Anaphylaxis and Allergic Reaction

Table of Contents

(Adapted from an evidence-based guideline created using the National Prehospital Evidence-Based Guideline Model Process)

Aliases

Anaphylactic Shock

Patient Care Goals

  1. Provide timely therapy for potentially life-threatening reactions to known or suspected allergens to prevent cardiorespiratory collapse and shock
  2. Provide symptomatic relief for symptoms due to known or suspected allergens

Patient Presentation

Inclusion Criteria

Patients of all ages with suspected allergic reaction and/or anaphylaxis

Exclusion Criteria

No recommendations

Patient Management

Assessment

  1. Evaluate for patent airway and presence of oropharyngeal edema
  2. Auscultate for wheezing and assess level of respiratory effort
  3. Assess for adequacy of perfusion
  4. Assess for presence of signs of anaphylaxis
    1. Anaphylaxis – More severe and is characterized by an acute onset involving one of the following:
      1. The skin (urticaria) and/or mucosa with either respiratory compromise or decreased BP or signs of end-organ dysfunction
      2. Hypotension for that patient after exposure to a known allergen
        1. Adults: Systolic BP < 90 mmHg
        2. Pediatrics: see Appendix VIII – Abnormal Vital Signs
      3. Two or more of the following occurring rapidly after exposure to a likely allergen:
        1. Skin and/or mucosal involvement (urticaria, itchy, swollen tongue/lips)
          1. Skin involvement may be ABSENT in up to 40% of cases of anaphylaxis
        2. Respiratory compromise (dyspnea, wheeze, stridor, hypoxemia)
        3. Persistent gastrointestinal symptoms (vomiting, abdominal pain, diarrhea)
        4. Hypotension or associated symptoms (syncope, hypotonia, incontinence)
    2. Non-anaphylactic Allergic Reaction
      1. Signs involving only one organ system (e.g. localized angioedema that does not compromise the airway, or not associated with vomiting; hives alone)

Treatment and Interventions

  1. If signs of allergic reaction without signs of anaphylaxis, go to Step 4
  2. If signs of anaphylaxis, administer epinephrine 1mg/mL at the following dose and route:
    1. Adult (25 kg or more) 0.3 mg IM in the anterolateral thigh
    2. Pediatric (less than 25 kg) 0.15 mg in the anterolateral thigh
    3. Epinephrine 1 mg/mL may be administered from a vial or via auto-injector, if available
  3. For urticaria or pruritus, administer a diphenhydramine 1 mg/kg, up to maximum dose of 50 mg IM, IV, or PO)
    1. The IV route is preferred for the patient in severe shock
    2. As a supplement to diphenhydramine given for urticaria, any H2-blocking antihistamine (e.g. famotidine, cimetidine) can be PO in conjunction with diphenhydramine
  4. If respiratory distress with wheezing is present, consider administering and repeat as necessary
    1. Albuterol 5 mg nebulized
      AND/OR
    2. Epinephrine 0.1 mg/mL, 5 mL nebulized
  5. If stridor is present, consider administering epinephrine 0.1 mg/mL, 5 mL nebulized
  6. If IM epinephrine is administered, consider dexamethasone 0.6 mg/kg, max of 10 mg, PO, IM, IV, or IO
  7. If signs of anaphylaxis and hypoperfusion persist following the first dose of epinephrine, additional IM epinephrine can be repeated every 5 minutes at above noted doses
  8. For signs of hypoperfusion, also administer 20 mL/kg, max of 1 L normal saline rapidly (over 15 minutes) via IV or IO, and repeat as needed for ongoing hypoperfusion
  9. When cardiovascular collapse (hypotension with altered mental status, pallor, diaphoresis and/or delayed capillary refill) is present despite repeated IM doses of epinephrine in conjunction with at least 60 mL/kg, max of 3 L of NS boluses
    1. Epinephrine by push dose (dilute boluses)
      1. Prepare 10 mcg/mL by adding 1 mL of Epinephrine (0.1 mg/mL) to 9 mL normal saline, then administer 10 mcg boluses (1 mL) every 1 minutes titrated MAP greater than 65 mmHg
  10. Transport as soon as possible, and perform ongoing assessment as indicated. Cardiac monitoring is not required, but should be considered for those with known heart problems or who received multiple doses of epinephrine

Notes – Anaphylaxis and Allergic Reaction