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.
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
Graham DT, Kabler JD, Lunsford L: Vasovagal fainting: a diphasic response. Psychosomatic Medicine 1961;6:493-507.
Lin JTY, Ziegler DK, Lai CW, Bayer W: Convulsive syncope in blood donors. Ann Neurol 1982;11:525-528.