contrast agents and chemistry stuff

contrast is used in __ % of all imaging exams

30

radioopaque

light or white- structures filled or outlined by positive contrast

what is the most common contrast material

positive contrast

positive contrast

additive ( liquid, powder, paste)

negative contrast

air

gastrografin

positive contrast for GI studies, water soluble, iodinated

barium sulfate

positive contrast for GI studies. do not use if suspected perforation,

radiolucent

anatomy is filled with air appearing darker in xrays

double contrast studies

use both positive and negative contrast for some GI studies ( usually intestines)

gadolinium contrast

used in mri, less harmful for kidneys

factors affecting contrast selection

-ability to mix with body fluids

- viscosity

- ionic strength

- permanence

- osmolality

- amount of iodine

- toxicity potential

what type of contrast is easily distributed throughout body and easily eliminated by the body

iodinated / water soluble contrast

iodinated contrast can be administered via

orally, vaginally. IV, intra-arterially, retrograde procedure

tonicity

the concentration of solutes (salts or sugar) outside the cell vs inside the cell

hypotonic solution

fewer solutes outside --> water rushes inside cell

the cell swells and can burst (lysis)

hypertonic solution

more solutes outside the cell so water rushes out of cell to balance

cell will shrink (plasmolysis)

isotonic solution

balanced inside and out , equal movement of solutes and solvent

Molarity

moles of solute/liters of solution

Molality

moles of solute/kg of solvent

osmoles

particles that contribute to osmosis pressure

osmolarity

osmoles / liter of solution

osmolality

osmoles / kg of solution

iv fluids are usually ________

isotonic

water soluble positive contrast are made up of _______ and ______

cations and anions

cations

positively charged ions

Anions

negatively charged ions

high osmolar contrast material

ionic, older, and has more side effects

ex: gastrografin (GI tract only no perforation)

low or iso- osmolar contrast media

nonionic due to cations being replaced by glucose

less chance of reactions occurring

ex: isovue

______________ contrast material is hyperosmotic to body fluids because when they are dissociating to separate ions, it causes adverse effects.

hyperosmotic contrast

high

hypertonic

_____ and _____ are safer and preferred contrast material because they are closer to the toxicity of blood

low-osmolar and iso-osmolar

what happens if contrast is too hypertonic?

water leaves the cells, cell dehydration, pain, vein irritation, or even kidney stress

when should we use low osmolar contrast material?

when the patient has

- previous reactions to contrast

- asthma

- cardiac conditions

- pt is extremely debilitated

- pt is at high risk for extravasation

normal side effects to contrast

feeling warm or flushed, mild nausea, metallic taste in mouth

what should you do if pt experiences more than the normal side effects to contrast?

stop the contrast and exam, and get help

high osmolar contrast reactions occurring to _____ % of all exam with 99% being mild reactions

7-12%

viscosity

thickness of a liquid