Transcript What every Sonographer should know about Contrast Media

What every Sonographer
should know about Contrast
Media
Harry H. Holdorf PhD, MPA, RDMS (OB, Ab, BR), RT(ARRT-Ret.) AS(LRT)
The purpose of contrast media
The routes of contrast media
Categories and types of Contrast agents
Intra-Venous contrast chemistry
Non-Ionic contrast agents
Ionic contrast agents
Viscosity
Dosing
Common Radiopaque agents
IV Contrast Agent Extravasation
Allergy preparation: Special considerations
Adverse Reactions to iodinated contrast agents
Common responses to contrast agents
Mild adverse reactions
Moderate adverse reactions
Severe adverse reactions
Treating contrast agent reactions
Contraindications
Oral contrast
Contrast agents in Cardiology
Summary and conclusion
Purpose of Contrast Media
› To increase the difference in attenuation (radiation beam
absorption) between adjacent structures
› X-Ray attenuation is directly related to the atomic number of
the material in the path of the beam
– Allows the biological nature of the material to be identifiable to the
reading physician
– Allows the reading physician to distinguish between vessels, lymph
nodes, and other organs of the body from one another.
Common Contrast Media routes of delivery:
› Enteral: Administered through the Gastro-Intestinal Tract
– Includes the esophagus, stomach, small and large intestines
› Oral
› Gastric
› Rectal
Common Contrast Media routes of delivery:
› Parenteral: Administered into the body in a manner
other than the digestive tract
– Intravenous
› Directly administered into a vein
Categories of Contrast Agents
› Positive Contrast Agent
– Contrast agent appears more
radiopaque (white) than
surrounding tissues
– High atomic number
› Negative Contrast Agent
– Contrast agent appears more
radiolucent (dark) than
surrounding tissues
– Low atomic number
› Neutral
– Appears similar to
surrounding tissues
Positive Agents
• Barium Sulfite
• Water Soluble (iodinated)
Negative Agents
• Air
• Carbon Dioxide
• Administered orally in granular form or
rectally via insufflation
Neutral Agents
• Water
• VoLumen (Low density form of barium
sulfate
The Types of Contrast Agents: Positive
The Types of Contrast Agents: Negative
The types of Contrast Agents: Neutral
Intra-Venous (IV) Contrast
IV Contrast Agent Chemistry
› It is important to know the chemical properties of various
contrast agents to chose for the best patient outcome with
least risk of adverse side effects.
› Main Chemical Properties:
– Osmolality
› Measurement of the total number of particles in the contrast solution per
kilogram of water
› Direct measurement of the ionization of a solute in a solvent
– Viscosity
› Amount of friction generated by the concentration and size of contrast
molecules
– Dosing
› Amount of contrast administered to a patient
Non-Ionic Contrast Agents
› Low osmolality (particle) contrast media (LOCM)
› DOES NOT
– Increase the osmolality of the blood serum
– Change the osmotic pressure
› Sager for patients with compromised cardiac or renal status
– Advantages
› Less hemodynamic effect
› More water soluble (hydrophilic)
› Less likely to be reactive with cells
– Lower risk for allergic reactions
Ionic Contrast Agents
› High osmolality (particles) contrast media (HOCM)
› Increase water in blood which increases the total blood
volume
– Forces the heart to work harder in order to pump the increased
volume
– This phenomenon is referred to as INCREASED OSMOTIC PRESSSURE
and results in
› Hypervolemia-increased blood volume
› Blood vessel dilation
› Shock in severely dilated patients
– RENAL EFFECTS CAN BE SIGNIFICANT
› Expands kidney arteries which can cause:
– Release of vasoconstrictors which can constrict the renal arteries
› Diminishes blood supply to the kidneys
› Decreases renal function
› These types of contrast agents are utilized infrequently because of their
chemical properties and side effects.
Viscosity
› Amount of friction generated by concentration and size of
contrast molecules
› Higher the viscosity
– THICKER the agent. More difficult to inject
– Rapid injection can be more difficult with a more viscous agent
› Can trigger body’s pressure sensors, causing vasoconstriction and injection
therefore can be painful
– Important to heat the agent to body temperature before injection
› Reduces the viscosity
– Heating can be achieved through
› Contrast warmer
› Manually. Using tepid water
– Nonionic media is more viscous than ionic media at similar iodine
concentrations
Dosing
› It is critical to avoid overdosing iodine
› Iodine Toxicity can occur at levels greater than 80-90 grams
– Symptoms of iodine overdose include:
› Tremors
› Irritability
› Tachycardia
– If such symptoms occur
› STOP administration of medication immediately and initiate emergency action.
Common Radiopaque Agents
› Ominpaque (LOCM)
› Gastrografin
(HOCM)
› Hypaque (HOCM)
IV Contrast Agent Extravasation
› IV contrast agent extravasation is the accidental extra-vascular
injection of intravascular contrast media caused by:
– Dislodgment of the cannula
– Contrast leakage from the vessel puncture site
– Rupture of the vessel wall
› Most common complication of intravenous injections
– Occurs in less than 1% of patients
› Identifiable risk factors include:
– Non communicative patient
› Pediatrics and geriatrics
– Severely debilitated patients
– Multiple punctures of the same vein
– Injections performed on the dorsum of the hand and foot
Examples of Extravasation
IV Contrast Agent Extravasation
› Signs and symptoms of IV contrast agent extravasation
– Pain, tightness, or burning sensation at or near injection site
– Swelling at or near the injection sight
– Redness or discoloration at or near injection sight
› What to do in case of extravasation:
– Immediately stop the injection or infusion
– Remove the catheter from the injection site
› Treatment of IV contrast agent extravasation
– Elevation of affected extremity above the hart
– Alternating cold and hot packs
› 15-60 minute applications three times daily (day 1-3)
› Follow institution’s protocol and consult a physician
– Close observation for 2-4 hours
– Inform referring physician and radiologist
ALLERGY Preparation: Special Considerations
› Given to patients with a known contrast reaction history
– Reduces the risk of a severe adverse reaction
› Optimal Pre-Treatment Regimen
– Three 50mg doses of oral prednisone
› Taken 13, 7, and 1 hours prior to procedure
– Diphenhydramine 50mg dose
› Taken 1 hour prior to procedure
› Pre-Treatment regimen for Emergency Procedures:
– Methyprednisone (40mgIV) every 4 hours until procedure
– Diphenhydramine (50 mg IV) I hour prior to procedure
Adverse Reactions to Iodinated Contrast Media
› MOST reactions occur within 5 minutes of injections but may
occur as late as 24 hours post injection.
