Contrast agents are compounds used to improve visibility of internal structures in images. Common types are iodine-based radiographic agents that can be ionic or non-ionic, and vary in osmolality. While ionic agents can cause severe reactions in 1 in 1000 patients, non-ionic agents have reduced reactions five-fold while not changing fatality rates. Risk of nephrotoxicity increases with pre-existing renal insufficiency, dehydration, age over 70, and use of nephrotoxic drugs. Pretreatment and hydration can reduce risks of reactions and nephrotoxicity.

1. Contrast Agents dr shabeel pn

2. Contrast Agents Compounds used to improve the visibility of internal bodily structures in an image. Types: Radiographic agents based on iodine ionic or non-ionic agents Monomer or Dimer high osmolar, low osmolar, iso osmolar

3. Commonly used iodinated contrast agents Iso Osmolar 290 320 Non-ionic dimer Iodixanol (Visipaque 320) 884 350 Non-ionic Iohexol (Omnipaque 350) 796 370 Non-ionic monomer Iopamidol (Isovue 370) Non-Ionic Low Osmolar 580 320 Ionic Ioxaglate (Hexabrix) 2100 370 Ionic Metrizoate (Isopaque Coronar 370) High Osmolar 1550 300 Ionic Monomer Diatrizoate (Hypaque 50) Ionic Osmolality Iodine Content Type Name

4. Ionic Contrast Agents > 10 million diagnostic procedures / year Conventional ionic contrast reactions - 10% 1 in 1000 severe Contrast Myths not caused by iodine not related to shellfish not true allergy (no drug-antibody) mechanism remains unknown

5. Anaphylactoid (idiosyncratic) unpredictable dose independent prevalence 1-2% (0.04 - 0.22% severe) fatal 1 in 75,000

6. Chemotoxic predictable dose dependent due to osmolality or ionic composition Nonionic vs Ionic Contrast reactions decreased 5 fold Fatalities unchanged

7. Risk Factors Previous contrast reaction either moderate or severe asthma allergy history requiring medical treatment pretesting poor predictor of reaction Repeat Reactions, ionic bronchospasm 40% to facial edema 70% decrease to 6 - 9% with pretreatment decrease to 0.6% with pretreatment and switch to nonionic

8. Late Reactions 1 hr to 1 week following contrast injection Headache, myalgias, fever, skin reactions Risk Factors Previous contrast reaction Interleukin-2 treatment usually self-limited, treat severe reactions with steroids

9. Severity of Reactions - Minor Nausea & vomiting Urticaria Pruritis Diaphoresis

10. Severity of Reactions - Moderate Faintness Facial edema Laryngeal edema Bronchospasm

11. Severity of Reactions - Severe Pulmonary edema Respiratory arrest Cardiac arrest Seizures

12. Renal Toxicity (increased serum creatinine by more than 25% or > 0.5 mg%) 2-7% Risk Factors 5 - 10 fold increase with pre-existing renal insufficiency (increased creatinine) Dehydration CHF Age > 70 Taking nephrotoxic drugs (nonsteroidal inflammatory agents, gentomycin etc.)

13. Renal Toxicity (increased serum creatinine by more than 25% or > 0.5 mg%) direct relationship between serum creatinine and likelihood nephrotoxicity Hydrate 100 ml/hr Normal saline 4 hrs prior to procedure, continue for 24 hours Those on hemodialysis do not need extra sessions or dialysis immediately following contrast administration

14. Metformin (Glucophage) oral diabetic agent patients with renal insufficiency may develop lactic acidosis withhold drug for 48 hrs after contrast administration in all patients taking this drug

15. Screening Creatinine Which patients need screening creatinine? Consider if patient has one of the following risk factors: Known renal insufficiency Diabetes mellitus Lasix or nephrotoxic drugs Solitary kidney

16. Treatment Contrast Reactions Nausea & Vomiting usually self-limited protracted: Prochlorperazine (Compazine) 5-10 mg IM Urticaria Diphenhydramine (Benadryl) 25 - 50 mg IM, caution: drowsiness add Cimetidine (Tagamet) 300 mg in 20 ml, IV slowly

17. Treatment Contrast Reactions Hypotension Bradycardia (Vasovagal) elevate legs (infuses 700 ml) IV fluid (normal saline) O2 3 L/min atropine 0.6 mg IV push, repeat up to 3 mg total Tachycardia elevate legs IV fluid (normal saline) may require > 1 Liter O2 3 L/min

18. Treatment Contrast Reactions Bronchospasm or laryngeal edema O2 3 L/min Epinephrine 1:1000 (0.1 - 0.2 ml subq) or 1:10,000 1 ml IV over 3 min Beta 2 agonist 2 -3 puffs albuterol (Proventyl) metaproterenol (Alupent) terbutaline (Brethaine)

19. Treatment Contrast Reactions Anaphylactoid O2 3 L/min IV normal saline Epinephrine Benadryl 25 - 50 mg IV Tagamet 300 mg in 20 ml IV slowly Solu-medrol 1 gm IV Note: if patient taking beta blocker glucagon 1 - 5 mg IV bolus followed by infusion 5-15 ug/min or isoproternol 1:5000 (0.2 mg/ml) IV 0.5 - 1.0 ml diluted in 10 ml 1 mg increments

20. Treatment Contrast Reactions Seizures protect airway Diazepam (valium) 5 mg IV slowly Suspected pheochromocytoma phentolamine (Regitine) 5.0 ml (5 mg) IV bolus Pregnancy Discard breast milk for 24 hours following contrast administration

21. Extravasation Elevate extremity Ice pack 3x day Observe for 2-4 hours if volume > 5ml

22. Extravasation Plastic Surgery Consultation ionic > 30 ml nonionic > 100 ml skin blistering/significant tissue damage altered tissue perfusion increasing pain after 2-4 hours change in sensation distal to site of extravasation

23. Pretreatment Protocols Reduces minor reactions Benadryl 50 mg IM or PO 1 hr before procedure Prednisone 50 mg PO 13, 7, 1 hr before procedure Observe patient at least 30 minutes following injection

24. Pretreatment Protocols Reduction of Nephrotoxicity Creatinine level > 2 mg/dl Hydrate patient - Oral fluids if unable to drink use IV saline Mild Renal Insufficiency Patients – add N-acetyl-cysteine (Mucomyst) : 600 or 1,200 mg PO BID the day before and day of the procedure or 150 mg/kg IV over .5 hr or 50 mg/kg IV over 4 hr

25. Risk of Nephropathy A recent meta analysis: Radiology: Volume 239: May 2006 p.392-397: Drs Rao & Newhouse Properly controlled clinical studies of IV administered radiographic contrast media fail to demonstrate renal damage.

26. ACR Manual on Contrast Media guide for radiologists in the use of iodinated contrast media h ttp:// www.acr.org/s_acr/sec.asp?CID =2131&DID=16687

27. References of Interest Guidelines for Contrast Media from the European Society of Urogenial Radiology: AJR:181, December 2003 p. 1463 – 1471. Minimizing Adverse Reactions to Contrast Agents: Radiology Rounds, Massachusetts General Hospital, Volume 1, Issue 5 Oct 2003.