Lecture 2: Contrast Administration & Venipuncture Flashcards
What is one thing that a patient should be told prior to the administration of contrast?
Possible adverse reactions
Are contrast agents drugs? Why?
Yes:
1. they can be absorbed into systemic circulation and
2. they may produce a physiologic response in the body
Why do we use contrast agents?
- To visualize areas of the body where the organ or system of interest looks like the surrounding area (homogenous).
- Temporarily increase subject contrast.
True or false?
Positive contrast agents decrease density.
False. Adds density.
What are some examples of positive contrast agents?
- Barium sulfate,
- Gastrografin,
- Iodinated intravenous contrast media.
Do positive contrast agents appear white or black on an image?
Appear white due to their high atomic number
What is the chemical formula and atomic number of barium?
-BaSO4
-Z of Ba = 56
What type of solution is barium?
A suspension (Inert compound).
What is the common contrast agent used in imaging of the GI system?
Barium sulfate
What is flocculation?
Stomach acid can cause clumping, causing it to come out of suspension
What stabilizing agents are added to prevent flocculation?
Sodium carbonate or sodium citrate added to prevent flocculation.
What is the reason we use gas barium?
Expansion of the stomach and other structures
What side is the patient lying on?
Right side
Label 1-4
- Enema tip
- Enema tube
- Enema resevoir bag
- Ballon with inflator
When is Barium sulfate contrast media contraindicated?
- If perforation of the digestive tract is suspected.
- If patient is sedated
True or false?
Barium is absorbed by the body.
False; not absorbed
What happens if contrast enters the peritoneal cavity?
It would require to be surgically removed
What would happen if barium in the peritoneal cavity was not removed?
If not removed, it can result in barium peritonitis which is highly fatal.
If perferiation of the bowel suspected, what contrast agent should you use?
A water-soluble iodinated contrast (gastrographin)
If barium is seen in the trachea, should we continue with the study?
No
True or false?
If barium enters the vaginal canal, it will go into the peritoneum.
True
What is the issue with this patient?
Contrast in the peritoneal cavity
What is Vaginal rupture a result of?
Due to incorrect placement of the enema tube/catheter.
How does barium enter the peritoneum throught the vaginal canal?
Through the fallopian tubes
What should you do if a patient in need of rectal contrast has hemmaroids/complains of hemaroids?
Do not insert an enema/catheter and seek radiologists adivce
Why is age a factor that contributes to the risks of bowel perforation during adminstration of contrast?
Increased risk of perforation due to loss of tissue tone.
What other factors contribute to the risks of bowel perforation?
Diverticulitis, ulcerative colitis, long term steroid therapy and recent onset of constipation or diarrhea
What is one complication that a patient can have if they dont have enough fluids after contrast administration?
Obstruction in the bowels due to the barium becoming dry; this can lead to perforation.
Precautions with barium sulfate contrast
What is hypervolemia? What can this result in?
-Water absorption from the colon may result in excess fluid entering the circulatory system. Causes an increase in blood volume.
-Can result in pulmonary edema, seizures, coma and death.
What is one symptom of hypervolemia?
Drowsiness
Why should sedated patients should not undergo upper GI exams?
The swallowing reflex is diminished, greatly increasing the risk of aspiration (inhalation) of barium sulfate suspension with resultant barium pneumonia
What are Barium sulfate allergic reactions attributed to?
May be attributed to preservatives in the barium sulfate preparation or by latex used in barium enema retention catheters.
What are the 5 most common proceedures for which barium sulfate suspensions are used?
- Esophagus
- Stomach; upper GI series
- Small intestine; small bowel series
- Large intestine; barium enema
- GI exams (CT)
What common proceedures (Esophagus, Stomach; upper GI series, Small intestine; small bowel series, Large intestine; barium enema, GI exams (CT)) can be administered orally?
- Esophagus,
- Stomach; upper GI series,
- Small intestine; small bowel series,
- GI exams (CT)
What common proceedures (Esophagus, Stomach; upper GI series, Small intestine; small bowel series, Large intestine; barium enema, GI exams (CT)) can be administered rectally?
- Large intestine; barium enema,
- GI exams (CT))
What is intravascular radiopaque contrast primarily used for?
Used to add density to vasculature
What is Osmolality?
Is a measure of the total number of particles in solutvion per kilogram of solvent
Unit of solute concentration.
What does the osmolality of a solution control in the patients body?
Determines osmotic pressure, which controls the movement of water in the body.
True or false
Fluid moves from high areas of concentration to low areas of concentration?
Fluid moves from low areas of concentration to high areas of concentration
What are the 2 general types of contrast?
- Ionic
- Non-ionic
Do ionic contrast medias dissociate in a suspension?
Yes
Do non-ionic contrast medias dissociate in a suspension?
No
What does it mean if a solution is HOCM?
