The brain depends on oxygen from the blood and glucose, an essential nutrient. Without an adequate supply of these substances, nerve cells do not receive the proper amount of energy, the work of the nervous system may suffer. If blood flow temporarily decreases, then the brain’s defense mechanism is activated, the nervous system takes available blood and oxygen from other parts of the body, feeding the brain at the expense of other organs.
When the brain tries to pump blood around the body more actively, the respiration rate (hyperventilation) increases as well as the heart rate, which as a result lowers blood pressure (hypotension occurs). The combination of hyperventilation and hypotension can lead to temporary loss of consciousness (fainting or syncope) or make a person feel cold, lightheaded, sweating, and dizzy — a lightheaded state. The onset of fainting is usually sudden, and other symptoms may include blurred vision.
A brief “blackout” or fainting is a temporary loss of consciousness, followed by a return to full wakefulness. Fainting can be accompanied by a loss of muscle tone, which can lead to a fall or limpness of a person, due to which he cannot stay on his feet, all muscles relax sharply. To better understand why fainting can occur, it is helpful to explain how the brain and nervous system function.
The brain is made up of several parts, including two hemispheres, the cerebellum, and the brainstem. It needs continuous blood flow to provide oxygen and glucose (sugar) to nerve cells to sustain life. To be awake, you must include an area known as the reticular formation, located in the brainstem, and at least one hemisphere of the brain.
When fainting, either the reticular formation temporarily loses its blood supply, or both hemispheres of the brain are temporarily deprived of blood, oxygen, or glucose. If blood sugar levels are normal, blood flow must be briefly disrupted throughout the brain or in the reticular activating system for fainting to occur.
Fainting is not caused by a head injury. Loss of consciousness after a head injury is considered a concussion and is caused by other mechanisms. However, fainting itself threatens injury if a person falls and hits his head, loses consciousness while driving or during hazardous work.
Signs of fainting
When a person “turns off”, he does not realize that he lost consciousness and fell to the ground. After the victim comes to his senses, he realizes what happened. Before fainting, he may feel:
- lightheadedness and noise in the head, a feeling of “fog”;
- sweating chills;
- dizziness or rotation of the room;
- vision may disappear or become blurred, flashing flies;
- the hearing may be muffled, ringing in the ears;
- tingling sensation in the body.
Pre-syncope has the same symptoms, but the person does not completely faint. During fainting, a person may lose consciousness, in parallel, some twitching of the body may occur, which can be confused with a convulsive attack. After awakening, a short-term confusion of consciousness is possible, but this should resolve within a few seconds.
After a syncope, the person should return to normal mental function. But there may be other signs and symptoms of fainting, depending on the underlying cause. For example, if a person has a heart attack, they may complain of chest pain or pressure.
Causes of fainting
The main cause of fainting is a pronounced and sharp decrease in blood flow to the brain because:
- the heart cannot pump blood;
- the blood vessels are not toned enough to maintain blood pressure and deliver blood to the brain;
- there is not enough blood or fluid inside the blood vessels.
There may be a combination of all three reasons.
Types of fainting
Depending on the influencing causes and mechanisms of development, different types of syncope are distinguished.
Vasovagal syncope (associated with the vagus nerve) is the most common and common. In this situation, the balance between the chemicals – adrenaline and acetylcholine – is disturbed. Adrenaline stimulates the body, including speeding up the heartbeat and constricting blood vessels, thereby increasing blood pressure. Acetylcholine does the opposite. When the vagus nerve is stimulated, excess acetylcholine is released, heart rate slows down and blood vessels dilate, making it difficult for blood vessels to circulate and deliver blood to the brain. This provokes fainting.
Severe pain can stimulate the vagus nerve, which is a common cause of syncope (vasovagal syncope). Other harmful stimuli can do the same, including situational stressors. It is common for medical students and nurses to faint while watching their first surgery, autopsy, or bleeding. Some people pass out when they hear bad news. Someone passes out when they see blood or needles.
Other situations usually cause the heart rate to temporarily slow down and cause fainting. Straining when urinating, defecating, or coughing can trigger a vagal response, increase acetylcholine levels, and decrease blood flow to the brain.
Fainting is associated with low blood pressure (postural hypotension), dehydration, and anemia. There are several options here.
