Syncope, or fainting, is a temporary loss of consciousness, usually caused by decreased blood flow to the brain. Syncope is a symptom, rather than a disease itself, and has many causes. The vasovagal faint, which usually occurs in young, otherwise healthy people, is one particular form of syncope. Syncope accounts for about 300,000 emergency department visits per year, and about 6% of hospital admissions.
Syncope usually begins while a person is either sitting or standing upright. Sometimes, the onset may be almost instantaneous. In other cases, up to a few minutes before the attack there may be warning symptoms such as:
- profuse sweating (diaphoresis)
- nausea or vomiting
- light-headedness or weakness
- confusion or anxiety
- blurry or dim vision
- ringing in the ears
The patient usually becomes very pale and collapses. Loss of consciousness can last from seconds to several minutes. During this time, the patient may have a slight awareness of the situation, or may lose consciousness completely. During this time there may be some twitching or jerking of the body, but not usually incontinence or biting of the tongue; this helps distinguish the episode from a seizure. The patient's blood pressure is usually low with a weak pulse, but the heart rate may be fast or slow. Breathing is often very slow or shallow.
As the person lies flat, blood flow returns to the brain. The patient's vital signs, color, and alertness improve. Depending on the cause, the patient may have no sequelae (continuing symptoms), or may remain weak, confused, nauseated, or sweaty. A patient who tries to get up too soon may faint again.
Causes and symptoms
Dozens of different underlying problems can cause syncope; some are life-threatening, others are of little importance. Here is one way to classify them.
Orthostatic, or postural, syncope occurs when the body cannot supply enough blood to the brain in the upright position because of low blood pressure. The patient may have minimal symptoms of illness while lying flat, but becomes very faint when standing. Causes include:
The heart itself is the source of many episodes of syncope. There are numerous possible mechanisms. For example, certain cardiac arrhythmias (irregular heartbeat) reduce the output of the heart. In severe bradycardia (slow heartbeat), the ventricles beat too slowly to supply enough blood to the brain. In rapid tachycardias (rapid heartbeat), the heart beats quickly but very inefficiently, so relatively little blood and oxygen reach the brain.
Reflex-mediated syncope occurs when a certain stimulus triggers a bodily response that lowers the cardiac output. The most common example of this is the vasovagal faint (also known by many other names, including simple faint or neurocardiogenic syncope). This condition typically affects young, otherwise healthy people who experience something very unpleasant, such as pain, fear, or horror. Nervous system reflexes cause the blood pressure, and often the pulse, to drop. The patient experiences warning symptoms such as sweating, nausea, and light-headedness, and then faints if not able to lie down quickly. Other reflex-mediated faints often involve the Valsalva maneuver (taking a deep breath and bearing down), as when straining to urinate, defecate, cough, or lift a heavy object.
Medications may lead to fainting by their direct effects of lowering the blood pressure (anti-hypertensives, nitroglycerine) or slowing the heart rate (digoxin). Some drugs may promote arrhythmias (tricyclic antidepressants). Other drugs that may cause syncope include antiparkinsonians, phenothiazines and other antipsychotics, insulin and other hypoglycemics, alcohol, and cocaine.
Neurologic causes of syncope include stroke and transient ischemic attack, subarachnoid hemorrhage, and migraine. In these cases a part of the brain does not receive its normal blood supply, and the patient loses consciousness. Seizure is the condition most often mistaken for syncope, because patients with true seizures often lose consciousness as well.
The challenge for health professionals is to determine the cause of an episode of syncope, and especially whether the cause requires further medical intervention.
Antiparkinsonian—A drug which treats Parkinson's disease.
Aortic aneurysm—A dangerous widening and weakening of the wall of the aorta.
Aortic stenosis—A narrowing and stiffening of the aortic valve of the heart.
Arrhythmia—An abnormal beating pattern of the heart.
Bradycardia—Heart rate less than 60 beats per minute.
Cardiomyopathy—A disease which weakens the heart muscle.
Ectopic pregnancy—A dangerous condition in which a woman becomes pregnant but the pregnancy grows outside the uterus.
Incontinence—Loss of control over the release of urine or the bowels.
Myocardial infarction—Heart attack, or death of some part of the heart muscle.
Neurocardiogenic—Arising from the nervous and cardiac systems of the body.
Orthostatic—Related to being upright.
Pericardial tamponade—A condition in which fluid accumulates in the pericardium, the sac that surrounds the heart. This restricts the amount of blood that can enter the heart's chambers.
Sequelae—Conditions which result from an event.
Subarachnoid hemorrhage—A dangerous condition of bleeding within the subarachnoid space of the brain.
