Wasp Stings Follow-up

All patients who present with a moderate-to-severe reaction to a wasp sting that required treatment should be observed. A rebound or biphasic reaction has been reported in 1-20% of patients as initial treatment wears off.

Airway

Proactively treat patients who experience throat tightness resulting from a wasp sting. A treatment spectrum progresses from the asymptomatic patient to the patient with symptoms of mild throat tightness to the patient in respiratory distress from angioedema.

Assess the airway as soon as possible in the patient who experiences throat tightness. Although cross-lateral neck radiography to assess soft tissue can be helpful to rule out gross swelling, it has several disadvantages. It may not reveal early swelling. If transferred to the radiology department for the radiograph, the patient should be accompanied by both an intubation tray and a physician capable of managing the airway.

The airway is best visualized by either an otorhinolaryngologist or an emergency department (ED) physician using a Machida scope or, if a flexible fiberoptic scope is not available, indirect laryngoscopy. An intubation tray must be available at the bedside.

Supplemental oxygen supplied by a humidified cool mist is often helpful in the patient with minimal inflammation who does not need immediate intubation and is being observed.

Breathing

Continually monitor patients with pulse oximetry. Peak flow measurement may help evaluate the progression of bronchial spasm.

Evidence of poor ventilation with decreasing oxygen saturations, poor air movement, wheezing, poor air exchange, prolongation of the expiratory phase, or increased work of breathing requires aggressive management.

A nebulized beta agonist (eg, albuterol) can reduce bronchial spasm and improve oxygenation.

Use methylprednisolone 125 mg IV to decrease the inflammatory response of the airways.

Circulation

The cardiac rate and rhythm and the intravascular fluid compartment are 2 components of circulation that must be monitored.

Put the patient on a cardiac monitor and observe in an area where the patient can be intubated if necessary.

The BP must be monitored continuously because of the release of multiple factors in anaphylaxis that can reduce capillary integrity, increase capillary permeability, and subsequently decrease the amount of fluid in the vascular compartment and, at the same time, decrease the systemic vascular resistance.

• Direct outpatient care at preventing any further reaction.
• Provide patient education to reduce high-risk activities that may lead to exposure (see Activity).
• Prescribe self-administered auto-injectors (eg, EpiPen) to patients who have the potential for a severe reaction or who may be away from readily available medical assistance.
• Refer patients to an allergist for desensitization. This follow-up referral should be made expeditiously. The factors to consider are include initial reaction of the patient and the patient's risk of being stung again, such as the patient's occupation and time of year.

• Auto-injectors (eg, EpiPen): Patients should be taught the use of the EpiPen 0.3 mg auto-injector or the EpiPen Jr 0.15 mg before they leave the ED. The patient should be taught the indications for the use of the EpiPen such as the signs and symptoms of a severe allergic or anaphylactic reaction. They should be taught to inject the EpiPen into the anterolateral aspect of the thigh and that once the auto-injector is triggered to maintain the auto-injector in place for several seconds until all the medication is injected. The patient should be advised to keep one EpiPen in the home and one on his or her person at all times. Epinephrine is light sensitive and should be stored between 15^o -30^o C (59^o -86^o F).^[4] Placement of an EpiPen in the car where internal summer temperatures can be well over 100^o F is not recommended.
• Oral H1 blockers (eg, diphenhydramine, hydroxyzine)
• Corticosteroids (eg, prednisone, methylprednisolone)

• Transfer the patient to the nearest facility capable of providing critical care monitoring if critical care monitoring cannot be performed at the facility initially treating the patient (in accordance with the current standards established by the Emergency Medical Treatment and Labor Act [EMTALA]).
• A person capable of aggressively managing the patient's airway and monitoring and managing the patient's cardiopulmonary function should accompany the patient.
• The transporter should have all the equipment and medication necessary to resuscitate the patient.

• Teach the patient how to modify behavior, to dress, and to use toiletries and perfumes appropriately (see Activity).
• Refer the patient to an allergist for desensitization to Hymenoptera venom. Desensitization by venom immunotherapy can be accomplished by the injection of depot extracts using a slow and conventional schedule, which minimizes local and systemic side effects, or it can be accomplished rapidly by using a rush protocol with aqueous extracts if protection needs to be achieved rapidly. However, the incidence of severe reactions makes the rush protocol less than ideal for an outpatient procedure and requires hospitalization.^[5]
• Up to 25% of patients who are on venom immunotherapy will still develop a severe anaphylactic reaction when re-stung.^[5]
• Prescribe auto-injectors (eg, EpiPen) and oral H1 blockers (eg, diphenhydramine, hydroxyzine).

• Consider local wound infection in any wasp sting site that worsens, persists, or partially resolves only to swell up with increased redness, swelling, or pain. Other symptoms and signs that should be elicited include fever, chills, red streaks extending proximally from the site, and purulent drainage from the site.
• Wasp stings have also been associated with acute renal failure in children^[6] as well as the Kounis syndrome or allergic myocardial ischemia and infarction.^{[7, 8]}

• The prognosis for mild-to-moderate reactions is good.
• The goal is prevention of another exposure.

• Teach the patient how to modify behavior, to dress, and to use toiletries and perfumes appropriately (see Activity and Outpatient Medication).