A dangerous reduction of blood flow throughout the body tissues, which may occur with severe injury or illness. Shock in this sense is physiological shock, as distinct from the mental distress that may follow a traumatic experience.
In most cases, reduced blood pressure is a major factor in causing shock and is one of its main features. Shock may develop in any situation in which blood volume is reduced, blood vessels are abnormally widened, the heart’s action is weak, blood flow is obstructed, or there is a combination of these factors. Causes include severe bleeding or burns, persistent vomiting or diarrhoea, myocardial infarction, pulmonary embolism, peritonitis, and some types of poisoning.
Symptoms of shock include rapid, shallow breathing; cold, clammy skin; rapid, weak pulse; dizziness; weakness; and fainting. Untreated, shock can lead to collapse, coma, and death.
Emergency treatment is required. This involves an intravenous infusion of fluid, a blood transfusion, oxygen therapy, and, if necessary, morphine or similar powerful analgesics. Further treatment depends on the underlying cause. (See also anaphylactic shock; septic shock; shock, electric; toxic shock syndrome.)
A state of acute circulatory failure in which the heart’s output of blood is inadequate to provide normal PERFUSION of the major organs. It is accompanied by a fall in arterial blood pressure and is characterised by systemic arterial hypotension (arterial blood pressure less than 80 mm of mercury), sweating and signs of VASOCONSTRICTION (for example, pallor, CYANOSIS, a cold clammy skin and a low-volume pulse). These signs may be associated with clinical evidence of poor tissue perfusion, for example to the brain and kidneys, leading to mental apathy, confusion or restlessness and OLIGURIA.
Shock may result from loss of blood or plasma volume. This may occur as a result of haemorrhage or severe diarrhoea and vomiting. It may also result from peripheral pooling of blood due to such causes as TOXAEMIA or ANAPHYLAXIS. The toxaemia is commonly the result of a SEPTICAEMIA in which leakage through capillaries reduces circulating blood volume. Another form is called cardogenic shock, and is due to failure of the heart as a pump. It is most commonly seen as a result of myocardial infarction (see under HEART, DISEASES OF).
If failure of adequate blood ?ow to vital organs is prolonged, the effects can be disastrous. The ischaemic intestine permits the transfer of toxic bacterial products and proteins across its wall into the blood; renal ISCHAEMIA prevents the maintenance of a normal electrolyte and acid-base balance.
Treatment If the shock is a result of haemorrhage or diarrhoea or vomiting, replacement of blood, lost ?uid and electrolytes is of prime importance. If it is due to septicaemia, treatment of the infection is of paramount importance, and in addition, intravenous ?uids and vasopressor drugs will be required. Cardiogenic shock is treated by attention to the underlying cause. Full intensive care is likely to be required, and arti?cial ventilation and DIALYSIS may both be needed.
Collapse of the circulation resulting in inadequate tissue perfusion to the body cells.
n. the condition associated with circulatory collapse, when the arterial blood pressure is too low to maintain an adequate supply of blood to the tissues. The patient has a cold sweaty pallid skin, a weak rapid pulse, irregular breathing, dry mouth, dilated pupils, a decreased level of consciousness, and a reduced flow of urine.
Hypovolaemic shock is due to a decrease in the volume of blood, as occurs after internal or external *haemorrhage, burns, dehydration, or severe vomiting or diarrhoea. Cardiogenic shock results from reduced activity of the heart, as in coronary thrombosis, myocardial infarction, or pulmonary embolism. Shock may also be due to widespread dilatation of the blood vessels so that there is insufficient blood to fill them. This is the case in severe *sepsis (septic, bacteraemic, or toxic shock), with a resultant systemic inflammatory response associated with *disseminated intravascular coagulation and multiple organ failure. Vasodilatation may also be caused by a severe allergic reaction (anaphylactic shock: see anaphylaxis), overdosage with such drugs as opioids or barbiturates, or the emotional shock due to a personal tragedy or disaster (neurogenic shock). Sometimes shock may result from a combination of any of these causes, as in *peritonitis. The treatment of shock is determined by the cause.
A dangerous disorder characterised by a severe fall in blood pressure and damage to the body tissues as a result of SEPTICAEMIA. The toxins from the septicaemia cause widespread damage to tissue, provoke clotting in small blood vessels, and seriously disturb the circulation. The kidneys, lungs and heart are particularly affected. The condition occurs most commonly in people who already have a chronic disease such as cancer, CIRRHOSIS of the liver or DIABETES MELLITUS. Septic shock may also develop in patients with immunode?ciency illnesses such as AIDS (see AIDS/HIV). The symptoms are those of septicaemia, coupled with those of SHOCK: cold, cyanotic limbs; fast, thready pulse; and a lowered blood pressure. Septic shock requires urgent treatment with ANTIBIOTICS, intravenous ?uids and oxygen, and may require the use of drugs to maintain blood pressure and cardiac function, arti?cial ventilation and/or renal DIALYSIS.... septic shock
First described in 1978, this disorder is characterised by high fever, diarrhoea, SHOCK and a rash. It is frequently associated with the use of tampons (see TAMPON), but has occasionally been reported in men. The syndrome may also be linked to the use of contraceptives such as the diaphragm, cap and sponge (see under CONTRACEPTION), and skin wounds or infections may also be a cause. The disease is due to a staphylococcal toxin (see STAPHYLOCOCCUS; TOXINS). Treatment consists of supportive measures to combat shock and eradication of the staphylococcus by ANTIBIOTICS. The design of tampons has been improved. Recurrence of the disorder has been reported and women who have had an episode should stop using tampons and vaginal contraceptives.... toxic shock syndrome
A disorder in which the body produces excess INSULIN, which then reduces the amount of glucose in the blood (HYPOGLYCAEMIA). Treatment is with glucose or GLUCAGON. Untreated, the patient goes into a COMA and dies.... insulin shock
an adverse reaction to a sudden unexpected noise (an *acoustic incident). The condition is characterized by symptoms that may include pain, dizziness, tinnitus, anxiety, and depression. It is not usually associated with permanent reduction of hearing, in comparison to noise-induced hearing loss (see deafness).... acoustic shock
a bacterial disease characterized by fever, shock, and multiple organ failure. It is similar to the *toxic shock syndrome caused by staphylococci, but in these cases the infecting organisms are *Streptococcus Type A bacteria. See also necrotizing fasciitis.... streptococcal toxic shock syndrome
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