Pregnancy. Fainting can be associated with pregnancy. Possible explanations include compression of the inferior vena cava (the large vein that returns blood to the heart) with enlargement of the uterus and orthostatic hypotension.
Low blood pressure (orthostatic hypotension). The blood vessels must maintain their tone so that the body can withstand the effects of gravity when position changes. When the position of the body changes from a lying position to a standing position, the autonomic nervous system (the part of the brain that is not under conscious control) increases the tone of the walls of the blood vessels, sharply constricting them, and at the same time increases the heart rate so that blood flows faster to the brain. … As you age, your blood vessels can become less elastic and orthostatic hypotension (low blood pressure while standing) can occur, which can lead to fainting.
Anemia (low levels of red blood cells and hemoglobin), whether acutely from bleeding or gradually for various reasons, can cause fainting because there are not enough red blood cells to deliver oxygen to the brain.
Dehydration or lack of water in the body can also trigger fainting. It is caused by excessive water loss due to vomiting, diarrhea, sweating, or not drinking enough fluids. Certain medical conditions, such as diabetes, can cause dehydration due to excessive loss of water in the urine.
Cardiac syncope is associated with sudden cardiac arrest, heart valve lesions, and structural changes. Young people, especially athletes, may experience fainting due to abnormal thickening of parts of the heart muscle (hypertrophic cardiomyopathy). This can interfere with the flow of blood as it tries to leave the heart, especially when the stress on the heart muscle increases during exercise. Frequent fainting can be a harbinger of sudden cardiac arrest in actively exercising people.
Heart valve abnormalities can also cause fainting. The valves allow blood to flow in the right direction when the heart contracts. Valve disease can include abnormal narrowing (stenosis) or insufficiency (regurgitation). Either situation can cause problems maintaining adequate blood flow in the body.
Structural heart problems can cause fainting, either due to problems with the heart’s ability to pump blood adequately or due to valve problems. When the heart muscle is damaged or inflamed, it does not have the full ability to pump blood to meet the body’s needs. Examples include heart attack (myocardial infarction) or cardiomyopathy, in which the heart muscle becomes weak.
Changes in heart rhythm (palpitations and tachycardia). Changes in heart rate are also provocateurs of fainting. Fainting episodes are often caused by a temporary change in normal body function. Heart rhythm changes such as tachycardia and fibrillation are dangerous and potentially fatal causes of fainting. A rapid heartbeat or tachycardia is an abnormal heart rhythm that is generated in the upper or lower chambers of the heart, which is life-threatening because the heart beats too fast and there is not enough time between heartbeats to fill with blood. This then causes a decrease in the amount of blood that can be delivered to the body.
Diseases of the vertebrobasilar artery. Blood vessels in the brain are no different from any other blood vessels in the body and are at risk of narrowing as we age, due to smoking, high blood pressure, high cholesterol, and diabetes. In addition to the carotid artery, other vessels are involved in the blood supply to the brain – the vertebrobasilar system. It is also at risk of constriction, and in the event of a temporary disturbance of blood flow in the midbrain, deactivation of the reticular formation is possible, provoking fainting. The vertebral arteries run to the brain at the back of the neck and are enclosed in bony tunnels. If blood flow in these arteries is impaired, the brainstem and reticular activating system can shut off, leading to fainting.
Electrolyte imbalance, drug effects. Electrolyte and hormonal disturbances can also cause fainting. However, these reasons are related to their effects on the heart and blood vessels.
Narcotic drugs or medications can also be potential causes of fainting. Dangerous:
- high blood pressure medications that can dilate blood vessels
- antidepressants, which can interfere with the electrical activity of the heart;
- drugs that affect mental health, such as pain relievers, alcohol, and cocaine.
First aid for fainting
Fainting is an abnormal condition, although the cause may not be as serious. If the person is not breathing or has no pulse, call 112 or 03. If the person is breathing normally, place them in a comfortable position and help them recover.
How to help:
- If the person complains of faintness, pick up and place the person on the floor before they fall;
- loosen any tight clothing;
- Raise your legs – this raises blood pressure by reducing blood flow from the main vessels in your legs to your heart.
- Place a cool, wet compress on your forehead;
- try to prevent the person from getting up until they are fully recovered.
The patient can recover quickly, but let him remain to lie down until he feels he can sit up slowly. If he still feels weak, put him back down. Ask the patient if this is their first fainting spell. If he has recurring episodes of fainting, advise seeing a doctor.
