Lecture 4: Contrast complications Flashcards
why use contrast medium
- Opacify specific structures to increase contrast resolution
- With radiography only way to differentiate structures is when they are different opacities
what are the 4 types of contrast
- Gas
- Barium
- Iodinated
- Paramagnetic agents
what are the routes of administering contrast
IV, intrathecal, intraperitoneal, oral, intra-articular
Is hypague 76 contrast ionic or non-ionic
ionic
are iohexol 350 and 240 ionic or non-ionic contrasts
non-ionic
what are some indications for iodinated contrast
urinary study, angiography, CT, lymph angiography, arthrography, myelography
Only use ionic or non-ionic iodinated contrast in myelographs
non-ionic
Iodinated contrast is __times the osmolality of plasma
5-8 times
what is the advantage of ionic contrast
less expensive
what are the disadvantages of ionic contrast
hypertonicity- increased risk of reaction
You can not administer ionic contrast __
intrathecally
what are some advantages of non-ionic contrast
lower reaction rate, less hypertonic, useful for any procedure
what is the disadvantage for non-ionic contrast
expensive
what are some toxicities associated with iodinated contrast
- Osmolality- primary effect
- Ionic charge
- Chemical toxicity
- Allergic or idiosyncratic reaction
the osmolality/ hypertonicity of iodinated contrast causes a shift of water from ___ to ___ space, and a shift of water out of ___
extravascular to intravascular, RBC
what endothelial and RBC lesions are seen as the result of negative osmolality effects
- Desiccation and weakening of junctions
- Increase capillary permeability
- RBC dedicate and are rigid
- Risk of thrombosis formation
what are the cardiovascular effects of osmolality changes from iodinated contrast
- Vasodilation- severe hypotension
- Osmotic hypervolemia
- Reflex bradycardia
what are the renal affects of osmolality changes from iodinated contrast
diuresis, acute renal failure- hypertonicity and chemical toxicity
what are some non-specific reactions to osmolality changes from iodinated contrast
nausea, vomiting, chills, fever, headache
CNS is very sensitive to ionic composition changes and can result in __ or ___
seizures or cardiac dysfunction
ionic or non-ionic: results in ionic composition changes that can cause seizures or cardiac dysfunction
ionic (does not occur with non-ionic)
T or f: sodium is toxic but compounds with megluimine are less toxic
true
t or f: non-ionic compounds have no sodium, therefore less toxic
true
Iodinated compounds directly induce ___degranulation and ___release
mast cell, histamine
T or F: iodinated contrasts suppress erythrocyte function
true
which intrathecal iodine injection site has increased adverse reactions: cisternal or lumbar
cisternal>lumbr
how do you determine volume of contrast given intrathecal
volume of contrast/mL of CSF
what factors have no effect on incidence of reactions in intrathecal iodine administration
dose, time of anesthesia, anesthetic protocol
__therapy may decrease risk of seizures when administering intrathecal iodine
fluid
what neurotoxicities are associated with iodinated contrast administration
- increased capillary permeability in BBB allows toxic substances to contact neurons
- Ionization disrupts neurotransmission
what are some intrathecal iodine reactions
- Seizures
- Hyperthermia
- Transient apnea
- Transient muscle spasms
- Hypotension
- Opisthotonus
what is gadolinium based contrast
injectable paramagnetic substance
paramagnetic substances shorten __ and __relxation times
T1 and T2
T or F: gadolinium is highly toxic
true
since gadolinium is highly toxic is must be ___
chelated, DTPA most common
what are the mechanism of reactions associated with gadolinium based contrast
stability, osmolality
what are some indications for gas contrast
cystography, pneumoventriculography, ultrasound, peritoneography, pericardiography
what are some reactions associated with gas contrast
air emboli- rare complication
what are some signs of air emboli from gas contrast
occlude flow, infarct of affected area
what is tx for air emboli from gas contrast
Place left lateral recumbency and catheterize right atrium to try and extract emboli (often fatal complication)
What reactions are associated with barium contrast
only concern if extravasation into body cavity- severe granulomatous inflammation
what are some signs of a barium reaction
abdominal pain, mild to severe peritoneal adhesions
what is tx for barium reaction
immediate lavaging may minimize reaction