Tachycardia—Heart rate greater than 100 beats per minute.
Transient ischemic attack (TIA)—A temporary interruption of the blood supply to part of the brain that causes a reversible impairment of some brain function.
Valsalva maneuver—The act of taking a deep breath and bearing down forcefully. This may be done intentionally, or as part of straining to move the bowels, urinate, or lift a heavy object, for example.
Nurses and aides are invaluable when they obtain details of the patient's episode not only from the patient, but also from family or friends, witnesses, and rescue personnel. The staff must not allow such people to leave without providing information, as well as phone numbers for further contact. Nurses and aides should focus on:
- the precise sequence of events leading up to, and following, the faint
- associated features (tongue biting, incontinence)
- the patient's memory of the event and any associated symptoms (pain, focal numbness or weakness, recent illness)
- past similar events and other medical history
- prescribed medications and how the patient takes them
- use of illicit drugs or alcohol
- possible emotional stress
- menstrual history
- record vital signs frequently including oxygen saturation
- attach a cardiac monitor
- undress the patient completely
- observe for physical signs such as sweating, pallor, restlessness, confusion, or pain
- immediately communicate all abnormal findings to the physician
The patient likely will require blood work (complete blood count, blood chemistries, cardiac enzymes, and perhaps blood typing and coagulation studies) and urine tests (pregnancy, urinalysis, and drug screen), usually performed by a clinical laboratory technician. An EKG technician or the nurse will record an electrocardiogram, and the nurse may check bedside blood sugar determination and stool guaiac. The nurse will either initiate these directly or check first with the physician, depending on local policies. In all cases the nurse must not allow the patient to void or defecate without collecting a specimen.
If the patient has no discernable pulse or respiration, the nurse and all available personnel immediately start cardiopulmonary resuscitation and summon help. The nurse and respiratory technician must ensure adequate oxygenation. The nurse starts an intravenous line (IV) in all but the least serious cases, and begins normal saline infusion if the blood pressure is low or the pulse is fast. The patient may need two large-bore IVs to replace fluids in a case of severe reduction in blood volume, or to receive drips of cardiac medications.
The nurse must give the patient nothing by mouth if there is any likely surgical cause of the problem (such as ruptured ectopic pregnancy), or if nausea persists. If the patient is about to vomit, the staff must quickly put the head down and roll the patient to the side. The nurse or aide should loosen tight clothing. The staff should keep the patient supine until clearly improved; thereafter, the patient may rise slowly while the nurse or aide checks for orthostatic pulse and blood pressure changes. More specific treatment depends on the underlying cause of the event.
The prognosis depends on such factors as the underlying cause of the problem, length of unconsciousness, injuries that may have occurred when fainting, and the patient's ability to modify circumstances that may have contributed to the event (learning to rise slowly, stopping alcohol abuse, switching to different medications).
Health care team roles
The nurse, typically in the emergency department, initially receives the patient, makes the initial assessment of the patient's condition, often begins early diagnosis and treatment measures, continues to monitor the patient, and communicates all relevant information to the physician. The nurse's aide helps prepare the patient for examination and assists the rest of the care team. The laboratory technician helps collect specimens and process them in the lab. The EKG technician records one or more cardiograms and may help with other heart monitoring tests. A respiratory technician assists when there is difficulty breathing, and may perform an arterial blood gas. Radiology technicians carry out required x-ray tests. A social worker may discuss the patient's living situation with the patient, family, and caregivers, and help arrange future assistance.
The nurse must provide clear instructions to the patient and caregivers. The patient may need to alter behavior (eat regularly, avoid stressful situations), stop or start various medications, have further tests or appointments, and understand warning signs requiring an immediate return to the hospital.
Blok, Barbara K. "Syncope." In Emergency Medicine: A Comprehensive Study Guide, edited by Tintinalli, Judith E., Gabor D. Kelen, and J. Stephan Stapczynski. 5th ed. New York: McGraw-Hill, 2000, pp.352-6.
Daroff, Robert B. and Joseph B. Martin. "Faintness, Syncope, Dizziness, and Vertigo." In Harrison's Principles of Internal Medicine, edited by Fauci, Anthony S., et al. 14th ed. New York: McGraw-Hill, 1998, pp. 100-4.
Rosenthal, Lawrence S. and Robert S. Mittleman. "Syncope." In Irwin and Rippe's Intensive Care Medicine, edited by Irwin, Richard S., Frank B. Cerra, and James M. Rippe. 4th ed. Vol. 1. Philadelphia: Lippincott-Raven, 1999, pp. 377-86.
Kenneth J. Berniker, M.D.