Wasp Stings Treatment & Management

Prehospital care and emergency department care

The "ABCs" of patient resuscitation and care take precedent. Airway patency and security is the prime concern, especially if there is any evidence of potential airway obstruction from angioedema manifested by stridor, hoarseness of voice, difficulty swallowing, or pooling of secretions. Breathing should be assessed for the rate, depth and adequacy of ventilation with pulse oximetry and auscultation of the chest to determine air movement, and the presence of wheezing from bronchial constriction and spasm. The patient's circulatory status should be evaluated for presence of distributive shock, assessing the blood pressure, nail bed capillary refill, and the patient's mental status.

Specific considerations

Local wound care

Apply ice to keep the area comfortably cool and to reduce swelling. Unlike honeybee stings, members of the wasp family (including hornets and yellow jackets) generally do not lose their stinging apparatus in the wound. Consider a secondary bacterial infection at the site in patients who present several days after the sting with fever or continued redness, warmth, swelling, and tenderness over the site or progression of the redness—red streaks that progress proximally.

Urticaria

Antihistamines remain the mainstay of therapy. H1 blockers such as oral diphenhydramine (Benadryl) or hydroxyzine (Atarax) have proven useful in reducing the severity of the itching and rash. Oral steroids (eg, prednisone, methylprednisolone [Medrol]) can be added to the regimen if needed, depending on the extent and severity of the patient's symptoms. Epinephrine, 0.3-0.5 mL subcutaneously in a 1:1000 solution, can also be used. Although it reverses the extent and itching of the urticaria, its benefit-to-risk ratio must be considered. The alpha effect of epinephrine increases the systemic vascular resistance, while its beta effect has a positive inotropic and chronotropic effect on the heart. This produces an increase in the heart's work and increases the myocardial oxygen demand. This may have a deleterious effect in patients with preexisting heart disease or coronary artery disease.

Anaphylaxis

The patient may present with airway obstruction due to angioedema, respiratory compromise due to bronchospasm, or circulatory collapse or with a combination of these 3 conditions. Follow the ABCs of emergency medicine as expediently as possible. The airway must be secured. Intubate the patient with rapid sequence technique upon evidence of impending airway obstruction due to swelling or evidence of respiratory failure due to bronchospasm. Establish 2 large-bore intravenous lines to provide a route for medication administration and for fluid bolus in the event of circulatory collapse. Place the patient on both pulse oximetry and a cardiac monitor.

Angioedema

If intubation is impossible because of the degree of swelling, obtain a surgical airway through cricothyrotomy. Surgical cricothyrotomy is contraindicated in patients younger than 8 years. In these cases, perform needle cricothyrotomy using the largest-bore needle practical as a temporizing measure. Obtain an emergency consultation with an anesthesiologist and an otorhinolaryngologist (ENT) to prepare the child for the operating room for definitive angioedema/airway management if parenteral beta agonists, histamine 1 (H1) blockers, and glucocorticoids do not relieve the obstruction.

Bronchospasm

Treatment of bronchospasm without obstruction depends on the acuity of the patient's presentation. Treat mild-to-moderate distress with a combination of nebulized beta agonist (eg, albuterol 0.5 mL of 0.5% solution in 2.5 mL of normal saline nebulized q15min) and parenteral glucocorticoids (eg, methylprednisolone 125 mg IV). As the severity of the respiratory distress increases, weigh the benefit-to-risk ratio of using a parenteral beta agonist (eg, epinephrine). As bronchospasm worsens, a point of peaked expiratory flow and forced expiratory volume decrease occurs and the only area being ventilated with the nebulized beta agonist is the appropriately named dead space.

Epinephrine, 0.3-0.5 mL of a 1:1000 solution, may be administered intramuscularly. Its onset of action should be 3-5 minutes; however, impending circulatory collapse with peripheral vasoconstriction due to anaphylaxis may make this route ineffective. Intravenous epinephrine using 3-5 mL (0.3-0.5 mg) of the 1:10,000 solution (0.1 mg/mL) diluted in 10 mL of normal saline or distilled water should be administered slowly over a 1- to 2-minute period, depending on the patient's condition.^[3]

As an alternative, 3-5 mL of 1:10,000 solution can also be administered via the endotracheal tube. Administer this solution via a catheter with the tip placed below the end of the endotracheal tube and then flushed through with several milliliters of saline or distilled water. Several positive ventilations follow to force the epinephrine into the terminal bronchioles and alveoli.

Vasopressin 40 IU has also been used for refractory hypotension.

Hypotension

The cause of hypotension is multifactorial. Histamine, prostaglandin, and leukotriene can reduce the systemic vascular resistance by vasodilating the peripheral vessels and increase the capillary endothelial permeability, allowing extravasation of fluid into the third space. The net effect of both of these processes increases the vascular bed and decreases the amount of fluid in the vascular compartment. Begin treatment with the establishment of 2 large-bore intravenous lines and crystalloid fluid boluses. Vasopressors then can be added, depending on the patient's clinical appearance. Epinephrine can be administered via continuous infusion by mixing 1 mg in 250 mL of normal saline and infusing at a rate of 0.5-1 mL/min. Norepinephrine (Levophed) can also be used. It has the advantage of having more of an alpha effect and less of a beta effect than epinephrine.

Consider a surgical airway in any patient with evidence of upper airway edema or laryngeal spasm who is experiencing respiratory deterioration. The equipment and expertise to perform a cricothyrotomy should be readily available if orotracheal or nasotracheal intubation cannot be achieved.

A consultation with an otorhinolaryngologist may be necessary to visualize the epiglottic and supraglottic regions with a flexible fiberoptic laryngoscope in patients who experience throat tightness or throat closing and who present with little or no objective signs of airway compromise.

In patients with symptoms of throat tightness or throat closing with mild-to-moderate signs of airway compromise or patients who have evidence of early airway obstruction on flexible fiberoptic laryngoscopy, consultation with an anesthesiologist may be necessary to assist in securing the airway.

Patients who have moderate-to-severe signs and symptoms of airway compromise, such as increasing dyspnea, hoarseness, dysphagia, inability to clear secretions, use of accessory muscles, or decreasing oxygen saturation on pulse oximetry, require emergent consultation with both an anesthesiologist and an otorhinolaryngologist to place a surgical airway if intubation is unsuccessful. Rapid sequence intubation in these patients should be used with caution. The airway may be maintained open only by the patient's laryngeal muscles. The use of paralytics may allow the airway to be completely occluded.

Advise patients who have experienced an allergic reaction to prior wasp stings or to any Hymenoptera stings to exercise caution while outdoors during mild-to-warm weather. Advise these patients to avoid wearing any scented material (eg, perfume, hairspray, soaps, deodorants, sunscreen). Brightly colored clothing, especially floral designs, should be avoided. Tell patients who have experienced a severe reaction to a wasp sting to curtail solitary outdoor activities. Advise that the patient should be accompanied when outdoors and away from populated areas (eg, hiking, fishing) in case help is needed.

Because odors tend to attract wasps, tell patients and their families to examine the home environment to decrease risks of attracting insects. Cover garbage pails. Remove rotting fruit on the vine or tree or after having fallen to the ground.

Encourage patients to carry EpiPen auto-injectors when outdoors and to have one device in the home. Advise the patient that auto-injectors left in the car for prolonged periods during hot days may not be effective. They should periodically review the expiration date of the auto-injectors.