Shock (redirected from distributive shock)

Shock 

Definition

Shock is a medical emergency in which the organs and tissues of the body are not receiving an adequate flow of blood. This deprives the organs and tissues of oxygen (carried in the blood) and allows the buildup of waste products. Shock can result in serious damage or even death.

Description

There are three stages of shock: Stage I (also called compensated, or nonprogressive), Stage II (also called decompensated or progressive), and Stage III (also called irreversible).

In Stage I of shock, when low blood flow (perfusion) is first detected, a number of systems are activated in order to maintain/restore perfusion. The result is that the heart beats faster, the blood vessels throughout the body become slightly smaller in diameter, and the kidney works to retain fluid in the circulatory system. All this serves to maximize blood flow to the most important organs and systems in the body. The patient in this stage of shock has very few symptoms, and treatment can completely halt any progression.

In Stage II of shock, these methods of compensation begin to fail. The systems of the body are unable to improve perfusion any longer, and the patient's symptoms reflect that fact. Oxygen deprivation in the brain causes the patient to become confused and disoriented, while oxygen deprivation in the heart may cause chest pain. With quick and appropriate treatment, this stage of shock can be reversed.

In Stage III of shock, the length of time that poor perfusion has existed begins to take a permanent toll on the body's organs and tissues. The heart's functioning continues to spiral downward, and the kidneys usually shut down completely. Cells in organs and tissues throughout the body are injured and dying. The endpoint of Stage III shock is the patient's death.

Causes and symptoms

Shock is caused by three major categories of problems: cardiogenic (meaning problems associated with the heart's functioning); hypovolemic (meaning that the total volume of blood available to circulate is low); and septic shock (caused by overwhelming infection, usually by bacteria).

Cardiogenic shock can be caused by any disease, or event, which prevents the heart muscle from pumping strongly and consistently enough to circulate the blood normally. Heart attack, conditions which cause inflammation of the heart muscle (myocarditis), disturbances of the electrical rhythm of the heart, any kind of mass or fluid accumulation and/or blood clot which interferes with flow out of the heart can all significantly affect the heart's ability to adequately pump a normal quantity of blood.

Hypovolemic shock occurs when the total volume of blood in the body falls well below normal. This can occur when there is excess fluid loss, as in dehydration due to severe vomiting or diarrhea, diseases which cause excess urination (diabetes insipidus, diabetes mellitus, and kidney failure), extensive burns, blockage in the intestine, inflammation of the pancreas (pancreatitis), or severe bleeding of any kind.

Septic shock can occur when an untreated or inadequately treated infection (usually bacterial) is allowed to progress. Bacteria often produce poisonous chemicals (toxins) which can cause injury throughout the body. When large quantities of these bacteria, and their toxins, begin circulating in the bloodstream, every organ and tissue in the body is at risk of their damaging effects. The most damaging consequences of these bacteria and toxins include poor functioning of the heart muscle; widening of the diameter of the blood vessels; a drop in blood pressure; activation of the blood clotting system, causing blood clots, followed by a risk of uncontrollable bleeding; damage to the lungs, causing acute respiratory distress syndrome; liver failure; kidney failure; and coma.

Initial symptoms of shock include cold, clammy hands and feet; pale or blue-tinged skin tone; weak, fast pulse rate; fast rate of breathing; low blood pressure. A variety of other symptoms may be present, but they are dependent on the underlying cause of shock.

Diagnosis

Diagnosis of shock is based on the patient's symptoms, as well as criteria including a significant drop in blood pressure, extremely low urine output, and blood tests that reveal overly acidic blood with a low circulating concentration of carbon dioxide. Other tests are performed, as appropriate, to try to determine the underlying condition responsible for the patient's state of shock.

Treatment

The most important goals in the treatment of shock include: quickly diagnosing the patient's state of shock; quickly intervening to halt the underlying condition (stopping bleeding, re-starting the heart, giving antibiotics to combat an infection, etc.); treating the effects of shock (low oxygen, increased acid in the blood, activation of the blood clotting system); and supporting vital functions (blood pressure, urine flow, heart function).

