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2280: CT > Week 2: Patient Prep and Contrast Agents > Flashcards

Week 2: Patient Prep and Contrast Agents Flashcards

1
Q

Why are laboratory values important

A

if patient is candidate for iodinated contrast

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2
Q

What laboratory values show info about patients kidney functions?

A

serum creatinine, BUN, eGFR

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3
Q

Normal range of Serum Creatinine

A

Canada: 50-90 umol/L for female
70-120 for male
American- 0.6-1.7 mg/dl

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4
Q

Normal Range of BUN

A

7-25 mg/dL

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5
Q

Normal Range of eGFR

A

above 60ml/min/1.73m

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6
Q

What goes eGRF measure

A

how much blood passes through kidneys per minute

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7
Q

What provied information about bloods coagulation ability

A

Prothrombin PT
Partial Thromboplastin time PTT
Platelet Count

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8
Q

Typical Range of PT

A

11-14 seconds

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9
Q

Typical Range of PTT

A

25-35 seconds

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10
Q

Typical Platete Count

A

150,00- 400,000 platekets per mm3

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11
Q

What blood thinners should we pay attention to

A

Warfarin, Coumadin, Heparin, Plavix, aspirin

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12
Q

Normal range of oral temperature

A

36.0 - 38.0 C

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12
Q

Average adult pulse

A

60-100 bpm

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13
Q

Average childs pulse

A

95-110 bpm

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14
Q

Average infants pulse

A

100-160 bpm

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15
Q

Adult normal respiration rate

A

14-20

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16
Q

adolescent youth normal respiration rate

A

18-22

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16
Q

a child’s normal respiration rate

A

22-28

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17
Q

Infancts normal respiration rate

A

30 or greater

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18
Q

Healthy adults BP range

A

120/80 mmHG

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19
Q

Why are iodinated Contrast agents good

A

-safe
-water solvable
-easy to administer
-easily distributed/ eliminated by body

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20
Q

Why do IV agents show large attenuation difference between structures

A

-different tissues enhance differently
-shows different in normal vs abnormal tissue

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21
Q

What is Osmolality

A

-number of particles in solution per unit liquid as compared with blood
-major factor in non-allergic reactions

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22
Q

High-osmolality compared to blood (HOCM)

A

7 time blood osmolaity

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23
Q

Isomolar agents compared to blood (IOCM)

A

same compared to blood (290 most/Kg H20

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23
Q

Low-osmolality compared to blood (LOCM)

A

2 times compared to blood

24
Q

What affects viscosity

A

-brand
-temperature
-concentration of CM

24
Q

What is viscosity

A

thickness or friction of luid as it flows

25
Q

What does viscosity affect when injection

A

injectability of CM through small-bore IV catheters/needles

26
Q

Ionic agents contain

A

molecules that will form ions in solutions

27
Q

Non-ionic agents contain

A

molecueles that dont disassociate

28
Q

How are iodinated agents cleared from the body

A

not metabolized but excreted almost fully by kidneys

28
Q

How long does it take for iodinated agents to clear

A

half life in patients 2 hours (eject 50%)

29
Q

Side Effect Symptoms and Signs

A
  • Warmth
  • Feeling of urination
  • Funny taste (metallic)
  • Few hives
  • Minor itchiness
  • Oral contrast may cause diarrhea
30
Q

How is CM dose determined

A

by iodine concentration and volume delivered

31
Q

Adverse Reaction Symptoms and Signs

A
  • Major hives
  • Breathing problems
  • Swelling of face, throat or tongue
  • LOC (loss of consciousness)
32
Q

Chemotoxic reactions

A

Result from the physiochemical properties of CM, dose & speed of injection

33
Q

Idiosyncratic reactions

A
  • All other reactions, largely unpredictable
  • often within an hour
  • mimic allergic reactions but are rarely because of an allergy
34
Q

Mild idiosyncratic reaction

A

short duration and self limiting

35
Q

Moderate idiosyncratic reaction

A

no immediately life threatening but an progress to

36
Q

Severe idiosyncratic reaction

A

potentially or immediately life threatening

36
Q

What can renal function be estimated using

A

-glomerular filtration rate GFR
-Effective renal Plasma flow ERPF
-Serum Creatine SeCR as index of GFR : fast and inexpensive
-estimated glomerular filtration rate (eGFR): gaining more attention, potentially better marker of CIN risk
- SeCR and eGFR most commonly used

37
Q

What are risk factors for idiosyncratic reaction

A

-previous CM reaction
-asthma
- history of allergies to food/drugs
- NOT risk factor: seafood allergy

