Question Of The Day #83

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 arrives to the Emergency Department with several hours of shortness of breath, nausea, and generalized weakness.  On physical exam, the vital signs are normal, there is no tachypnea, no hypoxemia, no respiratory distress, and the lungs are clear.  Clear lungs in a patient with respiratory distress should raise concern for acute coronary syndrome, pulmonary embolism, cardiac tamponade, anemia, and metabolic acidosis.    

The 12-lead EKG provided shows an inferior ST-elevation Myocardial Infarction (STEMI).  This is demonstrated through the ST segment elevations in the inferior EKG leads (II, III, AvF) and the reciprocal changes in the lateral leads (most notably in AvL).  The presence or absence of chest pain is not provided in this question, but patients with acute coronary syndromes do not always have chest pain.  Elderly patients and women are more likely to present with non-chest pain anginal equivalents, like shortness of breath, lethargy, or nausea.  Diagnosis of acute coronary syndrome is done through a combination of a 12-lead EKG, blood troponin levels, and history and physical exam.  A STEMI is the most severe of all acute coronary syndromes and requires prompt recognition and treatment with antiplatelets (i.e., aspirin plus clopidogrel or ticagrelor), heparin, pain management (morphine or nitroglycerin), and percutaneous coronary intervention (PCI).  Providing supplemental oxygen (Choice A) is not necessary as the patient has no hypoxemia and a normal lung exam.  Administration of sublingual nitroglycerin (Choice C) can help alleviate ischemic chest pain and other symptoms associated with a STEMI but is contraindicated in inferior STEMIs.  Using nitroglycerin in inferior STEMIs can result in dangerous hypotension due to cardiac preload reduction.  This patient has a STEMI, and a CT head to evaluate weakness (Choice D) will not be helpful.  In general, a detailed neurological exam assessing for motor deficits will be more valuable than a CT head to determine the etiology of a patient’s weakness.  The best next step in this case is to administer 324mg aspirin (Choice B) in this patient with a STEMI.