Treatment includes keeping the patient warm, with legs raised and head down to improve blood flow to the brain, putting a needle in a vein in order to give fluids or blood transfusions, as necessary; giving the patient extra oxygen to breathe and medications to improve the heart's functioning; and treating the underlying condition which led to shock.

Prognosis

The prognosis of an individual patient in shock depends on the stage of shock when treatment was begun, the underlying condition causing shock, and the general medical state of the patient.

Prevention

The most preventable type of shock is caused by dehydration during illnesses with severe vomiting or diarrhea. Shock can be avoided by recognizing that a patient who is unable to drink in order to replace lost fluids needs to be given fluids intravenously (through a needle in a vein). Other types of shock are only preventable insofar as one can prevent their underlying conditions, or can monitor and manage those conditions well enough so that they never progress to the point of shock.

Resources

Periodicals

Kerasote, Ted. "After Shock: Recognizing and Treating Shock." Sports Afield 217 (May 1997): 60+.

Key terms

Cardiogenic — Originating with the heart.

Deprivation — A condition of having too little of something.

Hypovolemic — Having a low volume.

Perfusion — Blood flow through an organ or tissue.

Sepsis — An overwhelming infection throughout the body, usually caused by bacteria in the bloodstream.

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shock (shok)

1. a sudden disturbance of mental equilibrium.

2. a profound hemodynamic and metabolic disturbance due to failure of the circulatory system to maintain adequate perfusion of vital organs.

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anaphylactic shock  see anaphylaxis.

cardiogenic shock  shock resulting from inadequate cardiac function, as from myocardial infarction or mechanical obstruction; characteristics include hypovolemia, hypotension, cold skin, weak pulse, and confusion.

endotoxin shock  septic shock due to release of endotoxins by gram-negative bacteria.

hypovolemic shock  shock due to insufficient blood volume, either from hemorrhage or other loss of fluid or from widespread vasodilation so that normal blood volume cannot maintain tissue perfusion; symptoms are like those of cardiogenic shock.

insulin shock  a hypoglycemic reaction to overdosage of insulin, a skipped meal, or strenuous exercise in an insulin-dependent diabetic, with tremor, dizziness, cool moist skin, hunger, and tachycardia, sometimes progressing to coma and convulsions.

septic shock  shock associated with overwhelming infection, most commonly infection with gram-negative bacteria, thought to result from the actions of endotoxins and other products of the infectious agent that cause sequestration of blood in the capillaries and veins.

serum shock  see anaphylaxis and see under sickness.

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shock (shk)

n.

1. Something that jars the mind or emotions as if with a violent, unexpected blow.

2. The disturbance of function, equilibrium, or mental faculties caused by such a blow; violent agitation.

3. A generally temporary massive physiological reaction to severe physical or emotional trauma, usually characterized by marked loss of blood pressure and depression of vital processes.

4. The sensation and muscular spasm caused by an electric current passing through the body or a body part.

5. The abnormally palpable impact of an accentuated heartbeat felt by a hand on the chest wall.

v.

1. To induce a state of physical shock in a person.

2. To subject a person to an electric shock.

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shock,

n 1. a state of collapse of the body after injury or trauma. Shock may be either primary or secondary. The principal effects of shock are slowing of the peripheral blood flow and reduction in cardiac output.
2. a circulatory insufficiency caused by a disparity between circulating blood volume and vascular capacity.

shock, galvanic,

n pain produced as a result of galvanic currents caused by similar or dissimilar metallic restorations.

shock, hemorrhagic,

n an ineffectual circulating volume of blood resulting from loss of whole blood.

shock, insulin,

n a coma resulting from too much insulin or an inadequate intake of food. Symptoms include wet or moist skin, hypersalivation or drooling, normal blood pressure, tremors, dilated pupils, normal or bounding pulse, and firm eyeballs. Sugar and acetoacetic acid may be present in bladder urine but are absent in the second specimen. The blood sugar is low (hypoglycemia). See also coma, diabetic.

