anaphylactic shock

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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anaphylactic shock

n.

A severe, sometimes fatal allergic reaction characterized by a sharp drop in blood pressure, urticaria, and breathing difficulties that is caused by exposure to a foreign substance, such as a drug or bee venom, after preliminary or sensitizing exposure. The reaction may be fatal if emergency treatment, including epinephrine injections, is not given immediately. Also called anaphylaxis.

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Anaphylactic shock

A severe systemic reaction to an allergen that occurs in hypersensitive individuals. It can cause spasms of the larynx that block the patient's airway and cause dyspnea.

Mentioned in: Shortness of Breath, Wilderness Medicine

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anaphylactic shock,

a severe and sometimes fatal systemic allergic reaction to an allergen, such as a drug, vaccine, specific food, serum, allergen extract, insect venom, or chemical. This condition may occur within seconds to minutes from the time of exposure to the allergen and is commonly marked by respiratory distress and vascular collapse. The quicker the systemic atopic reaction in the individual after exposure, the more severe the associated shock is likely to be.

observations The first symptoms are intense anxiety, weakness, and a feeling of impending doom. Sweating and dyspnea may occur. These are followed, often quickly, by pruritus and urticaria. Other symptoms include hypotension, shock, arrhythmia, respiratory congestion, edema of the glottis, nausea, and diarrhea.

interventions Treatment requires the immediate intramuscular or subcutaneous injection of epINEPHrine, with vigorous massage of the injection site to ensure faster distribution of the drug. The airway is maintained, and the patient is carefully monitored for signs of edema of the glottis, which may require the insertion of an endotracheal tube or a cricothyrotomy and oxygen therapy. The signs of edema of the glottis include stridor, hoarseness, and dyspnea. Cardiopulmonary resuscitation may be required for cardiac arrest.

nursing considerations Nursing care requires appropriate emergency treatment and close monitoring for respiratory distress, hypotension, and decreased circulatory volume. Patients with a history of severe allergic reactions are instructed to avoid offending allergens; some patients must carry emergency anaphylaxis kits, such as an EpiPen Auto-Injector containing injectable epINEPHrine.

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anaphylactic [an″ah-fi-lak´tik]

pertaining to or affected by anaphylaxis.

anaphylactic reaction anaphylaxis.

anaphylactic shock a serious and profound state of shock brought about by hypersensitivity (anaphylaxis) to an allergen such as a drug, foreign protein, or toxin. Sometimes it occurs upon second injection of a patient with a previously injected serum or protein.

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shock [shok]

1. a sudden disturbance of mental equilibrium.

2. a condition of acute peripheral circulatory failure due to derangement of circulatory control or loss of circulating fluid. It is marked by hypotension and coldness of the skin, and often by tachycardia and anxiety. Untreated shock can be fatal. Called also circulatory collapse.

Mechanisms of Circulatory Shock. The essentials of shock are easier to understand if the circulatory system is thought of as a four-part mechanical device made up of a pump (the heart), a complex system of flexible tubes (the blood vessels), a circulating fluid (the blood), and a fine regulating system or “computer” (the nervous system) designed to control fluid flow and pressure. The diameter of the blood vessels is controlled by impulses from the nervous system which cause the muscular walls to contract. The nervous system also affects the rapidity and strength of the heartbeat, and thereby the blood pressure as well.



Shock, which is associated with a dangerously low blood pressure, can be produced by factors that attack the strength of the heart as a pump, decrease the volume of the blood in the system, or permit the blood vessels to increase in diameter.

Types of Circulatory Shock. There are five main types: Hypovolemic (low-volume) shock occurs whenever there is insufficient blood to fill the circulatory system. Neurogenic shock is due to disorders of the nervous system. Anaphylactic (allergic) shock and septic shock are both due to reactions that impair the muscular functioning of the blood vessels. And cardiogenic shock is caused by impaired function of the heart.

Hypovolemic (Low-Volume) Shock. This is a common type that happens when blood or plasma is lost in such quantities that the remaining blood cannot fill the circulatory system despite constriction of the blood vessels. The blood loss may be external, as when a vessel is severed by an injury, or the blood may be “lost” into spaces inside the body where it is no longer accessible to the circulatory system, as in severe gastrointestinal bleeding from ulcers, fractures of large bones with hemorrhage into surrounding tissues, or major burns that attract large quantities of blood fluids to the burn site outside blood vessels and capillaries. The treatment of hypovolemic shock requires replacement of the lost volume.

