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Raditude 21 Ch.12
Contrast Agents
Question | Answer |
---|---|
Fills a structure with a material that has a different density than that of the structure. | Contrast agent |
Agent is a higher density than that of the structure. | Positive agent |
Agent is of a lower density than the surrounding structure. | Negative agent |
How do contrast agents serve to widen the difference in attenuation between adjacent structures? | Different tissues often enhance differently and intravascular contrast material is handled differently in normal tissue versus abnormal tissue. |
A property of intravascular contrast media that refers to the number of particles in the solution, per unit liquid, as compared with blood. | Osmolality |
High-osmolality contrast media can have how many times more osmolality than that of blood? | 7 times |
Low-osmolality contrast media can have how many more times osmolality than that of blood? | Roughly twice as much. |
Contrast media that has the same osmolality as blood is termed____. | Isosmolar |
A physical property of intravascular contrast media. It can be described as the thickness or friction of the fluid as it flows. | Viscosity |
What are three things that can affect viscosity? | Brand, temperature, and concentration. |
How are IV contrast agents classified? | Whether the molecules they contain will separate into charged particles (ions) when dissolved in an aqueous solution. |
Will the molecules of an ionic contrast agent separate or stay together when in solution? | They will dissociate into ions |
Do most nonionic contrast agents have low or high osmolality? | Low |
How are iodinated contrast media metabolized in the body? | They are not metabolized but are excreted by the kidney via glomelular filtration. |
What is the half life of iodinated contrast media? | 2 hours |
How many grams of iodine will be delivered when 125 mL of an agent with a concentration of 240 mgl/mL is injected? | 125 mL X 240 mgl/mL = 30,000mgl = 30gl |
What is a risk factor when administering iodinated contrast? | patient's hydration |
At what volumes has death occurred from contrast administration? | 250 to 300 mL undiluted HOCM ionic media |
What is the typical upper limit of contrast media given? | 200mL of an agent with a concentration of 320mgl/mL |
What body systems does contrast media affect when there is an adverse reaction? | Pulmonary and cardiovascular systems |
What factors should be considered when accounting for individual volume and concentration of contrast agents? | Age, weight, and size of the vessel into which it will be injected. |
What is the most common formula for pediatric patients when considering contrast agents? | 2mL/kg |
What does the term "contrast reaction" refer to? | All undesired effects including the many subjective side effects experienced to some degree by most patients who receive contrast. |
What are the two categories of adverse reactions to injectable contrast media? | Chemotoxic and idiosyncratic |
What causes a chemotoxic reaction? | Th physiochemical properties of the contrast media, the dose, and speed of injection. |
What does the term idiosyncratic refer to? | Unpredictable, not precisely understood. |
Do adults or children have a lower frequency of contrast reactions and are they chemotoxic or idiosyncratic on nature? | Children, idiosyncratic |
What are some common side effects of contrast media administered intravenously? | Nausea, vomiting, altered taste, perspiration, warmth, flushing, anxiety |
How are acute idiosyncratic reactions characterized? | Mild, moderate, severe |
What are symptoms of a mild idiosyncratic reaction? | Cough, itching, rash, pallor, nasal stuffiness, minimal swelling in the eyes and face, and facial rash. |
What are symptoms of a moderately idiosyncratic reaction? | Respiratory distress, bronchospasm, dyspnea, wheezing, mild laryngeal edema, pulse change, hypertension, and hypotension. |