DRG Category: 916
Mean LOS: 2.2 days
Description: Medical: Allergic Reactions Without Major Complication or Comorbidity
Anaphylactic shock, or anaphylaxis, is an immediate, life-threatening, multiple organ (skin, respiratory tract, cardiovascular system, gastrointestinal system) allergic reaction caused by a systemic antigen-antibody immune response to a substance (antigen) introduced into the body. The classic form of anaphylaxis results from prior sensitization to the antigen, with later reexposure producing symptoms of shock through an immunological mechanism. The term was first coined in 1902 when a second dose of a vaccination caused the death of an animal; the animal's death was described as the opposite of prophylaxis and was therefore called anaphylaxis, which means “without protection.” In the United States, experts estimate that from 20,000 to 50,000 people have anaphylactic shock each year; fatalities are infrequent, but as many as 1,000 people may die in the United States each year. Experts suggest that up to 15% of the North American population is at risk of experiencing anaphylaxis.
Traditionally, most experts have considered that classic anaphylaxis is caused by a type I, immunoglobulin E (IgE)–mediated hypersensitivity reaction only. The antigen combines with IgE on the surface of the mast cells and precipitates a release of histamine and other chemical mediators, such as serotonin and slow-reacting substance of anaphylaxis (SRS-A). The resulting increased capillary permeability, smooth muscle contraction, and vasodilation account for the cardiovascular collapse. More recently, the World Allergy Organization has broadened the definition of anaphylaxis to include not only IgE-mediated but also non-IgE-mediated and nonimmunological anaphylaxis events. Non-IgE anaphylaxis results from IgG- and complement-mediated activation, whereas nonimmunological anaphylaxis results from mast cell and basophil degranulation without the presence of immunoglobulins.
Bronchoconstriction, bronchospasm, and relative hypovolemia result in impaired airway, breathing, and circulation; vasodilation, increased vascular permeability, and nerve stimulation occurs, and death may follow if anaphylaxis is not promptly reversed. Although a delayed reaction may occur 24 hours after the exposure to an antigen, most reactions occur within minutes after exposure, and a recurrence of symptoms may occur after 4 to 8 hours. The most common causes of death from anaphylaxis are airway obstruction and hypotension.
Anaphylaxis can result from a variety of causes, but it most commonly occurs in response to food, medications, and insect bites. Severe reactions to penicillin occur with a frequency of 1 to 5 patients per 10,000 courses of medication, and deaths from penicillin occur in 1 case per 50,000 to 100,000 courses of medication. Insect stings cause 25 to 50 deaths per year in the United States. In population-based studies in the United States, ingestion of a specific food was responsible for 33% of cases, insect stings for 18.5% of cases, and medications for 13.7% of cases. Twenty-five percent of cases had no identifiable cause. Common sources are iodine-based contrast materials and medications that are derived from biological protein sources. These medications can include those derived from horse sera, vaccines, enzymes, and hormones. Foods such as fish, eggs, peanuts, milk products, and chocolate can cause allergic reactions and anaphylaxis. Rarely, anaphylaxis can also be caused by vigorous exercise such as jogging, tennis, soccer, and bicycling.
While susceptibility to anaphylaxis is increased among those who have inherited sensitivity to antigens, the genetic component has not been well defined. Several genes have been implicated specifically in development of anaphylaxis (IL4R, IL10, IL13) and in modulating the severity of anaphylaxis (PAF-AH, cKIT). More broadly, over 20 genes have been associated with the development of allergy, and of these, many are passed on in families. Family studies indicate that if both parents suffer from allergies, the allergy risk in their offspring is 80%. In addition to the genes involved in anaphylaxis, it is thought that interferon gamma (IFNG), β-adrenergic receptor (ADRB2), 5 lipoxygenase (ALOX5), PHF1, TARC, and the leukotriene C4 synthetase (LTC4S) genes play a role in allergy risk. Animal studies indicate that mutations in the transient receptor potential cation channel (TRPM4), which controls calcium influx, particularly in T cells and mast cells, can augment anaphylaxis.
Anaphylactic shock can occur at any age and in both men and women, but women seem a little more susceptible than men. Individuals with food allergies (particularly shellfish, peanuts, and tree nuts) and asthma may be at increased risk for having a life-threatening anaphylactic reaction. People near the end of the life span are most at risk. To prevent infants and children from experiencing severe allergic reactions, pediatricians carefully plan vaccines and diet to limit the risk of allergic reaction until a child's immune system is more mature. Severe food allergy is more common in children than in adults, but diagnostic contrast, insect stings, and anesthetics are more common in adults than in children. Teenagers with food allergies and asthma may be at high risk for an allergic reaction because they are more likely to eat outside the home and less likely to carry their medications. Some experts suggest that latex, aspirin, and muscle relaxant reactions are more common in women and insect sting anaphylaxes are more common in men. Older adults also have a great risk of anaphylaxis, and their risk of death is high owing to the presence of preexisting diseases.
