Contrast Agents Flashcards
gas or radiopaque substances that is injected into the body, introduced via catheter, or swallowed in order to facilitate radiographic imaging of internal structures that otherwis are difficutl to visuliaze radiographically
contrast
most organs and blood vessels have xray absorption to similar surrounding tissues.
used to enhance radiographic contrast pf soft tissue
contrast media
an inert inorganic metallic salt of the chemical element barium
used exclusivley for radiography of the GI tract and is administered either orally or rectally
barium sulfate
most palatable when cold and offered with a straw which helps it from coating the mouth
oral administration
disposable eneam kits are available that include a plastic bag, enema tubing, and a rectal catheter. A liquid barium suspension may be poured inot a disposal enema bag and diluted if required, tepid water
rectal administration
the principle problem with bariym complicationg the used of barium is its
hygroscopic nature
most organs and blood vessels have similar xray absorption characteristic. This causes radiographic images to be only faintly distinguishable
iodinated media
special water-soluble iodine compounds
most frequently used contrast agents other than barium
used when barium sulfate may be contradicted
water soluble (aqueous)
unlike barium, compounds absorb into bloodstream
may be used when high risk of barium impaction is suspected
advantage of water soluble
more expensive and generally produce less radiographic contrast
contraindicated for exams of esophagus or a fistula connecting esphagus to trachea
concentration of iodine determines the degree of attenuation
concentration depends largely upon the degree it will be diluted by body fluids
disadvanted of water soluble
referes to the number of particles in solution per kilogram of water
osmolality
human blood is about
300 mOsm/kg
water soluble contrast media ranges from
300 mOsm/kg to more than 1000 mOsm/kg
some contrast media molecules dissociate into two charged particles when placed in solution resulting in higher osmolality
ionization
specialized contrast agents that were developed for studies in which absorption of contrast into surrounding tissues or mixing of contrast with body fluids is not desired
used ofr lymphography
ethiodized oils
most commonly used oil is
ethiodol
barium and iodine compounds provide positive contrast meaning they absorb more radiation than surrounding tissues and make a white or light shadow on the image
air contrast
absorb less radiation and produce negative contrast or dark shadows
air and gases
ordinalry used to treat hypoglycemia
causes relaxation of the smooth muscles of the GI tract
useful as a diagnostic aid in exams of GI tract beacuase it slows peristalsis and prevents cramping
glucagon
most occur immediately within 30 minutes
warm feeling during injection
feel flush 1-3 minutes
metallic taste in mouth
mild reaction
erythema (reddining), uritcaria (hives), bronchospasm, vasovaga
intermediate reaction
anaphylactic shock respiratory or cardiac arrest seizures hypotension may be fatal
severe reaction
most frequently used antihistamine
produces anticholinergic (drying) side affect
can be given orally before injection of iodinated contrast media to patients who are at risk of having an allergic reaction, IM, or IV if the patient has an allergic reaction
Diphenhydramine (Benadryl)
25-50 mg orally, 10-50 mg IV and IM may be increased to 100 mg
adults
12.5 - 25 mg orally
children over 20 lbs
maximum safe dose in a 24 hr is
400 mg IM or IV
are anti-inflammatory medications, may be prescribed before injection of contrast media
short acting cortichosteroids
administered subcautanously IM or IV
stimulates the heart and sympathetic nervous system
epinephrine (adreneline)
minimizes possiblity of cardiac arrest
may be administered (IV)
long acting corticosteriod
acs as anti-inflammatory agent; prevents/reduces edma of tracheobronchial tree
methylprednisolone (solumedrol)
a problem imaging department encounter is
schdueling
