Contrast Media PDF

Summary

This document provides information about contrast media, including its types, uses, administration routes, and related concepts. It explains the characteristics and properties of different contrast agents, such as iodine concentration and osmolality. The document also touches upon potential risks and reactions related to contrast media.

Full Transcript

- - - - - - - - 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

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