Contrast Media PDF

- - - - - - - - Used to - \* assist in the visualization of structures - \* distinguish between adjacent tissues - Barium is must coomon for GI - Contrast media Administration Routes - - - - - - -...

- - - - - - - - Used to - \* assist in the visualization of structures - \* distinguish between adjacent tissues - Barium is must coomon for GI - Contrast media Administration Routes - - - - - - - - - - - - - used in hollow organs such as the digestive tract, bladder and joint capsules (*radiolucent)* - rarely used because of MRI and CT - \* carbon dioxide and air most common - Can be used signally or with positive contrast - - \* agents produce contrast by increasing organ density so that they are radiopaque - There are two types - barium (atomic \#=56) - iodine (atomic \#=53) - appear white on an x-ray image - - - - - - - - - - - - - - - - - \* most commonly used contrast media - Depending on the type can be administered by oral, vaginal, intravenous, and intra-arterial routes. May also be directly instilled through retrograde procedure(back ways against the flow) or directly into joints - Mix readily with blood and other body fluids. These are the only contrast media suitable for intravascular injection. - Used for CT examinations, angiography and special procedures. - Most are water soluble - Barium cannot be injected outside of GI tract - - Contain **iodine** atoms and various combinations of other atoms. These molecules vary in size, and some contain more iodine atoms than others (concentration of iodine) - - Iodine concentration: \# of iodine molecules (in mg/mL) - \* increased concentration, increases the attenuation factor of the contrast,(making it more radiopaque) - There are several different iodine concentrations depending on the organ to be highlighted - - \* osmolality is the total number of the osmoles(particles) in a solution per kg of solvent(water) - Iodine concentrations are listed on the packaging of contrast media and they are used to calculate the osmolality of the solutions. - This increase in shifting of fluid cause imbalance can cause a reaction to the contrast. Injecting a IV that exceeds osmolality of human blood called hyperosmolar solution affects the osmotic pressure within the body. - +-------------+-------------+-------------+-------------+-------------+ | **Contrast | **mOsm/kg | **% in | **Grams of\ | **Ionic or\ | | Name** | of\ | Solution** | Iodine per\ | Non-ionic** | | | water\ | | decilitre** | | | | Osmolality* | | | | | | * | | | | +-------------+-------------+-------------+-------------+-------------+ | **Conray | **1400** | **60** | **28** | **Ionic** | | 60** | | | | | | | | | | | | **(used for | | | | | | primarily | | | | | | for urology | | | | | | tests)** | | | | | +-------------+-------------+-------------+-------------+-------------+ | **Hypaque | **1415** | **60** | **28** | **Ionic** | | 60%** | | | | | | | | | | | | **(administ | | | | | | ered IV)** | | | | | +-------------+-------------+-------------+-------------+-------------+ | **Isovue | **616** | **61** | **30** | **Non-ionic | | 300** | | | | ** | | | | | | | | **(administ | | | | | | ered IV)** | | | | | +-------------+-------------+-------------+-------------+-------------+ | **Ominpaque | **504** | **51.8** | **48** | **Non-ionic | | 250 | | | | ** | | (administer | | | | | | ed IV)** | | | | | +-------------+-------------+-------------+-------------+-------------+ | **Urovist** | **640** | **30** | **141** | **Non-ionic | | | | | | ** | | **(drip-use | | | | | | d | | | | | | for | | | | | | urology)** | | | | | +-------------+-------------+-------------+-------------+-------------+ Higher osmolality more likely to cause an allergic reaction Increase will stimulate excression of ADH more concentrated urine - - - \*Molecules separate into two charged particles(ions), giving rise to a higher osmolality substance - This process is referred to as ionization. - Ions are atoms that has a negative charge highly reactive - - \* differs in that it does not dissociate - Meaning the particles will stay whole when in solution. - - - \* more adverse contrast reactions - Has a higher viscosity - Higher osmolality than non-ionic - Is a saline based solution - \* when in solution it splits into ions - Negative ions are termed Anions -- Iodine - Positive ions are termed Cations -- sodium and/or meglumine - 3:2 ratio or 1.5 particles of Iodine to other particles - - \* Less adverse contrast reaction- better tolerated by patient - Lower osmolality less attenuating - No dissociation in solution -- does not split up into ions - 3:1 ratio of iodine to other particles - Best choice for high risk patients such as diabetics, cardiac disease, multiple myolunia - - **Contraindications to contrast media administration** - Disorders of the water and electrolyte balance - Must be corrected before the examination. - Patient is taking anticoagulants - Pregnancy can be harmful to fetus - \* known dehydration or renal insufficiency(cant discrete contrast) - Known allergy to contrast media - Metformin within the past 48 hours - Abnormal blood counts such as (CBC), platelet count, PTT - As abnormal clotting factors can increase risk of bleeding - \*abnormal blood urea nitrogen, creatinine, eGFR - As this indicates impaired renal function - Excessive hydration (dilution of contrast) - Iodine can cause nausea and therefore a patient should be NPO for 6-8 hours before the procedure - - - - - - - - Technologist should: - Ensure that the administration of contrast media is appropriate for the patient and the examination (check lab results and history) - \* Prepare to treat an adverse reaction should one occur(CPR, where drugs are, equipment functioning) - Hydrate the patient properly. Before and after - - \* obtain a complete history that includes allergies, medications, health history, age, gender - Ensure emergency supplies are available in case of contrast media reaction(not expire and working) - Give a clear explanation to the patient of what to expect(risk, side effects) - Gather all necessary supplies to allow the Radiologist to inject contrast - - - - - - \* could be nausea and vomiting, flushing, urticaria(scattered hives) - - could cause a vasovagal response(widening of blood vessels cause fainting), bradycardia, hypotensiveness(low blood pressure), severe hives, facial/throat swelling, SOB, feeling faint, clammy, perspiring, nausea and a gray pallor - - could be anaphylaxis- rapid, weak pulse, dyspnea(SOB), severe vasodilation(fluid around throat), laryngeal edema, convulsions, hypotension or a myocardial infarct(heart attack) - - - - - - - - - - Collecting a relevant allergy and medical history from the patient - Contrast media questionnaire - More detail than typical clinical history for regular exams - - - - - - \* The patient is instructed to increase their fluid intake for at least the next day or two - Patient to call Emergency if any symptoms appear after they have returned home - Most reactions happen almost immediately but there is still a chance it could after later - - Most commonly used for CT and angiography - Same precautions as all other contrast injections - Follow instructions for loading injector - \* be certain that there is no air in pump syringe or tubing before attaching it to the patients IV