Treatment of Aspidae and Vespidae envenomation

Hymenoptera Envenomation: Cost-effective Tips

Cost-effective tips:

1. Prescribe antibiotics for Hymenoptera envenomation only when secondary bacterial infection occurs. The immediate local swelling, erythema, warmth, and pain are due to venom effects or allergic reactions and should not be mistaken for infection. Empiric antibiotic prophylaxis is generally not indicated. Secondary bacterial infections typically develop more than 24 hours after envenomation and should be treated if increasing inflammation, lymphangitis, fever, or leukocytosis develops.

2. Not all Hymenoptera envenomation require hospital admission. Patients who may be safely discharged home from the ED include those with limited local reactions as well as patients with mild anaphylactic reactions that respond readily to treatment and remain asymptomatic after 4-6 hours of observation. However, it is important to instruct the patient to return immediately if hoarseness, wheezing, dyspnea, dizziness, or worsening swelling occur.

3. Not all patients with a hypersensitivity reaction to Hymenoptera envenomation require a referral to an allergist. Patients with only mild local reactions are at minimal risk for anaphylaxis with subsequent stings and do not require referral to an allergist. However, patients with severe local reactions or systemic reactions (i.e., anaphylaxis) should be referred for further evaluation, education, and consideration for venom desensitization immunotherapy.

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Hymenoptera Envenomation: Risk Management Pitfalls

Risk Mangement Pitfalls:

1. “I didn’t think that patient would deteriorate at home after discharge from the ER.” Patients with life-threatening complications of anaphylaxis (such as respiratory distress or cardiovascular compromise) should be admitted to the hospital for observation and continued therapy, even if the symptoms improve in the first few hours of treatment. Patients with incomplete response to therapy, debilitated patients, and those with serious underlying cardiac or pulmonary illness should also be admitted. These patients are at increased risk for deterioration at home if discharged prematurely from the ER.

2. “I should have used epinephrine earlier for that patient with the anaphylactic reaction.” Epinephrine should be administered immediately for patients with evidence of an anaphylactic reaction, upper airway obstruction, or cardiovascular collapse. The intramuscular route provides faster onset of action and more reliable blood levels than subcutaneous administration, while the intravenous route should be reserved for patients in extremis since it may be associated with cardiac ischemia or dysrhythmias. Delays in administering epinephrine may allow airway obstruction or cardiovascular collapse to progress to the point of irreversibility and death.

3. “I should have intubated that patient with upper airway obstruction sooner.” If epinephrine and other immediate interventions fail to improve respiratory distress from anaphylaxis-induced upper airway obstruction, early endotracheal intubation should be strongly considered. A delay in airway control may result in progressive angioedema, making it impossible to intubate the patient and, therefore, necessitating a surgical airway.

4. “I wish I had checked the patient’s blood pressure sooner.” Intractable hypotension is the second leading cause of death in anaphylaxis after laryngeal edema associated with upper airway obstruction. Early recognition is of key importance. Patients with such cardiovascular collapse require early treatment with epinephrine, aggressive volume resuscitation with intravenous crystalloid, and continuous infusions of vasopressors.

5. “I was so busy treating the other aspects of the envenomation that I forgot to ask about tetanus immunization status.” Although it is easy to focus on treating the more impressive local and systemic reactions to these envenomations, it is important not to forget the basic principles of wound care, such as tetanus prophylaxis.

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Hymenoptera Envenomation: Case Study

Case Study:

Imagine these scenarios:

Paramedics call your emergency department to inform you that they are transporting a 12-year-old boy who was stung several hundred times by a swarm of honeybees. The patient is agitated and has innumerable erythematous papular stings to his face and extremities. What are your immediate priorities, and what are your subsequent concerns for delayed toxicity?

A 7-year-old girl is brought to triage by her parents after she was stung a single time by a wasp. She is lethargic with facial swelling and a generalized urticarial rash. In addition, she has respiratory distress with bilateral wheezes on lung examination, and pulse oximetry demonstrates oxygen saturations of 87% on room air. How should this life-threatening situation be managed?

A 2-year-old male is transported to your emergency department after stumbling into a fire ant nest. He is crying, irritable, and tachycardic but has no respiratory distress. He has multiple erythematous papules on his legs that are beginning to form fluid-filled vesicles. What is the treatment for this envenomation?

Case Study Conclusion:

This 12-year-old boy sustained massive bee envenomation, likely the result of an aggressive swarm of Africanized honeybees. You observed that he had several hundred bee stings to his face, extremities, and torso, but no evidence of anaphylaxis. The immediate priorities of airway, breathing, and circulation were attended to. He was breathing comfortably without stridor, wheezes, or hypoxia. He had moderate tachycardia but no hypotension. Intravenous access was obtained, and the patient was treated with intravenous fluids, corticosteroids, antihistamines, and analgesia. Although he remained stable for several hours in the emergency department, you admitted him for observation due to your concerns that he may develop delayed toxicity secondary to the massive envenomation. In the hospital, the patient did indeed decompensate 12 hours after admission with vomiting, tachycardia, hypotension, and altered mental status. Laboratory evaluation revealed hemolysis, hemoglobinuria, rhabdomyolysis, renal insufficiency, and hepatic transaminase enzyme elevations. Aggressive supportive care measures in the intensive care unit were required to stabilize the patient. His condition gradually improved, and he was discharged home in good condition after 1 week in the hospital.

You immediately recognized that this 7-year-old girl was experiencing an anaphylactic reaction to the wasp sting and brought her to the resuscitation room for aggressive management of this life-threatening emergency. Oxygen and nebulized albuterol were administered, and the patient was given an intramuscular injection of epinephrine simultaneously. Intravenous access was obtained, and the patient received fluids, antihistamines, and corticosteroids. Her initial blood pressure was 72/40 mm Hg, and this improved to 90/64 mm Hg after 1 dose of epinephrine and 2 boluses of normal saline. Her wheezing and oxygen requirement resolved, and her mental status improved. She continued to have generalized urticaria, but the rash had faded considerably. You breathed a sigh of relief as you consulted the allergy-immunologist and made arrangements for hospital admission.

Your initial examination of the child revealed no respiratory distress or other signs of anaphylaxis, and the parents were not aware of the child having any prior exposure to fire ants. After confirming that the child had no significant compromise of vital signs, you felt comfortable that the child’s envenomation could be treated with good wound management and symptomatic care. The affected areas were gently cleansed with soap and water, and cool compresses were applied. The child’s tetanus status was confirmed to be current. The patient’s pain and itching were treated with oral ibuprofen and diphenhydramine. His irritability and tachycardia resolved as he stopped crying and became more comfortable. Prior to discharge home, you reassured the parents, who were thankful for the good care their child received.

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