Fluid goes into the area of injected contrast (veins, arteries
What type of contrast is HOCM?
Ionic
What type of contrast is LOCM?
Non-ionic
What does it mean if a contrast agent is LOCM?
LOCM; fluid goes out from the area of injected contrast
What type of contrast agent is ussually related to allergic reactions?
Ionic
What does it mean if a contrast agent is Isomolar?
No movement of fluid
True or false?
Water Soluble Iodinated Contrast Media tend to have high viscosity.
True
What is the viscosity of a contrast agent influenced by?
Influenced by concentration of the molecule.
How are water Soluble Iodinated Contrast Medias warmed and why are they warmed?
Warmed through a contrast warmer to reduce viscosity and facilitate rapid injection
What are the expected side effects must be explained to the patient prior to Intravenous Contrast Media?
- Feeling of warmth and flushing
- Metallic taste in mouth
- Nausea and/or vomiting
- Headache
- Sensation of urination
What are the three possible types of allergic reactions that are possible with intervenous contrast media?
- Mild
- Moderate
- Severe
What is an example of a mild allergic reaction to intervenous contrast media?
-Urticaria (Hives)
If a patient that needs contrast adminstration has a history of mild allergic reaction to contrast, what should be done?
Premedication with steroids and antihistamine
What are examples of a severe allergic reaction to contrast?
- Dyspnea related to laryngeal edema
- Seizure
- Cardiac arrest
If a patient that needs contrast adminstration has a history of severe allergic reaction to contrast, what should be done?
Do NOT preform the exam. Contact radiologist.
What are examples of a moderate allergic reaction to contrast?
Tachycardia/Bradycardia, Hypertension/Hypotension, Dyspnea, Bronchospasm/wheezing
What is a Vasovagal Response?
Reaction to the procedure itself.
Patient may be experiencing high anxiety concerning the procedures and/or results that cause symptoms simular to allergic reactions
How can we eliminate patients anxiety and prevent the vasovagal response?
-Therapeutic communication techniques;
a. Explain proceedure
b. Explain usual side effects
c. Allow patient to express feelings
d. Ensure patient has understanding about the purpose of exam
What are the clinical manifestations of a vasovagal reaction?
- Pallor (pale skin)
- Cold sweats
- Rapid pulse
- Syncope or complaint of feeling faint
- Bradycardia
- Hypotension
If a patient has a vasovagal resoponse, what should you do?
-Give the person a snack
-Trandelenberg position
What are the Renal Effects of Intravenous Contrast Media?
Contrast Induced Nephropathy (CIN)
What is Contrast Induced Nephropathy (CIN)?
A transient and reversible form of acute renal failure.
Still VERY bad
When can Contrast Induced Nephropathy (CIN) occur?
If a patient who has kidney issues is given contrast
What patients are especially susceptible due to pre-existing impaired/lower kidney function?
Diabetics, patients with renal disease, elderly patients (>70) and patients with a solitary kidney
If a patient has Low egfr+high Cr+Increased blood urea nitrogen (BUN) what does that mean?
Poor kidney function
If a patient has an estimated glomerular filtration rate (eGFR) <30 egfr, can contrast be administered?
No
If a patient has >40 eG, can contrast be administered?
Yes
If a patient has 30 < eGFR < 40, can contrast be administered?
Contrast with hydration; risks explained to patient by radiologist; written consent obtained.
What is N-acetylcysteine used for?
-Can prevent impairment of kidney function. (additive)
-May be used in patients with high risk of renal failure if contrast is essential for scan.
What is the exception to the administration of contrast when a patient fails a egfr test?
Dialysis occuring 24 hours after contrast administration
What drug interacts with contrast?
Melformin
What type of contrast interacts with melformin?
Non iodinated contrast agents
What is lactic acidosis?
A lethal condition from a decrease in blood pH as a result of non iodinated contrast given to a patient taking melformin
What does melformin do, and why is it harmful for a patient taking it to be administered contrast?
-Metformin causes increase glucose uptake by cells.
-By-product of glucose metabolism is lactic acid, which can accumulate in the system in the event of impaired renal function.
Should melformin be discontinued prior to contrast administration?
Site dependant-generally 48 hours prior
True or false?
Negative contrast agents appear white
False; radiolucent
What are some examples of negative contrast agents?
E.g., Air/Carbon dioxide/Gas (or gas producing granules)
True or false?
Negative contrast agents have a low atomic number.
True
Are negative and positive contrast agents often used together?
Yes
What are the 4 syringe types used for Parenteral Drug Administration?
- Standard hypodermic syringe
- Insulin syringe
- Tuberculin syringe
- Prefilled syringe
True or false
Syringes can be prefilled.
True
True or false
Syringes can be reused.
False; disposed after use
What is an insulin syringe used for?
Insulin administration
What is a Tuberculin Syringe used for?
TB tests
What is the most common type of syringe that an MRT will be using?
