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Anaphylaxis: understanding the varying degrees of anaphylaxis

Allergy, Asthma, Infant and Children | February 11, 2015 | Author: The Super Pharmacist

Children, allergy, Asthma

Anaphylaxis: understanding the varying degrees of anaphylaxis

When most people think of anaphylaxis, they think of a life-threatening condition in which every second counts. While this describes severe anaphylaxis, anaphylaxis actually occurs in varying degrees of severity or as part of different syndromes. Indeed, physicians usually reserve the term anaphylaxis for the most severe of the three syndromes. Strictly speaking, there are three syndromes of anaphylaxis: anaphylaxis urticaria, angioedema, and severe anaphylaxis (with asthma and/ or anaphylactic shock). Depending on the severity of the anaphylaxis syndrome, any of the three can be fatal unless properly and promptly treated. Moreover, these three anaphylaxis syndromes can sometimes occur together and all three should be considered in anyone developing anaphylactic symptoms.

Degrees of anaphylaxis

Urticaria

UrticariaUrticaria, perhaps better known as “hives,” denotes a skin rash that causes itchy, red welts. Urticaria is a telltale sign of an allergic reaction. Hives may occur near a site of injury with an allergen. For example, a person who is allergic to a bee sting may develop hives around the sting. Hives may also occur diffusely, that is, over most or all of the surface of the skin. This is more common with food allergies but may occur as a severe reaction to a focal injury, like an insect sting.

While urticaria is sometimes considered the least dangerous or deadly of the anaphylaxis syndromes, it is important to recognise that hives may simply be the first manifestation of a more serious allergic reaction. If the person with hives develops a hoarse voice, wheezing, drooling, difficulty swallowing, throat tightness, and/or nausea/vomiting it may indicate a more severe form of anaphylaxis.

Angioedema

Angioedema is a swelling that occurs when fluids leave the blood vessels and enter the tissues. While angioedema can occur in any “loose” tissue in the body, but the term is usually used to describe a swelling of the face, lips, mouth, and the internal structures of the throat. Angioedema may occur within minutes to hours after the person has been exposed to the allergen. Because angioedema can occur so rapidly and affect the mouth and throat, the condition may interfere with breathing, which makes it an extremely serious event.

Severe anaphylaxis

Severe anaphylaxis is an allergic reaction that causes bronchospasm (the closing of the airways) and/or severe hypotension (a rapid drop in blood pressure; anaphylactic shock). One or both of these clinical signs are accompanied by either urticaria, angioedema, or both. Essentially, the airways constrict and the blood vessels dilate; the former interferes with breathing while the latter prevents the body from generating blood pressure.

Severe anaphylaxis may not necessarily start as a severe clinical issue. In fact, many cases may begin as a moderate asthma attack.

Severe anaphylaxis may escalate to profound shock in less than 15 minutes. 

As many as 20% of patients who have experienced severe anaphylaxis and survived may have a second episode within the next 30 hours.

Rapid recognition of anaphylaxis

Anyone who may be experiencing anaphylaxis should be seen by a physician immediately (call emergency services). On the other hand, if you are preparing for the possibility of anaphylaxis in the future it may be helpful to know the diagnostic criteria that physicians use to make a rapid diagnosis of anaphylaxis:

Diagnostic Criteria for Anaphylaxis

1. Acute onset (minutes to several hours) of an illness with involvement of the skin or mouth such as hives, itchiness, and/or redness over the entire body or angioedema and at least one of the following:

  • Respiratory compromise such as shortness of breath, wheezing, lips turning blue, etc.
  • Reduced blood pressure or symptoms such as collapse, passing out, and losing control of the bladder

2. Two or more of the following that occur rapidly after exposure to a probable allergen

  • Involvement of the skin or mouth such as hives, itchiness, and/or redness over the entire body or angioedema
  • Respiratory compromise such as shortness of breath, wheezing, lips turning blue, etc.
  • Reduced blood pressure or symptoms such as collapse, passing out, and losing control of the bladder
  • Gastrointestinal symptoms that will not go away such as crampy abdominal pain and vomiting

3. Reduced blood pressure after exposure to a KNOWN allergen for that patient

Treatment of anaphylaxis

The treatment of anaphylaxis is guided by the severity of the allergic reaction. Mild urticaria or angioedema is a self-limited process and will go away on its own. Nevertheless, even mild anaphylactic reactions are taken very seriously and usually treated aggressively, ideally before they have a chance to get worse.

Urticaria without asthma, angioedema, or anaphylactic shock

Treatment of anaphylaxisThe primary treatment for hives without signs of more serious reaction are antihistamines. These may include drugs like diphenhydramine, promethazine and loratadine. 

In a hospital setting, these drugs may be given intravenously, along with ranitidine or cimetidine since they may be more effective in treating acute urticarial when given in combination.

Glucocorticoids or adrenaline are usually not necessary, helpful, or given in cases of urticaria without angioedema or anaphylactic shock.

Urticaria with asthma (but without angioedema or anaphylactic shock)

When urticaria is present with symptoms of asthma such as shortness of breath and wheezing, it may be a sign of impending anaphylactic shock and/or bronchospasm (the closure of the airways). Therefore, the patient is treated more aggressively than may be required of a simple asthma attack. In addition to inhaled bronchodilators such as salbutamol, patients may also be given an injection of adrenaline into a muscle. This may also be combined with antihistamines.

Angioedema

Angioedema is treated with a combination of intravenous antihistamines and adrenaline injected into a muscle. Antihistamines alone are not effective in treating angioedema. While most cases of angioedema are not life-threatening, the fact that the condition can advance rapidly and block the airway means it should be managed by a healthcare professional. 

Severe anaphylaxis

Severe anaphylaxis should be treated immediately as is it potentially fatal in all cases. Intramuscullar adrenaline should be injected into the upper thigh as soon as severe anaphylaxis is recognised and followed with emergency care.

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References

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Caballero T, Baeza ML, Cabanas R, et al. Consensus statement on the diagnosis, management, and treatment of angioedema mediated by bradykinin. Part I. Classification, epidemiology, pathophysiology, genetics, clinical symptoms, and diagnosis. J Investig Allergol Clin Immunol. 2011;21(5):333-347; quiz follow 347.

Bluestein HM, Hoover TA, Banerji AS, Camargo Jr CA, Reshef A, Herscu P. Angiotensin-converting enzyme inhibitor–induced angioedema in a community hospital emergency department. Annals of Allergy, Asthma & Immunology. 2009;103(6):502-507.

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