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Encyclopedia > Fainting
Name of Symptom/Sign:
Fainting
Classifications and external resources
ICD-10 R55.
ICD-9 780.2
DiseasesDB 27303
eMedicine med/3385  ped/2188 emerg/876
MeSH D013575

Fainting, also called syncope (IPA: [ˈsɪnkəpi] and [ˈsɪŋkəpi]), is a sudden, and generally momentary, loss of consciousness, or blacking out caused by the Central Ischaemic Response, because of a lack of sufficient blood and oxygen in the brain. The first symptoms a person feels before fainting are dizziness; a dimming of vision, or brownout; tinnitus; and feeling hot. Moments later, the person's vision turns black, and he or she drops to the floor (or slumps if seated in a chair). If the person is unable to slump from the position to a near horizontal position, he or she risks dying of the Suspension Trauma effect. Image File history File links Mergefrom. ... It has been suggested that this article or section be merged with Fainting. ... Meteora track listing Easier to Run (6) Faint (7) Figure. ... The term symptom (from the Greek meaning chance, mishap or casualty, itself derived from συμπιπτω meaning to fall upon or to happen to) has two similar meanings in the context of physical and mental health: Strictly, a symptom is a sensation or change in health function experienced by a patient. ... In medicine, a sign is a feature of disease as detected by the doctor during physical examination of a patient. ... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) is a coding of diseases and signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as classified by the World Health Organization (WHO). ... // R00-R99 - Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R09) Symptoms and signs involving the circulatory and respiratory systems (R00) Abnormalities of heart beat (R000) Tachycardia, unspecified (R001) Bradycardia, unspecified (R002) Palpitations (R008) Other and unspecified abnormalities of heart beat (R01) Cardiac murmurs and other... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... Consciousness is a quality of the mind generally regarded to comprise qualities such as subjectivity, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and ones environment. ... It has been suggested that this article or section be merged with Fainting. ... // Pre-syncope is a sensation of feeling faint. ... This article or section does not cite its references or sources. ... Tinnitus (IPA pronunciation: or ,[1] from the Latin word for ringing[2]) is the perception of sound in the human ear in the absence of corresponding external sound(s). ... Suspension trauma, also known as Harness Hang Syndrome (HHS) is an effect which occurs when the human body is held upright without any movement for a period of time. ...

Contents

Causes

Factors that influence fainting are taking in too little food and fluids, low blood pressure, hypoglycemia, growth spurts, physical exercise in excess of the energy reserve of the body, emotional distress, and lack of sleep. Even standing up too quickly or being in too hot a room can cause fainting. Recommended treatment is to allow the person to lie on the ground with his or her legs slightly elevated. As the dizziness and the momentary blindness passes, the person may experience visual disturbances in the form of small bright dots (phosphene). These will also pass within a few minutes. If fainting happens frequently, or if there is no obvious explanation, it is important to see a doctor about it. A sphygmomanometer, a device used for measuring arterial pressure. ... Hypoglycemia (hypoglycæmia in the UK) is a medical term referring to a pathologic state produced by a lower than normal level of glucose (sugar) in the blood. ... ... Entoptic phenomena are visual effects whose source is within the eye itself. ... A phosphene is an entoptic phenomenon characterized by the sensation of seeing light. ...


More serious causes of fainting include cardiac (heart-related) causes such as an abnormal heart rhythm (an arrhythmia), where the heart beats too slowly, too rapidly or too irregularly to pump enough blood to the brain. Some arrhythmias can be life-threatening. Other important cardio-vascular conditions that can be manifested by syncope include subclavian steal syndrome and aortic stenosis. Therefore smoking directly plays a role in syncope, as it affects the heart. It should be avoided at all costs by syncope patients. The heart and lungs, from an older edition of Grays Anatomy. ... A cardiac arrhythmia, also called cardiac dysrhythmia, is a disturbance in the regular rhythm of the heartbeat. ... In medicine, subclavian steal syndrome (SSS), also subclavian steal phenomenon and subclavian steal steno-occlusive disease, is a constellation of signs and symptoms that arise from retrograde (reversed) vertebral artery (blood) flow due to a proximal subclavian artery stenosis (narrowing) and/or occlusion. ... Aortic valve stenosis (AS) is a heart condition caused by the incomplete opening of the aortic valve. ...


Types

Vasovagal (situational) syncope, one of the most common types, may occur in scary or embarrassing situations or during blood drawing, coughing, or urinating. Other types include postural syncope (caused by a changing in body posture), cardiac syncope (due to heart-related conditions), and neurological syncope (due to neurological conditions). There are many other causes of syncope including low blood sugar levels and lung disease such as emphysema and a pulmonary embolus. The cause of the fainting can be determined by a doctor using a complete history, physical, and various diagnostic tests.


