Anaphylaxis is an allergic reaction that has life-endangering effects on the circulatory and respiratory systems. Anaphylaxis is an almost immediate, rapidly progressive multisystem allergic reaction to a foreign protein injected into the body by stinging and biting insects, snakes, and sea creatures or ingestion or inhalation of food, chemicals, and medications.
Early recognition and prompt treatment, particularly in a wilderness setting, is essential to preserve life. The onset of symptoms usually follows quickly after an exposure (minutes after a sting or bite, within 30-60 minutes following ingestion). Rebound or recurrent reactions can occur within 24 hours of the original episode.
In addition to shortness of breath, weakness and dizziness, victims also frequently complain of a sense of impending doom, cough, chest tightness, trouble swallowing, abdominal cramps, or generalized itching.
Physical findings include rapid heart rate, low blood pressure, and other evidence of shock, upper airway obstruction (stridor) and lower airway obstructions (wheezes) with labored breathing, generalized skin redness, hives, and swelling of the mouth, face, and neck.
Epinephrine should only be administered to patients having symptoms suggestive of an acute systemic reaction (i.e., generalized skin rash, difficulty breathing, fainting, or facial swelling).
- Inject 0.3 mg of 1/1000 epinephrine into the lateral aspect of the deltoid, or the anterior aspect of the thigh (either subcutaneous or intramuscular).*
- Maintain an open airway and position of comfort. Initiate either positive pressure ventilations (PPV) or full cardiopulmonary resuscitation (CPR) as indicated.
- Repeat epinephrine injections every 5 minutes if condition worsens; or as needed.
- Administer antihistamine by mouth (50 mg of diphenhydramine HCl every 4-6 hours for an average adult) so long as the patient is awake and can swallow.
- Consider Prednisone 60 mg/day (or equivalent dose of an oral corticosteroid).
- Evacuate to definitive care if safe to do so. Consider an advanced life support intercept.
- If evacuation is not possible, monitor carefully for biphasic reaction. Repeat treatment per protocol as necessary.
Because a rebound reaction can occur, all victims of an anaphylactic reaction should be evacuated. Rebound reactions should be treated in the same manner as the initial reaction, using epinephrine in the same dosage.
* The preferred concentration of epinephrine for IM injection is 1mg/1ml. Although the lateral mid-thigh is preferred, an injection into the deltoid may be the only practical option.
Commercially available auto-injectors such as the EpiPen deliver 0.3 mg as a standard adult dose or a 0.15 mg for a smaller person or child (less than 55 lbs.; 25 kg), depending on body mass. The auto-injector is the most user-friendly device, but also the most expensive.
Epinephrine is also supplied in 1ml ampules, and vials of various sizes, for a fraction of the cost. CWS graduates at the WEMT and WFR level are trained in the use of syringes, needles, vials, and ampules for this purpose.
For patients weighing less than 55 lbs. (25kg), the doses are: epinephrine 0.01 mg/kg or the appropriate auto-injector; diphenhydramine 1mg/kg; and prednisone 1mg/kg. Multiply the weight in pounds by 0.45 to get the weight in kilograms.
The organization may need a prescription from a medical advisor to obtain the injectable epinephrine, syringes and prednisone used in the protocol.
Antihistamines do not require a prescription in the United States and Canada. It is essential for prescribers and organizations to be familiar with state, provincial, or national regulations that may address the prescribing of medication and the acceptable means of injecting epinephrine.
The above specified protocol has been authorized for use by Center for Wilderness Safety for WEMT, WFR, WAFA, WFAA and WFA trained employees of the employer named on page 3 of this document, provided they meet the requirements of the authorization criteria listed in this protocols packet. Only certified WEMT and WFR are permitted to manually administer epinephrine via syringe (as opposed to an auto-injector).
NOTE: Prednisone is a schedule III prescription anabolic steroid, and if carried by the organization (employer), it may require a prescription from a medical advisor. It is essential for prescribers and organizations to be familiar with state, provincial or national regulations that may address the prescribing of medication.