quizzes- contrast media

Patient Information and Consent

The patient must be provided with sufficient

information to allow them to make an informed choice

of whether or not to accept the risks of proposed

iodinated contrast administration.

Patients should be thoroughly questioned prior to

having contrast administered and it must be

documented

Radiographic CM - two branches

1- positive, iodinated barium

2- negative, water, co2, air

negative compounds

appear less dense than the adjacent tissue

Properties of air or co2

risk of air or co2

water- neutral

risk for h2o

positive cm-

Positive Contrast Compounds appear

 denser than the

surrounding tissue

Barium Sulphate ( Ba SO4)

Barium Sulphate ( Ba SO4) PROS and CONS

small bowel- barium

To demonstrate the small bowel

including the D1, D2, D3,D4 and jejunum

the barium is used thinner 1-6 times from

the thin mix. Done to investigate or

diagnose malrotation, intussusception,

Crohns, Hirschsprung's

Large bowel Barium Enema –Single or double contrast

This examination has been largely replaced by CT

colonography and colonoscopy.

It is done to investigate or diagnose tumours,

inflammatory disease, diverticular disease, polyps.

procedure

• 1-2 litres of dilute barium (1-3 times) is introduced via a rectal

catheter. Into the large bowel. This usually has a balloon ( similar to a

urinary catheter) to prevent the catheter coming out of the rectum

• The images are performed in the lateral position initially and then AP ,

decubitus AP , and obliques with the object tot “straighten out” even

section of the large bowel from the rectum to the ileo-caecal valve.

• Air is often introduced to distend the gut

• Post evacuation imaging may be included. to help demonstrate small

mural lesions.

iodine

Most of the world's industrial

iodine is obtained from brines

(water strongly saturated in salt)

associated with wells in & USA

Japan and from caliche ore

mined in Chile.

 Discovered in the early 1820’s

 Used in imaging since the 1920’s

 It is the same mineral that is in

iodised salt

non ionic vs ionic

monomer vs dimer

osmolality

Your body has an osmolarity or 290

 Your whole system is regulated to stay this way

 If you have too much water you need to also

have salt to allow balance

 If you are given a high osmolar compound like

CM you body needs water to balance it.

 This fluid comes from your soft tissues and the

kidneys and heart are then required to move

this fluid to return you body to its normal

electrolyte balance

 This is fine balance of sodium potassium, water,

vasopressin hormones

low osmolar compounds

 Gastrografin

- Ioscan

- Urografin

used for sbo oral

medium osmolar compounds

omnipaque

optiray

ultravist

isovie

Can be used for most radiographic imaging including vascular

use, intrathecal, CT scanning, gut imaging

Known to produce moderate osmolar effects such as heat, pain,

taste, sensation of peeing, vagueness, headache, watery eyes,

sneezing and hives.

Higher concentrations have higher osmolarity ( higher iodine

content). But lower concentration have lower osmolarity .

Should not be given to patients who have history of

-allergic reactions to Iodine

-Renal disease without consideration

- Elevated thyroid function hormones

iso osmolar compounds

visipaque

Should not be given to patients who have history of -

allergic reactions to Iodine

-Renal disease without consideration

- Elevated thyroid function hormones

ionic status

If there are short chains of O N H then the

compound is not that stable-

 It can disassociate and the free cations and

anions are attracted to other free +ions and –

ions in the body and make a new compound .

 This newly compounds may be even more

toxic and produce unknown compounds and

side effects

 SO ONLY USE THEM WHEN THIS HAS BEEN

CONSIDERE

A Hyper osmolar compound will

adsorb fluid from the surrounding

structures

This fluid shift in the body causes cardiac

arrythmia, changes in blood pressure, which

leads to fainting.

 The higher the concentration of iodine in the

compound, the higher the osmolarity ,

 A high osmolar product contributes to the

taste, heat sensation , vomiting and the

peeing sensation, vagueness, lacrymisation.,

muscle twitching

Osmolarity ( Osmolality)100

SO ONLY USE A HIGH OSMOLAR

PRODUCT IF THERE IS NO

ALTERNATIVE

When to use High osmolar CM

 Diluted as a bowel labeller( 3-5%)

 As a diagnostic and /or

therapeutic agent for Small bowel

obstructions ( e.g. faecal loading,

shocked gut, adhesive bowel

obstruction

 100mls of 76% maximum dosage

 100mls of Gastrografin $25, 100mls

of Omnipaque,

(Ultravist, Optiray or similar $12)

Which concentration – 180, 240, 300, 350

375

You need to be able to see the CM on the image

 A higher number of gram per mls makes it denser

 But it is also higher in osmolarity

 it is more vicious

 A 240 is preferred for children and neonates while 350 is

normal for adults

 ICM can be diluted

Storage

ICM should be stored in its original packing on

a shelf away from radiation.

