wheezing, crackles, rhonchi, or distant or absent sounds.  A low oxygen level should be immediately addressed with supplemental oxygen before moving forward.  The patient’s breathing rate and lung sounds can be very helpful in discovering the diagnosis and guiding treatment.  Lastly, circulation should be assessed.  Check the heart rate, blood pressure, peripheral pulses, skin color and temperature, and evaluate for any sites of hemorrhage.  The presence of hypotension or tachycardia should be addressed appropriately based on the presumed cause.  After the primary assessment (“ABCs”) and initial treatment actions, a more detailed history and physical exam should be conducted. 

Pertinent causes of shortness of breath for the emergency practitioner to know are outlined in the chart below. 

This patient presented to the Emergency department with 2 days of shortness of breath without chest pain, cough, or fevers.  The exam shows tachycardia, hypotension, mild tachypnea, clear lungs, and distant heart sounds.  Tension pneumothorax (Choice B) can cause hypotension and tachycardia and COPD is a risk factor for pulmonary bleb formation and rupture.  However, the lungs are equal and clear bilaterally, so this diagnosis is not likely.  Septic shock due to pneumonia (Choice C) is also less likely as there is no fever, the lungs are clear, and the patient lacks a cough.  The ultrasound image given also provides a clear explanation for the patient’s symptoms.  This patient is at risk for pulmonary embolism (Choice A) given his cancer history which can cause a hypercoagulable state and predispose him to clot formation.  Again, an understanding of the ultrasound image will provide the diagnosis.

The ultrasound image is a subxiphoid view of the heart demonstrating a pericardial effusion (red stars) with compression of the right ventricle (yellow arrow). 

This presentation is consistent with cardiac tamponade (Choice D).  Cardiac tamponade is a condition defined by the accumulation of fluid in the pericardial sac to the point of right ventricular collapse and obstructive shock.  Common presenting symptoms of cardiac tamponade include shortness of breath, chest pain, or nonspecific symptoms.  Risk factors for this diagnosis are penetrating chest trauma (hemopericardium), cancer (malignant effusion), lupus, end stage renal disease, uremia, HIV, Tuberculosis, or history of chest radiation.  The presence of hemodynamic instability (hypotension and tachycardia) is a hallmark of this condition, although early stages of tamponade can be seen on cardiac ultrasound before vital signs decompensate.  The patient may have Beck’s triad of muffled distant heart sounds, jugular venous distension, and hypotension, although the majority of patients with cardiac tamponade do not have all three of these signs together.  Treatment involves IV fluids, bedside pericardiocentesis (ultrasound guided preferred), and surgical pericardiotomy (“pericardial window”).