Shock

In medicine, shock is a critical condition brought on by a sudden drop in blood flow through the body. There is failure of the circulatory system to maintain adequate blood flow. This sharply curtails the delivery of oxygen and nutrients to vital organs. It also compromises the kidney and so curtails the removal of wastes from the body. Shock can be due to a number of different mechanisms including not enough blood volume (hypovolemic shock) and not enough output of blood by the heart (cardiogenic shock). The signs and symptoms of shock include low blood pressure (hypotension), overbreathing (hyperventilation), a weak rapid pulse, cold clammy grayish-bluish (cyanotic) skin, decreased urine flow (oliguria), and mental changes (a sense of great anxiety and foreboding, confusion and, sometimes, combativeness). Shock is a major medical emergency. It is common after serious injury. Emergency care for shock involves keeping the patient warm and giving fluids by mouth or, preferably, intravenously.

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1. The condition in which the cells of the body receive inadequate amounts of oxygen secondary to changes in perfusion; most commonly secondary to blood loss or sepsis. 2. A sudden physical or biochemical disturbance that results in inadequate blood flow and oxygenation of an animal's vital organs. 3. A state of profound mental and physical depression consequent upon severe physical injury or an emotional disturbance. 4. A state characterized by inadequacy of blood flow throughout the body to the extent that damage occurs to the cells of the tissues; if the s. is prolonged, the cardiovascular system itself becomes damaged and begins to deteriorate, resulting in a vicious cycle that leads to death. See diastolic s., systolic s.. [Fr. choc, fr. Germanic]

- anaphylactic s. a severe, often fatal form of s. characterized by smooth muscle contraction and capillary dilation initiated by cytotropic (IgE class) antibodies; typically an antibody-associated phenomenon (type I allergic reaction). SEE ALSO: anaphylaxis, serum sickness.

- anaphylactoid s. a reaction that is similar to anaphylactic s., but which does not require the incubation period characteristic of induced sensitivity (anaphylaxis); it is unrelated to antigen-antibody reactions. SYN: anaphylactoid crisis (1), pseudoanaphylactic s..

- anesthetic s. s. produced by the administration of anesthetic drug(s), usually in relative overdosage.

- break s. the s. produced by breaking a constant current passing through the body.

- cardiac s. SYN: cardiogenic s..

- cardiogenic s. s. resulting from decline in cardiac output secondary to serious heart disease, usually myocardial infarction. SYN: cardiac s..

- chronic s. the state of peripheral circulatory insufficiency developing in elderly patients with a debilitating disease, e.g., carcinoma; a subnormal blood volume makes the patient susceptible to hemorrhagic s. as a result of even a moderate blood loss such as may occur during an operation.

- counter-s. countershock.

- cultural s. a form of stress associated with the beginning of a person's assimilation into a new culture vastly different from that in which he or she was raised.

- declamping s. SYN: declamping phenomenon.

- deferred s., delayed s. a state of s. coming on at a considerable interval after the receipt of the injury.

- diastolic s. the abnormally palpable impact, appreciated by a hand on the chest wall, of an accentuated third heart sound.

- electric s. a sudden violent impression caused by the passage of a current of electricity through any portion of the body.

- endotoxin s. s. induced by release of endotoxin from Gram-negative bacteria, especially by Escherichia coli.

- hemorrhagic s. hypovolemic s. resulting from acute hemorrhage, characterized by hypotension, tachycardia, pale, cold, and clammy skin, and oliguria.

- histamine s. the s. state produced in animals by the injection of histamine; characterized by bronchiolar spasm in the guinea pig and constriction of hepatic veins in the dog.

- hypovolemic s. s. caused by a reduction in volume of blood, as from hemorrhage or dehydration.

- insulin s. severe hypoglycemia produced by administration of insulin, manifested by sweating, tremor, anxiety, vertigo, and diplopia, followed by delirium, convulsions, and collapse. SYN: wet s..

- irreversible s. s. that has progressed because of cell injury beyond the stage where resuscitation is possible.

- nitroid s. a syndrome resembling that produced by the administration of a large dose of a nitrite, sometimes caused by a too rapid intravenous injection of arsphenamine or some other drug; See nitritoid reaction.

- oligemic s. s. associated with pronounced fall in blood volume, sometimes resulting from increased permeability of blood vessel s.

- osmotic s. a sudden change in the osmotic pressure to which a cell is subjected, usually in order to cause it to lyse.

- primary s. s. mainly nervous in nature, from pain, anxiety, etc., which ensues almost immediately upon the receipt of a severe injury.

- protein s. the systemic reaction following the parenteral administration of a protein.

- pseudoanaphylactic s. SYN: anaphylactoid s..

- reversible s. s. that will respond to treatment and from which recovery is possible.

- septic s. 1. s. associated with infection that has released large enough quantities of toxins or vasoactive substances including, cytokines, to be associated with hypotension; 2. s. associated with septicemia caused by Gram-negative bacteria.

- serum s. anaphylactic or anaphylactoid s. caused by the injection of antitoxic or other foreign serum.

- shell s. SYN: battle fatigue.

- spinal s. transient depression or abolition of reflex activity below the level of an acute spinal cord injury or transection.

- systolic s. the abnormally palpable impact, appreciated by a hand on the chest wall, of an accentuated first heart sound.

- toxic s. toxic s. syndrome.

- vasogenic s. s. resulting from depressed activity of the higher vasomotor centers in the brain stem and the medulla, producing vasodilation without loss of fluid so that the container is disproportionately large. In oligemic s., blood volume is reduced; in both, return of venous blood is inadequate.

- wet s. SYN: insulin s..

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Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock? [international randomized trial]

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shock 'shäk n

1) a sudden or violent disturbance in the mental or emotional faculties

2) a state of profound depression of the vital processes of the body that is characterized by pallor, rapid but weak pulse, rapid and shallow respiration, reduced total blood volume, and low blood pressure and that is caused usu. by severe esp. crushing injuries, hemorrhage, burns, or major surgery

3) sudden stimulation of the nerves or convulsive contraction of the muscles that is caused by the discharge through the animal body of electricity from a charged source compare ELECTROCONVULSIVE THERAPY

shock vt

1) to cause to undergo a physical or nervous shock

2) to subject to the action of an electrical discharge

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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, and a reduced flow of urine.

Shock may be due to a decrease in the volume of blood, as occurs after internal or external haemorrhage, burns, dehydration, or severe vomiting or diarrhoea. It may be caused by reduced activity of the heart, as in coronary thrombosis, myocardial infarction, or pulmonary embolism. It may also be due to widespread dilation of the veins so that there is insufficient blood to fill them. This may be caused by the presence of bacteria in the bloodstream (bacteraemic or toxic shock), a severe allergic reaction (anaphylactic shock: see anaphylaxis), overdosage with such drugs as narcotics 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.

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(shok) 1. a sudden disturbance of mental or physical equilibrium. 2. a condition of profound hemodynamic and metabolic disturbance characterized by failure of the circulatory system to maintain adequate perfusion of vital organs. It may result from inadequate blood volume (hypovolemic shock), inadequate cardiac function (cardiogenic shock), or inadequate vasomotor tone (neurogenic shock and septic shock). Called also circulatory collapse.