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any condition in which the circulatory systemcirculatory system,
group of organs that transport blood and the substances it carries to and from all parts of the body. The circulatory system can be considered as composed of two parts: the systemic circulation, which serves the body as a whole except for the lungs, and the
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 is unable to provide adequate circulation to the body tissues, also called circulatory failure or circulatory collapse. Shock results in the slowing of vital functions and in severe cases, if untreated, in death. It may be caused by inadequate pumping by the heart, by reduction of the blood volume due to dehydration or to loss of blood or plasma, or by reduced blood pressure resulting from dilation of the blood vessels. Inadequate pumping may occur as a result of various kinds of heart disease. Blood loss may result from injuries or from such internal conditions as bleeding ulcers. Burns produce extensive plasma loss from blood vessels into the burned area; crush injuries may result in loss of blood and plasma into the injured tissues. Dilation of blood vessels may be caused by injury to the nervous system, or by pain or emotional stress. Faintingfainting
or syncope
, temporary loss of consciousness caused by an insufficient supply of oxygen to the brain. It can be concurrent with any serious disease or condition, such as heart failure, hypertension (high blood pressure), arrhythmia, hemorrhage, injury to the
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 is a form of shock brought about by a sudden reduction of the blood supply to the brain. Symptoms of shock include weakness, pallor, cold and moist skin, and thirst. The arterial blood pressure is reduced, the pulse is weak and rapid, and the surface veins of the limbs may collapse. Emergency aid for shock victims includes maintaining a clear breathing passage, administering oxygen, controlling bleeding, and keeping the patient warm and in a supine position with legs elevated. Therapy may include blood or plasma transfusion to restore the normal circulation, as well as treatment of the underlying cause of shock. The term shock is also applied to a variety of other conditions such as electric shockelectric shock,
effect of the passage of a current of electricity through the body. Fatality may result from shocks of from 1 to 2 amperes and 500 to 1,000 volts. However, the effect of electric shock on the body depends not only on the strength of the current, but on such
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, allergic shock (see anaphylaxisanaphylaxis
, hypersensitive state that may develop after introduction of a foreign protein or other antigen into the body tissues. When an anaphylactic state exists, a second dose of the same protein (commonly an antibiotic such as penicillin, or certain insect venoms) will
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), and emotional shock. See first aidfirst aid,
immediate and temporary treatment of a victim of sudden illness or injury while awaiting the arrival of medical aid. Proper early measures may be instrumental in saving life and ensuring a better and more rapid recovery.
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a packed conical pile of hay or straw, usually put together where the harvesting takes place. The hay is collected from the fellings when they have a moisture content of 25 to 40 percent and is dried completely in shocks over a period of two to three days. Then the hay shocks are stacked into ricks in the open field, under an awning, or in a barn. About 0.75–2 centners are used to make a rick in areas with a damp climate, and about 2.5–4 centners in dry areas. Hay bucks and harvester-stackers are used to collect the hay into shocks. Gathering straw into a shock is done simultaneously with the combine harvesting of cereals; for this operation the combines are equipped with straw collectors.



a sudden life-threatening condition resulting from severe injury and characterized by progressive impairment of all the physiological systems of the body. The main characteristic of shock is the failure of capillary circulation in the tissues owing to impairment of cardiac output and arterial and venous tonus, capillary dysfunction, and changes in the rheological properties of blood. Shock can be brought on by an injury, burns, surgery (traumatic shock, burn shock, surgical shock), incompatible blood transfusion (hemolytic shock), anaphylaxis (anaphylactic shock), functional cardiac disorders (cardiogenic shock), ischemia of tissues and organs, and excessive loss of blood. The condition was described in detail by the French surgeon H. F. Ledran (1737) and by the Russian physician N. I. Pirogov (1870), who described the symptoms of the erectile phase (brief transient excitement) and torpid phase (subsequent sharp functional inhibition) of shock. The clinical manifestations of shock vary considerably. Progressively increasing extreme weakness and a progressive drop in blood pressure are the most characteristic.

Many aspects of the mechanisms underlying the development of shock still remain unclear. From the neuroreflex viewpoint, the various dysfunctions are due to numerous pain impulses that produce sharp excitation and subsequent inhibition of the nervous system, including the vital centers of the medulla oblongata. From the hemodynamic viewpoint, the decrease in the volume of circulating blood, which leads to peripheral circulatory insufficiency, is the principal factor. From the toxemic viewpoint, shock is caused by the entry into the blood of biologically active substances of tissue origin that interfere with the local and systemic blood flow. It is reasonable to assume that each of these factors plays a part: the primary abrupt activation of the central nervous system by extreme nerve impulses (or toxic substances) increases the amount of catecholamines released into the blood, causing a redistribution of the volume of circulating blood—spasms of the blood vessels of the skin, muscles, kidneys, and abdominal cavity accompanied by the increased flow of blood through arteriovenous anastomoses with maintenance of the circulation in the heart and brain (centralization of the circulation). This period of shock is clinically manifested by pallor and clamminess of the skin, contraction of the pupils, cold perspiration on the face, decreased urine flow, and moderately rapid breathing. The blood pressure is normal or slightly lowered.

