Ver el código de «Anaphylaxis»

{{Adult top}} [[Anaphylaxis (peds)]].''
==Background==
*Type I [[Hypersensitivity Reaction|hypersensitivity reaction]] that is either severe in nature or having two or more organ systems  involved.
*Clinically [[Anaphylaxis]] and its treatment is virtually identical whether it is the traditional IgE dependent anaphylaxis reaction (vast majority), or the IgE independent ''anaphylactoid'' reaction
*Precipitants
**Food (most common)
**Medications
**Insect stings
**Latex
**Aerobic exercise
**Idiopathic (rare)

==Clinical Features==
[[File:Hives2010.jpg|thumbnail|Raised [[urticaria]]]]
[[File:Angioedema2013.jpg|thumbnail|[[Angioedema]] of tongue]]
[[File:Angioedema2010.jpg|thumb|Angioedema of face.]]
*Cutaneous symptoms (90%)
**[[Hives]]
**[[Angioedema]]
**Itching
**Morbilliform rash
*Respiratory symptoms (70%)
**[[Wheezing]]
**[[Shortness of breath]]
**Throat itching or tightness
**Hoarseness
**Stridor
**Hypoxia, cyanosis
*Gastrointestinal symptoms (40%)
**Abdominal pain
**Nausea, vomiting
**[[Diarrhea]]
*Cardiovascular symptoms (35%)
**[[Hypotension]]
**Chest pain
**Palpitations
*Central Nervous System
**Uneasiness 
**Altered mental status
**Headache, dizziness, confusion
**Syncope

===Expected Course===
====Uniphasic (80-90%)====
*Symptoms peak within 30 minutes to 1 hour after onset, resolve within 30 minutes to 1 hour of receiving treatment<ref>Ewan PW. '''ABC of allergies – Anaphylaxis,''' ''BMJ'' 1998; 316: 1442-1445 </ref>
====Biphasic (10-20%)====
''Biphasic reactions are rare and can occur anywhere from 10 minutes up to six days after an initial reaction.''<ref> Milne K. Biphasic Allergic Reactions: Observation, Treatment Guidelines http://www.acepnow.com/article/biphasic-allergic-reactions-observation-treatment-guidelines/</ref>
*Uniphasic response, followed by asymptomatic period of hour or more, then return of symptoms
*The second phase does not necessarily resemble the first!
*More likely with a severe initial presentation or repeated epinephrine doses. Additionally hypotension, widened pulse pressure, unknown trigger, and drug trigger in children<ref>Ellis AK, Day JH: Incidence and characteristics of biphasic anaphylaxis: A prospective evaluation of 103 patients. Ann Allergy Asthma Immunology. 2007; 98:64-69</ref><ref name="aaaai"/>
*Little evidence to support the use of discharge steroids to prevent a biphasic reaction
*0.4% of patients with anaphylaxis had a rebound event while in the ED<ref name="biphasic"/>

==Differential Diagnosis==
{{Acute Allergic DDX}}
{{Shock DDX}}
{{Erythematous rash DDX}}

==Evaluation==
''[[Anaphylaxis]] is highly likely when ANY ONE of the following criteria is fulfilled''<ref>Brown SGA, Mullins RJ and Gold MS. '''Anaphylaxis: diagnosis and management,''' ''MJA'' 2006; 185: 283–289  </ref><ref>Lieberman P et al. '''The diagnosis and management of anaphyalxis: An updated practice parameter,''' ''J Allergy Clin Immunol'' 2005;115;3:S483-S523 </ref>

===Criterion 1 (90% of patients)===
*Acute onset of an illness involving the skin, mucosal tissue, or both AND at least one of the following:
**Respiratory Compromise
**Reduced blood pressure or associated symptoms ([[Syncope]], [[Dizziness]])

===Criterion 2 (10-20% of patients)===
*TWO OR MORE of the following that occur rapidly after exposure to a LIKELY allergen for that patient
**Involvement of the skin-mucosal tissue (hives, swollen lips-tongue-uvula)
**Respiratory compromise
**[[Reduced BP|Hypotension]] or associated symptoms 
**Persistent gastrointestinal symptoms: ([[Vomiting|vomiting]], [[Diarrhea|diarrhea]], crampy [[Abd Pain|abdominal pain]])

===Criterion 3===
*[[Reduced BP|Hypotension]] after exposure to a KNOWN allergy for that patient (minutes to hours):
**Adults: systolic blood pressure (SBP) <90 mmHg or >30% reduction from baseline
**Pediatrics
***1 month - 1 year: SBP <70 mmHg
***1 year - 10 years: SBP <(70 mmHg + [2 x age])
***11 years - 17 years: SBP <90 mmHg

