Emergency Central is a collection of disease, drug, and test information including 5-Minute Emergency Medicine Consult, Davis’s Drug, McGraw-Hill Medical’s Diagnosaurus®, Pocket Guide to Diagnostic Tests, and MEDLINE Journals created for emergency medicine professionals. Explore these free sample topics:
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- Transient loss of consciousness associated with loss of postural tone
- Ultimately, it is the lack of oxygen to the brainstem reticular-activating system, which results in a loss of consciousness and postural tone.
- Most commonly, an inciting event causes a drop in cardiac output.
- Cerebral perfusion is re-established by autonomic regulation as well as the reclined posture, which results from the event.
- Accounts for 3% of ED visits
- Pregnant patients frequently experience presyncope or syncope from various causes. 5% of patients experience syncope, 28% experience presyncope throughout their pregnancy.
- Placenta acts as an AV malformation, causing decreased SVR that potentiates orthostatic symptoms.
- Fetus lying on IVC can lead to neurogenic and hypovolemic syncope.
- Pregnant patients at higher risk of DVT/pulmonary embolism (PE), UTI, seizures (preeclampsia), valvular incompetencies. Must exclude these diagnoses in ED evaluation.
- Elderly with highest incidence as well as increased morbidity
- >1/3 will have numerous potential causes.
- Neutrally mediated syncope:
- Reflex response causing vasodilatation and bradycardia with resulting cerebral hypoperfusion
- Vasovagal (common faint):
- Often incited by pain or fear
- Prodromal findings are usually present.
- Typically lasts <20 sec
- Tilt-table testing is the gold standard to diagnose.
- Carotid sinus syncope:
- Cough, sneeze
- GI stimulation (e.g., defecation)
- Positional changes cause abrupt drop in venous return to heart.
- Volume depletion:
- Severe dehydration (e.g., vomiting, diarrhea, diuretics)
- Hemorrhage (see “Hemorrhagic Shock”)
- Autonomic failure:
- Diabetic or amyloid neuropathy
- Parkinson disease
- Drugs (e.g., β-blockers) and alcohol
- Cardiac arrhythmias:
- Typically sudden and without prodromal symptoms
- Tachydysrhythmia or bradydysrhythmia
- Inherited syndromes (e.g., long QT syndrome, Brugada syndrome)
- Pacemaker/implantable cardioverter defibrillator malfunction
- Structural cardiac or cardiopulmonary disease:
- Valvular disease (especially aortic stenosis)
- Hypertrophic cardiomyopathy
- Acute myocardial infarction
- Aortic dissection
- Pericardial tamponade
- Pulmonary embolus
- Transient spike in intracranial pressure that exceeds cerebral perfusion pressure
- Postsyncopal headache is almost universal
- May be presentation of a subarachnoid hemorrhage
- Cerebrovascular steal syndromes