disease. The clinician should be careful not to become complacent or attribute clinical signs and symptoms solely to these conditions, as allergic reactions can progress insidiously.
Anaphylaxis to stings can occur abruptly years after the first exposure, even without intervening stings. Furthermore, approximately 20% of patients exhibit biphasic anaphylaxis responses where the initial symptoms resolve and there is a symptom‐free period before the onset of the late phase reaction 4‐6 hours after the initial symptoms began. The symptoms of the late reaction can be markedly different from those of the initial reaction, and can be life‐threatening even if those of the initial reaction were not. It is nearly impossible to predict which patients will exhibit this biphasic response. This could result in repeat EMS calls for allergic reactions featuring substantially different symptoms, particularly if a patient refuses transport initially or is seen and discharged from an ED before the late phase reaction occurs [19].
If the patient experiencing a severe allergic reaction or anaphylaxis routinely takes beta‐blocker medications, the action of epinephrine may be blunted. Glucagon may be given in 1 mg increments by any parenteral route to overcome the effects of beta‐blockade. Cutaneous symptoms are the most common clinical response in both adults and children. Hypotension is uncommon in children, but it has been reported in up to 60% of adults with significant allergic reactions. Patients will sometimes complain of a prodrome of chest pain or shortness of breath before development of a more generalized severe allergic reaction.
EMS clinicians should have a high index of suspicion when responding to calls of shortness of breath or chest pain. Attempt to ensure there was no contact with an allergen that could cause the symptoms. For instance, allergy‐producing contrast media are frequently given in free‐standing imaging centers. Consider the possibility of allergic reactions and anaphylaxis when responding to calls of shortness of breath or chest pain at these facilities [20]. Anaphylaxis should be one of the etiologies considered when responding to cardiac arrests in outdoor areas, such as golf courses, as the patient may have been stung or bitten before the cardiac arrest.
Although bites from a Gila monster are infrequent, allergic reactions can occur. If it is still attached to the patient, the clinician should remove it by prying its jaws apart with a stick or metal object, holding a flame under the lizard’s chin, or submerging it in cold water [21]. Obviously, care should be taken to avoid additional bites to the patient or EMS personnel.
To determine the most appropriate destination facility for allergic reaction patients, it helps to consider the etiology of the reaction and the availability of certain subspecialties, such as otolaryngology, anesthesia, critical care, toxicology, and so on. They may be necessary to definitively treat the reaction. Transportation time should also be considered. If the patient is unstable or is likely to become unstable during an extended transport time to an appropriate facility, then air medical evacuation should be considered. Transport to the closest available facility for stabilization followed by transfer of the patient to a higher level of care is also an option. This will depend on the availability of air medical services, the distance to the closest facility, weather, traffic, terrain, and other conditions that must be factored in when making destination decisions.
Conclusion
Allergic reaction and anaphylaxis are frequently seen in the prehospital environment. EMS clinicians should be alert to the potential for rapid progression of allergic reactions to anaphylaxis and be prepared to hemodynamically support the patient and provide appropriate airway management. All patients with moderate or severe allergic reactions should be provided with oxygen, IV fluid administration, and continuous monitoring during transport. Clinicians should be familiar with the common medications and the dosages used to treat allergic reactions. Antihistamines and epinephrine are the mainstays of treatment. In cases of generalized allergic reaction and anaphylaxis, epinephrine administration should not be delayed. Early administration of epinephrine is critical in severe allergic reactions to prevent progression to anaphylaxis. Transport to an appropriate hospital should occur as soon as feasible.
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