==Management==
*'''[[Epinephrine]]'''
**1:1000 '''IM''' 0.3 - 0.5mg (0.3 - 0.5mL) every 5 - 15 minutes<ref>Dhami S. et al. Management of anaphylaxis: a systematic review. Allergy. 69 (2014) 168–175. http://onlinelibrary.wiley.com/store/10.1111/all.12318/asset/all12318.pdf?v=1&t=hrspdbpk&s=8067bfd5903c7ffebf4a274f062a71633ebe0507</ref><ref>Sheikh A, Shehata YA, Brown SGA, Simons FER. '''Adrenaline (epinephrine) for the treatment of anaphylaxis with and without shock.''' ''Cochrane Database of Systematic Reviews'' 2008, Issue 4. Art. No.: CD006312. DOI:10.1002/14651858.CD006312.pub2</ref>
**Give as soon as possible
**Always IM initially <ref>Simons FER, Gu X, Simons KJ. '''[[Epinephrine]]absorption in adults: Intramuscular versus subcutaneous injection,''' ''J Allergy Clin Immunol'' 2001;108:871-3 </ref>
**If response to IM is inadequate: give epinephrine infusion 1:10,000 2 - 10 µg/min
**'''How to make a quick epinephrine drip:''' ''Take your code-cart epinephrine (it does not matter if it is 1:1,000 or 1:10,000) and inject 1mg into a liter bag of NS.  Final concentration is 1mcg/ml.  Run at 1cc/min and titrate to effect''.
*Pediatric: [[Epinephrine]] '''1:1000 0.01mg/kg (max 0.5mg) IM''' every 5 to 15 minutes
**IV infusion: 0.05 - 1 mcg/kg/min
*'''Supplemental oxygen'''
**''Consider [[Intubation|endotracheal intubation]] if airway edema present''
*'''Normal saline bolus'''
**If unresponsive to [[epinephrine]] assume distributive [[Shock|shock]] and give 1 - 2 liters of normal saline
*'''Also consider'''
**[[Albuterol]] for bronchospasm resistant to IM epinephrine
**[[Antihistamines]] (for symptom control AFTER hemodynamically stable)
***[[Diphenhydramine]]: 25 to 50mg IV (1mg/kg in children)
***[[Ranitidine]]: 50mg IV (0.5mg/kg in children) (has been found to improve urticaria but not angioedema at 2 hours<ref>Lin, RY et al. Improved Outcomes in Patients With Acute  Allergic Syndromes Who Are Treated With  Combined H1 and H2 Antagonists. Annals of Emergency Medicine. 36:5 NOVEMBER 2000.</ref>)
***[[Cetirizine]] 10mg IV (6-11 years old: 5-10 mg IV; 6 mo - 5 years: 2.5 mg IV)
***AVOID promethazine as this can worsen hypotension
**Glucocorticoid
***MAY blunt biphasic reaction although little evidence to support usage<ref>Choo KJ, Simons E, Sheikh A: Glucocorticoids for the treatment of anaphylaxis: Cochrane systematic review. Allergy 2010; 65:1205-1211.</ref>
***[[Methylprednisolone]]: 125mg IV (2mg/kg in children)
***[[Dexamethasone]]: 10mg IV or PO (0.6mg/kg in children)
**[[Glucagon]]
***1 - 5mg IV over 5 minutes followed by infusion of 5 - 15 µg/min<ref>Campbell RL, et al. Emergency department diagnosis and treatment of anaphylaxis: a practice parameter. Ann Allergy Asthma Immunol. 2014; 113:599e608.</ref>
***If taking beta-blocker AND unresponsive to [[Epi|epinephrine]]
**Consider adding additional pressor support if persistent hypotension present
***For example: '''[[vasopressin]]''' 2-8 units for persistent refractory shock (case series only)<ref>Schummer et al. The Pivotal Role of Vasopressin in Refractory Anaphylactic Shock. Anesthesia & Analgesia: August 2008 - Volume 107 - Issue 2 - pp 620-624.</ref><ref>Dünser et al. Treatment of Anaphylactic Shock: Where Is the Evidence? Anesthesia & Analgesia: August 2008 - Volume 107 - Issue 2 - pp 359-361</ref>
***[[Norepinephrine]] 0.05 to 0.5 mcg/kg per minute

==Disposition==
===Admit===
*Severe and moderate presentations, especially if symptoms did not respond promptly to epinephrine or required repeat dosing
*Labs that may be requested by allergist/admitting team if uncertain diagnosis
**Histamine level - serum elevation 30-60 min following anaphylaxis, window easily missed
**Tryptase - peaks at 2-4 hrs, remains elevated 6-12 hrs

===Discharge===
*Consider discharge after 1 hour observation, if no severe symptoms and no repeat epinephrine doses (AAAAI recommendations)<ref name="aaaai">Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. J Allergy Clin Immunol 2020; 145:1082. https://www.aaaai.org/Aaaai/media/Media-Library-PDFs/Professional%20Education/Podcasts/Anaphylaxis-2020-grade-document.pdf</ref>
**NPV of 1-hour observation was 95%, with NPV for biphasic anaphylaxis after >6 hours of observation of 97.3% <ref>Shaker M, Wallace D, Golden DBK, Oppenheimer J, Greenhawt M. Simulation of health and economic benefits of extended observation of resolved anaphylaxis. JAMA Netw Open 2019;2:e1913951.</ref>
*Send home with an [[epinephrine]] autoinjector! (Epi-Pen)
**Up to 6% of the people with anaphylaxis have a repeat ED visit for anaphylaxis within 7 days<ref name="biphasic">Grunau BE et al. Incidence of Clinically Important Biphasic Reactions in Emergency Department Patients With Allergic Reactions or Anaphylaxis. Ann Emerg Med. 2013 Nov 13</ref>

==See Also==
*[[Allergic Reaction]]
*[[Angioedema]]

==External Links==

==References==
<references/>

[[Category:Critical Care]]