In order to effectively treat a person who often faints, you need to identify their true cause.
Numerous studies are used to determine the causes of fainting:
- the patient’s medical history – as with most medical conditions, history is the key to figuring out why a person faints, as most episodes of fainting do not occur in the doctor’s office. People nearby often witness fainting and can talk about possible causes;
- a complete physical examination – the doctor will look for signs or symptoms to help diagnose the cause of the fainting;
- heart monitoring (such as a Holter monitor) – heart rhythm abnormalities can come and go, and this is not always detected during the examination. A heart monitor (Holter) can be worn on an outpatient basis for 24 or 48 hours, or up to 30 days (event monitor). Heart rhythm and frequency abnormalities can be detected by analyzing his records;
- electrocardiogram (ECG);
- complete blood count, glucose levels;
- kidney examination;
- assessment of the thyroid gland;
- a table tilt test (detection of orthostatic reactions);
- The table tilt test can be used to detect orthostatic hypotension and is usually performed on an outpatient basis. The patient is placed at an angle on a table for 30 to 45 minutes (each institution has its own protocol) and blood pressure and pulse rate are measured when the patient is in different positions;
- CT (computed tomography) or MRI (magnetic resonance imaging). Depending on the suspected cause of fainting, imaging of the brain may be done with computed tomography (CT) or magnetic resonance imaging (MRI).
Often these tests are normal, so the medical team assumes that the cause of the fainting is not life-threatening. However, it is up to the doctor and patient to decide whether additional testing is needed in a hospital or on an outpatient basis.
Modern methods of treatment
If the episode of fainting resolves quickly and the person returns to normal function without signs of injury, it is advisable to see a GP or neurologist to discuss treatment options.
Often, if episodes of fainting do not go away quickly or recur, the person is hospitalized, connected to a heart monitor, given IV fluids, and supplied with oxygen.
You can check your blood sugar to see if your glucose is low (sugar hypoglycemia). Treatment for the causes of fainting will be individual for each person and depends on the cause.
Prevention of fainting at home
Depending on the cause, fainting can be prevented. For example, people who have had a vasovagal episode, knowing the warning signs, can squat or lie down before passing out and prevent an episode of fainting.
Elderly people with orthostatic hypotension (low blood pressure while sitting or lying down) can prevent fainting by waiting a few seconds after changing positions. This is all that is needed to normalize the body’s response.
If the episodes are medication-related, doses must be adjusted if they are considered a potential cause of fainting.
If dehydration is the cause, drinking enough fluids is sufficient to prevent dehydration.
How to understand that fainting may occur?
People with the following conditions are at increased risk of fainting:
- low blood sugar (hypoglycemia);
- Any condition in which rapid blood loss occurs, such as due to internal bleeding;
- heart and circulatory problems;
- heatstroke or heat exhaustion;
- eating disorders (eg, anorexia and bulimia);
- toxic shock syndrome.
Those who stand in one place for a long time, especially in extreme heat, are also prone to fainting. In addition, anxiety (such as sudden stress or fright), severe pain, sudden changes in body position (such as getting up too quickly), and certain medications can also cause fainting.
A person who loses consciousness often experiences dizziness, nausea, weakness, or blurred vision prior to unconsciousness, and may have cold, clammy, pale skin. The person can be disoriented, incoherent, motionless, and silent.
What is the danger of fainting?
Fainting is a form of unconsciousness that is quick and short, often due to low blood sugar or standing in one place for too long. Fainting can also be caused by a more serious medical condition.
Unconsciousness is abnormal, a person does not show vigilance and does not fully respond to his environment. Unlike normal sleep, a person who is unconscious cannot cough, clear their throat, or turn their head if they vomit. In an unconscious state, a person can suffocate, so it is very important that the airways are clean and free.
Can you die if you faint?
Fainting itself, with rare exceptions, does not lead to death. But if help is not provided on time or a person is injured, then yes, death is possible.
If the person vomits while unconscious, turn the person quickly to allow the fluid to drain, protecting the person’s airway from aspiration and suffocation. Do not try to give an unconscious person anything by mouth – it is dangerous. Do not shake or spank the unconscious person to try to get them to regain consciousness.
If the person has been injured during fainting, first aid should be provided for any injury (such as bumps, bruises, or cuts). Bleeding must be stopped by direct pressure on the wound.