EVALUATION OF SYNCOPE IN THE EMERGENCY DEPARTMENT

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Syncope is defined as a “sudden transient loss of consciousness with concurrent diminution in postural tone followed by spontaneous recovery not requiring cardioversion.”25 Syncope is a symptom rather than a primary disease process. Syncope is distinct from a seizure disorder, vertigo, dizziness, coma, shock, or other states of altered consciousness. Nonetheless, on initial presentation, differentiating syncope from other conditions may be difficult.

Syncope accounts for up to 3% of emergency department (ED) visits and between 1% to 6% of all hospital admissions.9, 21, 22, 33, 37, 42 The frequency of loss of consciousness (reported to vary between 12% to 48% in young adults) often is associated with trauma or alcohol ingestion.24 The annual incidence of syncope in institutionalized patients older than 75 years is 6%.31

Because the unexpected loss of consciousness is a frightening experience, patients often present for initial evaluation and treatment. Although most often the clinical course of syncope is benign, it may cause serious trauma or be an ominous prodrome of sudden cardiac death.8, 17, 19, 34, 36, 37 Unfortunately, the clinical evaluation of syncope is often expensive, time-consuming, and often does not lead to a definitive diagnosis. The clinical approach relies on the careful review of the history of the event, a discerning physical examination, and analysis of the 12-lead electrocardiogram (ECG). Using this clinical information and an ECG, the cause of a syncopal episode is determined in many cases (approximately 50% of cases) and provides a safe and effective disposition plan for those patients in whom the cause is ellusive.29, 30

Section snippets

Etiology

The clinical evaluation of patients with sudden loss of consciousness must consider the pathophysiology of syncope and the vast array of underlying diagnoses that may present as syncope (Table 1).22, 33, 34, 37 The most common reported causes for syncope include the following, in descending order: undetermined cause, neurally mediated syncope, arrhythmia, neurologic causes (including seizure), orthostatic hypotension, and situational syncope.22

PATHOPHYSIOLOGY

Normal function of specific CNS structures (e.g., the reticular activating system, cerebral cortices), is required for the preservation of consciousness. Hypoperfusion of these structures may cause syncope. Such reductions of blood flow occur with transient systemic hypotension or with regional hypoperfusion, such as with vasoconstriction of cerebral arteries as in hyperventilation (resulting in hypocapnea) or interruptions by atherosclerotic processes.

Syncope can indicate underlying neurologic

EMERGENCY EVALUATION

Essential to the clinical evaluation of syncope in the ED is the determination of an accurate diagnosis, or a risk stratification of those patients without a firm diagnosis so that appropriate treatment decisions can be made. An appropriate history, physical examination, and limited diagnostic testing (e.g., ECG and rhythm monitoring) are sufficient to either establish the diagnosis or furnish sufficient information to determine whether further diagnostic testing or hospitalization is necessary

TREATMENT AND DISPOSITION

Treatment of syncope is directed at symptomatic support, modification or discontinuation of medications causing the loss of consciousness, management of the underlying disorder (e.g., use of pacemaker for third-degree AV block) and avoidance of activities in which syncope could endanger either the patient or others (e.g., swimming or driving a car). There are no standard guidelines for when a patient can resume all activities after a syncopal event, and emergency physicians should be aware of

CONCLUSION

In summary, when evaluating a patient with loss of consciousness, the emergency physician should differentiate syncope from other causes, such as seizure. Historical factors, as well as careful attention to the physical examination and the ECG are the most important elements to the initial assessment of the syncopal patient. The cause of the syncopal event is unexplained for many patients, and therefore the use of clinical guidelines for risk stratification helps to guide decisions on whether

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  • Address reprint requests to Oliver W. Hayes, DO, FACEP, Section of Emergency Medicine, College of Osteopathic Medicine, B-305-C West Fee Hall, Michigan State University, East Lansing, MI 48824–1316

    *

    Division of Emergency Medicine, Michigan State University, East Lansing, Michigan

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