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Wednesday, 27 April 2011

IV Contrast induced reactions


"Hives" (urticaria)

• Discontinue injection if not completed
• No treatment needed in most cases - reassure the patient
• Consider diphenhydramine PO/IM/IV 25-50 mg
• If severe/widely disseminated: Epinephrine SC (1:1,000) 0.1-0.3 ml (= 0.1-0.3
mg) (if no cardiac contraindications)

Facial or laryngeal edema

• 0.1-0.3 ml epinephrine SC or IM (1:1,000) (= 0.1-0.3 mg) or, if hypotensive, 1 ml epinephrine IV (1:10,000) slowly (= 0.1 mg). Repeat as needed up to 1 mg.
• Give oxygen 6-10 L/min (via mask)
• If not responsive to therapy or if there is obvious acute laryngeal edema, seek
appropriate assistance (e.g., cardiopulmonary arrest response team)


• Give oxygen 6-10 L/min (via mask)
• Monitor: ECG, O2 saturation (pulse oximeter), and BP
• Give beta-agonist inhalers, such as metaproterenol, terbutaline, or albuterol
2-3 puffs; repeat as needed
• If unresponsive, epinephrine SC or IM (1:1,000) 0.1-0.3 ml (= 0.1-0.3 mg) or,
if hypotensive, epinephrine (1:10,000) slowly IV 1 ml (= 0.1 mg) - Repeat up
to 1 mg
• Alternatively, give aminophylline 6 mg/kg IV in D5W over 10-20 minutes
(loading dose), then 0.4-1 mg/kg/hr, as needed (caution: hypotension)
• Call for assistance for severe bronchospasm or if O2 saturation <88% persists

Hypotension with tachycardia

• Legs elevated 60 degrees or more (preferred) or Trendelenburg position
• Monitor: ECG, O2 saturation (pulse oximeter), and BP
• Give oxygen 6-10 L/min (via mask)
• Rapid large volumes of IV isotonic Ringer's lactate or normal saline
• If poorly responsive: Epinephrine (1:10,000) slowly IV 1 ml (=0.1 mg) (if no
cardiac contraindications). Repeat as needed up to a maximum of 1 mg
• If still poorly responsive seek appropriate assistance (e.g., arrest team)

Hypotension with bradycardia (vagal reaction)

• Monitor: ECG, O2 saturation (pulse oximeter), and BP
• Legs elevated 60 degrees or more (preferred) or Trendelenburg position
• Secure airway and give oxygen 6-10 L/min (via mask)
• Rapid large volumes of IV isotonic Ringer's lactate or normal saline
• If unresponsive, atropine 0.6-1 mg IV slowly - repeat up to 2-3 mg in adult
• Ensure complete resolution of hypotension and bradycardia prior to discharge.

Severe hypertension

• Give oxygen 6-10 L/min (via mask)
• Monitor: ECG, O2 saturation (pulse oximeter), and BP
• Give nitroglycerine 0.4-mg tablet, sublingual (may repeat x 3)
• Transfer to intensive care unit or emergency department
• For pheochromocytoma−phentolamine 5 mg IV

Unconscious / unresponsive / pulseless / collapsed patient

• CALL CODE (Know the code phone number at your hospital. A code is not the
time to look for the number in a phone book!)
Institute Basic Life Support
1. Establish airway, head tilt, chin lift
2. Initiate ventilation and external chest compression
3. Continue uninterrupted until help arrives




- Contrast agents with higher osmolality are more likely to cause adverse reactions of all kinds.
- Low-osmolality agents have a significantly higher cost, which prevents them from being used exclusively.
- Anaphylactic reactions are serious, potentially life-threatening reactions associated with the administration of contrast material. Acute bronchospasm, profound hypotension, and severe urticaria may occur within minutes of administration of as little as 1 mL of contrast material. These reactions are not “true” allergic reactions, because they can occur in patients who have not been exposed to contrast material previously.
- Dose-dependent, systemic adverse reactions to contrast material include nausea and vomiting, a metallic taste in the mouth, and generalized warmth or flushing. These reactions are usually nonlife-threatening, self-limited problems.
- Renal failure is another form of adverse reaction that is dependent on the dose of contrast material used. (12% of all hospital aqcuired RF)
- Contrast induced nephropathy is diagnosed by a generally accepted definition which is the elevation of serum creatinine to greater than 25 percent of baseline within three days of receiving contrast material.
- Patients with preexisting renal insufficiency and diabetes are at greatest risk of developing permanent renal failure following administration of contrast material. Patients with multiple myeloma are also at increased risk of developing renal failure, especially if they are dehydrated. The risk of renal failure in patients with myeloma is caused by an interaction of light chains and contrast material.