“Centralization” of the circulation under conditions of extremely severe and prolonged injury becomes the principal mechanism of circulatory failure and further aggravation of the patient’s condition. The decreased flow of blood to the tissues leads to the accumulation of the products of anaerobic metabolism, biogenic amines, kinins, and other substances. Upon entering the bloodstream, these products, along with other humoral factors, such as increased concentration of some hormones and reduced partial pressure of oxygen, further disrupt the regulatory functions of the nervous system.

The chief factors in the pathogenesis of shock in its late stages are hypoxia, decreased vascular tonus, dysfunction of the tissue microcirculation, and gross derangement of cell metabolism, which results in injury to the cell membranes. The transfer of intravascular fluid to the tissues causes a decrease in the volume of circulating blood. This stage is marked by cyanosis, rapid pulse, lowered blood pressure, and dilatation and slow reaction of the pupils.

The subsequent stage of shock is complicated by congestion in small blood vessels, intravascular agglutination of the erythrocytes, decreased blood flow to the heart, acute cardiac insufficiency, and functional impairment of the vital organs. This stage is clinically manifested by gray cyanosis, thready pulse, abrupt drop in blood pressure, rapid, shallow breathing, dilatation of the pupils, and unconsciousness.

In cases of shock, emergency therapeutic measures are undertaken, chosen according to the cause of the shock, stage of its development, and severity of the patient’s condition. Other measures include the administration of pain relievers, keeping the patient warm, the transfusion of blood and blood substitutes, the administration of oxygen, and the injection of hormones, vitamins, and cardiovascular and other agents.

The term “shock” is also applied to persons in an unusual mental state or persons with severe emotional disturbances (mental, or emotional, shock).


“Problemy reaktivnosti i shoka.” Trudy 1-i Vsesoiuznoi konferentsii patofiziologov. Moscow, 1952.
Petrov, I. R., and G. Sh. Vasadze. Neobratimye izmeneniia pri shoke i krovopotere. Leningrad, 1966.
Weil, M. H., and H. Shubin. Moscow, 1971. Diagnostika i lechenie shoka. (Translated from English.)
Cannon, W. B. Traumatic Shock. New York-London, 1923.
Shires, G. T. Shock. Philadelphia, 1973.



A pulse or transient motion or force lasting thousandths to tenths of a second which is capable of exciting mechanical resonances; for example, a blast produced by explosives.
Clinical manifestations of circulatory insufficiency, including hypotension, weak pulse, tachycardia, pallor, and diminished urinary output.


Pathol a state of bodily collapse or near collapse caused by circulatory failure or sudden lowering of the blood pressure, as from severe bleeding, burns, fright, etc.
References in periodicals archive ?
Acute blood loss and hemorrhagic shock can be seen in both birds and mammals as a consequence of trauma, internal bleeding associated with neoplasia or ulceration, or coagulopathies due to toxicoses or liver disease or after surgical interventions.
With advances in resuscitation strategies, the ability to diagnose hemorrhagic shock before it is obvious and to guide that resuscitation over time will maximize the ability of combat medics to diagnose and treat combat wounded.
Four weeks after his admission there, he died of hemorrhagic shock as a result of gastric hemorrhage.
Biopure Corporation (Cambridge, MA; 617-234-6826) announced that its investigational hemoglobin-based oxygen therapeutic, Hemopure (hemoglobin glutamer - 250 (bovine)), has been shown to improve tissue oxygenation and prevent tissue damage in ischemic conditions relating to hemorrhagic shock, brain hypoxia and heart attack, according to results from pharmacology studies recently reported at the 27th Annual Meeting of the International Society on Oxygen Transport to Tissue (ISOTT) at Dartmouth College (Hanover, NH).
hemorrhagic shock - Pipeline Review, Half Year is built using data and information sourced from Global Markets Direct's proprietary databases, Company/University websites, SEC filings, investor presentations and featured press releases from company/university sites and industry-specific third party sources, put together by Global Markets Direct's team.
The first award focuses on providing first responders and emergency physicians with a simple, inexpensive, easy to use system that predicts the onset of hemorrhagic shock before the patient's vital signs reach a critical stage.
Here we report a rare case of hemorrhagic shock caused by intestinal bleeding from Brunner's gland hyperplasia.
Over the past 40 to 50 years, the treatments commonly used for resuscitation of hemorrhagic shock in both the civilian and military sector, including crystalloid solutions and packed red blood cells, actually dilute the remaining coagulation factors and platelets further which may increase the tendency for more bleeding.
The new nanomedicine was developed to address the need for better field treatments for massive human blood loss, which can cause cardiovascular collapse, also known as hemorrhagic shock.
This case demonstrates an extremely rare cause of spontaneous retroperitoneal hemorrhage (a non-secretory benign adrenocortical tumour) in such a patient and highlights the need to consider all retro-peritoneal organs in the management of hemorrhagic shock.
today announced that enrollment was completed in a Phase IIa clinical study of MP4OX (oxygenated pegylated hemoglobin) in severely injured trauma patients with hemorrhagic shock causing lactic acidosis.