Page 107 - 2025 Ranger Medic Handbook

Anaphylaxis Reaction Emergencies
Anaphylactic shock is a life-threatening medical emergency that is caused by a generalized allergic reaction affecting
the cardiovascular, respiratory, cutaneous, and gastrointestinal systems. It is a severe immune-mediated reaction that
occurs when a previously sensitized patient is reexposed to an offending allergen such as: bee/wasp stings, penicillin
or other drug allergies (especially when given IM/SC/IV), seafood (especially shrimp/shellfish), and nuts of various types.
Allergens may produce an allergic reaction by being ingested, inhaled, injected, or absorbed through the skin/mucous
membranes. Shock is produced by the release of histamine that causes “leaky” vessels resulting in hives/edema and
hypotension; it also causes bronchospasm/wheezing. This produces both a volume problem and a vascular resistance
problem. Anaphylactic shock differs from less severe allergic reactions in that it is characterized by hypotension and
obstructed airflow (upper and/or lower) that can be life-threatening.

Signs/Symptoms SECTION 3
S/Sx: Wheezing (bronchospasm), dyspnea, stridor (laryngeal edema), angioedema, urticaria (hives), hypotension, tachy-
cardia. Clinical observation is the only diagnostic test. Use rapidity of onset and constellation of symptoms to suggest
the diagnosis. A prior history of similar symptoms may be the only other clue. Observe closely with frequent assess-
ment/reassessment of mental status, vital signs, and pulse oximetry. Anaphylaxis is likely if ANY of the following three
criteria are met:
■ Acute onset (minutes to several hours) with involvement of skin and or mucosal tissue (hives, pruritus, swollen lips/
tongue) plus 1 of the following: respiratory compromise (e.g., dyspnea, wheezing, stridor or other signs of broncho-
spasm) or cardiovascular compromise (eg, decreased blood pressure, syncope).
■ Two or more of the following that occur quickly (minutes to several hours) after exposure to a likely allergen: involve-
ment of skin-mucosa, respiratory compromise, reduced blood pressure, persistent GI symptoms (e.g., vomiting,
abdominal pain).
■ Reduced blood pressure (systolic < 90 for adult) after exposure to a known allergen for the patient.
Initial Management & Extended Management
For patients with S/Sx of airway involvement and/or circulatory collapse:
Epinephrine is the mainstay of therapy. Administer Epi-Pen OR epinephrine 0.3–0.5mg (0.5mL of 1:1,000 IM into the
anterolateral thigh. DO NOT USE INTRAVENOUSLY. Repeat epinephrine q5min prn. Administer oxygen with pulse ox-
imetry monitoring. If severe respiratory distress exists, aggressive airway management with bag-valve-mask and airway
adjuncts (oral and nasopharyngeal airways). Control airway early if no response to epinephrine. Initiate IV normal saline
TKO (saline lock). Administer 500–1000cc crystalloid or colloid bolus for hypotension then titrate to establish systolic
blood pressure > 90mmHg or palpable radial pulse if BP cuff not available. Although epinephrine is the treatment for
true anaphylaxis, consider treating concurrent symptoms with the following medications. Administer diphenhydramine
50mg IV/IM/PO for skin findings/puritisis. Administer dexamethasone 10mg IV/IM/PO for repeat anaphylaxic reactions. If
wheezing is present after epinephrine administration, consider Albuterol, 2–3 puffs q5min, repeat up to 3 times. Consider
additional H2 blocker (famotidine 20mg PO bid) as 3–5 day course of additional antihistamine.
Considerations
Immediate definitive airway if impending airway obstruction from angioedema is suspected. Delay may lead to complete
obstruction, difficult intubation and cricothyroidotomy. Give 6–8L O 2 /min via face mask if required or up to 100% if
airway controlled. Albuterol metered dose inhaler (2–3 puffs) for bronchospasm. Place patient in recumbent position
and elevate lower extremities.
Crystalloid (saline) fluid bolus IV titrated to restore and maintain blood pressure. Recurrence of symptoms may occur in
up to 20% of patients (generally within 6 hours but recurrences up to 72 hours following initial resolution of symptoms
have been reported).
Apply ice to minimize any local reaction sites. If due to bee/wasp sting(s), carefully remove all stingers. Avoid applying
pressure to venom sac while stinger is inserted in patient.

2025 RANGER MEDIC HANDBOOK 93