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What is Anaphylaxis?
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A severe allergic reaction is called Anaphylaxis by Plato 18 year
Anaphylaxis refers to a severe allergic reaction in which prominent dermal and systemic signs and symptoms manifest. The full-blown syndrome includes urticaria (hives) and/or angioedema with hypotension and bronchospasm. The classic form, described in 1902, involves prior sensitization to an allergen with later re-exposure, producing symptoms via an immunologic mechanism. An anaphylactoid reaction produces a very similar clinical syndrome but is not immune-mediated.
The most common inciting agents in anaphylaxis are parenteral Antibiotics (especially penicillins), IV contrast materials, Hymenoptera stings, and certain foods (most notably, peanuts). Oral medications and many other types of exposures also have been implicated. Anaphylaxis also may be idiopathic.
Frequency:
In the US:
The true incidence of anaphylaxis is unknown, partly because of the lack of a precise definition of the syndrome. Some clinicians reserve the term for the full-blown syndrome, while others use it to describe milder cases. Fatal anaphylaxis is relatively rare; milder forms occur much more frequently. Some authors consider up to 15% of the US population "at risk" for anaphylaxis. The frequency of anaphylaxis is increasing and this has been attributed to the increased number of potential allergens to which people are exposed. Up to 500-1,000 fatal cases of anaphylaxis per year are estimated to occur in the US.
Internationally:
Reactions to insects and other venomous plants and animals are more prevalent in tropical areas because of the greater biodiversity in these areas.
Mortality/Morbidity:
Approximately 1 in 5000 exposures to a parenteral dose of a penicillin or cephalosporin Antibiotic causes anaphylaxis. More than 100 deaths per year are reported in the United States. Fewer than 100 fatal reactions to Hymenoptera stings are reported each year in the United States but this is considered to be an underestimate. One to 2% of people receiving IV radiocontrast experience some sort of reaction. The majority of these reactions are minor, and fatalities are rare. Low molecular weight contrast causes fewer and less severe reactions.
Race: Well-described racial differences in the incidence or severity of anaphylaxis do not exist. Cultural and socioeconomic differences may influence exposure rates.
Sex: No major differences have been reported in the incidence and prevalence of anaphylactic reactions between men and women.
Age: Anaphylaxis occurs in all age groups. While prior exposure is essential for the development of true anaphylaxis, reactions occur even when no documented prior exposure exists. Thus, patients may react to a first exposure to an Antibiotic or insect sting. Adults are exposed to more potential allergens than are pediatric patients. The elderly have the greatest risk of mortality from anaphylaxis due to the presence of preexisting disease.
History:
Anaphylactic reactions almost always involve the skin or mucous membranes. More than 90% of patients have some combination of urticaria, erythema, pruritus, or angioedema.
The upper respiratory tract commonly is involved, with complaints of nasal congestion, sneezing, or coryza. Cough, hoarseness, or a sensation of tightness in the throat may presage significant airway obstruction.
Eyes may itch and tearing may be noted. Conjunctival injection may occur.
Dyspnea is present when patients have bronchospasm or upper airway edema. Hypoxia and hypotension may cause weakness, dizziness, or syncope. Chest pain may occur due to bronchospasm or myocardial ischemia (secondary to hypotension and hypoxia).
GI symptoms of cramplike abdominal pain with nausea, vomiting, or diarrhea also occur but are less common, except in the case of food allergy .
In a classic case of anaphylaxis, the patient or a bystander provides a history of possible exposures that may have caused the rapid onset of skin and other manifestations.
This history often is partial; exposure may not be recalled, or it may not be considered significant by the patient or physician. For example, when queried about medications, a patient may not mention over-the-counter (OTC) products. The clinician may not realize that, while reactions are usually rapid in onset, they also may be delayed.
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All Plato's Answers
Anaphylaxis refers to a severe allergic reaction in which prominent dermal and systemic signs and symptoms manifest. The full-blown syndrome includes urticaria (hives) and/or angioedema with hypotension and bronchospasm. The classic form, described in 1902, involves prior sensitization to an allergen with later re-exposure, producing symptoms via an immunologic mechanism. An anaphylactoid reaction produces a very similar clinical syndrome but is not immune-mediated.
The most common inciting agents in anaphylaxis are parenteral Antibiotics (especially penicillins), IV contrast materials, Hymenoptera stings, and certain foods (most notably, peanuts). Oral medications and many other types of exposures also have been implicated. Anaphylaxis also may be idiopathic.
Frequency:
In the US:
The true incidence of anaphylaxis is unknown, partly because of the lack of a precise definition of the syndrome. Some clinicians reserve the term for the full-blown syndrome, while others use it to describe milder cases. Fatal anaphylaxis is relatively rare; milder forms occur much more frequently. Some authors consider up to 15% of the US population "at risk" for anaphylaxis. The frequency of anaphylaxis is increasing and this has been attributed to the increased number of potential allergens to which people are exposed. Up to 500-1,000 fatal cases of anaphylaxis per year are estimated to occur in the US.
Internationally:
Reactions to insects and other venomous plants and animals are more prevalent in tropical areas because of the greater biodiversity in these areas.
Mortality/Morbidity:
Approximately 1 in 5000 exposures to a parenteral dose of a penicillin or cephalosporin Antibiotic causes anaphylaxis. More than 100 deaths per year are reported in the United States. Fewer than 100 fatal reactions to Hymenoptera stings are reported each year in the United States but this is considered to be an underestimate. One to 2% of people receiving IV radiocontrast experience some sort of reaction. The majority of these reactions are minor, and fatalities are rare. Low molecular weight contrast causes fewer and less severe reactions.
Race: Well-described racial differences in the incidence or severity of anaphylaxis do not exist. Cultural and socioeconomic differences may influence exposure rates.
Sex: No major differences have been reported in the incidence and prevalence of anaphylactic reactions between men and women.
Age: Anaphylaxis occurs in all age groups. While prior exposure is essential for the development of true anaphylaxis, reactions occur even when no documented prior exposure exists. Thus, patients may react to a first exposure to an Antibiotic or insect sting. Adults are exposed to more potential allergens than are pediatric patients. The elderly have the greatest risk of mortality from anaphylaxis due to the presence of preexisting disease.
History:
Anaphylactic reactions almost always involve the skin or mucous membranes. More than 90% of patients have some combination of urticaria, erythema, pruritus, or angioedema.
The upper respiratory tract commonly is involved, with complaints of nasal congestion, sneezing, or coryza. Cough, hoarseness, or a sensation of tightness in the throat may presage significant airway obstruction.
Eyes may itch and tearing may be noted. Conjunctival injection may occur.
Dyspnea is present when patients have bronchospasm or upper airway edema. Hypoxia and hypotension may cause weakness, dizziness, or syncope. Chest pain may occur due to bronchospasm or myocardial ischemia (secondary to hypotension and hypoxia).
GI symptoms of cramplike abdominal pain with nausea, vomiting, or diarrhea also occur but are less common, except in the case of food allergy .
In a classic case of anaphylaxis, the patient or a bystander provides a history of possible exposures that may have caused the rapid onset of skin and other manifestations.
This history often is partial; exposure may not be recalled, or it may not be considered significant by the patient or physician. For example, when queried about medications, a patient may not mention over-the-counter (OTC) products. The clinician may not realize that, while reactions are usually rapid in onset, they also may be delayed.
Viewed 5599 times
All Plato's Answers