Fainting is a falling down and the loss of consciousness that occurs for a brief interval, typically less than one minute. Not enough blood reaching the brain usually causes an episode of fainting. The most common reasons for fainting in adolescents are standing in one position for a long time with the knees locked, a sudden stress such as having blood drawn or receiving a vaccination, standing up suddenly especially after resting in bed and severe pain.
When a teen stands in one position for a long time, blood collects in the lower part of the body, especially the legs. As a result, there is less blood in the upper part of the body including the brain. A vascular reflex where the walls of the blood vessels relax and blood collects in the enlarged vessels contributes to a fainting episode. A vascular reflex can also be caused by emotional upsets and crowded hot surroundings. Vigorous exercise and resultant dehydration may contribute to lower blood pressure and could also cause a fainting episode.
Neurally mediated fainting can occur in three forms. In one form, the heart rate slows and less blood is pumped to the brain. In another form, the heart rate is steady, but nervous signals cause the blood pressure to decrease and less blood reaches the brain. And in the third form of neurally mediated fainting, there are combinations of both slowing of the heart rate and decrease in the blood pressure.
Who is likely to faint?
Between the ages of eight and eighteen years about ! Five percent of children and adolescents will have at least one fainting episode. Most of the teens who faint do not have underlying disease although adolescents with heart problems may have a higher chance of fainting. Students in standing formation during hot weather, for example, at a military academy graduation may be subject to fainting especially if they are dehydrated. The medical term for this is neurocardiogenic fainting. Vasovagal faint could occur in an adolescent who has blood drawn. Some teens, when they are ill for example with influenza, may faint on coughing or during urination. These are also vasovagal faints. A hysterical faint usually occurs when there is an “audience” to view the episode. In this case, the individual usually has a gentle, graceful swoon. And fainting may occur when the teen is dehydrated. This may occur during athletic competition and the teen has inadequate hydration. Or a teen on diuretics, a medication that causes increased urination, could faint from dehydration under some circumstances. Pregnant teens may also be more susceptible to fainting. And adolescents with anorexia may be prone to fainting due to low blood pressure and a slow pulse.
Adolescents with certain types of heart disease may be prone to fainting. For example, some heart rhythm disturbances, problems with the flow of blood from the left ventricle or problems with the coronary arteries may cause a fainting episode.
What are they symptoms of fainting?
There may be no symptoms before an individual faints and loses consciousness. More typically, the teen may feel nauseous or sweaty. The heart rate may increase rapidly or become irregular. Some teens feel as if their heart is jumping around in their chest. The teen becomes pale, lightheaded, dizzy and weak. He or she then faints.
How is fainting evaluated?
The clinician will obtain a medical history and perform a physical examination. It is especially important to obtain a thorough history around the time of the fainting episode. Any reports from individuals who observed the adolescent fainting are important. Sometimes that is all that is needed especially if the faint occurred around the time of a blood test or vaccination. Weight, height, blood pressure and pulse (vital signs) will usually be obtained.
However, the clinician may need to do other tests to determine the cause of fainting. These may include a blood count to rule out anemia, and blood chemistries may be drawn to examine for low blood sugar or other electrolyte disturbances.
An electrocardiogram may be ordered to detect heart rhythm problems and an echocardiogram to outline the heart anatomy. Sometimes the heart rhythm is studied over a twenty-four-hour period with a Houlter monitor. If the fainting episode occurred during exercise, it is especially important that the heart anatomy be checked to see if there is an abnormality with the heart called Hypertrophic Cardiomyopathy. The coronary arteries should also be checked by ultrasound, and a cardiologist may be consulted.
At times, it is not clear if the adolescent has suffered a fainting episode or a seizure. In this case, an electroencephalogram may be performed to determine if the teen has a seizure disorder. A neurologist may also be consulted.
A tilt-table test may be ordered for the teen who faints after standing in one position over a long period of time. In this test, the teen lies on his or her back on the table, and the vital signs including pulse and blood pressure are observed for a few minutes. The table is gradually tilted to a nearly upright position and the pulse, blood pressure and any symptoms are noted. Sometimes, a medication is given to increase the teen’s heart rate and this allows the clinician to determine if the body responds normally to an increased rate and sends the pooled blood back to the brain.
How is a faint treated?
If the teen is unconscious and breathing normally, he or she should be placed in a flat position on his or her back. Then one should raise his or her legs above the level of the chest in order to return more blood to the brain. If the teen is unconscious and has no pulse or is not breathing, then give CPR and call 911 for help. After the teen recovers, then fluids such as orange juice are helpful. The adolescent should lie down for ten to fifteen minutes after he or she returns to consciousness.
How is fainting prevented?
If there is a cause for the fainting episode, then treatment can be aimed at the cause. For example, if a teen faints when having a blood test, then a special chair and observation usually prevent a repeat episode of fainting. If fainting occurs on standing for long periods, then that type of situation could be avoided. Relaxing and retightening the leg muscles can help to propel blood to the brain in the standing situation. If there is a heart problem that leads to fainting, then the specific problem must be addressed. A problem with blood sugar may be treated with diet or medication. It is especially important for adolescent athletes to maintain good fluid balance during competition especially during hot and humid weather. Any fluid losses should be replaced with cold fluids including balanced electrolyte solutions or water. If fainting is due to low weight such as anorexia, then that medical problem will be addressed.
Related topics:
Diabetes, diuretics, exercise, first aid, immunizations, military service, seizures, sports
