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What every Sonographer should know about Contrast Media Harry H. Holdorf PhD, MPA, RDMS (OB, Ab, BR), RT(ARRT-Ret.) AS(LRT) The purpose of contrast media The routes of contrast media Categories and types of Contrast agents Intra-Venous contrast chemistry Non-Ionic contrast agents Ionic contrast agents Viscosity Dosing Common Radiopaque agents IV Contrast Agent Extravasation Allergy preparation: Special considerations Adverse Reactions to iodinated contrast agents Common responses to contrast agents Mild adverse reactions Moderate adverse reactions Severe adverse reactions Treating contrast agent reactions Contraindications Oral contrast Contrast agents in Cardiology Summary and conclusion Purpose of Contrast Media › To increase the difference in attenuation (radiation beam absorption) between adjacent structures › X-Ray attenuation is directly related to the atomic number of the material in the path of the beam – Allows the biological nature of the material to be identifiable to the reading physician – Allows the reading physician to distinguish between vessels, lymph nodes, and other organs of the body from one another. Common Contrast Media routes of delivery: › Enteral: Administered through the Gastro-Intestinal Tract – Includes the esophagus, stomach, small and large intestines › Oral › Gastric › Rectal Common Contrast Media routes of delivery: › Parenteral: Administered into the body in a manner other than the digestive tract – Intravenous › Directly administered into a vein Categories of Contrast Agents › Positive Contrast Agent – Contrast agent appears more radiopaque (white) than surrounding tissues – High atomic number › Negative Contrast Agent – Contrast agent appears more radiolucent (dark) than surrounding tissues – Low atomic number › Neutral – Appears similar to surrounding tissues Positive Agents • Barium Sulfite • Water Soluble (iodinated) Negative Agents • Air • Carbon Dioxide • Administered orally in granular form or rectally via insufflation Neutral Agents • Water • VoLumen (Low density form of barium sulfate The Types of Contrast Agents: Positive The Types of Contrast Agents: Negative The types of Contrast Agents: Neutral Intra-Venous (IV) Contrast IV Contrast Agent Chemistry › It is important to know the chemical properties of various contrast agents to chose for the best patient outcome with least risk of adverse side effects. › Main Chemical Properties: – Osmolality › Measurement of the total number of particles in the contrast solution per kilogram of water › Direct measurement of the ionization of a solute in a solvent – Viscosity › Amount of friction generated by the concentration and size of contrast molecules – Dosing › Amount of contrast administered to a patient Non-Ionic Contrast Agents › Low osmolality (particle) contrast media (LOCM) › DOES NOT – Increase the osmolality of the blood serum – Change the osmotic pressure › Sager for patients with compromised cardiac or renal status – Advantages › Less hemodynamic effect › More water soluble (hydrophilic) › Less likely to be reactive with cells – Lower risk for allergic reactions Ionic Contrast Agents › High osmolality (particles) contrast media (HOCM) › Increase water in blood which increases the total blood volume – Forces the heart to work harder in order to pump the increased volume – This phenomenon is referred to as INCREASED OSMOTIC PRESSSURE and results in › Hypervolemia-increased blood volume › Blood vessel dilation › Shock in severely dilated patients – RENAL EFFECTS CAN BE SIGNIFICANT › Expands kidney arteries which can cause: – Release of vasoconstrictors which can constrict the renal arteries › Diminishes blood supply to the kidneys › Decreases renal function › These types of contrast agents are utilized infrequently because of their chemical properties and side effects. Viscosity › Amount of friction generated by concentration and size of contrast molecules › Higher the viscosity – THICKER the agent. More difficult to inject – Rapid injection can be more difficult with a more viscous agent › Can trigger body’s pressure sensors, causing vasoconstriction and injection therefore can be painful – Important to heat the agent to body temperature before injection › Reduces the viscosity – Heating can be achieved through › Contrast warmer › Manually. Using tepid water – Nonionic media is more viscous than ionic media at similar iodine concentrations Dosing › It is critical to avoid overdosing iodine › Iodine Toxicity can occur at levels greater than 80-90 grams – Symptoms of iodine overdose include: › Tremors › Irritability › Tachycardia – If such symptoms occur › STOP administration of medication immediately and initiate emergency action. Common Radiopaque Agents › Ominpaque (LOCM) › Gastrografin (HOCM) › Hypaque (HOCM) IV Contrast Agent Extravasation › IV contrast agent extravasation is the accidental extra-vascular injection of intravascular contrast media caused by: – Dislodgment of the cannula – Contrast leakage from the vessel puncture site – Rupture of the vessel wall › Most common complication of intravenous injections – Occurs in less than 1% of patients › Identifiable risk factors include: – Non communicative patient › Pediatrics and geriatrics – Severely debilitated patients – Multiple punctures of the same vein – Injections performed on the dorsum of the hand and foot Examples of Extravasation IV Contrast Agent Extravasation › Signs and symptoms of IV contrast agent extravasation – Pain, tightness, or burning sensation at or near injection site – Swelling at or near the injection sight – Redness or discoloration at or near injection sight › What to do in case of extravasation: – Immediately stop the injection or infusion – Remove the catheter from the injection site › Treatment of IV contrast agent extravasation – Elevation of affected extremity above the hart – Alternating cold and hot packs › 15-60 minute applications three times daily (day 1-3) › Follow institution’s protocol and consult a physician – Close observation for 2-4 hours – Inform referring physician and radiologist ALLERGY Preparation: Special Considerations › Given to patients with a known contrast reaction history – Reduces the risk of a severe adverse reaction › Optimal Pre-Treatment Regimen – Three 50mg doses of oral prednisone › Taken 13, 7, and 1 hours prior to procedure – Diphenhydramine 50mg dose › Taken 1 hour prior to procedure › Pre-Treatment regimen for Emergency Procedures: – Methyprednisone (40mgIV) every 4 hours until procedure – Diphenhydramine (50 mg IV) I hour prior to procedure Adverse Reactions to Iodinated Contrast Media › MOST reactions occur within 5 minutes of injections but may occur as late as 24 hours post injection. › ALWAYS have a crash cart and emergency drug box available › Diagnostic Medical Sonographers must be CPR certified › Anaphylactic reactions are believed to be caused by the release of histamine in the body – Released from certain cells in the lungs, stomach and lining of blood vessels Common Responses to Contrast Agents SIGNS and SYMPTOMS RESPONSES Warmth or flush feeling No treatment necessary Metallic taste Symptoms resolve rapidly Nausea If vomiting occurs: Vomiting Turn patient on their side to prevent Coughing aspiration Mild Adverse Reactions to Contrast Agents Signs/Symptoms Responses Mild urticarial (Hives) Notify radiologist and physician Coughing Observe patient in the department Dizziness Nasal stuffiness Shaking Itching/pruritus Moderate Adverse Reactions to Contrast Agents Signs/Symptoms Responses Erythema Notify radiologist or physician Moderate or severe urticaria Prepare to help administer antihistamine or epinephrine if ordered Bronchospasm Prepare IV fluids and Oxygen if ordered Wheezing Severe Adverse Reactions to Contrast Agents Signs/Symptoms Responses Respiratory or cardiac arrest Maintain airway Seizures Call rapid response or code Hypotensive Treat for shock, respiratory or cardiac arrest as symptoms require Laryngeal or bronchial edema Treating Contrast Agent Reactions › Always notify the radiologist and nurse of any reaction › Your Emergency Drug Box should contain the following: – – – – – – – Epinephrine Hydrocortisone Atropine Benadryl Sodium Chloride (saline) Lactated ringers Oxygen Contraindications to IV Contrast Agents › Reversible renal failure › Previous anaphylaxis reactions › Pregnant patients – Contrast DOES cross the placental barrier › Multiple myeloma (cancer of the blood) – Leads to acute renal failure › Pheochromocytoma (adrenal tumor) – Releases large amounts of adrenaline › ALWAYS consult with a radiologist or physician before making the decision to administer IV contrast Oral contrast: Barium Sulfate Oral contrast Agents: BARIUM SULFATE Barium – – – – – – 2% mixture Suspended in water Contraindicated if patient is suspected of: colon/gastro-intestinal obstruction or perforation Tracheoesophageal fistula Obstructing lesions of the small intestine Pyloric stenosis Inflammation or neoplastic lesions of the rectum Recent rectal biopsy or colonoscopy Oral Contrast Agents-Water Soluble › Gastrografin, Gastrovue, Ominpaque – Water soluble, ionic, high osmolality contrast media – Prescription drug intended to be therapeutically and biologically inert when ingested/injected into the body for use in organ or tissue enhancement. – Particularly suited for times when a more viscous agent such as barium sulfate (NOT water soluble) is not feasible or potentially dangerous. Other Factors to be Considered › Patient care factors › Take into account patient history, diagnosis, and contraindications › Which contrast agent(s) are to be utilized for which procedures and protocols and for which diagnosis › Consent › Venipuncture › Documentation and labeling of contrast media › Storage of contrast media › Joint Commission guidelines for contrast media Contrast Agents in Echocardiography Microbubble contrast agents have been developed and are introduced as a safe and effective echo-enhancer in present-day clinical practice. Contrast echocardiography has evolved rapidly in the last decade, with major developments in both contrast media and ultrasound equipment. Understanding of the physical principles underlying the interaction of ultrasound and microbubbles has enhanced our ability to optimize the technique. › Used predominantly for the detection of intra-cardiac shunts, the wide usage of Contrast-Enhanced Ultrasound more importantly resulted in routine use of contrast for left heart opacification. › CEU is also used for the assessment of left ventricular function during stress echocardiography and when imaging is suboptimal. Summary and Conclusions › Contrast agents help the radiologist’/cardiologist distinguish between different structures and organs of the body › Sonographers must be educated and mindful when either using or observing the administration of contrast agents › If utilized and administered properly, contrast agents present a relatively low risk for patients › Important and crucial to inform/educate patients about what they are being administered, risks involved, and purpose Further information… › ACR manual on contrast media › Contrast agent tutorial: Department of Radiology/University of Wisconsin › Radiologyinfo.org-patient safety Project: Presentation Contrast Enhanced Ultrasound › How is contrast utilized in ultrasound, especially Echocardiography?