| Anaphylactic shock is a sudden circulatory collapse that results from a severe allergic reaction. It occurs when the immune system reacts to a foreign substance (allergen). In anaphylactic shock, the immune system releases many chemical substances, including histamine and serotonin. These chemicals cause narrowing of the breathing passages (bronchospasm) and relaxation (dilation) of blood vessels. During the reaction, fluid may pool in the lungs (pulmonary edema) and upper airway obstruction may result from laryngeal edema. Hives (urticaria) and deep tissue swelling (angioedema) may also be observed. The result of anaphylaxis may be life-threatening respiratory and circulatory failure, otherwise known as anaphylactic shock.
Substances (allergens) that trigger allergic reactions are carried in foods, medications, and insect stings, and eventually circulate in the bloodstream. Anaphylaxis can occur in response to any allergen. Although the initial exposure to an allergen does not usually cause severe symptoms, the potential to develop more severe symptoms of anaphylaxis increases with each subsequent exposure.
Common causes include food allergies (33%), insect bites or stings (14%), drug allergies (13%), or exercise (7%). The foods most likely to cause severe allergic reactions are nuts, legumes, seeds, fish, and shellfish (e.g., shrimp). Specific foods that commonly cause allergies are milk, eggs, wheat, peanuts, soybeans, chocolate, and all products containing these foods as ingredients. On occasion, skin contact or inhalation of a food (such as flour) is all that is needed to cause a reaction. However, reactions to penicillin types of antibiotic cause 75% of fatal anaphylaxis in the US. Allergic reactions to latex products may also occur (Noone). Pollens and other inhaled allergens rarely cause anaphylaxis. Some individuals have an anaphylactic reaction with no identifiable cause.Risk: Anaphylaxis can occur in anyone regardless of age, sex, or race. Individuals with a history of any type of allergic reaction, a known sensitivity to a particular food, or those who have asthma are at increased risk of developing anaphylactic shock (James). Incidence and Prevalence: The true incidence of anaphylaxis is not known. Estimated incidence of fatal anaphylaxis is 500 to 1,000 individuals per year in the US, with a reaction to peanuts and tree nuts the most common cause (Krause; Kemp). The risk of an anaphylactic reaction occurring in an individual in the US is 1% to 3% (Kemp). Although fatal anaphylactic shock is rare, milder forms occur more frequently. Food allergies are present in 2.5% of adults and 6% to 8% of children, although by age 10 many children outgrow allergies to milk and eggs (Singh).
Prevalence of anaphylactic reaction occurring in response to ingestion of aspirin or NSAIDs is 1.1% to 3.6% (Stevenson). Incidence of fatal reactions to allergen immunotherapy is rare at 1 death per 2 million injections (Kemp). |
Source: Medical Disability Advisor
| History: If individuals are alert and coherent, they may report a history of an allergic reaction. Often, within 1 to 15 minutes of exposure to the allergen they describe a sudden onset of symptoms such as restlessness; anxiety; nausea; a pins-and-needles feeling in the arms or legs (paresthesia); and itching (pruritus) and swelling of the lips, tongue, or other areas. They may report feeling lightheaded or dizzy and may have chest tightness, palpitations, or difficulty breathing (dyspnea). Most individuals report development of a skin rash that is usually itchy. Anaphylactic food reactions may occur up to 1 to 2 hours after ingestion of the allergenic food, and may result in coughing, sneezing, abdominal pain, vomiting, and diarrhea in addition to other symptoms. Physical exam: Physical examination of individuals with anaphylactic shock is dependent on the organ systems affected and the severity of the attack. Vital signs may be abnormal with low blood pressure, rapid respirations, and rapid heart rate. Decreased level of consciousness, altered neurological status, and seizures may result due to inadequate circulation to the brain. Shortness of breath, coughing, and hoarseness are present when the anaphylaxis causes narrowing of airways or upper airway swelling. Swollen lips and tongue are common and may result in upper airway obstruction. Inadequate oxygenation and low blood pressure may cause weakness, dizziness, or decreased level of consciousness.
Chest pain may occur due to narrowing airways or inadequate blood flow to the heart (cardiac ischemia). More than 90% of individuals with anaphylactic shock have some combination of skin symptoms such as hives, swelling, rash, or itching. The skin may be cool, moist, and pale. In extreme or advanced stages, complete cardiopulmonary arrest may occur. Tests: No immediate tests are required to establish the diagnosis. Skin tests are done later to identify the allergen. |
Source: Medical Disability Advisor
| Anaphylactic shock is an emergency condition requiring immediate professional medical attention. CPR and other lifesaving measures may be required. This may include placing a tube through the nose or mouth into the airway (endotracheal intubation) or emergency surgery to place a tube directly into the trachea (tracheostomy). Epinephrine is given by injection and/or inhalation. This opens the airways and raises the blood pressure by constricting blood vessels.
Treatment for shock includes intravenous fluids and medications that support the actions of the heart and circulatory system. Antihistamines and corticosteroids may be given to further reduce symptoms after lifesaving measures and epinephrine are administered.
