All: Anaphylaxis/Acute allergic rxn

Rx
-vitals, high-flow O2, monitor, IV
-Airway-intubate early, esp hoarse pts, "lump in my throat"; may need 1-2 tube sizes smaller due to edema; get cric kit ready
-Breathing - high-flow o2, albuterol neb
-Circulation - 1-2L IVfluids -> IV epi
-D/C antigen - remove stinger, d/c IV drug infusions
1) Epinephrine - less severe signs, give subq/IM epi .3-.5 cc (.3-.5mg) (0.01mg/kg max 0.5) 1:1000 q 5-10 min -> repeat -> repeat -> go to IV; antlat thigh>delt
- for severe resp distress, laryngeal edema, severe shock; .1 cc of 1:1000 in 10 cc saline over 5-10 min infuse -> no response -> epi infusion 1 mg (1cc of 1:1000) in 500 cc saline at .5 to 2 cc/min (1-4 mic/min), titrate to effect (also 1-4 mic/min of 1:10,000)
-5-10mic iv bolus (0.2mic/kg) for hypotn; 0.1-0.5mg IV if CV collapse
2) antihistamines - diphenydramine 25-50 mg IV (1mg/kg upto 50mg), ranitidine 50 mg
3) steroids - severe - methylprednisolone 125 mg IV (1-2mg/kg), oral prednisone 60 mg (1.0mg/kg) less severe
4) glucagon 1-5mg (20-30mic/kg) over 5min q5 min (in pts taking bblockers), drip 5-15 mic/min - hypotension refractory to epi, causes emesis
5) vasopressors - norepi, vasopressin, metaraminol

dispo
-mild rxn - observe 1 hr
-given epi - observe 6 hr
-severe rxn - admit to ICU
-discharge pts with Rx for antihistamines and prednisone for 4 days

-common causes - PCN, asa/other nsaids, ACEI, bactrim, contrast, hymenoptera stings, peanuts, shellfish, milk, eggs, monosodium glutamate, nitrites, dyes, idiopathic
-concurrent use of Bblockers is a risk for severe, prolonged anaphylaxis
-rxns are biphasic, with further mediator release 4-8 hrs later in up to 20% of cases

si/sx
-urticaria (hives) cutaneous, IgE mediated reaction, yielding itchy red wheals
-angioedema - face and neck
-anaphylaxis includes cv or resp compromise by definition
-resp - stridor, dyspnea, wheezing
-gi - n, cramps, diarrhea, vomiting
-pruritis and urticaria most common itial sx

Resources:
-Just the Facts in EM
-Annals EM, april 06, 47:4