Fainting

/Home/Alzheimer's Symptoms/Alzheimer's and Fainting

FAINTING OVERVIEW

Fainting, which medical professionals call syncope (pronounced SIN-ko-pea), is a temporary loss of consciousness. Unlike a seizure, the person who faints usually regains alertness soon after regaining consciousness. Fainting is caused by a temporary loss of the brain’s blood supply. Fainting can sometimes be a sign of a more serious condition.

People of any age can faint, but elderly persons more often have a serious underlying cause.
- Three percent of adults aged 30-62 years have an episode of syncope, but 6% of those older than 75 years faint.

- Syncope accounts for 1-3% of emergency department visits and 1-6% of hospital admissions.

- The biggest risk is in people with heart disease, especially those with congestive heart failure or coronary heart disease.
 

FAINTING CAUSES

Fainting has many different causes.

Vasovagal syncope: Also known as the "common faint," this is the most frequent cause of syncope. It results from an abnormal circulatory reflex. The heart pumps more forcefully and the blood vessels relax, but the heart rate does not compensate fast enough to maintain blood flow. People older than 45 years rarely experience a first "common faint." Causes of vasovagal syncope include the following:

- Environmental factors - Most commonly in a hot, crowded setting

- Emotional factors - Stress or the sight or threat of injury

- Physical factors - Standing too long with locked knees

- Illness - Fatigue, hypoglycemia (low blood sugar), dehydration, or other current illness


Situational syncope: Susceptible people have episodes of syncope only in particular situations. Causes of situational syncope include the following:

- Cough syncope occurs in people with lung disease when coughing forcefully.

- Swallow syncope occurs upon swallowing in some people with disease in the throat or esophagus.

- Micturition syncope occurs when a susceptible person empties an overfilled bladder. It is most common in males who are intoxicated with alcohol.

- Carotid sinus hypersensitivity occurs in some elderly people when turning the neck, shaving, or wearing a tight collar.

- Postprandial fainting can occur in elderly people when their blood pressure falls about an hour after eating.


Postural syncope: This occurs when a person lying down, who feels perfectly well and alert, sudden faints upon standing up. The brain's blood flow decreases when they stand owing to a drop in blood pressure. This sometimes occurs in people who have recently started or changed certain cardiovascular medications. This type of fainting results from either or both of the following causes:

- Low circulating blood volume, caused by blood loss (external or internal), dehydration, or heat exhaustion

- Impaired circulatory reflexes, caused by many medications, disorders of the nervous system, or congenital problems


Cardiac syncope: Heart disease causes a person to faint by a variety of mechanisms. Cardiac causes of fainting are generally life threatening. They include the following:

- Cardiac rhythm abnormality ( arrhythmia): Electrical problems of the heart impair its pumping ability. This causes a decrease in blood flow. The heart rate may be either too fast or too slow to pump blood well. This condition usually causes fainting without any warning symptoms.

- Cardiac obstruction: Blood flow can be obstructed within the blood vessels in the chest. Cardiac obstruction can cause fainting during physical exertion. A variety of diseases cause obstruction, including heart attacks, diseased heart valves, pulmonary embolism, cardiomyopathy, pulmonary hypertension, cardiac tamponade, and aortic dissection.

- Heart failure: The heart's pumping ability is impaired. This lowers the force with which blood circulates through the body and may decrease blood flow in the brain.


Neurologic syncope: Neurologic problems cause fainting (or loss of consciousness) by various mechanisms.

- Seizures are a cause of unconsciousness but are different from fainting. With seizures, the blood flow to the brain does not decrease. Unconsciousness results from disordered electrical discharges within the brain. Seizure typically causes prolonged (longer than 8 seconds) shaking of the arms and legs followed by confusion and disorientation after awakening.

- Stroke (bleeding in the brain) can cause syncope associated with headache.

- Transient ischemic attack (TIA or mini-stroke) can cause fainting, usually preceded by double vision, loss of balance, slurred speech, or vertigo (a spinning sensation).

