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Contrast Media and Managing Contrast Reactions

Contrast Media and Managing Contrast Reactions

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Contrast Media and Managing Contrast Reactions

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  1. Contrast Media and Managing Contrast Reactions Dr Iain Morrison Kent and Canterbury Hospital KSS Radiology Trainee Induction 2011

  2. Encyclopaedic Knowledge of Pharmacology

  3. Radiologist

  4. A brief History

  5. Barium Sulphate

  6. Thorostrast 1931 – 1950’s Alpha emission T1/2 22 yrs

  7. Thorostrast

  8. Iodinated Contrast

  9. Types of Iodinated Contrast Agent High osmolar contrast media - HOCM Ionic monomer Low osmolar contrast media - LOCM Ionic dimer Non ionic monomer Non ionic dimer

  10. Types of Iodinated Contrast Agent High osmolar contrast media - HOCM Ionic monomer Low osmolar contrast media - LOCM Ionic dimer Non ionic monomer Non ionic dimer

  11. HOCM - Ionic monomer

  12. Ionic Monomers • Urografin – Bladder studies • Gastrografin – GI studies

  13. Types of Iodinated Contrast Agent High osmolar contrast media - HOCM Ionic monomer Low osmolar contrast media - LOCM Ionic dimer Non ionic monomer Non ionic dimer

  14. Non-ionic Monomers

  15. Non-ionic Monomers Iodine : particle ratio 3:1 Low osmolality 500-700 mosm/kg

  16. Non-ionic Monomers • Iohexol (Omnipaque) • Iopamidol (Iopamiro, Isovue, Niopam, Solutrast) • Iopentol (Imagopaque) • Iopromide (Ultravist) • Ioversol (Optiray)

  17. Non-ionic Monomers • Omnipaque/Niopam/Ultravist • Most frequently used intravenous agents • Low allergy and reaction profile • CT and IVU

  18. Types of Iodinated Contrast Agent High osmolar contrast media - HOCM Ionic monomer Low osmolar contrast media - LOCM Ionic dimer Non ionic monomer Non ionic dimer

  19. Non-Ionic Dimer

  20. Non-ionic Dimer Iodine:particle ratio 6:1 Low osmolality 300 mosm/kg – Isosmolar Examples Iotrolan (Isovist) Iodixanol (Visipaque)

  21. Non-ionic Dimer • Visipaque • Used in patients at risk of renal impairment • Lower incidence of contrast induced nephropathy (CIN) • e.g. eGFR 40 – 60 • Excellent arteriographic agent since isomolar • No burning sensation, but viscous

  22. Cautions prior to contrast injection • Allergy history • Renal function • Diabetic on Metformin

  23. Allergy History • The patient is asked for a history of contrast allergy, asthma and whether there is an allergy to multiple allergens • If previous allergy to contrast, an assessment is made of the severity and strength of the history • Previous severe reaction is a contraindication • Attempts should be made to convey calm, not anxiety • Never say ‘Die’ • Patients that are anxious have an increase risk of having a reaction to contrast media

  24. Renal Function • Must have eGFR prior to injection • Except in emergency, e.g. ?leaking AAA • eGFR 60 or more, use non-ionic monomers e.g. Omnipaque • eGFR 40 – 60, use non-ionic dimer e.g. Visipaque • eGFR <40, try to avoid, or take advice from renal, e.g. pre-hydration

  25. Diabetic on Metformin • Find out renal function • If eGFR is <60, stop Metformin starting from injection • Check eGFR 48 hrs after injection • Re-start Metformin then if satisfactory

  26. Administration of contrast medium to breast feeding mothers • Less than 1 % of the administered dose of contrast iodinated or gadolinium based is excreted in the breast milk • Less than 1% of the contrast in breast milk taken in by and infant is absorbed by the GI tract • The recommended dose for and infant having a contrasted study is 0.2ml/kg.  The amount excreted in breast milk represents less than 1 % of that amount • Contrast is nearly 100% excreted from the body within 24 hours after receiving contrast • Manufacturers guidelines: substitute bottle feeding for breast milk for 24 hours following the injection of contrast • Gadolinium: Avoid

  27. Caution after contrast injection • Keep patient on hospital premises for 1 hr following injection

  28. Gadolinium • Para-magnetic MR contrast agent • Much better safety profile than iodinated contrast • Allergic reactions rare • Always check renal function • Danger of NSF