shock, neurogenic,

n shock caused by loss of nervous control of peripheral vessels, resulting in an increase in the vascular capacity. Onset is usually sudden but is quickly reversible if the cause is removed and treatment is instituted immediately.

shock, primary,

n shock that has a neurogenic basis in which pain and psychic factors affect the vascular system. Occurs immediately after an injury.

shock, secondary,

n shock that occurs some time after the injury (6 to 24 hours later). It is associated with changes in capillary permeability and subsequent loss of plasma into the tissue spaces. Changes in capillary permeability are probably related to histamine release associated with tissue injury.

shock, traumatic,

n a shock produced by trauma, whether psychic or physical. In general usage, this term refers to shock following physical trauma, with hemorrhage, peripheral blood vessel dilation, and changes in capillary permeability.

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shock

a condition of acute peripheral circulatory failure due to derangement of circulatory control or loss of circulating fluid. It is marked by hypotension, coldness of the skin and tachycardia.

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allergic shock

see anaphylactic shock.

shock bodies

hyaline globules composed of fibrin degradation products which act as microthrombi and cause hemorrhage and necrosis.

burn shock

the loss and redistribution of fluid, electrolytes and plasma protein, increased blood viscosity and increased peripheral resistance that follow a severe burn contribute to shock.

cardiogenic shock

classically associated with acute myocardial infarction in humans; in animals may be caused by intrinsic congestive heart failure, cardiac depression caused by anesthetic overdosage or other drugs with negative inotropism, rarely, thromboembolism.

colloidoclastic shock

shock due to breakdown of the physical equilibrium of the body colloids. Thought to cause anaphylactic shock due to the absorption of the colloids into the bloodstream.

distributive shock

see vasogenic shock (below).

electric shock

see electrical injuries.

electroplectic shock

electric shock. See also electrical stunning.

endotoxic shock

caused by endotoxins, especially Escherichia coli. See also toxemic shock.

shock gut

animals in shock develop changes in the gut including congestion and hemorrhage into the lumen.

hypovolemic shock

shock due to reduced blood volume as a result of water deprivation, fluid loss due to diarrhea, vomiting, extensive burns, intestinal obstruction, whole blood loss.

insulin shock

a condition of circulatory insufficiency resulting from overdosage with insulin, which causes too sudden reduction of blood sugar. It is marked by tremor, weakness, convulsions and collapse.

irreversible shock

shock which has reached the stage where irreparable damage has been done to tissues, e.g. liver, kidneys and treatment will not salvage the patient although it might prolong life for a long time.

shock lung

animals in shock due to massive burns, septicemia, disseminated intravascular coagulation (DIC), acute viral or bacterial pneumonias or trauma develop an acute respiratory distress syndrome. The pulmonary lesion is a nonspecific acute or subacute interstitial pneumonia.

nervous shock

a temporary cessation of function in nervous tissue caused by an acute insult such as trauma without the part having been directly or detectably damaged. The loss of function is only temporary, usually for a few minutes but it may last for several hours. There may be residual signs due to direct damage when the shock passes. Stunning by a lightning stroke is an example.

shock organs

those organs, specific to each animal species, which respond to allergens circulating in the blood.

septic shock

see toxemic shock.

spinal shock

flaccid paralysis up and down the body from the site of the spinal cord lesion. Accompanied by a fall in skin temperature, vasodilatation and sweating. Signs disappear within an hour or two. There may be residual signs due to physical injury to tissue.

toxic shock

see toxemic shock.

vasogenic shock, vasculogenic shock

shock exists because of the severe reduction in effective circulating blood volume caused by sequestration of blood and other fluids in the vascular system and their withdrawal from the circulating blood. Is the classical shock of traumatic injury, burns, uterine prolapse, extensive surgery.