 It MUST be used before its expiry date

 It should be checked for crystals or clarity

before injecting

 IA CM warmer is NOT a store cupboard and the

stock should be rotated and not kept warm for

more than 28 days

 The temperature should be monitored. CM

should not be kept above its recommended

temperature.

Risks for any iodine and gadolinium

Previous allergic reaction

2. Allergic history- asthma, hay fever, etc

3. Poor renal function ( dialysis, renal trauma, stones, infections)

4. Vasculopathy

5. Diabetes type 1 & 2

6. Drug interaction

7. Pregnancy

8. Medical History

Renal Function

 Iodinated CM is excreted

though the urine

 It is filtered by the nephrons

 The glomerulus and via the

Bowmans capsule and

collecting system to the

urinary bladd

Renal

Function

and

checking

 It is measured as eGFR- estimated glomerular

function from a POC blood check

 Renal function over 60 is normal

 >45 is considered low

 And <15 is renal failure

 It is affected by trauma, vasculopathy (

history of stroke, HT, vascular disease, renal

cysts, single kidney, infections)

 Old age may not be a good determinate of

renal function

Renal

impairment tests

(estimated Glomerular

Function

rate

the eGFR takes into account your age, your

sex and your ethnic background. It is what we

call a normalized test. It measures how well

your kidneys are working.

 Serum creatinine level

 not normally raised until GFR ↓ by 50%

Renal

Excretion

Contraindications /risk factor- Thyroid

• Patients who have an over active

thyroid gland should not be given

ICM. It can produce an array of side

effects that can be life threatening. (

MNG, Graves disease)

• An Under active thyroid is not a

concern

• ICM may make thyroid function testing

less accurate for up to 6 months.

The allergic response

Allergic reactions, are linked to an antibody produced by the

body called immunoglobulin E (IgE).

Each IgE antibody can be very specific..

When a susceptible person is exposed to an allergen, the body

starts producing a large quantity of similar IgE antibodies. The

next exposure to the same allergen may result in an allergic

reaction.

Symptoms of an allergic reaction will vary depending on the type

and amount of allergen encountered and the manner in which

the body's immune system reacts to that allergen.

Recognising an allergic reaction

Lie the person flat> administer

adrenaline, oxygen> call help line

Sneezing, Tingling of lips, Swelling of face,

lips, eyes , Hives, Abdominal pian vomiting,

Pale, floppy , difficulty in breathing or

talking, tightness of throat , collapse

Treatment of Allergic reactions

Oxygen- this will improve blood

oxygenation

Adrenaline ( epinephrine- to support

the heart and respiratory system-

given IM, IV)

Antihistamine-( Phenergan IV- takes 10-15 minutes to work

Steroid – also slow acting – 15-30 minutes to reduce

swelling

Bronchodilators- may help wheeze later

Contraindications /risk factor-

Other medications

Metformin- a support drug to stabilise diabetic patients

and their blood sugars. If patients have poor renal

function and are on Metformin , then ICM should not

be given ( this applies to Gadolinium also)

• Beta Blockers- as these slow the heart rate, they may

affect the use of adrenaline during a cardiac crisis

• Some chemo therapy drugs- these drugs may interact

with CM

Concerns that may be raised-

these are not contraindications

1. Breast feeding

• There is no evidence that any iodine crosses into the breast milk,

but if concerns are raised then 24 hours is considered a sufficient

time to excrete the majority of the CM

2. Multiple injection of ICM

• There is some evidence that multiple injections of ICM may

produce a reduction in RF. But this may be reduced with

sufficient hydration and renal function surveillance.

3. Pregnancy

• ICM is considered safe for the a pregnant patient.

CVC line patency –

PICCS, PORTS

They can get blocked with a

substance called fibrin which is like a

clot.

• These prevent the line being patent

or sometimes false blockage

• Or the line can get damaged and

break.

• A small amount of IV contrast is

injected into the line an images

taken in fluoroscopy at 15 frames

/sec to see blood flow