What Is Shock And What Are The Types Of Shock

What Is Shock ? Shock (circulatory shock), characterized by very low blood pressure is a potentially fatal condition. It requires immediate medical intervention.

In the United States alone, the cases of shock reported every year exceeds 1 million. The medical condition called, shock, is not the same as the emotional shock that people generally feel from sudden stress.
Shock can result from various causes and the symptoms manifested can also vary accordingly. When blood pressure is extremely low, blood supply to the cells of the body become inadequate, starving them of oxygen. This affects the proper functioning of various organs like the heart, kidneys, brain etc. If immediate medical treatment does not restore blood supply to these organs, they become irreparably damaged due to cell death. This multiple organ failure is fatal.

Types of Shock

Types of Shock Vary and Shock can be caused by low circulatory volume of blood (Hypovolemic shock), insufficient pumping of blood by the heart (Cardiogenic shock), or excessive dilation of blood vessels (Distributive shock).

1. Hypovolemic Shock:

  • Reduction in the volume of blood results in less quantity of blood entering the heart and, consequently, less of it being pumped out to the rest of the body.
  • Low blood volume may be a result of excessive loss of blood or other body fluids. Blood loss may have been caused by either external bleeding as in an accident or internal bleeding occurring from a ruptured blood vessel or a bleeding stomach ulcer. Sometimes ruptured ectopic pregnancy may be the reason. Loss of other body fluids could result from severe burns or diarrhea. Pancreatitis and kidney disease can also cause fluid loss. So does indiscriminate use of diuretics that increase secretion of urine.
  • If people fail to take sufficient fluids either due to physical difficulties such as lack of mobility, severe joint pain etc., or because of mental disability like Alzheimer, the resulting fluid insufficiency can cause hypovolemic shock.

2. Cardiogenic shock:

If the pumping action of the heart is reduced due to a heart attack or pulmonary embolism ( a blood clot in the lungs), it can result in the reduction of the quantity of blood getting pumped each time. Several other heart conditions like Arrhythmia (abnormal heart rhythm), heart valve malfunction and rupture of the septum of the heart and excessive pressure on the heart due to sudden filling up of pericardial space with fluid (cardiac tamponade) can also precipitate a cardiogenic shock.

3. Distributive (Septic, Anaphylactic) Shock:

When blood vessels dilate, the effective pressure in those vessels decrease and less blood reaches the tissues fed by them. This vasodilation may be due to an allergic (anaphylactic) reaction sepsis resulting from a bacterial infection. Injury to the spinal cord which affects the nerve control over arterial tone can cause vasodilation. Toxins, poisons and an over dose of vasodilatory drugs can also result in distributive shock.

Symptoms of different Types of Shock

The symptoms of hypovolemic shock and cardiogenic shock are similar. Confusion and drowsiness are the initial signs of shock. Skin may be sweaty and cold to touch, and often looks pale with a bluish tinge. Rapid breathing, weak pulse and low blood pressure – too low to be measured by a blood pressure cuff, – are the symptoms of a worsening shock which may eventually culminate in death.

On the contrary, in the initial stages of distributive shock, warm flushed skin due to dilation of capillaries and strong, bounding pulse are the symptoms observed. But later on, skin becomes clammy and cold and lethargy sets in. Many symptoms of shock may not be present in case of septic shock. In the elderly, confusion may be the only sign. Urine flow is greatly reduced due to reduced blood supply to the kidneys.

Prognosis and Treatment of Different Types of shock

Shock often results in death if not treated immediately. The treatment depends on the severity of the shock and its cause; the outcome varies with the time lapsed, the extent of organ damage and the medical condition of the patient.

As First- Aid, a person in shock should be kept warm and made to lie down with legs raised 1 to 2 feet (30 to40 centimeters), to encourage flow of blood to the heart. Measures should be taken to stop bleeding. Airway should be kept free of obstruction. Feeding through mouth should be avoided and head should be kept turned to the side to prevent aspiration of vomit.

Emergency medical personnel may provide supplementary oxygen through a face mask or breathing device. Intravenous supply of fluids in large volumes, administered at a high rate help to increase blood pressure. Blood transfusion may be given, in case of shock due to heavy blood loss. In an emergency, to avoid any delay, type O negative blood can be given without blood matching. Required drugs are given intravenously but sedatives that tend to decrease blood pressure are avoided.

Shock due to vasodilation is treated with vasoconstrictors such as epinephrine, as in the case of people with an allergic reaction (anaphylaxis). Low-dose dopamine is given to people with other forms of shock. Bacterial infection is treated with antibiotics.

In shock caused by a heart attack, drugs that constrict the blood vessels help to increase blood flow to the brain or heart. Care is taken to avoid consequent reduction in flow to other organs for prolonged periods. When inadequate pumping action of the heart has caused shock, measures are taken to improve the performance of the heart. Abnormal heart rhythms are corrected. Atropine, to increase heart rate and other drugs, to improve the ability of the heart muscles, are given if required. Blood volume is also increased if necessary.

In case of shock due to heart attack; if shock persists even after emergency treatment, a balloon pump may be inserted into the aorta for temporary reversal of shock. This is followed by emergency percutaneous transluminal coronary angioplasty or coronary artery bypass surgery. Emergency PTCA opens a blocked coronary artery, thus improving the pumping action of the heart and reversing the shock.

A clot- busting (thrombolytic) drug can be given as an alternative to emergency surgery, provided it is not contraindicated by other existing medical conditions such as a bleeding ulcer or a recent history of stroke. If the heart is unable to fill with blood due to increased pressure from the fluid collection in the pericardium (cardiac tamponade), excess fluid can be removed through a needle inserted into the pericardium. A heart valve malfunction or rupture of the septum, may require surgical intervention.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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