Shock: what is it, causes, symptoms, treatment, prognosis

What is shock?

Shockis a life-threatening condition in which oxygen delivery to organs is reduced, causing organ damage and sometimes death. Blood pressure is usually low.

• There are several reasons for the development of shock: Low blood volume, impaired pumping function of the heart, or excessive dilation of blood vessels.
• If the shock is caused by a decrease in blood volume or insufficient pumping function of the heart, patients may feel become lethargic, sleepy, or disorientated, and their skin becomes cold, sweaty, pale and bluish.
• When shock develops as a result of excessive dilation of blood vessels, the skin may become hot to the touch, pink, and the pulse - not weak, but rather strong and sharp ("bouncing").
• Patients who develop shock should be warmed and laid down with their legs elevated.
• Intravenous fluids, oxygen, and sometimes drugs are given to restore blood pressure.

Shock develops when blood pressure becomes so low that the body's cells cannot are getting enough blood and therefore not getting enough oxygen. As a result, the work of the cells of most organs is disrupted, including the brain, kidneys, liver and hearts. If blood flow (perfusion) in these cells is not restored as soon as possible, they are irreversibly damaged and die. If a large number of cells of an organ are affected or die, it may fail and the person may die.

Failure of two or more organs is called multiple organ failure syndrome (MDS), and this diagnosis poses a significant risk of death. When shock develops, patients need immediate emergency treatment, which they usually receive in an intensive care unit.

Do you know that…

Shock has nothing to do with sudden emotional stress.

Although a drop in blood pressure is usually the cause of shock, in the early stages of shock, blood pressure may be normal. In addition, blood pressure can be low in the absence of shock.

The clinical concept of shock is not the “shock” that people mean when they talk about sudden emotional stress.

Causes and risk factors

There are several reasons for the development of shock:

• low blood volume (hypovolemic shock);
• insufficient pumping function of the heart (cardiogenic shock);
• excessive dilation of blood vessels (redistribution shock).

Do you know that…

In some cases, when shock develops, the pressure drops to such low values ​​that it is not even possible to measure with a cuff pressure gauge.

- Hypovolemic shock.

Decreased blood volume, causing the heart to receive less than normal with each beat the amount of blood and therefore less than usual amount of blood is pumped to the organs and cells.

Blood volume may decrease because of:

• heavy bleeding;
• excessive loss of body fluids;
• insufficient fluid intake (less often).

Rapid blood loss can be caused by:

• external bleeding, such as caused by trauma;
• internal bleeding, for example from stomach ulcers or intestines, if a blood vessel is ruptured or an ectopic pregnancy is interrupted.

Excessive loss of body fluids other than blood can result from:

• extensive burns;
• inflammation of the pancreas (pancreatitis);
• perforation of the intestinal wall;
• heavy diarrhea or vomiting;
• some kidney disease;
• overuse of diuretics that increase urine production;
• uncontrolled diabetes.

Fluid intake may not be sufficient if you have a disability (such as severe joint disease) or mental health problems (such as Alzheimer's disease) when people are not drinking enough fluids, even though they may feel thirsty.

- Cardiogenic shock.

An inadequate pumping function of the heart can also lead to a decrease in the volume of blood pumped with each heartbeat. The most common causes of insufficient heart pumping function are:

• complications myocardial infarction;
• formation of a blood clot in the lungs (pulmonary embolism);
• sudden dysfunction of the heart valve (especially the artificial valve);
• heart rhythm disorder (arrhythmia);
• infections of the heart muscle or heart valves;
• the inability to fill the heart with blood due to the rapid accumulation of fluid in the membrane surrounding the heart (cardiac tamponade);
• other conditions that disrupt the structure of the heart, such as rupture of the heart wall (myocardial rupture).

- Redistributive shock.

Excessive dilation of blood vessels (vasodilation) leads to an increase in blood vessel capacity and a decrease in blood pressure. This can reduce blood flow and oxygen delivery to organs.

Blood vessels can become excessively dilated due to:

• a serious allergic reaction (anaphylaxis or anaphylactic shock);
• severe bacterial infection (shock caused by this infection is called septic shock);
• overdose of drugs or ingestion of poisons that dilate blood vessels;
• spinal cord and sometimes brain injuries (neurogenic shock);
• some endocrine diseases, for example Addison's disease.

The mechanisms by which these disorders cause vasodilation vary. For example, damage to the spinal cord blocks nerve signals from the brain to the blood vessels, which usually leads to narrowing of the blood vessels; poisons or toxins released by bacteria can directly cause blood vessels to dilate.

Signs and symptoms

In case of shock for a reason decreased blood volume or insufficient contractile function of the heart, the developing symptoms are similar to each other.

• The disease may begin with lethargy, drowsiness, and disorientation.
• The skin becomes cold, sweaty, and often turns pale, acquiring a bluish tinge.
• If you press on the skin, its normal color returns much more slowly than usual.
• Blood vessels may become more visually visible as a bluish mesh under the skin.
• The pulse is weak and fast, unless the shock is caused by a slow pulse.
• Typically, when trying to sit up, the person feels dizzy or may faint.
• Breathing is fast, but as death approaches, breathing and pulse slow down.
• The pressure drops so low that it is often not even possible to measure it with a cuff pressure gauge.
• Urination decreases and eventually stops.
• In the end, coma and death may occur.