› ALWAYS have a crash cart and emergency drug box available
› Diagnostic Medical Sonographers must be CPR certified
› Anaphylactic reactions are believed to be caused by the
release of histamine in the body
– Released from certain cells in the lungs, stomach and lining of blood
vessels
Common Responses to Contrast Agents
SIGNS and SYMPTOMS
RESPONSES
Warmth or flush feeling
No treatment necessary
Metallic taste
Symptoms resolve rapidly
Nausea
If vomiting occurs:
Vomiting
Turn patient on their side to prevent
Coughing
aspiration
Mild Adverse Reactions to Contrast Agents
Signs/Symptoms
Responses
Mild urticarial (Hives)
Notify radiologist and physician
Coughing
Observe patient in the department
Dizziness
Nasal stuffiness
Shaking
Itching/pruritus
Moderate Adverse Reactions to Contrast Agents
Signs/Symptoms
Responses
Erythema
Notify radiologist or physician
Moderate or severe urticaria
Prepare to help administer antihistamine or
epinephrine if ordered
Bronchospasm
Prepare IV fluids and Oxygen if ordered
Wheezing
Severe Adverse Reactions to Contrast Agents
Signs/Symptoms
Responses
Respiratory or cardiac arrest
Maintain airway
Seizures
Call rapid response or code
Hypotensive
Treat for shock, respiratory or cardiac arrest as
symptoms require
Laryngeal or bronchial edema
Treating Contrast Agent Reactions
› Always notify the radiologist and nurse of any reaction
› Your Emergency Drug Box should contain the following:
–
–
–
–
–
–
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Epinephrine
Hydrocortisone
Atropine
Benadryl
Sodium Chloride (saline)
Lactated ringers
Oxygen
Contraindications to IV Contrast Agents
› Reversible renal failure
› Previous anaphylaxis reactions
› Pregnant patients
– Contrast DOES cross the placental barrier
› Multiple myeloma (cancer of the blood)
– Leads to acute renal failure
› Pheochromocytoma (adrenal tumor)
– Releases large amounts of adrenaline
› ALWAYS consult with a radiologist or physician before making
the decision to administer IV contrast
Oral contrast: Barium Sulfate
Oral contrast Agents: BARIUM SULFATE
Barium
–
–
–
–
–
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2% mixture
Suspended in water
Contraindicated if patient is suspected of:
colon/gastro-intestinal obstruction or perforation
Tracheoesophageal fistula
Obstructing lesions of the small intestine
Pyloric stenosis
Inflammation or neoplastic lesions of the rectum
Recent rectal biopsy or colonoscopy
Oral Contrast Agents-Water Soluble
› Gastrografin, Gastrovue, Ominpaque
– Water soluble, ionic, high osmolality contrast media
– Prescription drug intended to be therapeutically and biologically inert
when ingested/injected into the body for use in organ or tissue
enhancement.
– Particularly suited for times when a more viscous agent such as
barium sulfate (NOT water soluble) is not feasible or potentially
dangerous.
Other Factors to be Considered
› Patient care factors
› Take into account patient history, diagnosis, and contraindications
› Which contrast agent(s) are to be utilized for which procedures and
protocols and for which diagnosis
› Consent
› Venipuncture
› Documentation and labeling of contrast media
› Storage of contrast media
› Joint Commission guidelines for contrast media
Contrast Agents in Echocardiography
Microbubble contrast agents have been developed and are
introduced as a safe and effective echo-enhancer in present-day
clinical practice.
Contrast echocardiography has evolved rapidly in the last
decade, with major developments in both contrast media and
ultrasound equipment.
Understanding of the physical principles underlying the
interaction of ultrasound and microbubbles has enhanced our
ability to optimize the technique.
› Used predominantly for the detection of intra-cardiac shunts,
the wide usage of Contrast-Enhanced Ultrasound more
importantly resulted in routine use of contrast for left heart
opacification.
› CEU is also used for the assessment of left ventricular
function during stress echocardiography and when imaging is
suboptimal.
Summary and Conclusions
› Contrast agents help the radiologist’/cardiologist distinguish
between different structures and organs of the body
› Sonographers must be educated and mindful when either
using or observing the administration of contrast agents
› If utilized and administered properly, contrast agents present a
relatively low risk for patients
› Important and crucial to inform/educate patients about what
they are being administered, risks involved, and purpose
Further information…
› ACR manual on contrast media
› Contrast agent tutorial: Department of Radiology/University of
Wisconsin
› Radiologyinfo.org-patient safety
Project: Presentation
Contrast Enhanced Ultrasound
› How is contrast utilized in ultrasound, especially
Echocardiography?