Contrast Media and Managing Contrast Reactions

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