Sting, Bee, Emergency Medicine

Basics

Description

Injection of hymenoptera venom causes:
- Release of biologic amines
- Local or systemic allergic reactions
Reactions are:
- Usually IgE-mediated type I hypersensitivity reactions
- Rarely type III (Arthus) hypersensitivity reactions

Etiology

Hymenoptera " order of the phylum Arthropoda
Includes bees (Apidae family), wasps and hornets (Vespidae family), fire ants (Formicidae family)

Diagnosis

Signs and Symptoms

History
History and physical exam " keys to diagnosis
Physical Exam
5 types of reactions to stings:

Local reaction:
- Most common type of reaction
- Local pain, erythema, and edema at sting site
- Symptoms occur immediately and resolve within 1 " 2 hr
Large local reaction:
- Similar to local reaction but affects larger area or entire limbs
- Peaks at 48 hr and can last several days
- Mild to moderate fever
Systemic reaction:
- Includes anaphylaxis
- Can be fatal (usually owing to respiratory failure)
- Respiratory:
  - Wheezing
  - Coughing
  - Stridor
  - Shortness of breath
  - Hoarseness
  - Angioedema
- GI:
  - Nausea
  - Vomiting
  - Diarrhea
  - Abdominal pain
- Cardiovascular:
  - Hypotension
  - Chest pain
  - Tachycardia
  - Shock
- Other:
  - Urticaria
  - Pruritus
  - Flushing
- Symptoms occur within 15 " 20 min and last ≤72 hr
Toxic reaction:
- Result of multiple stings and large doses of venom
- Symptoms similar to anaphylaxis
Unusual reactions:
- Owing to unusual immune response
- Vasculitis
- Nephrosis
- Serum sickness
- Neuritis
- Encephalitis
- Reaction delayed (days to weeks after sting)

Essential Workup

History and physical exam key to diagnosis
No radiologic or lab test will confirm hymenoptera envenomation or anaphylaxis

Diagnosis Tests & Interpretation

Lab

CBC, electrolytes, BUN, creatinine, glucose, arterial blood gases (ABGs):
- Not routine
- Consider when significant systemic effects present

Diagnostic Procedures/Surgery
ECG:

When significant systemic effects present in patients at risk for cardiovascular disease

Differential Diagnosis

Insect bites sometimes cause pain; stings always cause pain.
Cellulitis:
- Difficult to distinguish between large local reactions and cellulitis
- Infections of hymenoptera envenomations are rare and usually caused by wasp envenomations.
- Local reaction can resemble periorbital cellulitis.
Gout
Soft tissue trauma
Systemic/toxic reactions:
- Pulmonary embolus
- Anaphylaxis from different agent
- Hyperventilatory syndrome/anxiety
- Acute coronary syndrome

Treatment

Pre-Hospital

Most deaths occur within 1st hour owing to either respiratory obstruction or anaphylaxis causing cardiovascular and respiratory collapse.

Initial Stabilization/Therapy

Acute Severe Systemic Reaction/Anaphylaxis

ABCs:
- Intubation/ventilation with rapidly increasing signs of laryngeal compromise
- Oxygen
- 0.9% normal saline (NS) IV access
Epinephrine SC/IV
Antihistamines IV
Corticosteroids
When signs of systemic reactions:
- Assess for patent airway
- Establish IV access

Ed Treatment/Procedures

Systemic reactions:
- Epinephrine for respiratory symptoms/hypotension
- Antihistamines " H1 (diphenhydramine) and H2 (cimetidine, ranitidine, or famotidine) blockers
- Steroids (prednisone, methylprednisolone, or dexamethasone)
- Inhaled ²-agonist for wheezing/shortness of breath
- For persistent hypotension:
  - 0.9% NS IV fluid resuscitation
  - Vasopressor (epinephrine/α-adrenergic) for hypotension resistant to IV fluids
Removal of remnants of stinger at site of envenomation (bees may leave stingers with venom sacs) by scraping, not squeezing
Local reactions:
- Cool compress
- Elevation
- Remove constrictive clothing or jewelry
- Topical antihistamine/topical steroidal cream as needed
- Oral antihistamine or steroids as needed

Medication

Albuterol, ²-agonist (inhaled): 3 mg in 5 mL NS (peds: 0.1 mg/kg of 5 mg/mL concentration) via nebulization
Cimetidine: 300 mg (peds: 5 mg/kg) IV/IM/PO
Diphenhydramine:
- 50 " 100 mg (peds: 1 mg/kg) IV for severe reactions
- 25 " 50 mg (peds: 1 mg/kg) PO QID for severe local reactions
Epinephrine:
- 0.1 mg: 1 mL of 1:10,000 dilution (peds: 0.01 mg/kg 0.1 mL/kg of 1:10,000 dilution up to 1 mL) IV over 5 min for shock
- 0.3 mg (0.3 mL of 1:1,000 dilution); (peds: 0.01 mg/kg up to 0.5 mg) SC for severe reactions but not in shock
Famotidine: 40 mg IV (peds: 1 mg/kg/d div. BID IV)
Methylprednisolone: 125 mg (peds: 1 " 2 mg/kg) IV
Norepinephrine: 2 " 4 Όg/kg/min (peds: 0.1 Όg/kg/min) titrated continuous infusion
Prednisone: 60 mg (peds: 1 " 2 mg/kg) PO
Ranitidine: 50 mg IV/IM (peds: 2 " 4 mg/kg/d div. q6 " 8h IV/IM)

Follow-Up

Disposition

Admission Criteria

Worsening symptoms, airway compromise
Persistent unstable vital signs require ICU admission.
Life-threatening reaction requires 24-hr observation.
Systemic reaction requires minimum of 6 hr of observation.

Discharge Criteria

Minimal isolated local reaction
Systemic reactions that resolve and do not recur during 6-hr observation period

Issues for Referral
Follow-up:

Provide patients with life-threatening reactions, emergency anaphylaxis kits (EpiPen; peds: EpiPen Jr if <15 kg), and medical identification bracelets (Medi-Alert).
Systemic reaction requires follow-up for possible immunotherapy.

Followup Recommendations

Allergist follow-up for patients with systemic reactions.

Pearls and Pitfalls

Treat patients who present with systemic reactions to bee stings aggressively.
Provide prescriptions for EpiPen to patients discharged after presenting with life-threatening reactions to bee stings.

Additional Reading

Bahna SL. Insect sting allergy: A matter of life and death. Pediatr Ann. 2000;29:753 " 758.
Freeman T. Stings of hymenoptera insects: Reaction types and acute management. UpToDate. Accessed on Sept 25, 2009.
McDougle L, Klein GL, Hoehler FK. Management of hymenoptera sting anaphylaxis: A preventive medicine survey. J Emerg Med. 1995;13:9 " 13.
Moffitt JE, Golden DB, Reisman RE. Stinging insect hypersensitivity: A practice parameter update. J Allergy Clin Immunol. 2004;114:869 " 886.
Reisman RE. Insect stings. N Engl J Med. 1994;331:523 " 527.

Codes

ICD9

989.5 Toxic effect of venom

ICD10

T63.441A Toxic effect of venom of bees, accidental, init

SNOMED

241820008 Bee sting (disorder)
282095007 Allergic reaction to bee sting (disorder)
241931004 Bee sting-induced anaphylaxis (disorder)

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