Morning Report

Morning Report: Acute Allergic Reaction

Presented by Dr. A. Topaz


A 37 year old female, PMHx anxiety, hereditary spherocytosis with splenectomy presents to the ED with acute allergic reaction of unknown origin with shortness of breath and rapid left lateral neck swelling. The patient was outdoors two hours before arrival and cannot recall any exposure/bites/ingestion/trauma prior to feeling sudden neck swelling and shortness of breath. She reports using an epi pen, taking two Benadryl pills and rubbing hydrocortisone over the area with no relief. She has had similar episodes in the past, but never such neck swelling.

Patient is actively distressed but talking. Denies fevers, chills. C/o left lateral neck swelling with pain, stiffness and trouble swallowing. Denies chest pain, palpitations, wheezing, N/V, abdominal pain, rash.

Vitals: 115/77 / 109/ 98.7/ 23/ 100%

Physical: Patient actively distressed, tachypnic and grasping left neck. Normocephalic. Oropharynx clear- no drooling/erythema/edema. Conjunctivae normal/PERRLA. Neck- normal ROM despite actively swelling left lateral neck. Tachycardic, heart sounds normal, distal pulses +2. Breath sounds clear b/l. No wheezing/rales/rhonchi. Tachypnic, no accessory muscle use. Abdomen soft, nontender, nondistended. BS+. Normal ROM. No cervical LN. Ax0 x3. Skin warm, dry, flushed.


WBC- 15.0 H/H- 15.7/45 Plt- 524 Chemistry- WNL

EKG- NSR/ No acute ischemia CXR- No acute cardiopulmonary abnormalities

ED Course:

Patient immediately hooked up to monitor, able to communicate clearly. Intubation kit, trach kit made available. Calls placed to respiratory, anesthesia, and ENT stat.

Patient started on 1 L NS bolus.

Given 125 mg Methylprednisolone (Solumedrol) IV push

Given 10 mg Dexamethasone (Decadron) IV push

Given 25 mg Benadryl IV push

Given Famotidine (Pepcid) IVPB 20 mg

After one hour, lateral neck swelling resolving, patient reports breathing easier. Admitted to PCP for step down monitoring.


Majority of allergic reactions regardless of cause develop within 15 min- nearly all within 6 hours; shorter the interval to onset, the more severe the reaction.

Fatalities in 1st hr- airway/hypotension. Progess swiftly to shock- must realize that sx may recur biphasically 8-12 hrs post initial reaction in up to 20% of patients. Delayed reactions- may occur 5-14 days after inciting event; often serum sickness like signs and sx: fever/ malaise/ headache/ arthritis/LN/ urticarial. Immune complex mediated

Activation of mast cells and basophils involving crosslinking of IgE’s and aggregation of IgE receptors. Secretory granules include histamine, tryptase, carboxypeptidase which downstream activate PLA2, COX and lipoxygenases, giving end products such as prostaglandins, leukotrienes, platelet activating factors., with subsequent downstream effects. I.e.:

Histamine à vasodilation, vasc perm, HR, gland secretion

Prostaglandin/Platelet activating factorà pulmonary and coronary vasoconstrictor, peripheral vasodilator


Varied – multiple factors capable of provoking mast or basophils

Over 12 million visits for allergic reactions in US from 93-04/ constitute 1% of ED visits

B Lactam antibiotics are the biggest culprit in the US; 400-800 deaths annually; 1 death per 10,000 exposures.


Extensive, including: Often mimicked by vasovagal reactions (most common), MI, arrhythmias, status asthmaticus, epiglottitis, hereditary angioedema, carcinoid, vocal cord dysfunction.

Clinical ; involvement of two or more body systems, with or without hypotension or airway compromise.



Rapid administration of epinephrine

Patients w/o signs of CV compromise: 0.3-0.5 mg (1:1000) IM q 5-10 min according to response

Epipen: 0.3 mg epi for adults   EpiPenJunior: 0.15 mg for children <30 kg

Most patients do not need more than a single dose. IM provides higher and more rapid peak concentrations than SC administration.

If patient refractory despite repeated IM administration, or signs of CV collapse, start IV epi.

Iniitially give 0.1 mg IV (1:100,000) – which is 0.1 mL of the 1:1,000) in 10 mL NS @ 1-2 mL/min/ over 5-10 min

If refractory to this bolus, give 1 mg (1.0 mL of the 1:1000) in 500 mL of 5% dextrose or NS @ .5-2 mL/min, titrating to effect.

  • ABCs: IV Fluid/O2/ cardiac and pulse oximetry monitoring/O2 administration
  • Decontamination (i.e. remove stinger)
  • Crystalloids: If hypotensiveà NS bolus 1-2 L (10-20 ml/kg in children) concurrently with epi infusion

Second line therapy:

  • All patients with anaphylaxis should receive corticosteroids.
  • -Methylprednisolone 80-125 mg IV ( 2 mg/kg in children, up to 125 mg)

Or Hydrocortisone 25-=500 mg IV   (5 -10 mg/kg in children, up to 500 mg)

Methylprednisolone better; less fluid retention than hydrocortisone (pref for elderly/renal/cardiac)

.Can switch to oral steroids after initial dose of IV steroids and antihistamines.


All patients with anaphylaxis should receive H-1 blocker. Recommended to give H-2 as well.

Give diphenhydramine 25-50 mg IV. Give ranitidine 50 mg IV over 5 min (preferred) or cimetidine (300 mg IV).

If wheezing, can add bronchodilator. If severely refractive, can add anticholinergic (ipratropium) or magnesium 2 g IV/ 20-30 minutes.


  1. One risk for prolonged anaphylaxis are patients on B-blockers. Such patients with hypotension refractory to epi and fluids, give glucagon 1 mg IV q 5 minutes until hypotension resolves, followed by 5-15 micrograms/min infusion.

  2. Admission rare, but observe at least 4 hours. Consider longer observation if past history of severe reactions or on B-blockers

  3. Discharge- ) Educate 2.) Epipen rx 3.) Prescribe diphenhydramine 25-50 mg PO for several days, Prednisone 40-60 mg PO several days 4.) Refer to allergist


Tintinalli’s Emergency Medicine: Chapter 27, Anaphylaxis, Acute allergic reactions, and angioedema.

Kemp SF, Lockey RF, Simmons FER, on behalf of the World Allergy Organization Ad Hoc Committee on Epinephrine in Anaphylaxis: Epinephrine: the drug of choice for anaphylaxis. A statement of the World Allergy Organization. Allergy 63: 1061,2008.



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