Approach to the adult patient with syncope in the emergency department
- Daniel McDermott, MD
Daniel McDermott, MD
- Associate Clinical Professor of Emergency Medicine
- University of California at San Francisco
- James Quinn, MD, MS
James Quinn, MD, MS
- Professor of Emergency Medicine
- Stanford University
Syncope is a transient loss of consciousness, associated with loss of postural tone, with spontaneous return to baseline neurologic function requiring no resuscitative efforts. The underlying mechanism is global hypoperfusion of both the cerebral cortices or focal hypoperfusion of the reticular activating system. It is not to be confused with loss of consciousness associated with altered mental status or stroke and similarly in vague dizziness and chronic lightheadedness in patients with pre-syncope. To address this issue an international consortium gathered to define syncope and standardize the reporting of outcomes to guide future research .
Syncope is a common complaint in the emergency department (ED), accounting for 1 to 3 percent of all ED visits and hospital admissions in the United States [2-6]. Although most potential causes are benign and self-limited, others are associated with significant morbidity and mortality. The differential diagnosis is broad, and management focuses on the underlying cause when this is discernible. However, during the ED evaluation the cause of syncope often remains unclear and management must focus on risk stratification to differentiate among patients safe for discharge and those who require emergent investigation and in-hospital management. Presyncope (ie, near loss of consciousness) and true syncope should be considered a spectrum of the same symptom. Although near syncope is less dramatic and some of the studies and guidelines about its significance less compelling, clinicians should approach them in similar fashion.
When researchers have made a clear effort to distinguish true presyncope from dizziness and vague lightheadedness the outcomes of syncope and near or presyncope parallel on another in terms of significant underlying causes and serious outcomes . In a recent study, researchers in Canada specifically addressed a presyncopal cohort and concluded that patients with pre-syncope can have significant underlying causes .
This topic review will discuss how to evaluate and manage patients presenting to the ED with syncope. Detailed discussions of specific types of syncope and the evaluation of syncope in children and adults are found elsewhere. (See "Pathogenesis and etiology of syncope" and "Reflex syncope" and "Emergent evaluation of syncope in children and adolescents".)
Syncope has many causes that are often difficult to determine in the emergency department (ED). After reviewing the history, physical examination, and the electrocardiogram (ECG) physicians in the ED are able to determine a clear underlying diagnosis only about 50 percent of the time [9,10]. Patients often remain undiagnosed despite exhaustive diagnostic testing [4,11]. Tables listing the most dangerous and most common etiologies of syncope are provided (table 1 and table 2 and table 3).
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- Authors' unpublished data.
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- DIFFERENTIAL DIAGNOSIS
- Life-threatening conditions
- Common conditions
- Other conditions
- PHYSICAL EXAMINATION
- ANCILLARY STUDIES
- - Cardiac monitoring
- Laboratory evaluation
- Neurologic studies
- APPROACH TO DIAGNOSIS
- RISK STRATIFICATION
- PATIENT DISPOSITION
- SUMMARY AND RECOMMENDATIONS