Vasovagal syncope is a brief loss of consciousness preceded by a sense of anticipation. It occurs when there is an initial increase in sympathetic tone and pulse/blood pressure in response to stress, followed by a precipitous drop in sympathetic tone, pulse, and blood pressure, causing fainting. When it occurs in the ED, patients should be made to lie down and monitored for recovery without injury or sequelae. The diagnosis involves understanding the context, stressor, and recovery sequence. Preventing fainting involves recognizing early signs and avoiding standing during unpleasant experiences.

1. Vasovagal Syncope (Faint, swoon)
Presentation
The patient experiences a brief loss of consciousness, preceded by a sense of
anticipation. First, there is a period of sympathetic tone, with increased pulse
and blood pressure, in anticipation of some stressful incident, such as bad
news, an upsetting sight, or a painful procedure. Immediately following the
stressful occurrence, there is a precipitous drop in sympathetic tone, pulse
and blood pressure,causing the victim to fall down or lose consciousness.
Transient bradycardia and few clonic limb jerks may accompany vasovagal
syncope, but there are usually no sustained palpitations, arrhythmias or
seizures, incontinence, tongue biting, or injuries beyond a contusion or
laceration from the fall. Ordinarily, the victim spontaneously revives after
spending a few minutes supine, and suffers no sequelae, and can recall the
events leading up to the faint. The whole process may transpire in the ED, or
a patient may have fainted elsewhere, in which case the diagnostic challenge
is to reconstruct what happened and rule out other causes of syncope.
What to do:
• Arrange for patients, family, and friends anticipating unpleasant
experiences in the ED to sit or lie down and be constantly attended.
• If someone faints in the ED, catch him so he is not injured in the fall,
lie him supine onthe floor for 5-10 minutes, protect his airway,record
several sets of vital signs, and be ready to proceed with resuscitation if
the episode turns out to be more than a simple vasovagal syncope.
• If a patient is brought to the ED following a faint elsewhere, ask about
the setting, precipitating factors, descriptions of several eyewitnesses,
and sequence of recovery. Be alert for evidence of seizures, hysteria,
and hyperventilation (see sections below). Record several sets of vital
signs, including orthostatic changes, and examine carefully for signs of
trauma and neurologic residua.
• After full recovery, explain to the patient that this is a common
physiological reaction and how, in future recurrences, he can recognize
the early lightheadedness and prevent a full swoon by lying down or
putting his head between his knees.
What not to do:
• Do not let families stand for bad news, let parents stand while
watching their children being sutured or let patients stand for shots or
venipunctures.
• Do not traumatize the faint victim with ammonia capsules, slapping, or
dousing with cold water.

2. Discussion
Vasovagal syncope is a common occurrence in the ED. Observation of the
sequence of stress, relief, faint makes the diagnosis, but, better yet, the
whole reaction can usually be prevented. It should be noted that although
most patients suffer no sequelae, vasovagal syncope with prolonged asystole
can produce seizures as well as rare incidents of death. The differential
diagnosis of a loss of consciousness is extensive and therefore loss of
consciousness should not immediately be assumed to be due to vasovagal
syncope.