Causes of loss of consciousness, fainting, what is theirdifference first aid

Update: October 2018

Syncope is an unconscious state due to
sharp oxygen starvation of the brain and accompanied
depression of reflexes and vegetovascular disorders. it
short-term loss of consciousness.

For the first time the syncope was described by the ancient doctor Aretey. Greek
name of fainting (syncope, ie felling) from the coast
Cappadocia (modern Turkey) gradually reached New Orleans,
where flowed into the jazz rhythms of black orchestras.

Causes of Consciousness

The cerebral cortex is extremely sensitive to lack
oxygen. It is the starvation of the cortex that becomes the main cause
fainting. From severity and duration
oxygen deficiency depends on the depth and duration of syncope.
Such starvation can develop by several mechanisms:

Cerebral ischemia

it недостаточный приток крови по артериям вследствие:

  • embolism, thrombosis, spasm or atherosclerotic narrowing
    plaques of the lumen of blood vessels that feed the brain
  • insufficient cardiac output
  • or venous stasis.

Metabolic disorders

  • by type of hypoglycemia (drop in blood sugar) during fasting
  • insulin overdose
  • disorders of glucose utilization with fermentopathy
  • there may also be protein metabolism disorders with accumulation
    acetone-like ketone substances poisoning head cells
  • various poisonings can be included here (see symptoms
    food poisoning, mercury poisoning symptoms, carbon monoxide poisoning

Classification of fainting

Depending on the basic conditions of occurrence, all fainting
divided into three large groups.

  • Reflex develops on the background of pain, strong fear,
    emotional stress, after coughing, sneezing, urinating, with
    swallowing, defecation, on the background of pain in the internal organs, with
    physical exertion.
  • Associated with orthostatic loads, syncopes can be
    diabetes, amyloidosis, taking antihypertensive drugs,
    Parkinson’s disease, a decrease in circulating blood volume, a delay
    blood in the veins.
  • Cardiogenic associated with diseases of the heart and blood vessels.

Symptoms of fainting

Directly loss of consciousness precedes the period

  • nausea
  • sour taste in the mouth
  • dizziness, flashing flies before his eyes, darkness in
  • increased sweating
  • hand shake
  • pale skin and mucous membranes
  • noise in ears.

Then a sudden loss of consciousness develops, during which
a person may fall and hit.

  • In the period of fainting the muscles are relaxed, the body is motionless.
  • The pupils are dilated and do not respond to light, the pulse is rare and
    shallow breathing is reduced, blood pressure is reduced.
  • During deep fainting, involuntary
    urination and muscle cramps.

Fainting in healthy

A completely healthy person under certain circumstances may
довести себя до fainting.


With hard diets, fasting, the brain loses glucose and
starts the metabolic pathway of starvation of the cortex. If the fasting start
work hard physically, it is possible to get hungry

Abuse of sweet and simple carbohydrates

If you eat some sweets or tea with honey, then at the reception
carbohydrate pancreas throws a portion of insulin into the blood.
Since the carbohydrate is simple, it is quickly absorbed and its concentration in
blood quite large immediately after eating. A portion of insulin will be
adequate to this blood sugar level. But then, when the whole
simple sugar is utilized, insulin in the blood will still work
and in the absence of sugar will begin to decompose blood proteins. As a result
ketone bodies will enter the bloodstream, which will work like acetone,
вызвав метаболические нарушения в коре и спровоцировав fainting.


With injuries, you can lose consciousness both from severe pain and
on the background of bleeding. Both states reflexively cause
centralization of blood circulation with accumulation of the main mass of blood in
vessels of the abdominal cavity and depletion of cerebral blood flow.

Stuffy Room, Tight Belt or Collar

If in clothes with a tight collar and a belt for a long time to stand in a stuffy
помещении или транспорте, то можно упасть в fainting.