Prefilled Syringe: Saline Flush
Where is the Tip of a syringe?
Where the needle attaches
Where is the Barrel on the syringe?
Where the calibration scales(ml) are printed and the part that holds the drug
Where is the Plunger on a syringe?
The part that fits inside the barrel and changes the pressure inside the barrel as it is pulled in or out
What are these?
Standard hypodermic syringes
What are the three parts of a needle? Describe each part:
- Hub: part that attaches to the syringe
- Cannula/Shaft: length of the metal part
- Bevel: slanted part at the tip of the needle
What material are needles made of?
Stainless steel
How are needles sized?
Sized according to length and gauge
What is the gauge (G) of a needle?
refers to the thickness or diameter of the needle.
What is the length of a needle refering to?
Refers to the measurement in inches of the shaft portion.
Which diameter is larger; a small gauge value or a large gauge value?
A small gauge value
True or false?
Shorter needles are used for intramuscular injections.
False; Shorter needles are used for subcutaneous injections
True or false?
Longer needles are used for intramuscular injections.
True
What determines gauge size used?
The viscosity of the fluid and speed of injection
True or false?
A larger gauge will have a faster rate of injection.
False; Larger gauge will have a slower rate of injections
True or false?
Lower gauge will allow you to have a higher rate of injection.
True
True or false?
The gauge stays in the patient after the needle is removed.
True
Which way should the bevel be facing before insertion into the patient?
Bevel facing up
What is the purpose of the bevel?
The bevel portion separates the tissue apart for the needle to easily pass through the tissue and penetrates the skin.
What colour is the 18 gauge needle in CT?
Green
What colour is the 20 guage needle in CT?
Pink
What colour is the 22 gauge in CT?
Blue
What is the needle hub attached to?
The needle and the plain tip
What is the Luer-Lock Syringe?
Locking device at tip of syringe that holds the needle firmly in place.
What is 2ml equal to in cc?
2cc (interchangable)
What are the methods to recapping needles?
- Needle scoop method
2.Needle Scoop Method (Variation)
What method is this?
Needle scoop method
What method is this?
Needle Scoop Method (Variation)
What are Blunt Fill Needles used for?
Drawing up medication;NEVER on a patient
If medication is to be injected through intravascular, subcutaneous or intradermal injection; what should the medication be stored in?
Ampule or a vial.
What is this?
An ampule
What is this?
A vile
Is an ampule single use or multi use?
Single use
The bag has 2 ports. What is each port for?
-Blue cap; For spiking IV line
-White port; for injecting medication
Medications that are of a large volume (50 – 1000ml) are packaged in what?
Heavy plastic or glass containers.
What are plastic/glass vials protected by?
Rubber stopper that is protected by a metal cap and a rubber diaphragm.
Watch Lab videos
“Videos for lab one”
How can contrast media be administered through IV?
- By bolus
- By infusion
What is an infusion?
Is a larger amount of drug, fluid, or fluid containing a drug that is administered over a longer period.
What is a bolus? (injected intravenously)
A bolus is a designated amount of a drug that is administered over a short period of time (contrast injector).
True or false?
Both a bolus and infusion require veinipuncture.
True
Why should the lower extremities be avoided with venipuncture?
- There is a greater hazard of embolus formation in the lower extremities related to IV infusion.
- Scanner is timed based on contrast return from upper extremities.
Why should the volar side of the wrist not be used for venipuncture?
Because the radial nerve in the area may cause the patient extreme pain.
Why is it better to select a larger vein for contrast administration as opposed to a smaller one?
There is a greater risk of extravasation in smaller veins
Label these 4 veins:
What is the Power Injection Flow Rate for a 22G needle
(exluding diffusics)
Up to 3cc/s
What is the Power Injection Flow Rate for a 20 G needle
(exluding diffusics)
3 – 4cc/s
What is the Power Injection Flow Rate for an 18 G needle?
(exluding diffusics)
5cc/s and up
What is the beneift of using Diffusics needles?
Allows a higher power injection flow rate for larger gauge needles (smaller diameter)
True or false?
Contrast agent is less likely to dehydrate an elderly patient.
False; Contrast agent is more likely to dehydrate an elderly patient.
What can be done to protect elderly patients during veinipuncture from any damage?
- Smaller needle may need to be used (if you are able to)
- Put turniquet over the clothing
True or false?
Extravasation of LOCM is better tolerated than that which occurs with HOCM.
True
How is Extravasation of Intravenous Contrast Media treated?
- Remove the needle and apply pressure to the site.
- Elevate the limb to reduce edema
- Place a warm compress to produce vasodilation and resorption of extravasated fluid and edema.
- Some time later, place a cold compress to produce vasoconstriction and reduce inflammation
What are common complications of contrast media extravasation?
- Skin ulceration
- Soft-tissue necrosis
- Compartment syndrome
Read up on visapaque