Vasovagal syncope

Main article: Vasovagal syncope

The vasovagal type can be considered in two forms: Vasovagal syncope is the most common cause of syncope, also known as fainting. ...

  • Isolated episodes of loss of consciousness, unheralded by any warning symptoms for more than a few moments. These tend to occur in the adolescent age group, and may be associated with fasting, exercise, abdominal straining or circumstances promoting vaso-dilatation (eg heat, alcohol). The subject is invariably upright. The tilt-table test, if performed, is generally negative.
  • Recurrent syncope with complex associated symptoms. This is so-called Neurally Mediated Syncope (NMS). It is associated with any of the following: preceding or succeeding sleepiness, preceding visual disturbance ("spots before the eyes"), sweating, light-headedness. The subject is usually but not always upright. The tilt-table test, if performed, is generally positive.

A pattern of background factors contributes to the attacks. There is typically an unsuspected relatively low blood volume, for instance, from taking a low salt diet in the absence of any salt-retaining tendency. Heat causes vaso-dilatation and worsens the effect of the relatively insufficient blood volume. That sets the scene, but the next stage is the adrenergic response. If there is underlying fear or anxiety (e.g. social circumstances), or acute fear (e.g. acute threat, needle phobia), the vaso-motor centre demands an increased pumping action by the heart (flight or fight response). This is set in motion via the adrenergic (sympathetic) outflow from the brain but the heart is unable to meet requirement because of the low blood volume, or decreased return. The high (ineffective) sympathetic activity is always modulated by vagal outflow, in these cases leading to excessive slowing of heart rate. The abnormality lies in this excessive vagal response. The tilt-table test typically evokes the attack. A tilt table test is a medical procedure often used to diagnose dysautonomia or syncope. ... A tilt table test is a medical procedure often used to diagnose dysautonomia or syncope. ...


Much of this pathway was discovered in animal experiments by Bezold (Vienna) in the 1860s. In animals, it may represent a defence mechanism when confronted by danger ("playing possum"). This reflex occurs in only some people and may be similar to that described in animals.


The mechanism described here suggests that a practical way to prevent attacks would be, counter-intuitively, to block the adrenergic signal with a Beta Blocker. But simpler plan is to explain the mechanism, discuss causes of fear, and optimise salt as well as water intake.


Pure cardiac syncope

Fainting can also occur if pressure on the carotid artery in the neck triggers a vagal signal to the Vaso-Motor Centre, reflexly causing a vagal response to slow the heart. A pure cardiac arrhythmia is a serious matter that can appear as syncope but this is unusual. Severe narrowing of the Aortic Valve leading to syncope is included for completeness.


Syncope from vertebro-basilar arterial disease

Arterial disease in the upper spinal cord, or lower brain, causes syncope if there is a reduction in blood supply, which may occur with extending the neck or after drugs to lower blood pressure.


Clinical symptoms

If the patient states, "I felt dizzy with blurry vision, muscle weakness, during the fall I bumped my knee, hit my head and passed out," then it is not syncope, it is termed pre or near-syncope.


If the patient states, "I felt dizzy, shadows came over my eyes, and when I woke up I was lying on the floor," then it is diagnosed as syncope.


Patients who experience a syncoptic episode do not remember falling.


See also

Orthostatic hypotension (also known as postural hypotension, orthostatic intolerance and, colloquially, as head rush or a dizzy spell) is a sudden fall in blood pressure, typically greater than 20/10 mm Hg, that occurs when a person assumes a standing position, usually after a prolonged period of rest. ...

External links

Look up fainting in Wiktionary, the free dictionary.

  Results from FactBites:
 
Fainting Causes, Diagnosis, and Treatment on MedicineNet.com (470 words)
When loss of consciousness is temporary and recovers spontaneously it is referred to as fainting or syncope.
Other common non-heart causes of temporary loss of consciousness include fainting after blood is drawn or after certain situational events (situational syncope), such as after urination, defecating, or coughing.
This occurs because of a reflex of the involuntary nervous system (vasovagal reaction) that leads to slowing of the heart rate and dilation of the blood vessels in the legs, thus lowering the blood pressure.
Fainting - Health Encyclopedia News Story - WNBC | New York (989 words)
Fainting is a temporary loss of consciousness due to a drop in blood flow to the brain.
When you faint, you not only experience loss of consciousness, but also loss of muscle tone and paling of color in your face.
Fainting may occur while you are urinating, having a bowel movement (especially if straining), coughing very hard, or when you have been standing in one place too long.
  More results at FactBites »

 
 

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