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    Contrast Allergy – Treatment

    Critical Care / Resuscitation, Toxicology

    Last Updated Jun 04, 2021
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    By David Barbic, Ryan Koo

    Context

    • Contrast allergies are rare events, most commonly following intravascular use of contrast media, though can occur with other routes of administration.
    • Most reactions are mild and self-limited; however, reactions can be life threatening.
    • Reactions are either anaphylactoid or non-anaphylactoid (chemotoxic) in origin.
    • Reactions can be acute or delayed; as well as allergic-like (anaphylactoid) or physiologic.
    • Treatment is determined via clinical presentation and severity of reaction.

    Signs and Symptoms

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    Recommended Treatment

    Delayed Reactions

    • Reactions are typically self-limited and require only supportive care on an outpatient basis:
      • Cutaneous symptoms – antihistamines, corticosteroids.
      • Fever – antipyretics.
      • Nausea – antiemetics.
      • Hypotension – fluid resuscitation and observation 4-6 hours usually required.
    • If symptoms are progressive, referral to consultation with an allergist or dermatologist indicated.

    Acute Reactions

    • A patient with acute onset of symptoms following administration from contrast should be presumed a contrast allergy unless otherwise explained.
    • Stop contrast administration.
    • Mild reactions: usually self-limited, but require observation for at least 30 minutes and until symptom resolution.
    • Moderate or severe reactions: immediate therapy – obtain IV access and O2.
    • Further treatment is determined by the clinical presentation, listed below.

    Patient Unresponsive

    • Securing of airway and resuscitation according to ACLS/PALS guidelines.
    • Perform treatment protocols for a severe allergic-like contrast reaction.

    Allergic-like Symptoms

    Hypotension and Tachycardia

    • Epinephrine – see below for dosage.
    • Shock management – rapid fluid resuscitation.
      • Adults: 1-2 L of NS IV.
      • Infants, children & adolescents: 20 mL/kg over 5-10 mins (max of 0.5-1 L).

    Bronchospasm

    • Mild – ß-agonist inhaler (i.e. salbutamol) – 2 puffs (100 mcg/puff) via metered dose inhaler; repeat up to 3 times.
    • Moderate to severe (or other organ system involvement) – epinephrine and adjunctive ß-agonist inhaler.

    Laryngeal Edema

    • Epinephrine.

    Widespread Cutaneous Symptoms (i.e. edema, urticaria, erythema)

    • Mild to moderate – H1 antihistamine (i.e. diphenhydramine)
      • Adults: 25-50 mg IM or IV (PO can be considered if mild).
      • Children: 1 mg/kg up (max 50 mg; PO can be considered if mild).
    • Severe – epinephrine.

    Notes on epinephrine dosage:

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    Image source: UpToDate.

    Physiologic Symptoms

    Hypotension and Bradycardia

    • Initiate management of a vasovagal reaction
      • Lie patient supine with legs elevated > 60 degrees
    • If symptoms of end-organ dysfunction, initiation of rapid fluid resuscitation with 1-2L of NS IV
      • Infants, children & adolescents should receive NS boluses of 20 mL/kg over 5-10 minutes, repeat as needed
    • If not responsive to initial fluid bolus, administer atropine
      • Adults: 0.6-1 mg IV every 3-5 minutes (maximum 3 mg: consider epinephrine infusion 1-4 mcg/min up to 20mcg/min)
      • Infants, children, adolescents: 0.02 mg/kg IV (maximum 0.5 mg); can be repeated once 3-5 minutes after initial dose (maximum total dose = 1 mg)

    Hypertension

    • Monitor; self-limited pending urinary clearance of contrast (can be facilitated via IV/oral hydration)
    • If hypertensive crisis (>200 mmHg SBP or >120 mmHg DBP)
      • Labetalol IV 20 mg over 2 minutes; dose can be doubled every 10 minutes if further administration required
      • Furosemide IV 20-40 mg over 2 minutes (given to increase clearance not reduce volume)

    Seizures/Convulsions

    • Turn patient on side to prevent aspiration and suction airway as required
    • Slow administration of Lorazepam IV 2-4 mg (Careful > 4 mg: resp depression and hypotension)

    Hypoglycemia

    • If able to swallow: oral glucose – two sugar packets or 15 g glucose tablet/gel or ½ cup of juice.
    • If unable to swallow and IV access available – 25 g (adults) or 2 mL/kg (children) D50W IV over 2 minutes; then D5W IV at 100 mL/hour.
    • If no IV access available – Glucagon IM 1 mg (0.5 mg if <20 kg).

    Cardiopulmonary Symptoms

    • Initiate appropriate protocols for manifesting symptoms (i.e. chest pain, arrhythmia, pulmonary edema, etc).

    Nausea and Vomiting

    • If transient, supportive treatment; consider antiemetics if severe.

    Criteria For Hospital Admission

    • All patients with severe reactions should be admitted for observation.
    • Admission should be considered for patients who are at risk of a biphasic response (i.e. do not respond promptly to IM epinephrine, required more than one dose of epinephrine, or received epinephrine after a >60 minute delay).

    Criteria For Safe Discharge Home

    • Mild to moderate reactions – observe until symptom resolution.
    • All patients who have experienced an allergic-like contrast reaction should be referred for skin testing to identify future safe contrast alternatives and pre-medication requirements.

    Quality Of Evidence?

    Justification

    References to primary studies lacking; however, extremely high congruency and well-established clinical guidelines from medical societies responsible for oversight of contrast administration worldwide.

    Moderate

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