Management of Contrast Reactions

Types & Triggers - Reaction Rundown

Contrast Reaction Classification & Triggers

-   Contrast: HOCM > LOCM > IOCM; Ionic > Non-ionic.
-   Patient: Asthma, allergies, anxiety, dehydration, renal/cardiac issues.

⭐ Prior contrast reaction: most significant risk factor (future reaction risk ↑ 5-6x).

Risk & Prevention - Shielding Strategies

• Risk Factors:
  • Prior moderate/severe contrast reaction (📌 Strongest)
  • Asthma, multiple severe allergies
  • Symptomatic cardiac disease
  • Meds: β-blockers, NSAIDs, IL-2
• Prevention:
  • Identify high-risk patients.
  • Use Low-Osmolar (LOCM) or Iso-Osmolar Contrast Media (IOCM).
  • Premedicate if indicated.

⭐ Prior allergic-like reaction to same class contrast: ~5-6x ↑ risk.

• Premedication:

Mild to Moderate Mayhem - Calming the Storm

• Always First: STOP contrast, ABCDE assessment, Monitor vitals (BP, HR, SpO2, RR), Reassure patient.

⭐ Most contrast reactions are non-allergic (anaphylactoid) and occur within 5-20 minutes of injection. Always observe patients during this critical window.

Severe Shock Showdown - Code Red Contrast

Anaphylaxis/severe shock post-contrast. 📌 A.S.A.P. I.M. Epi (Alert, Stop contrast, Airway, Position, IM Epinephrine)

• Immediate:
  • Stop contrast. Call for HELP (Code Red).
  • Airway: High-flow O₂ (10-15 L/min).
  • Position: Supine, legs elevated (if hypotensive).
• Meds:
  • Epinephrine IM: Adult 0.3-0.5 mg ($1:1000$ solution). Anterolateral thigh. Repeat q5-15min.
    • 
  • IV Fluids: Normal Saline 1-2 L rapid bolus.
  • Antihistamines: Diphenhydramine 25-50 mg IV/IM + Ranitidine 50 mg IV.
  • Corticosteroids: Hydrocortisone 100-200 mg IV (prevents biphasic reaction).
  • Bronchodilators: Salbutamol nebulized for wheezing.
• Refractory Shock:
  • IV Epinephrine infusion: $1:10000$ or $1:100000$ dilution. Start 0.1 mcg/kg/min.
  • Glucagon 1-2 mg IV (if on β-blockers).
  • ICU transfer.

⭐ IM epinephrine (anterolateral thigh) is first-line for anaphylaxis. Delayed administration ↑ mortality.

High‑Yield Points - ⚡ Biggest Takeaways

• Mild reactions (nausea, urticaria): Observation, antihistamines (e.g., diphenhydramine).
• Moderate reactions (diffuse urticaria, bronchospasm): Oxygen, epinephrine (IM/SC), antihistamines, corticosteroids.
• Severe/Anaphylaxis: ABCDE, epinephrine (IM/IV), IV fluids, oxygen, corticosteroids, H1/H2 blockers.
• Epinephrine is key for anaphylaxis: 0.3-0.5 mg (1:1000) IM for adults.
• Pre-treatment for high-risk: Corticosteroids (e.g., Prednisolone) & antihistamines.
• Key risk factors: Previous reaction, asthma, atopy, cardiac disease.
• Delayed reactions (skin rashes) occur hours-days later; manage symptomatically.