38
Q

Renal failure

A

The inability of the kidneys to maintain homeostasis, resulting in the
accumulation of nitrogenous wastes

39
Q

Renal insufficiency

A

Renal function is abnormal but capable of sustaining essential bodily
functions

40
Q

Nephropathy

A
  • any condition or disease affecting the kidneys
  • sometimes used synonymously with renal impairment
41
Q

Contrast Induced Nephropathy (CIN)

A
  • IV contrast media that affects kidney function
  • Progressive rise in SeCr within 24 hrs & typically nonoliguric (high urine output)
  • CM can result in significant nephrotoxic effects in high-risk patients for nephropathy.
42
Q

Postcontrast acute kidney injury (PC-AKI)

A

an acute impairment of renal function that occurs within 48 hours of intravascular administration of contrast material.

43
Q

What are CIN risk factors

A

-eGfr less than 30
-history of DM and recent IV CM
-Large volume of CM
-History of congestive heart failure

43
Q

How to prevent CIN

A

-identify patients at high risk
-use LCOM or IOCM
-ensure patient hydration
-minimize CM volume
-allow 48 between CM procedures
-discontinue nephrotoxic medication before procedure

44
Q

Metformin Therapy

A

-CM can result in CIN, patient taking metformin who go into renal dysfunction can have an accumulation of lactic acidosis
- if eGFR less than 60 metformin should be temporarily discontinued after CM and can be resumed after 48 hours

45
Q

Can a patient on dialysis receive CM?

A
  • If dialysis is temporarily DO NOT give CM to patient
  • if the patient is on end-stage renal failure CM can be given and can continue their routine dialysis schedule
46
Q

CM effect on thyroid function

A
  • normal thyroid = no effect
  • hypothyroidism = insignificant effect
  • hyperthyroidism = CM may precipitate thyroid storm (thyroid hormone reaches dangerously high level, life threatening)
47
Q

What pulmonary effects can CM cause

A

-bronchospasm
-pulmonary arterial hypertension
-pulmonary edema
- to reduce risk use LOCM

48
Q

Patients at an increased risk for pulmonary effects have a history of

A

-pulmonary hypertension
-bronchial asthma
-heart failure

49
Q

What affect does CM have on the CNS

A
  • can provoke seizures in patients who have disease that disrupts blood-brain barrier
  • control or reduce risk of seizure by administering 5-10 mg of diazepam 30 minutes before CM
50
Q

Delayed Reactions to CM

A
  • reactions that occur 1hr to 1 week after CM
  • skin reactions primarily (red spots, hives, welts or bumps)
  • salivary glad swelling possible (more common in patients who have under gone chemotherapy)
50
Q

Gastrointestinal CM

A
  • help to distinguish loops of bowel from cyst, abscess, or neoplasm
  • oral CM: used for most abdomen and pelvis CT (use Ba-sulfate or more commonly iodinated water-soluble solution)
  • Rectal CM: useful for some indications. includes air, Ba-sulfate or 1-3% iodinated water-soluble solution
51
Q

Barium Sulfate Solutions

A
  • DO NOT use if bowel perforation suspected because that could lead to peritonitis and risk of death
    -Most commonly used are positive agents that contain a 1% to 3% barium sulfate suspension (BaSO4) formulated to resist settling
  • in general the higher the dose the better the bowel pacification (typically used minimum of 500 mL diluted barium sulfate given 45 min-2hrs before exam)(additional 200mL can be given just before scanning the stomach and the small bowel)
52
Q

low HU oral contrast

A
  • resembles water on image
  • o.1% brim sulfate solution
  • measures 15-30 HU
  • advantages: improved bowel distention (compared to water), faster transit than standard CM barium, more effective visualization of both bowel wall and mucosa
53
Q

Iodinated Agents for Oral Administration

A
  • HOCM and LOCM: positive agents, can be diluted and administered orally. stimulate peristalsis and cause diarrhea
  • 2-5% solution normally used, 1000-1500 mL over 1-3 hrs immediately before scan to descend stomach and small intestine
54
Q

Water as CM

A
  • Sometimes used in place of a positive agent
  • It does not obscure mucosal surface
  • Transits rapidly
  • Distends the bowel poorly
55
Q

Air and Carbon Dioxide as CM

A
  • Produces very high negative contrast
  • Administered rectally
  • Particularly useful in CT colonography/ Virtual colonoscopy
  • Both room air and CO2 provide reliable colonic distention (CO2 is better tolerated by most patients)
55
Q

Intrathecal CM

A

iodinated contrast agents injected into the intrathecal
space surrounding the spinal cord

2280: CT (13 decks)

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