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Positioning Spring 2015 > contrast media > Flashcards

contrast media Flashcards

1
Q

subject contrast

A

the radiographic contrast caused by the difference in the composition of the patient’s body tissues

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2
Q

contrast media

A

diagnostic agents that are introduced into the body or injected into the vascular system, joints, and ducts to enhance subject contrast in anatomic areas where low subject contrast exists

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3
Q

types of contrast media

A
  1. radiolucent (negative) contrast agents
  2. radiopaque (positive) contrast agents
  3. specialty contrast agents
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4
Q
  1. radiolucent/negative contrast agents
A 
composed of elements with low atomic numbers 
administered as: 
gas or carbon dioxide 
produce areas of increased density 
appears black or dark on radiograph
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5
Q

what is the most common negative contrast agent

A

room air

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6
Q

double contrast agents

A

when a negative contrast agent is combined with a positive contrast agent

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7
Q

types of negative contrast agents

A

gas, CO2, air

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8
Q

negative contrast agents must NEVER…..

A

be injected intravenously

serious/ fatal consequences can occur

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9
Q
  1. positive/ radiopaque contrast agents
A

composed of elements with a high atomic number
appears bright on a radiograph
more absorption of xray beam

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10
Q

examples of positive contrast agents

A

barium

iodine

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11
Q

soft tissue atomic number

A

7.4

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12
Q

barium atomic number

A

56

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13
Q

iodine atomic number

A

53

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14
Q

gadolinium

A

a positive contrast agent used in MRI

atomic number of 64

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15
Q

barium sulfate

A

inert powder composed of crystals that are used for examination of digestive system

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16
Q

barium sulfate is combined with what to form barium sulfate

A

oxygen and sulfate

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17
Q

what is the chemical formula for barium sulfate

A

BaSO4

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18
Q

a mixture of barium sulfate and water forms a

A

colloidal suspension not a solution

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19
Q

Barium sulfate never dissolves in what

A

water

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20
Q

flocculation

A

when the powder has a tendency to clump and come out of its suspension when in the body

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21
Q

what is used to prevent flocculation

A

stabilizing agents

ex: sodium carbonate or sodium citrate

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22
Q

enternal

A

within, or by way of the intestine or gastrointestinal tract

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23
Q

intrathecal

A

introduced into or occurring in the space under the arachnoid membrane of the spinal cord of the brain
(into subarachnoid space)

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24
Q

contraindications of barium sulfate

A 
suspected perforation ( barium is not absorbed by body)
if barium enters peritoneal cavity may need to be surgically removed
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25
Q

when patients have a history of suspected perforation, what should be used instead of barium sulfate

A

a water soluble iodine contrast agent

AKA gastrografin gastroview hypaque

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26
Q

Adverse reactions of barium sulfate

A 
obstruction/constipation 
extravasation 
vaginal rupture
hypervolemia 
allergic reactions
sedated patients 
barium in appendix
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27
Q

obstruction/ constipation

A

pts. instructed to drink lots of water after barium sulfate
barium residue in the colon can dry and cause pt. to become constipated
bowel obstruction may occur if they don’t drink enough water

28
Q

extravasation

A

leakage from a vessel into the tissue
happens if barium leaks from the GI tract into abdominal cavity
can lead to peritonitis

29
Q

what patients are at risk for extravasation

A

pts. with diverticulitis or ulcerative colitis

30
Q

vaginal rupture

A

rare complication
due to misplacement of catheter before lower GI exams.
female pts. should be asked if they can feel the tip in their rectum.

31
Q

hypervolemia

A

blood disorder consisting of an increase in the volume of circulating blood
happens when water from the BE is shifted from colon into the circulatory system

32
Q

what is added to barium sulfate to reduce the possibility of hypervolemia

A

table salt

33
Q

allergic reactions

A

due to preservatives in the barium sulfate or latex in the BE catheter

34
Q

sedated pts.

