Contrast Agents

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Contrast Agents

• James H. Corley, MS, RPh, BCNP
• Associate Professor
• Medical College of Georgia
• jcorley_at_mail.mcg.edu

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Contrast Agents

• Compounds used to improve the visibility of
  internal bodily structures in an image.
• Types
• Radiographic agents based on iodine
• ionic or non-ionic agents
• Monomer or Dimer
• high osmolar, low osmolar, iso osmolar

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Commonly used iodinated contrast agents
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Ionic Contrast Agents

• gt 10 million diagnostic procedures / year
• Conventional ionic contrast reactions - 10
• 1 in 1000 severe
• Contrast Myths
• not caused by iodine
• not related to shellfish
• not true allergy (no drug-antibody)
• mechanism remains unknown

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Anaphylactoid (idiosyncratic)

• unpredictable
• dose independent
• prevalence 1-2 (0.04 - 0.22 severe)
• fatal 1 in 75,000

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Chemotoxic

• predictable
• dose dependent
• due to osmolality or ionic composition
• Nonionic vs Ionic
• Contrast reactions decreased 5 fold
• Fatalities unchanged

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Risk Factors

• Previous contrast reaction either moderate or
  severe
• asthma
• allergy history requiring medical treatment
• pretesting poor predictor of reaction
• Repeat Reactions, ionic
• bronchospasm 40 to facial edema 70
• decrease to 6 - 9 with pretreatment
• decrease to 0.6 with pretreatment and switch to
  nonionic

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Late Reactions

• 1 hr to 1 week following contrast injection
• Headache, myalgias, fever, skin reactions
• Risk Factors
• Previous contrast reaction
• Interleukin-2 treatment
• usually self-limited, treat severe reactions with
  steroids

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Severity of Reactions - Minor

• Nausea vomiting
• Urticaria
• Pruritis
• Diaphoresis

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Severity of Reactions - Moderate

• Faintness
• Facial edema
• Laryngeal edema
• Bronchospasm

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Severity of Reactions - Severe

• Pulmonary edema
• Respiratory arrest
• Cardiac arrest
• Seizures

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Renal Toxicity (increased serum creatinine by
more than 25 or gt 0.5 mg)

• 2-7
• Risk Factors
• 5 - 10 fold increase with pre-existing renal
  insufficiency (increased creatinine)
• Dehydration
• CHF
• Age gt 70
• Taking nephrotoxic drugs (nonsteroidal
  inflammatory agents, gentomycin etc.)

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Renal Toxicity (increased serum creatinine by
more than 25 or gt 0.5 mg)

• direct relationship between serum creatinine and
  likelihood nephrotoxicity
• Hydrate 100 ml/hr Normal saline 4 hrs prior to
  procedure, continue for 24 hours
• Those on hemodialysis do not need extra sessions
  or dialysis immediately following contrast
  administration

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Metformin (Glucophage)

• oral diabetic agent
• patients with renal insufficiency may develop
  lactic acidosis
• withhold drug for 48 hrs after contrast
  administration in all patients taking this drug

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Screening Creatinine

• Which patients need screening creatinine?Consider
  if patient has one of the following risk
  factors
• Known renal insufficiency
• Diabetes mellitus
• Lasix or nephrotoxic drugs
• Solitary kidney

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Treatment Contrast Reactions

• Nausea Vomiting
• usually self-limited
• protracted Prochlorperazine (Compazine) 5-10 mg
  IM
• Urticaria
• Diphenhydramine (Benadryl) 25 - 50 mg IM,
  caution drowsiness
• add Cimetidine (Tagamet) 300 mg in 20 ml, IV
  slowly

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Treatment Contrast Reactions

• Hypotension
• Bradycardia (Vasovagal)
• elevate legs (infuses 700 ml)
• IV fluid (normal saline)
• O2 3 L/min
• atropine 0.6 mg IV push, repeat up to 3 mg total
• Tachycardia
• elevate legs
• IV fluid (normal saline) may require gt 1 Liter
• O2 3 L/min

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Treatment Contrast Reactions

• Bronchospasm or laryngeal edema
• O2 3 L/min
• Epinephrine 11000 (0.1 - 0.2 ml subq) or
  110,000 1 ml IV over 3 min
• Beta 2 agonist 2 -3 puffs
• albuterol (Proventyl)
• metaproterenol (Alupent)
• terbutaline (Brethaine)

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Treatment Contrast Reactions

• Anaphylactoid
• O2 3 L/min
• IV normal saline
• Epinephrine
• Benadryl 25 - 50 mg IV
• Tagamet 300 mg in 20 ml IV slowly
• Solu-medrol 1 gm IV
• Note if patient taking beta blocker
• glucagon 1 - 5 mg IV bolus followed by infusion
  5-15 ug/min or
• isoproternol 15000 (0.2 mg/ml)
• IV 0.5 - 1.0 ml diluted in 10 ml
• 1 mg increments

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Treatment Contrast Reactions

• Seizures
• protect airway
• Diazepam (valium) 5 mg IV slowly
• Suspected pheochromocytoma
• phentolamine (Regitine) 5.0 ml (5 mg) IV bolus
• Pregnancy
• Discard breast milk for 24 hours following
  contrast administration

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Extravasation

• Elevate extremity
• Ice pack 3x day
• Observe for 2-4 hours if volume gt 5ml

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Extravasation

• Plastic Surgery Consultation
• ionic gt 30 ml
• nonionic gt 100 ml
• skin blistering/significant tissue damage
• altered tissue perfusion
• increasing pain after 2-4 hours
• change in sensation distal to site of
  extravasation

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Pretreatment Protocols

• Reduces minor reactions
• Benadryl 50 mg IM or PO 1 hr before procedure
• Prednisone 50 mg PO 13, 7, 1 hr before procedure
• Observe patient at least 30 minutes following
  injection

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Pretreatment Protocols

• Reduction of Nephrotoxicity
• Creatinine level gt 2 mg/dl
• Hydrate patient - Oral fluids if unable to drink
  use IV saline
• Mild Renal Insufficiency Patients add
  N-acetyl-cysteine (Mucomyst) 600 or 1,200 mg PO
  BID the day before and day of the procedure or
  150 mg/kg IV over .5 hr or 50 mg/kg IV over 4 hr

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Risk of Nephropathy

• A recent meta analysis Radiology Volume 239
  May 2006 p.392-397 Drs Rao Newhouse
• Properly controlled clinical studies of IV
  administered radiographic contrast media fail to
  demonstrate renal damage.

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ACR Manual on Contrast Media

• guide for radiologists in the use of iodinated
  contrast media
• http//www.acr.org/s_acr/sec.asp?CID2131DID1668
  7

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References of Interest

• Guidelines for Contrast Media from the European
  Society of Urogenial Radiology AJR181, December
  2003 p. 1463 1471.
• Minimizing Adverse Reactions to Contrast Agents
  Radiology Rounds, Massachusetts General Hospital,
  Volume 1, Issue 5 Oct 2003.

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• James H. Corley, MS, RPh, BCNPAssociate
  ProfessorMedical College of Georgiajcorley_at_mail.
  mcg.edu