Syncope is defined as a transient loss of consciousness and accounts for an estimated 1% to 3% of emergency department (ED) visits.
While syncope typically is of benign origin, it occasionally signals significant mortality and morbidity, which can make determining the disposition of syncope patients a challenge.
The San Francisco Syncope Rule (96% sensitivity, 62% specificity) is a clinical tool used to determine which syncope patients are at low risk for a short-term (7-day) serious outcome (i.e. MI, arrhythmia, PE, stroke, SAH, significant hemorrhage, any condition causing or likely to cause a return ED visit or hospitalization). Specifically, absence of all of the following 5 findings (acronym CHESS) were associated with no serious outcome within 7 days of the syncopal episode according to this rule:
Congestive heart failure
Hematocrit less than 30
EKG Abnormalities
Systolic BP less than 90
Shortness of breath
While this decision rule, in addition to one's clinical skill, may be used as a guide in caring for and dispositioning syncopal patients, know that its ability to be extrapolated to a general population of ED patients has yet to be validated.
References
Birnbaum A, et al. "Failure to Validate the San Francisco Syncope Rule in an Independent Emergency Department Population." Annals of Emergency Medicine. August 2008, 52 (2): 151-9.
Quinn J, et al. "Derivation fo the San Francisco Syncope Rule to Predict Patients with Short Term Serious Outcome." Annals of Emergency Medicine. Febuaruy 2004, 43(2).