With a strong fright in persons with mobile vegetative nervous
системой может случиться fainting. Similar can be observed in
tantrums that literally power off thought and imagination

Other reasons

  • If you dive in the heat of cold water, you can cause a spasm.
    neck vessels and lose consciousness.
  • When a person climbs into the mountains or to a great height above
    sea ​​level, the partial pressure of oxygen in the blood increases.
    Oxygen is worse utilized by cells. Oxygen can come
  • If you take a long and concentrated steam bath, you can lose
    consciousness. This state can be earned with any other
    heat stroke, such as sun.
  • If you get angry from inhaling smoke or smoke a lot of cigarettes, you can
    get metabolic and hypoxic disorders in the cells of the cortex
    головного brain.
  • При укачивании также можно потерять consciousness.
  • The second stage of intoxication may include not
    только сон, но и fainting. More typical loss of consciousness after
    alcohol poisoning.
  • The rarer reasons for playing wind instruments
    or weightlifting.

Fainting in pregnant women

A pregnant woman in normal fainting should not fall. Although in
An interesting position creates multiple prerequisites for
deterioration of cerebral blood flow. Stretched fetus uterus strenuously
presses not only on the internal organs, provoking venous congestion,
but also on the inferior vena cava, worsening the venous return to the heart and
slightly reducing portions of blood pushed by the heart to the brain.
Therefore, with an older tum is not recommended:

  • self lean forward and down
  • wear tight clothes or underwear
  • squeeze neck with collars or scarves
  • sleep on your back.

Directly after childbirth compression causes of fainting

In second place in the frequency of unconscious causes in pregnant women
anemia (see pregnancy and low hemoglobin). During gestation
fetal iron is unnecessarily spent on the growth of a future baby and
depletes the mother’s blood the main carrier of oxygen –
hemoglobin. After birth bleeding, anemia can not only
persist, but grow. Therefore, it is important to engage
correction of low hemoglobin and red blood cells during pregnancy,
reduce blood loss during childbirth and treat postpartum anemia (see
iron preparations for anemia).

Fainting woman

Gentle ladies and ladies of the past centuries considered it good form
get away from all sorts of everyday difficulties and delicate situations when
relief banal fainting. Contributed to this passage tight
corsets that squeeze the ribs and make breathing difficult
nutrition, leading to anemia and mobile psyche, loose
reading french novels. Nekrasov and Leskov characters
peasant and bourgeois descendants suffered fainting
much less often, and no hysterical loss of consciousness was known at all.

Today, women most often faint among
complete health on the background of menstrual bleeding. It happens
the following reasons:

  • neglect of taking iron on critical days
    drugs that prevent the development of acute post-hemorrhagic
    anemia in the background of heavy periods,
  • the presence of undertreated gynecological or hormonal problems,
    leading to impaired uterine contractility and
    provoking menstrual pain, easily stopped

Fainting with diseases

Vascular diseases

Атеросклероз, стенозы сосудов шеи и головного brain приводят к
chronic cerebral circulatory disorders in which, along with
with impaired memory, sleep, and hearing, there may be periodic
syncopes of different durations.

Traumatic brain injury

Injuries головы (сотрясения, ушибы головного brain) сопровождаются
loss of consciousness of different depths. Actually fainting is a criterion
according to which the rapid diagnosis of concussion.


Shock (болевой, инфекционно-токсический) часто сопровождается
violation of consciousness. In case of injuries or internal diseases
organs pain or toxins trigger the reflex chain of the vascular
реакций, приводящих к угnotению коры brain.

Heart pathology

Heart defects and large vessels provoke insufficient release
крови в большой круг кровообращения и недостаточное питание brain.
Acute myocardial infarction is often complicated by loss of consciousness due to
a sharp drop in the contractility of the heart. Also to syncopations
severe rhythm disturbances are going on: sick sinus syndrome,
atrial fibrillation, ventricular fibrillation, transverse blockade
heart and frequent extrasystoles. Typical rhythm disturbance, with
which there are bouts of loss of consciousness – a syndrome

Pulmonary pathology

For example, bronchial asthma, lead to impaired gas exchange
between the lungs and the tissues. As a result кислород недостаточно
penetrates the brain. Also loss of consciousness accompanied by
pulmonary thrombembolia and pulmonary hypertension.