- Other rare causes include certain tongue problems and migraines.


Psychogenic syncope: Hyperventilation from an anxiety disorder can cause fainting. Rarely, people pretend to faint to minimize stress or for some recognized gain.


FAINTING SYMPTOMS

Unconsciousness is an obvious sign of fainting.


Vasovagal syncope

- Before fainting, you may feel light-headed and shaky and experience blurred vision.
 
- You may "see spots in front of your eyes."
 
- During this time, observers note paleness, dilated pupils, and sweating.
 
- While unconscious, you may have low pulse rate (less than 60 beats/minute).
 
- You should quickly regain consciousness.


Situational syncope

- Consciousness returns when the situation is over, usually very quickly.


Postural syncope

- You may have noted a blood loss (black stools, heavy menstrual periods) or fluid loss (vomiting, diarrhea, fever).
 
- You may have experienced light-headedness when sitting or standing.
 
- Observers may note paleness, sweating, or signs of dehydration (dry lips and tongue).


Cardiac syncope

- You may report palpitations (awareness of pounding, fast, or abnormal heartbeat), chest pain, or shortness of breath.
 
- Observers may note a weak, abnormal pulse, paleness, or sweating.
 
- Syncope often occurs without warning or following exertion.


Neurologic syncope

- You may have headache, loss of balance, slurred speech, double vision, or vertigo (a feeling that the room is spinning).
 
- Observers note a strong pulse during the unconscious period and normal skin color.


Seizures

People experiencing a seizure may report strange sensations that precede the unconscious period. (This is referred to as an aura.)

- Incontinence (inability to hold urine or stool) is common.

- If observers are present during the seizure, they note sustained convulsions (lasting longer than 8 seconds).
 
- A prolonged period of confusion, lasting several minutes, follows the seizure.
 
- During a seizure, people often scrape themselves or bite their tongues.


WHEN TO SEEK MEDICAL CARE

Because fainting can be caused by a serious condition, you should be transported to a hospital emergency department in an ambulance. Calling your health care provider may waste time.

The only exceptions are people who meet certain conditions.

- If all of these conditions apply, and you have a primary health care provider who is familiar with your medical condition, you may not have to go to the hospital.

- Have a family member or companion call your health care provider and ask if you should be taken to the hospital.

- If your health care provider is not available within 15 minutes, you should go to the hospital.

- Do not attempt to drive yourself; call 911 for emergency transport.


The following conditions may make a trip to the hospital unnecessary:

- Recurrent fainting or obvious vasovagal syncope in a healthy person younger than 30 years

- No other obvious symptoms present

- No known heart disease, high blood pressure, or bleeding or blood clotting problems
 

EXAMS AND TESTS

The cause of fainting is determined in only half of cases.

- Most diagnoses are made through a medical history and physical examination along with an electrocardiogram, or ECG (heart tracing).

- ECG findings that are normal are reassuring.

- Further testing is based on the findings of this initial evaluation.

Cardiac syncope: If a cardiac cause is suspected, several tests are available. Most are used to identify coronary heart disease, heart failure, or arrhythmias.

Noncardiac syncope: Testing depends on the suspected cause. A CT scan is useful only if seizure, stroke, or significant head injury is suspected. Head-up tilt testing is useful to diagnose vasovagal syncope.


FAINTING TREATMENT -- SELF-CARE AT HOME

If possible, help the person who has fainted to the ground to minimize injury.

Stimulate the person vigorously (yelling, briskly tapping). Call 911 immediately if the person does not respond.

Check for the pulse in the neck and begin CPR, if needed.

After the person recovers, encourage him or her to lie down until medical help arrives. Even if you believe the cause of the fainting is harmless, have the person lie down for 15-20 minutes before attempting to get up again.

Ask about any persistent symptoms, such as headache, back pain, chest pain, shortness of breath, abdominal pain, weakness, or loss of function, because these may indicate a life-threatening cause of the fainting.


