Special procedures (contrast studies) Flashcards
How much of an emergency is barium leakage?
What does it cause, what is mortality rate, etc
Barium leakage results in peritonitis/mediastinitis, fibrosis, granuloma formation.
50% mortality rate
How much of an emergency is barium leakage?
What does it cause, what is mortality rate, etc
Barium leakage results in peritonitis/mediastinitis, fibrosis, granuloma formation.
50% mortality rate
Describe two situations where administration of ORAL hypertonic iodinated contrast could be fatal?
1) Shocky patients - if administered orally - will pull fluid into the intestinal tract - further dehydrating them
2) Where aspiration may occur - esophagrams, bronchoesophageal fistulas –> pulmonary edema
Describe two situations where administration of hypertonic iodinated contrast could be fatal?
1) Shocky patients - if administered orally - will pull fluid into the intestinal tract - further dehydrating them
2) Where aspiration may occur - esophagrams, bronchoesophageal fistulas –> pulmonary edema
Metrizamide was one of the first non-iodinated contrast agents used - and was seen causing neurotoxic effects when used for myelography.Why did this occur?
2-deoxy-D-glucose side chain that inhibited glucose metabolism in the brain
What are the two categories of iodinated contrast media?What characteristics separate these groups?
Ionic and non-ionic.
Ionic: When in solution - dissociates into the negative iodinated anion, and positively charged cation (sodium) Dissociation = greater osmoliaity (2-3x that of non-ionic)
Non-ionic - do not dissociate in solution
What is range of osmolality of ionic contrast agents vs non-ionic media?
Ionic: 1900-2100mOsm/kg
Non-ionic: 290-900mOsm/kg (closer to blood)
Blood: 275-300mOsm/kg
How frequently are contrast reactions seen in human patients, and what is that number related to?
What are examples of idiosyncratic and non-idiosyncrati reactions?
Idiosyncratic - true allergic reaction - histamine release, complement cascade, immune-mediated, hypertonicity
Non-idiosyncratic:
acute renal failure - due to vasoconstriction, direct toxic effects on renal tubular cells
anti-coagulant effects - ionic agents have more anti-coagulant effects,
BBB damage - ionic agents increase BBB permeability, Bradycardia - vasovagal reaction
CHF - osmotic hypervolemia and worsen CHF
ECG changes - increased HR and prolonged QT interval
Endothelial lesions - increased permeability and thrombi formation,
Rigid erythrycotyes (difficulty moving through capillaries),
Decreased left ventricular function (after intracoronary injections),
Nausea/vomiting,
Peripheral vasodilation - agents have direct effect on endothelium - increasing their permeatility
When should ionic agents NOT be used and why? (4 examples)
1) Dehydrated/renal disease patients - may result in acute renal failure
2) Intrathecal injection - seizures can be 1400x as toxic than IV injection
3) Anytime the BBB may be damaged - can result in increased intracranial pressure and decreased glucose uptake/metabolism (metrimazole)
4) CHF
What are generic and brand names most commonly used for intrathecal injections?
Which has a higher LD50 for intrathecal injection?
Iohexol - Omnipaque
(stupid ass mnemonic - people who are omnipotent could put a hex on you)
LD50: 840mg I/kg
Iopamidol - Isovue
LD50: 1490mgI/kg
Describe two situations where administration of hypertonic iodinated contrast could be fatal?
1) Shocky patients - if administered orally - will pull fluid into the intestinal tract - further dehydrating them
2) Where aspiration may occur - esophagrams, bronchoesophageal fistulas –> pulmonary edema
Metrizamide was one of the first non-iodinated contrast agents used - and was seen causing neurotoxic effects when used for myelography.Why did this occur?
2-deoxy-D-glucose side chain that inhibited glucose metabolism in the brain
What are the two categories of iodinated contrast media?What characteristics separate these groups?
Ionic and non-ionic.
Ionic: When in solution - dissociates into the negative iodinated anion, and positively charged cation (sodium) Dissociation = greater osmoliaity (2-3x that of non-ionic)
Non-ionic - do not dissociate in solution
What is range of osmolality of ionic contrast agents vs non-ionic media?
Ionic: 1900-2100mOsm/kg
Non-ionic: 290-900mOsm/kg (closer to blood)
Blood: 275-300mOsm/kg
How frequently are contrast reactions seen in human patients, and what is that number related to?
What is the difference between idiosyncratic and non-idiosyncratic reactions?
Idiosyncratic - non-dose dependent
Non-idiosyncratic - dose dependent
What are examples of idiosyncratic and non-idiosyncrati reactions?
Idiosyncratic - true allergic reaction
Non-idiosyncratic:
acute renal failure - due to vasoconstriction, direct toxic effects on renal tubular cells
anti-coagulant effects - ionic agents have more anti-coagulant effects,
BBB damage - ionic agents increase BBB permeability, Bradycardia - vasovagal reaction
CHF - osmotic hypervolemia and worsen CHF
ECG changes - increased HR and prolonged QT interval
Endothelial lesions - increased permeability and thrombi formation,
Rigid erythrycotyes (difficulty moving through capillaries),
Decreased left ventricular function (after intracoronary injections),
Nausea/vomiting,
Peripheral vasodilation - agents have direct effect on endothelium - increasing their permeatility
When should ionic agents NOT be used and why? (4 examples)
1) Dehydrated/renal disease patients - may result in acute renal failure
2) Intrathecal injection - seizures can be 1400x as toxic than IV injection
3) Anytime the BBB may be damaged - can result in increased intracranial pressure and decreased glucose metabolism (metrimazole)
4) CHF
What are generic and brand names most commonly used for intrathecal injections?
Iohexol - Omnipaque (stupid ass mnemonic - people who are omnipotent could put a hex on you) LD50 - 840mg I/kg Iopamidol - Isovue LD50: 1490 - mg I /kg
What are brand names for Diatrizoate, and is it ionic or non-ionic
Ionic
Cystograffin, renograffin, gastrograffin
How do you measure barium using weight-to-volume?
Give example
Certain amount of barium sulfate added to enough water to obtain predetermined total volume.
20% w/v suspension can be prepared by adding 20g of barium sulfate to water to = 100mL
20% w/v suspension can be prepared by adding 40g of barium sulfate to wter to =200mL