  29. NSF • Nephrogenic Systemic Fibrosis • Severe rare dermopathy • Only occurring in patients with renal failure • No effective treatment, can be fatal • Has been noted that Gd usage is linked • Seen in patients who had large (2-3x) doses for MRA • Reduced risk in chelated Gd compounds

  30. NSF • The European Medicines Agency has classified the gadolinium-containing contrast agents into three groups • Least likely (safest) to release free gadolinium ions Gd3+ in the body have a cyclical structure: Dotarem, Gadovist , ProHance • Intermediate have an ionic linear structure: Magnevist, MultiHance, Primovist, Vasovist • Most likely to release Gd3+ have a linear non-ionic structure: Omniscan, OptiMARK

  31. Gadolinium • Do not give if eGFR <40 • Might consider it in single dose of ‘safer’ agent if clinically important

  32. Contrast Media Reactions

  33. Contrast Media Reactions

  34. Contrast Reactions • Mild • Nausea, vomiting, cough, sneezing, warmth, headache, dizziness, shaking, altered taste, itching, pallor, flushing, chills, sweats, rash, hives, nasal stuffiness, anxiety, sneezing, swelling of eyes & face • Moderate • Tachycardia, bradycardia, hypertension hypotension, pronounced cutaneous reaction, dyspnoea, bronchospasm • Severe • Laryngeal oedema, convulsions, profound hypotension, arrhythmias, unresponsiveness, cardiopulmonary arrest

  35. Types of Reaction • Anaphylactoid reactions • occur unexpectedly , often referred to as “idiosyncratic”. • Non-Anaphylactoid reactions • osmotic, chemotoxic, direct organ toxicity, vasomotor effects • more predictable and better understood. • Combination • Anaphylactoid and non-Anaphylactoid reactions occurring together

  36. Types of Reaction • Anaphylactoid reactions • occur unexpectedly , often referred to as “idiosyncratic”. • Non-Anaphylactoid reactions • osmotic, chemotoxic, direct organ toxicity, vasomotor effects • more predictable and better understood. • Combination • Anaphylactoid and non-Anaphylactoid reactions occurring together

  37. Non-Anaphylactoid Reactions Vasovagal Reactions: • A result of increased vagal tone on the heart and blood vessels • Bradycardia and decreased blood pressure , apprehension, confusion, sweating, unresponsiveness. • Some vagal reactions may not be caused by the contrast media but needle pucture, general situation etc.

  38. Non-Anaphylactoid Reactions Chemotoxic Reactions: • Include cardiac depression, arrhythmia, ECG changes, renal tubular injury • Some chemotoxic side effects appear to relate to the ionic nature of the contrast • Nonionic contrast media are associated with fewer chemotoxic side effects

  39. Incidence of Adverse Effects • True incidence not known • Most adverse effects are mild to moderate • Many patients experience physiologic disturbances (warmth or heat) • Use of nonionic contrast media is associated with a much lower incidence of adverse effects compared to historically. • Serious contrast reactions are rare 0.16 per 1000 examinations using low osmolality contrast media (LOCM). • Minor reactions, particularly delayed (2 hrs) more common with Nonionic dimers

  40. Treatment of Severe Contrast Reactions

  41. Treatment of Severe Contrast Reactions • Bronchospasm • O2 by mask • B-agonist inhaler • Adrenaline i.m. 1:1000 • 0.1 ml if BP normal • 0.5 ml if BP down Morcos SK BJR 78(2005), 686-693

  42. Treatment of Severe Contrast Reactions • Laryngeal oedema • O2 by mask • Adrenaline i.m. 1:1000 0.5 ml Morcos SK BJR 78(2005), 686-693

  43. Treatment of Severe Contrast Reactions • Isolated hypotension • Elevate patient legs • O2 by mask • i.v. Fluid rapidly (N/saline or Ringer’s) • If no response, i.m. Adrenaline 1:1000 0.5 ml Morcos SK BJR 78(2005), 686-693

  44. Treatment of Severe Contrast Reactions • Hypotension and bradycardia (vasovagal) • Elevate patient legs • O2 by mask • Atropine 0.6 – 1.0mg i.v. Repeat after 3 mins to 3mg • i.v. Fluids rapidly Morcos SK BJR 78(2005), 686-693

  45. Treatment of Severe Contrast Reactions • Generalised anaphylactoid reaction • Call for resus team • Suction airway • Elevate legs • O2 • i.m. Adrenaline 1:1000 0.5 ml +/- repeat • i.v.Fluids • H1 blocker e.g. diphenhydramine 25 – 50 mg • B2 agonist inhaler Morcos SK BJR 78(2005), 686-693