Neurogenic Shock. This type, often accompanied by fainting, may be brought on by severe pain, fright, unpleasant sights, or other strong stimuli that overwhelm the usual regulatory capacity of the nervous system. The diameter of the blood vessels increases, the heart slows, and the blood pressure falls to the point where the supply of oxygen carried by the blood to the brain is insufficient, which can bring on fainting. Placing the head lower than the body is usually sufficient to relieve this form of shock.

Anaphylactic (Allergic) Shock. This type (see also anaphylaxis) is a rare phenomenon that occurs when a person receives an injection of a foreign protein but is highly sensitive to it. The blood vessels and other tissues are affected directly by the allergic reaction. Within a few minutes, the blood pressure falls and severe dyspnea develops. The sudden deaths that in rare cases follow bee stings or injection of certain medicines are due to anaphylactic reactions.

Septic Shock. This type, resulting from bacterial infection, is being recognized with increasing frequency. Certain organisms contain a toxin that seems to act on the blood vessels when it is released into the bloodstream. The blood eventually pools within parts of the circulatory system that expand easily, causing the blood pressure to drop sharply. Gram-negative shock is a form of septic shock due to infection with gram-negative bacteria.

Cardiogenic Shock. This type may be caused by conditions that interfere with the function of the heart as a pump, such as severe myocardial infarction, severe heart failure, and certain disorders of rate and rhythm.

Pathogenesis of shock. (ARDS = adult respiratory distress syndrome, GI = gastrointestinal, IL = interleukin, TNF = tumor necrosis factor.) From Damjanov, 2000.

anaphylactic shock see anaphylactic shock.

cardiogenic shock shock resulting from primary failure of the heart in its pumping function, as in myocardial infarction, severe cardiomyopathy, or mechanical obstruction or compression of the heart; clinical characteristics are similar to those of hypovolemic shock.

colloidoclastic shock colloidoclasia.

cultural shock feelings of helplessness and discomfort experienced by an outsider attempting to comprehend or effectively adapt to a different cultural group or unfamiliar cultural context.

electric shock see electric shock.

hypovolemic shock shock resulting from insufficient blood volume for the maintenance of adequate cardiac output, blood pressure, and tissue perfusion. Without modification the term refers to absolute hypovolemic shock caused by acute hemorrhage or excessive fluid loss. Relative hypovolemic shock refers to a situation in which the blood volume is normal but insufficient because of widespread vasodilation as in neurogenic shock or septic shock. Clinical characteristics include hypotension; hyperventilation; cold, clammy, cyanotic skin; a weak and rapid pulse; oliguria; and mental confusion, combativeness, or anxiety.

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; if untreated it may progress to coma and convulsions.

respirator shock circulatory shock due to interference with the flow of blood through the great vessels and chambers of the heart, causing pooling of blood in the veins and the abdominal organs and a resultant vascular collapse. The condition sometimes occurs as a result of increased intrathoracic pressure in patients who are being maintained on a mechanical ventilator.

septic shock shock associated with overwhelming infection, usually by gram-negative bacteria, although it may be produced by other bacteria, viruses, fungi, and protozoa. It is thought to result from the action of endotoxins or other products of the infectious agent on the vascular system causing large volumes of blood to be sequestered in the capillaries and veins; activation of the complement and kinin systems and the release of histamine, cytokines, prostaglandins, and other mediators may be involved. Clinical characteristics include initial chills and fever, warm flushed skin, increased cardiac output, and a lesser degree of hypotension than with hypovolemic shock; if therapy is ineffective, it may progress to the clinical picture associated with hypovolemic shock.

shell shock old term for posttraumatic stress disorder.

spinal shock the loss of spinal reflexes after injury of the spinal cord that appears in the muscles innervated by the cord segments situated below the site of the lesion.

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anaphylactic

pertaining to anaphylaxis.

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anaphylactic reaction

see anaphylaxis.

anaphylactic shock

a serious and generalized state of shock brought about by hypersensitivity (anaphylaxis) to an allergen, such as a drug, foreign protein or toxin.