Anaphylaxis

Anaphylaxis
SpecialtyAllergy and immunology
SymptomsItchy rash, throat swelling, numbness, shortness of breath, lightheadedness, low blood pressure,[1] vomiting
Usual onsetOver minutes to hours[1]
TypesAnaphylactoid reaction, anaphylactic shock, biphasic anaphylaxis
CausesInsect bites, foods, medications,[1] drugs/vaccines
Diagnostic methodBased on symptoms[2]
Differential diagnosisAllergic reaction, asthma exacerbation, carcinoid syndrome[2]
TreatmentEpinephrine, intravenous fluids[1]
Frequency0.05–2%[3]

Anaphylaxis (Greek: ana- 'up' + phylaxis 'guarding') is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site.[4][5] It typically causes more than one of the following: an itchy rash, throat closing due to swelling that can obstruct or stop breathing; severe tongue swelling that can also interfere with or stop breathing; shortness of breath, vomiting, lightheadedness, loss of consciousness, low blood pressure, and medical shock.[6][1] These symptoms typically start in minutes to hours and then increase very rapidly to life-threatening levels.[1] Urgent medical treatment is required to prevent serious harm and death, even if the patient has used an epipen or has taken other medications in response, and even if symptoms appear to be improving.[6]

Common causes include allergies to insect bites and stings, allergies to foods – including nuts, milk, fish, shellfish, eggs and some fresh fruits or dried fruits; allergies to sulfites – a class of food preservatives and a byproduct in some fermented foods like vinegar; allergies to medications – including some antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin;[7] allergy to general anaesthetic (used to make people sleep during surgery); allergy to contrast agents – dyes used in some medical tests to help certain areas of the body show up better on scans; allergy to latex – a type of rubber found in some rubber gloves and condoms.[6][1] Other causes can include physical exercise, and cases may also occur in some people due to escalating reactions to simple throat irritation or may also occur without an obvious reason.[6][1] The mechanism involves the release of inflammatory mediators in a rapidly escalating cascade from certain types of white blood cells triggered by either immunologic or non-immunologic mechanisms.[8] Diagnosis is based on the presenting symptoms and signs after exposure to a potential allergen or irritant and in some cases, reaction to physical exercise.[6][1]

The primary treatment of anaphylaxis is epinephrine injection into a muscle, intravenous fluids, then placing the person "in a reclining position with feet elevated to help restore normal blood flow".[1][9] Additional doses of epinephrine may be required.[1] Other measures, such as antihistamines and steroids, are complementary.[1] Carrying an epinephrine autoinjector, commonly called an "epipen", and identification regarding the condition is recommended in people with a history of anaphylaxis.[1] Immediately contacting ambulance / EMT services is always strongly recommended, regardless of any on-site treatment.[6] Getting to a doctor or hospital as soon as possible is absolutely required in all cases, even if it appears to be getting better.[6]

Worldwide, 0.05–2% of the population is estimated to experience anaphylaxis at some point in life.[3] Globally, as underreporting declined into the 2010s, the rate appeared to be increasing.[3] It occurs most often in young people and females.[9][10] About 99.7% of people hospitalized with anaphylaxis in the United States survive.[11]

  1. ^ a b c d e f g h i j k l m "Anaphylaxis". National Institute of Allergy and Infectious Diseases. April 23, 2015. Archived from the original on 4 May 2015. Retrieved 4 February 2016.
  2. ^ a b Caterino JM, Kahan S (2003). In a Page: Emergency medicine. Lippincott Williams & Wilkins. p. 132. ISBN 9781405103572. Archived from the original on 2017-09-08.
  3. ^ a b c Simons FE, Ardusso LR, Bilò MB, El-Gamal YM, Ledford DK, Ring J, Sanchez-Borges M, Senna GE, Sheikh A, Thong BY, World Allergy O (February 2011). "World allergy organization guidelines for the assessment and management of anaphylaxis". The World Allergy Organization Journal. 4 (2): 13–37. doi:10.1097/wox.0b013e318211496c. PMC 3500036. PMID 23268454.
  4. ^ Sampson HA, Muñoz-Furlong A, Campbell RL, et al. (February 2006). "Second symposium on the definition and management of anaphylaxis: summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium". The Journal of Allergy and Clinical Immunology. 117 (2): 391–7. doi:10.1016/j.jaci.2005.12.1303. PMID 16461139.
  5. ^ Tintinalli, Judith E. (2010). Emergency Medicine: A Comprehensive Study Guide (Emergency Medicine (Tintinalli)). New York: McGraw-Hill Companies. pp. 177–182. ISBN 978-0-07-148480-0.
  6. ^ a b c d e f g NHS (29 November 2019). "Overview – Anaphylaxis". NHS (National Health Service). United Kingdom: British government. Retrieved 4 March 2022.
  7. ^ Oxford Handbook of Emergency Medicine (4th ed.). Oxford Medical Productions. p. 42.
  8. ^ Khan BQ, Kemp, SF (August 2011). "Pathophysiology of anaphylaxis". Current Opinion in Allergy and Clinical Immunology. 11 (4): 319–25. doi:10.1097/ACI.0b013e3283481ab6. PMID 21659865. S2CID 6810542.
  9. ^ a b The EAACI Food Allergy and Anaphylaxis Guidelines Group (August 2014). "Anaphylaxis: guidelines from the European Academy of Allergy and Clinical Immunology". Allergy. 69 (8): 1026–45. doi:10.1111/all.12437. PMID 24909803. S2CID 11054771.
  10. ^ Lee JK, Vadas, P (July 2011). "Anaphylaxis: mechanisms and management". Clinical and Experimental Allergy. 41 (7): 923–38. doi:10.1111/j.1365-2222.2011.03779.x. PMID 21668816. S2CID 13218854.
  11. ^ Ma L, Danoff TM, Borish L (April 2014). "Case fatality and population mortality associated with anaphylaxis in the United States". The Journal of Allergy and Clinical Immunology. 133 (4): 1075–83. doi:10.1016/j.jaci.2013.10.029. PMC 3972293. PMID 24332862.