Allergy rates in children seem to vary by race and ethnicity. Black children have more allergies to wheat, soy, corn, fish, and shellfish than White children. Hispanic children have more allergies to corn, fish, and shellfish than White children. This same study suggested that Black and Hispanic children are at higher risk of adverse outcomes, a shorter duration of follow-up with an allergy specialist, and higher rates of anaphylaxis as compared to White children (Mahdavinia et al., 2017). Sexual and gender minority status has no known effect on the risk for anaphylaxis.
The global incidence of anaphylaxis is unknown, but fatal anaphylaxis is relatively rare, whereas milder forms occur more frequently. Internationally, the frequency of anaphylaxis is increasing due to an increase in exposure to allergens. Allergic reactions to insects, venomous plants, and venomous animals are more prevalent in tropical areas.
PLANNING AND IMPLEMENTATION
Collaborative
The plan of care depends on the severity of the reaction, but airway management is the first priority. Discontinue the administration of any possible allergen immediately. Consider applying a tourniquet to the extremity with the antigen source; this procedure can retard antigen exposure to the systemic circulation, but the tourniquet needs to be released every 5 minutes, and it should not be left in place longer than 30 minutes. Complete an assessment of the patient's airway to ensure patency, adequate breathing, and oxygenation. If the patient has airway compromise, endotracheal intubation and noninvasive ventilation or mechanical ventilation with oxygenation may be necessary. More severe or prolonged cases of anaphylactic shock are aggressively treated with the establishment of IV access and infusion of normal saline or lactated Ringer solution as well as supplemental oxygen therapy. The patient may require urinary catheterization to monitor urinary output during periods of instability.
| Medication or Drug Class | Dosage | Description | Rationale |
|---|
| Epinephrine | Preparation and dose vary by route, which can be IV, subcutaneous, intramuscular, sublingually, or down the endotracheal tube; subcutaneous dose is 0.3–0.5 mg of a 1:1,000 solution and repeated at 20-min intervals; an IV drip may be used for protracted cases; prefilled syringe is often used | Catecholamine | Decreases inflammation and allergic response |
| Diphenhydramine (Benadryl; H1 blocker) may be given to inhibit further histamine release; ranitidine (H2 blocker) may be given at the same time | 25–50 mg IV with 50 mg of ranitidine IV | Antihistamine | Inhibits histamine release and relieves skin symptoms but has no immediate effect on the systemic reaction; combination of H1 and H2 blockers together have been found to be effective |
Other Medications: Corticosteroids (methylprednisolone) and aminophylline for swelling and bronchospasm; inhaled beta-adrenergic agonists such as albuterol; severe hypotension can be treated with vasopressor agents such as dopamine. Glucagon may be useful in treating cardiovascular effects for patients taking beta blockers.
Independent
The most important priority for nurses is to ensure adequacy of the airway, breathing, and circulation. Keep intubation equipment available for immediate use. Insert an oral or nasal airway if the patient is at risk for airway occlusion but has adequate breathing. Use an oral airway for unresponsive patients and a nasal airway for patients who are responsive. If endotracheal intubation is necessary, secure the tube firmly and suction the patient as needed to maintain the airway. If the patient has a compromised circulation that does not respond to pharmacologic intervention, begin cardiopulmonary resuscitation with chest compressions.
Teach the patient and family how to prevent future allergic reactions. Explain the nature of the allergy, the signs and symptoms to expect, and measures to perform if the patient is exposed to the allergen. Teach the patient that if shortness of breath, difficulty swallowing, or the formation of the “lump in the throat” occurs, they should go to an emergency department immediately. If the allergen is a medication, make sure the patient and family understand that they must avoid the various sources of the medication in both prescription drugs and over-the-counter preparations for the rest of their lives. Encourage the patient to notify all healthcare providers of the allergy prior to treatment.
Evidence-Based Practice and Health Policy
Turner, P., Campbell, D., Motosue, M., & Campbell, R. (2020). Global trends in anaphylaxis epidemiology and clinical implications. Journal of Allergy and Clinical Immunology: In Practice, 8, 1169–1176.
- Anaphylaxis is an emergency situation that occurs with an acute systemic allergic reaction that can be fatal. The true global incidence of anaphylaxis is difficult to determine because many times it occurs in community and not hospital settings. In spite of difficulties quantifying the incidence, the authors suggest that a global increase is occurring because of allergies to medication and food. Anaphylaxis accounts for less than 1% of hospital admissions, with most of the Western developed countries with increasing rates and Taiwan with decreasing rates.
- In spite of this increase, mortality rates have not increased. The authors suggest that older age, delayed administration of epinephrine, and keeping a patient in an upright position with a dependent lower body are risk factors for fatal anaphylaxis.