A wide range of conditions can produce "shortness of breath." Dyspnea is merely a symptom and does not connote a specific condition or diagnosis. Emergency physicians should consider dyspnea in terms of organ systems. These include the airway, the lungs, the heart, the blood (including metabolic causes), and neuromuscular causes. (See Table 1
.) Muscular weakness can produce dyspnea, and causes include myasthenia gravis, Guillain- Barr? syndrome, and thyrotoxicosis.8,9
Gastroesophageal reflux is responsible for approximately 4% of chronic undifferentiated dyspnea.10,11
In three prospective studies, 207 patients underwent comprehensive laboratory and physiological testing for chronic dyspnea. A cardiac or pulmonary problem was the primary etiology in three-quarters of the cases.10-12
In these settings, most cases of dyspnea were due to one of the following processes: hyperactive airways or chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), acute pneumonia, or acute pulmonary embolism (PE).Dyspnea In The Emergency Department
Although it is difficult to track the prevalence of isolated dyspnea in adult ED, approximately 2-3% of all ED patients complain of respiratory distress.13,14
Many patients have dyspnea in conjunction with another symptom, such as diaphoresis, chest pain, palpitations, cough, or fever. These associated symptoms may provide important clues to the etiology.
An important goal in emergency medicine is detection of serious or life-threatening causes of dyspnea. For this reason, psychogenic dyspnea should be diagnosed after exclusion of organic causes. This does not require extensive diagnostic testing in all cases. History, physical, and simple ED tests may obviate the need for further studies. Patients previously in good health with dyspnea who are younger than 40 are diagnosed with psychogenic dyspnea in one-third of ED visits.10
Another important goal is detection of PE. Pulmonary embolism is of special import, not just because of potential lethality, but because patients may not appear critically ill. While there are other serious causes of dyspnea, such as pulmonary edema, profound acidosis, and pericardial tamponade, these patients appear supremely distressed. They present with dramatic findings on examination and are unlikely to be discharged by even the unwary clinician. On the other hand, the patient with pulmonary embolism may exhibit only modest findings, inviting a superficial evaluation.