This month’s winner is Michele Kravitz who correctly identified an allergic reaction and the need to treat with a pediatric-specific epinephrine autoinjector. Nicely done!
Assessment
According to the Centers for Disease Control, reports of food allergies have been on the rise over a 10-year period. It is unclear if this change is due to increasing rates of allergy or simply increased awareness and better reporting.
Regardless, it is currently estimated that food allergy affects approximately 4 percent of children under the age of 18 in the United States. Eight foods account for nearly all reported allergic reactions: milk, eggs, peanuts, tree nuts (almonds, walnuts, etc.), fish, shellfish, soy and wheat.[1]
Severity of allergic reaction can vary depending on the patient as well as the particular food. Reactions can be localized or may result in anaphylaxis.
Treatment
When responding to a patient having an allergic reaction it is important to determine how severe the reaction is. Generally, it is sufficient to differentiate between three levels: allergic reaction, anaphylaxis and anaphylactic shock.
1. An allergic reaction (regardless of severity) occurs when an antigen enters the body. An antigen is a substance that triggers the immune system to respond. Immunoglobulin E binds to the antigen and provokes the release of histamine and other chemicals, which promote inflammation in the body; how broadly this inflammation occurs influences the classification of the reaction.
A simple allergic reaction will often present with hives, redness and itching on the skin. These symptoms are generally limited to the area of the body which was exposed to the antigen. An example of an allergic reaction would be redness and watering of the eyes from exposure to pollen.
2. Anaphylaxis occurs when histamines and other immune chemicals result in effects throughout the body. These effects can include dilation of the blood vessels, leaking of fluid from blood vessels and contraction of the muscles that surround the air passages in the lungs.
Anaphylaxis should be suspected when a patient presents with hypotension or respiratory distress after exposure to a known or suspected antigen.
3. Anaphylactic shock occurs if anaphylaxis progresses and hypotension becomes significant.
Treatment of patients with a simple allergic reaction is largely supportive. Many EMS systems indicate that diphenhydramine be used for such cases. When a patient is experiencing anaphylaxis or anaphylactic shock, however, epinephrine is the treatment of choice.
Despite some teaching to the contrary, there are no absolute contraindications to the use of epinephrine in anaphylaxis. EMS providers may be hesitant to aggressively use epinephrine on a conscious patient, preferring instead to give diphenhydramine or adopting a wait-and-see attitude. This is a risky decision.
The mechanisms of action for diphenhydramine and epinephrine can be thought of like a sink filling up with water. In this example, the water represents the histamines and other immunologic chemicals in the body. Diphenhydramine works by competitively binding to the receptor sites in the body that are normally bound by histamines.
In our example of the sink, giving a patient diphenhydramine is like opening up the drain to allow water to flow out. While opening the drain will help to empty the sink, there is still water flowing in from the faucet.
Epinephrine works to counter an anaphylactic reaction by constricting blood vessels, relaxing smooth muscle in the lungs and decreasing the release of histamine. Giving epinephrine to an anaphylaxis patient is like turning off the faucet filling up the sink.
Many patients with a history of anaphylaxis or other serious allergies are often prescribed epinephrine auto injectors. These devices deliver a dose of medication by the intramuscular route and are intended to be used by patients or bystanders in case of exposure to an antigen.
EMS protocols may allow for providers to either carry auto injectors or use a patient’s auto injector to deliver this medication.
Outcome
Based on Stephen’s history and presentation, it is apparent that he is suffering an anaphylactic reaction after exposure to peanuts.
You ask the staff if Stephen has an epinephrine auto injector prescribed to him. After consulting his emergency forms, they tell you that he does and the injector is brought to the room.
You ask Stephen if he feels that he can administer the injector himself. He shakes his head “no.” Based on your protocols, you elect to administer the epinephrine yourself.
After checking that Stephen’s name is on the auto injector and that the medication is not expired, you remove it from its packaging and press the injector down on Stephen’s outer thigh, holding for 10 seconds.
Shortly after administering the medication, you notice that Stephen’s breathing is noticeably improved. He starts answering your questions and your engineer is able to obtain a set of vital signs.
You radio an update to the responding ALS unit and continue to monitor for any changes in his status.
References
Centers For Disease Control And Prevention. “Food Allergy Among U.S. Children: Trends in Prevalence and Hospitalizations.” MCHS Data Brief. Centers For Disease Control And Prevention, Oct. 2008. Web. 10 Sept. 2014.
