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Anaphylaxis (Anaphylactic shock…)

Summary

Anaphylaxis is an acute, potentially life-threatening, type 1 hypersensitivity reaction, involving the sudden IgE-mediated release of histamine mediators from mast cells and basophils in response to a trigger (e.g., food, insect stings, medication). Anaphylactoid reactions (a subtype of pseudoallergy) are IgE-independent reactions that result from direct mast-cell activation (e.g., in response to opioids); the clinical presentation and management are the same as for anaphylaxis. Typical signs and symptoms of both reactions include the acute onset of urticarial rash, angioedema, stridor, dyspnea, bronchospasm, circulatory failure (distributive shock), vomiting, and diarrhea. The diagnosis is clinical and is based on combinations of typical symptoms, plus the presence of a known or suspected trigger. Rapid recognition and treatment are key to prevent death from airway loss, respiratory failure, or cardiovascular collapse. Management consists of initial resuscitation measures that focus on administering IM epinephrine, removing triggers, securing the airway, and giving IV fluid boluses, which take precedence over adjunctive treatment like steroids and antihistamines.

Definition

Etiology

  • Trigger is idiopathic in 20% of patients [1]
  • Most common triggers leading to fatal anaphylaxis [2][1][3]
    • Younger patients: food allergies; (e.g., peanut, tree nuts), insect stings (e.g., bee stings)
    • Older patients: drug reactions, radiocontrast media
    • Hospitalized patients: food, medications (e.g., antibiotics, NSAIDs), latex

Pathophysiology

Clinical features

Onset of symptoms [2][4]

In general, the onset of symptoms is acute (within minutes to hours of exposure to a likely antigen).

Antigen-dependent onset of anaphylaxis [2][4]
Trigger

Median time to circulatory arrest

Food 30 min
Insect 15 min
Medication 5 min

Affected organ systems [2][4]

Beware of atypical manifestations without skin/mucosal symptoms (10% of patients) to avoid misdiagnosis and treatment delay. [1]

Diagnostic criteria for anaphylaxis [4][6][1]

If any of the following criteria are fulfilled, anaphylaxis is likely. The onset of symptoms must be acute (minutes to hours).

If anaphylaxis diagnostic criteria are met, empiric treatment should be given without delay.

Management

The most important measures in anaphylaxis are to remove the inciting allergen and administer epinephrine as soon as possible. Delay can lead to airway compromise, respiratory failure, refractory shock, and death.

Epinephrine injections for anaphylaxis should always be given intramuscularly in a concentration of 1:1,000 (as opposed to the 1:10,000 solution used in cardiac arrest). Injecting the 1:1,000 solution into a vein can lead to cardiac arrhythmia/arrest.

Diagnostics

Anaphylaxis is a clinical diagnosis (see “Diagnostic criteria for anaphylaxis”).

Laboratory studies [2][8][9]

Imaging [2][9]

Airway management and ventilation

See also “Airway management” and “Mechanical ventilation” for more details.

Obtain early anesthesia or ENT consultation in patients with a rapid decline or anticipated airway compromise.

References: [2][4][7]

Subsequent management

Refractory anaphylaxis [2][4][7]

Adjunctive therapy [2][4][7]

Antihistamines and steroids should be administered in anaphylaxis only after the initial resuscitation measures (IM epinephrine, fluids and/or vasopressors) have been given.

A lack of response to epinephrine, antihistamines, and steroids should raise suspicion of differential diagnoses such as bradykinin-mediated angioedema, which requires its own specific treatment (see “Treatment of angioedema”).

Monitoring and disposition [2][4][7]

Acute management checklist

Differential diagnoses

Differential diagnoses of anaphylaxis [4]

Symptom clusters

Conditions
Multisystem involvement
Acute upper airway obstruction/stridor

Acute respiratory distress/wheezing [4]

Loss of consciousness
Hypotension
Skin rash/flushing

The differential diagnoses listed here are not exhaustive.

Complications

We list the most important complications. The selection is not exhaustive.

Prevention

Pretreatment for in-hospital triggers [12][13][14]