Diabetes ведет к потерям сознания на фоне гипогликемии и
ketoacidosis, which can quickly develop into a coma. Therefore so
It is important to comply with the regimen and dosage of glucose-lowering drugs.

Diseases accompanied by irritation of reflex zones
vagus nerve

it язвенная болезнь желудка и 12-перстной кишки, панкреатиты,
особенно деструктивные вызывают перераздражение vagus nerve,
which the heart also innervates. As a result ухудшаются условия
кровоснабжения коры brain.

Other reasons

  • Sharp decrease in the volume of the circulating blood against
    bleeding, vomiting, or diarrhea does not adequately
    supply the brain with oxygen.
  • Vegetative-vascular dystonia does not give the vessels timely and
    adequately adjust the clearance to the requirements of changing external
    environment. The result is extremely frequent fainting n background
    sharp pressure surges.
  • Poisoning with neurotoxic snake venom, alcohol and his
    surrogates, organophosphorus compounds also lead to
  • Loss of consciousness can be a side effect. neuroleptics,
    hypnotic, hypotensive, ganglioblockers, tranquilizers,
    isoniazid derivatives.
  • Fainting can be a consequence of uraemia in renal
  • Increased sensitivity of carotid sinus baroreceptors
    may lead to syncope.

Fainting in children

Children suffer from fainting for the same reasons as adults.
Since the adaptive capabilities of the child’s body are weak, each
fainting in a child is a reason to be examined by a pediatrician and a neurologist.
For quite harmless short-term loss of consciousness in a child
can hide the formidable diseases of the nervous system or blood.

Fainting teen

it часто следствие быстрого роста. Girls are more likely to suffer from
hidden anemia and vascular dystonia, young people – from
dysplasia of the connective tissue of the heart. For example, such a lightweight
malformations like mitral valve prolapse, which most often
thin young men suffer, almost the only vivid manifestation
имеет потемнение в eyes или потерю сознания при резком
getting up.

How is syncope different from loss of consciousness?

Acute thrombosis, embolism or rupture of blood vessels are becoming
causes of ischemic or hemorrhagic stroke that may
start losing consciousness. At the same time, loss of consciousness is more
продолжительная и глубокая, чем fainting. She can easily go
in whom.

Epilepsy, accompanied by impaired consciousness (for example,
атонические припадки) – это также не совсем fainting. At the base
Epipadia is a violation of the excitation of nerve cells of the cortex.
Which trigger the imbalance of excitation and inhibition, for the second time
causing metabolic abnormalities in neurocytes.


Loss of consciousness

The reasons
  • Reflex reaction
  • Ортостатическая гипотензия brain
  • Caridal pathologies
  • Stroke
  • Epilepsy
 Duration Not more than a few minutes. Usually 20-30 seconds. More than 5 minutes
 Exit state Fast Slow
Наличие потери памяти  на предшествовавшие события Not there is
Restoration of normal behavior and orientation Full and instant Not happening or slow
After fainting – changes in EEG not there is

In any case, fainting and loss of consciousness is a cause for
emergency care and subsequent treatment to the doctor.

Fainting Aid

  • Fainted must be laid on a flat surface with
    raised above the level of the body legs, eliminating as much as possible
    cause of loss of consciousness (remove from direct heat source,
    undo the taut belt and collar, free the neck from unnecessary
  • Provide fresh air.
  • Give breathing vapors of ammonia.
  • On the forehead and temples put a towel dipped in cold

First aid for loss of consciousness

If interventions with normal syncope are ineffective in
The first two minutes, you must immediately call the ambulance team.
assistance that can provide specialized assistance and take
patient to hospital for treatment and clarification of the causes of loss
of consciousness.

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