If shock develops as a result excessive dilation of blood vessels, the symptoms are slightly different. The skin can become hot and redden, and the pulse becomes not weak, but, on the contrary, strong and sharp ("jumping"), especially at the beginning. However, in the future, with shock due to excessive expansion of blood vessels, the skin also becomes cold and clammy, a person develops lethargy.

In the earliest stages of shock, especially septic shock, many symptoms may be absent or unnoticed if not specifically looked for. In older people, disorientation may be the only symptom. Urine production may decrease (due to reduced blood supply to the kidneys), causing waste to accumulate in the blood. Blood pressure may decrease.

Diagnostics

Diagnostics include:

• blood tests;
• other tests depend on the probable cause.

The diagnosis of shock is based primarily on signs of organ damage found on examination by a physician. For example, in a patient:

• the level of consciousness may decrease;
• there may be no urine production;
• there may be cyanosis of the fingers and toes (cyanosis).

There may also be signs of trying to compensate for low blood volume or insufficient pumping function of the heart. For example, there may be a rapid heartbeat (tachycardia), breathing or profuse sweating.

Blood tests can aid the diagnosis, but no diagnostic sign alone is exhaustive, and doctors evaluate each of them in dynamics (i.e. deterioration or improvement) and taking into account the general condition the patient. One blood test (lactate level) measures the amount of waste cells in the blood. An increase in the level of lactate in the blood indicates an insufficient supply of oxygen and blood to the organs and the possible development of shock. Blood tests indicating high or low white blood cell or bacterial counts or others microorganisms in the blood can help identify an infection that can cause septic shock.

Blood tests can also indicate damage to specific organs. For example, high creatinine levels may indicate kidney damage, and high troponin levels may indicate heart damage.

Other tests are done depending on the likely cause of the shock. For example, if you suspect a serious infection, your doctor may order a culture of blood and other body fluids. If the patient has signs of heart problems, they may be referred for electrocardiography and other imaging tests of the heart.

Standard treatments

Treatment includes:

• seeking help and stopping bleeding;
• intravenous fluids and / or blood transfusion;
• sometimes drugs to increase blood pressure;
• other activities depending on the reason.

First aid

Most important is to seek help and to stop any major bleeding. After this, the person needs to be warmed up and laid, raising his legs.

When the ambulance arrives, the patient may be given an oxygen mask or a breathing tube installed. Fluids can be injected into a vein (intravenously) at high speed and in large volumes to increase pressure.

Upon arrival at the emergency room, the patient may be given a blood transfusion if the shock is caused by bleeding. Typically, a cross-compliance test is done prior to a blood transfusion, but in an emergency when there is no time for this, a Group I negative blood transfusion can be performed.

If shock is caused by a severe infection, intravenous fluids and antibiotics are given. If the shock is caused by a heart attack or another heart problem, other procedures or surgery may be needed.

For some types of shock, drugs may be given intravenously to increase blood pressure. However, doctors use these drugs only for a short time because they can reduce blood flow to other tissues in the body or cause an irregular heartbeat. Drugs can increase blood pressure by:

• constriction of blood vessels, such as when given adrenaline (used for anaphylaxis) or norepinephrine (sometimes used for other forms of shock);
• stimulation of the pumping function of the heart, as, for example, with the introduction of dobutamine or milrinone.

Treatment of the cause

Intravenous fluids, blood transfusions, and drugs may not be enough to counteract shock if bleeding or fluid loss continues, or if shock is due to myocardial infarction, infection, or other problem not related to blood volume. Treating the cause of the shock is key.

If the shock is caused by insufficient pumping function of the heart, every effort is made to improve the efficiency of the heart. In addition to solutions and drugs, other treatments include transdermal transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting if shock is caused myocardial infarction. Surgery may also be needed if shock is caused by a damaged heart valve or a ruptured heart wall. Excess fluid that is compressing the heart during cardiac tamponade can be removed with a needle or surgically.

If the shock is caused by an infection (for example, sepsis), treatment of infection consists of antibiotic therapy and elimination of the source of infection. If the shock is caused by bleeding, surgery may be needed to stop the bleeding. If the shock is due to an endocrine disorder (such as Addison's disease) or anaphylaxis, corticosteroids may be required.

Forecast

Shock is usually fatal if left untreated. If a patient with shock is treated, the prognosis depends on:

• causes of shock;
• other diseases the patient has;
• the presence and severity of failure of any organ;
• the time that passed before the start of treatment;
• the type of treatment prescribed.

Multiple organ failure syndrome carries a significant risk of death. The risk of death increases as the number of organs affected increases. Regardless of treatment, the likelihood of death from shock following a major heart attack or septic shock, especially in the elderly, is very high.