  • Consider corticosteroid and/or antihistamine pretreatment if known triggers are crucial to clinical care and difficult to avoid: e.g., radiocontrast material (most common), chemotherapeutic agents, blood products, antivenom.
  • Regimens vary by institution and indication. [14]
  • 1. Anagnostou K, Turner PJ. Myths, facts and controversies in the diagnosis and management of anaphylaxis. Arch Dis Child. 2018; 104(1): pp. 83–90. doi: 10.1136/archdischild-2018-314867.
  • 2. Campbell RL, Li JTC, Nicklas RA, Sadosty AT. Emergency department diagnosis and treatment of anaphylaxis: a practice parameter. Ann Allergy Asthma Immunol. 2014; 113(6): pp. 599–608. doi: 10.1016/j.anai.2014.10.007.
  • 3. Ring J, Beyer K, Biedermann T, et al. Guideline for acute therapy and management of anaphylaxis. Allergo Journal International. 2014; 23(3): pp. 96–112. doi: 10.1007/s40629-014-0009-1.
  • 4. Walls R, Hockberger R, Gausche-Hill M. Rosen's Emergency Medicine. Philadelphia, PA: Elsevier Health Sciences; 2018.
  • 5. Hariri G, Joffre J, Leblanc G, et al. Narrative review: clinical assessment of peripheral tissue perfusion in septic shock. Annals of Intensive Care. 2019; 9(1). doi: 10.1186/s13613-019-0511-1.
  • 6. Loprinzi Brauer, et al. Prospective Validation of the NIAID/FAAN Criteria for Emergency Department Diagnosis of Anaphylaxis. JACI: In Practice. 2016; 4(6). doi: 10.1016/j.jaip.2016.06.003.
  • 7. Lieberman P, Nicklas RA, Randolph C, et al. Anaphylaxis—a practice parameter update 2015. Annals of Allergy, Asthma & Immunology. 2015; 115(5): pp. 341–384. doi: 10.1016/j.anai.2015.07.019.
  • 8. Long B, Koyfman A, Gottlieb M. Evaluation and Management of Angioedema in the Emergency Department. Western Journal of Emergency Medicine. 2019; 20(4): pp. 587–600. doi: 10.5811/westjem.2019.5.42650.
  • 9. Moellman JJ, Bernstein JA, Lindsell C, et al. A Consensus Parameter for the Evaluation and Management of Angioedema in the Emergency Department. Academic Emergency Medicine. 2014; 21(4): pp. 469–484. doi: 10.1111/acem.12341.
  • 10. Tupper J, Visser S. Anaphylaxis: A review and update. Can Fam Physician. 2010; 56(10): pp. 1009–11. pmid: 20944042.
  • 11. Alqurashi W, Ellis AK. Do Corticosteroids Prevent Biphasic Anaphylaxis?. The Journal of Allergy and Clinical Immunology: In Practice. 2017; 5(5): pp. 1194–1205. doi: 10.1016/j.jaip.2017.05.022.
  • 12. Davenport MS, Cohan RH. The Evidence for and Against Corticosteroid Prophylaxis in At-Risk Patients. Radiol Clin North Am. 2017; 55(2): pp. 413–421. doi: 10.1016/j.rcl.2016.10.012.
  • 13. International Collaborative Study of Severe Anaphylaxis. Risk of anaphylaxis in a hospital population in relation to the use of various drugs: an international study. Pharmacoepidemiol Drug Saf. 2003; 12(3): pp. 195–202. doi: 10.1002/pds.822.
  • 14. O’Malley RB, Cohan RH, Ellis JH, et al. A Survey on the Use of Premedication Prior to Iodinated and Gadolinium-Based Contrast Material Administration. Journal of the American College of Radiology. 2011; 8(5): pp. 345–354. doi: 10.1016/j.jacr.2010.09.001.
  • Pollak AN, Murphy M, Stathers CL et al. Critical Care Transport. Jones and Bartlett Publishers; 2011.
  • Campbell RL, Kelso JM. Anaphylaxis: Acute diagnosis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/anaphylaxis-acute-diagnosis. Last updated July 25, 2016. Accessed February 16, 2017.
  • Campbell RL, Kelso JM. Anaphylaxis: Emergency treatment. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. http://www.uptodate.com/contents/anaphylaxis-emergency-treatment. Last updated July 21, 2016. Accessed February 16, 2017.
  • Kemp SF. Pathophysiology of anaphylaxis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/pathophysiology-of-anaphylaxis. Last updated February 23, 2017. Accessed March 9, 2017.
  • Mustafa SS, Kaliner MA. Anaphylaxis. In: Anaphylaxis. New York, NY: WebMD. http://emedicine.medscape.com/article/135065. Updated February 22, 2017. Accessed March 9, 2017.
  • Lewis SR, Butler AR, Parker J, Cook TM, Schofield-Robinson OJ, Smith AF. Videolaryngoscopy versus direct laryngoscopy for adult patients requiring tracheal intubation: a Cochrane Systematic Review. Br J Anaesth. 2017; 119(3): pp. 369–383. doi: 10.1093/bja/aex228.
  • Apfelbaum JL, Hagberg CA, Caplan RA, et al. Practice Guidelines for Management of the Difficult Airway. Anesthesiology. 2013; 118(2): pp. 251–270. doi: 10.1097/aln.0b013e31827773b2.
  • De Backer D, Fagnoul D. Intensive Care Ultrasound: VI. Fluid Responsiveness and Shock Assessment. Annals of the American Thoracic Society. 2014; 11(1): pp. 129–136. doi: 10.1513/annalsats.201309-320ot.
  • Bakker J, Nijsten MW, Jansen TC. Clinical use of lactate monitoring in critically ill patients. Annals of Intensive Care. 2013; 3(1): p. 12. doi: 10.1186/2110-5820-3-12.
last updated 10/29/2020
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