A

can cause aspiration because they are not conscious

35
Q

barium in appendix

A

no directly related complications have resulted from this

36
Q

iodinated contrast media are available as :

A
  1. oil based

2. water soluble

37
Q

T or F

oil based contrast media is relatively limited in radiography

A

TRUE

38
Q

what are oil based contrast media still possibly used for today?

A

lymphangiograms and bronchograms

39
Q

oil based contrast media are not miscible with blood, therefore…..

A

should never be injected intravenously or interarterially

40
Q

the fatty acid base of oil based contrast media are responsible for….

A

making the solution viscous and insoluble in water

41
Q

T or F

oil based contrast media needs to be stored in a cool dark area

A

True

42
Q

plastic syringes should not be used for injection of oil based contrast because

A

toxic substances from the plastic can dissolve into the media

43
Q

MAIN disadvantage of oil based contrast media

A

they persist in the body because they are insoluble in water

44
Q

adverse reactions of oil based contrast media

A 
anaphylactoid (allergic like) reaction 
anaphylactic shock 
pooling of blood 
can cause shock, respiratory failure, death 
the more abrupt, the more severe
45
Q

the most common cause of anaphylaxis are

A

medications, iodinated contrast agents, and insect venoms

46
Q

water soluble contrast media

A

low toxicity

generally absorbed by the body and excreted wihtin 24 hours

47
Q

2 types of water soluble contrast

A
  1. ionic iodinated contrast media

2. nonionic iodinated contrast media

48
Q

ionic iodine contrast media

A

dissociate into 2 molecular particles in water or blood plasma
one has a negative charge and the other a positive charge

49
Q

ionic iodine contrast media molecule

ANION PART

A

starts with six carbon bonded hexagon called a benzene ring
every other carbon site has an iodine atom which makes it triiodinated
of the 3 remaining carbon sites, one has a negatively charged acid group
the other 2 carbon sites are R2 and R3

50
Q

purpose of R2 and R3

A

increase the solubility or excretion rate of the contrast by the body

51
Q

ionic iodine contrast media molecule

CATION PART

A

salts
once injected, the cation separtaes from the anion and creates 2 separate ions in teh blood
the separtaion creates an increase in the blood plasma

52
Q

osmolality

A

refers to the concentration or number of particles in the solution per kilogram of water and is directly related to the occurrence of adverse reactions

53
Q

nonionic contrast media =

A

low osmolality

54
Q

ionic contrast media =

A

high osmolality

55
Q

True or False

ionic contrast agent may increase probability of a contrast media reaction

A

True

56
Q

osmolality of blood plasma

A

300 osmol/kg

57
Q

on average ionic iodinated contrast agents range from

A

1000 to 2400 osmol/kg

way higher than blood plasma

58
Q

osmolality of nonionic iodinated contrast agents is around

A

750 osmol/kg

much closer to blood plasma

59
Q

nonionic iodinated contrast media

A

developed to reduce the side effects of the ionic iodinated contrast media
these molecules do not separate in the solution

60
Q

nonionic iodinated contrast media molecule

A

tri iodinated benzene ring
does NOT carry an acid group
hydroxyl groups surround the benzene rings (increase the solubility of the media in blood plasma)

61
Q

T or F

warming contrast media reduces viscosity making it thin

A

TRUE

62
Q

allergic like effects of water soluble iodinated contrast media

A

urticaria (hives)
wheeing and edema
bronchospasm
nausea/ vommiting

63
Q

renal effects of water soluble iodinated contrast media

A

increased secretion of urine with dehydration

diminished blood supply to the kidneys

64
Q

T or F

patients with elevated blood levels have a greater chance of experiencing an adverse contrast media

A

TRUE

65
Q

normal cratinine levels for the adult are

A

0.6 to 1.5 mg/dl

66
Q

BUN levels for an adult should range between

A

8 to 25 mg/100 mL

Positioning Spring 2015 (6 decks)

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