Once the individual stabilizes, observation should continue for late reaction symptoms for at least 24 hours after a severe or extreme reaction. Hot showers, baths, and alcohol must be avoided for at least 24 hours to prevent a recurrence of low blood pressure.
A medic alert bracelet should be worn, and individuals should be cautioned after an episode of anaphylaxis to avoid exposure to the inciting agent. When no inciting agent is identified, the individual should be referred to an allergist to identify the cause of anaphylaxis. Individuals with food reactions should refrain from eating in restaurants where the ingredients in dishes cannot be identified. |
Source: Medical Disability Advisor
| Anaphylaxis is a severe disorder with a guarded prognosis. Symptoms usually resolve with prompt treatment. However, among individuals with severe anaphylactic shock, brain damage or death may occur infrequently, even with treatment. For survivors, permanent brain, kidney, or heart damage may result from lack of oxygen (hypoxia) if shock was prolonged. |
Source: Medical Disability Advisor
| Complications include brain damage, kidney damage, obstructed airway, cardiogenic shock, arrhythmias, and heart attack. Pre-existing medical disorders of the respiratory system or multiple sclerosis (MS) can worsen due to the anaphylactic reaction.
Exercise after ingestion of a food allergen or use of beta-adrenergic medications can result in a more severe reaction. |
Source: Medical Disability Advisor
| Those who have recovered without any physical impairment will only need to avoid exposure to known allergens. Those who have occupational allergies (i.e., exposure to latex, dust, or formaldehyde) may require appropriate work reassignments. Individuals with a history of anaphylactic shock or severe allergic reactions must have access to an emergency allergy kit that contains a preloaded dose of injectable epinephrine for self-administration in case of subsequent exposure to the allergen. A co-worker or company nurse should be trained in its use in case another reaction occurs. Specific accommodations may be needed for those with physical impairments following recovery from anaphylactic shock. The individual's physician should be consulted for guidance. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Was diagnosis of anaphylactic shock made based on the presenting symptoms, such as sudden onset of circulatory collapse, particularly in individual with known allergies?
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Were other conditions such as epiglottitis, heart attack, pulmonary embolism, seizure disorder, transfusion reaction, asthma, or hereditary angioedema ruled out?
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Was responsible allergen identified (i.e., food, medication, insect sting) so future encounters can be anticipated or avoided?
Regarding treatment:
- Did individual receive prompt emergency care and life support interventions (i.e. airway, intravenous fluids, epinephrine administration) as indicated?
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Did individual respond to the emergency treatment?
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Were endotracheal intubation or tracheostomy required?
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After resuscitation, did individual show any signs of neurological impairment or heart damage?
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If so, was individual evaluated by appropriate specialists (i.e., neurologist or cardiologist) for ongoing care?
Regarding prognosis:
- Was there any residual impairment?
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Was individual referred to an allergist?
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Was allergy testing done to determine the offending allergen?
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Was individual instructed about allergen avoidance?
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Was individual instructed regarding emergency self-care in the case of unintended exposure (i.e., epinephrine injection)?
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If occupation puts individual at increased risk of allergen encounter, is individual provided with appropriate protection?
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Have any complications developed associated with the anaphylactic reaction, such as neurological impairment or heart attack?
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If so, what is expected outcome?
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Has individual received appropriate care and rehabilitation for the associated physical impairments?
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Source: Medical Disability Advisor
| James, John M. "Food Allergies." eMedicine. Eds. Richard F. Lockey, et al. 3 Dec. 2004. Medscape. 29 Sep. 2004 <http://emedicine.com/med/topic806.htm>.Kemp, Stephen F., and Richard F. Lockey. "Anaphylaxis: A Review of Causes and Mechanisms." Journal of Allergy and Clinical Immunology 110 3 (2002): 341-348. MD Consult. Elsevier, Inc. 30 Sep. 2004 <http://home.mdconsult.com/das/journal/view/41221908-2/N/12514208?sid=297898164&source=MI>. Krause, Richard S. "Anaphylaxis." eMedicine. Eds. Roy Alson, et al. 1 Nov. 2004. Medscape. 30 Sep. 2004 <http://emedicine.com/emerg/topic25.htm>. Noone, Michael C., and J. David Osguthorpe. "Anaphylaxis." Otolaryngologic Clinics of North America 36 5 (2003): 1009-1020. MD Consult. Elsevier, Inc. 30 Sep. 2004 <http://home.mdconsult.com/das/journal/view/41221908-2/N/14136354?sid=297897173&source=MI>. Singh, J., and M. Clark. "Food Allergy." eMedicine Consumer Health. Eds. Scott H. Plantz, et al. 13 Jul. 2004. Medscape. 29 Sep. 2004 <http://emedicine.com/aaem/topic207.htm>. Stevenson, Donald D. "Anaphylactic and Anaphylactoid Reactions to Aspirin and other Nonsteroidal Anti-Inflammatory Drugs." Immunology and Allergy Clinics of North America 21 4 (2001): MD Consult. Elsevier, Inc. 30 Sep. 2004 <http://home.mdconsult.com>. |
Source: Medical Disability Advisor
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