MEDICAL TREATMENT

The treatment of fainting depends on the diagnosis.


Vasovagal syncope

- Lifestyle alterations: Drink plenty of water, increase salt intake (under medical supervision), and avoid prolonged standing.

- Medications: Medication may be prescribed if episodes are frequent.


Postural syncope

- Lifestyle alterations: Sit up and flex calf muscles for a few minutes before getting out of bed. Avoid dehydration. Elderly people with low blood pressure after eating should avoid large meals or plan to lie down for a few hours after eating.

- Medications: In most cases, medications that cause fainting are withdrawn or changed.


Cardiac syncope

- Medication and lifestyle alterations: These treatments are designed to optimize the heart's performance while limiting its demands. Controlling high blood pressure, for example, would call for a medication and lifestyle change. In some cases, specific anti-arrhythmic medication may be prescribed.

- Surgery: Bypass surgery or angioplasty is used to treat coronary heart disease. For some valve problems, valves can be replaced. Catheter ablation is available to treat some arrhythmias.

- Pacemaker: A pacemaker may be implanted to slow the heart in certain types of fast arrhythmias.

- Implanted defibrillators are used to control life-threatening fast arrhythmias.
 

NEXT STEPS -- FOLLOW-UP

If the cause of fainting or syncope is not determined, and you are not hospitalized, you should see your health care provider within a few days. Learn to check your own pulse and teach your family members what to do in case you faint again.

Many people never faint again after the first time.

You may be referred to a heart specialist if cardiac syncope is suspected.

If neurologic disease is suspected during the emergency department evaluation, you should be referred to a neurologist.


PREVENTION

Preventive measures depend on the cause and the severity of the fainting problem. Fainting can sometimes be prevented by taking simple precautions.

- If you faint in hot rooms, the solution is obvious: Avoid hot rooms.

- If you faint while standing up from a lying down position, take care to move slowly when standing up. Move slowly to a sitting position and rest a few minutes. When you are ready, stand up, using slow and fluid movements.

In other cases, the cause of fainting can be elusive. Several visits to your health care provider may be needed to establish a pattern of when fainting occurs and thus a diagnosis. Once the cause is determined, treatment can be started to prevent further episodes.

Cardiac syncope: Because of the high risk of death from cardiac syncope, people who experience it and their family members must understand their disease and its treatment (especially controlling the condition through diet and medications).

- Follow the recommendations of your health care provider precisely.

- Take prescribed medications regularly.

- Many elderly people either cannot afford or cannot remember to take their medications and need help from family members.

Recurrent syncope: See your health care provider about testing to establish a diagnosis if you faint periodically. Ask your health care provider about driving. Many states have laws applying to people who have a history of losing consciousness.


OUTLOOK

The prognosis of a person who has fainted depends greatly on the underlying cause. In one study, 25% of people (average age 61 years) with a cardiac cause of syncope died within 1 year. Many of them died suddenly. Fainting that is not associated with cardiac or neurologic disease, however, presents no special risk.


MULTIMEDIA

Media file 1: Checking for the pulse in the neck. The pulse is felt just beside the throat (trachea). If a pulse is felt, note whether it is regular and count the number of beats in 15 seconds. The heart rate (beats per minute) is this number multiplied by 4. Try this on yourself! A normal adult heart rate is between 60 and 100 beats per minute.


SYNONYMS AND KEYWORDS

fainting, cardiac syncope, common faint, lose consciousness, loss of consciousness, pass out, passing out, unconscious, unconsciousness, vasovagal syncope

___
WebMD Medical Reference from eMedicineHealth

Authors and Editors

Author: Michael D Witting, MD, Research Director, Assistant Professor, Department of Surgery, Division of Emergency Medicine, University of Maryland School of Medicine.

Editors: Scott H Plantz, MD, FAAEM, Research Director, Assistant Professor, Department of Emergency Medicine, Mount Sinai School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; James S Cohen, MD, Consulting Staff, James Cohen, PC.

Reviewed on August 10, 2005