- Adverse reactions that occur 30 minutes or more after the administration of contrast material are considered delayed reactions.
- 30% receiving ionic contrast materials develop delayed reactions.
- 10% recieving nonionic agents is associated with delayed reactions.
- Symptoms resemble a flu-like syndrome and include fever, chills, nausea, vomiting, abdominal pain, fatigue, and congestion.

- Pt. with RF are at 10X increased risk to develope RF.
- If pt. had a previous reaction, but it is not sure that the pateint will have another one.
- Pt. with asthma, drug or food allergy.
- Sea food allergy
- On nephrotoxic deugs (NSAIDS, aminoglycosides)
- Advanced age is risk for RF.
- Metformin (Glucophage), has been associated with the development of severe lactic acidosis following administration of intravenous contrast media.
- Experts recommend stopping metformin therapy at the time of the procedure, or before, and for at least 48 hours following the administration of contrast material.


contrast media

  • side-effects from high osmolality / viscosity (fluid shifts from different compartments)
    • vasodilatation
    • heat
    • pain
    • osmotic diuresis
    • hemodynamic changes
  • pharmacokinetics
    • distribute volume into extracellular space
    • clearance by glomerular filtration and renal excretion
  • physiologic reaction
    • increased plasma osmolality causes fluid shift from RBCs and pulmonary tissue leading to increased plasma volume
    • then osmolar gradient reverses with passage of contrast bolus -> pulmonary capillary endothelium leaks protein into pulm interstitium --> increased pulmonary edema
    • transient cardiovascular changes (magnitude increased with tonicity of medium)
      • increased PAP
      • increased CO with decreased peripheral/pulmonary vascular resistance
      • decreased systemic arterial pressure (variable)
    • may activate gen receptors causing side effects


ACR-Proposed Premedication Regimen to Reduce Contrast Reactions

According to the version #7 (2010) ACR Manual on Contrast Media, the following regimens are recommended for premedication of patients at risk for developing contrast reaction.

Elective Premedication
  1. Prednisolone: 50 mg PO at 13 hours, 7 hours and 1 hour before contrast media injection, PLUS Diphenhydramine 50 mg IV, IM or PO 1 hour before contrast medium OR
  2. Methylprednisolone 32 mg PO 12 hours and 2 hours before contrast media injection. An anti-histamine (as in option 1) can be added. If unable to take oral medication, use hydrocortisone 200 mg IV instead
Emergency Premedication
  1. Methylprednisolone 40 mg or hydrocortisone 200 mg IV every 4 hours until contrast study required PLUS Diphenhydramine 50 mg IV 1 hour prior to contrast injection OR
  2. Dexamethasone 7.5 mg or betamethasone 6 mg IV every 4 hours until contrast study PLUS diphenhydramine 50 mg IV 1 hour prior to contrast injection OR
  3. Omit steroid entirely and give diphenhydramine 50 mg IV
"IV steroids have not been shown to be effective when administered less than 4 to 6 hours prior to contrast injection."


Monday, 25 April 2011


Renal cysts

The Bosniak classification system was designed to separate cystic renal masses into surgical and nonsurgical categories by analysis of specific CT features.

Category I: Category I lesions are simple benign cysts showing homogeneity, water content, and a sharp interface with adjacent renal parenchyma, with no wall thickening, calcification, or enhancement.

Category II: This category consists of cystic lesions with one or two thin (<=1 mm thick) septations or thin, fine calcification in their walls or septa (wall thickening > 1 mm advances the lesion into surgical category III) and hyperdense benign cysts with all the features of category I cysts except for homogeneously high attenuation. A benign category II lesion must be 3 cm or less in diameter, have one quarter of its wall extending outside the kidney so the wall can be assessed, and be nonenhancing after contrast material is administered.

Category IIF: This category consists of minimally complicated cysts that need followup. This is a group not well defined by Bosniak but consists of lesions that do not neatly fall into category II. These lesions have some suspicious features that deserve followup to detect any change in character.

Category III: Category III consists of true indeterminate cystic masses that need surgical evaluation, although many prove to be benign. They may show uniform wall thickening, nodularity, thick or irregular peripheral calcification, or a multilocular nature with multiple enhancing septa. Hyperdense lesions that do not fulfill category II criteria are included in this group.

Category IV: These are lesions with a nonuniform or enhancing thick wall, enhancing or large nodules in the wall, or clearly solid components in the cystic lesion. Enhancement was considered present when lesion components increased by at least 10 H.


(Text main source:


Renal oedema

Reduced echogenicity on US, which is especially prominent in the renal pyramids which appear anechoic and maybe mistaken for cysts. Renal capsule nay appear unusually prominent. A transient increase in parenchymal echogenicity due to disruption of tissue interfaces.

Etiology: Acute GN, Acute PN, Nephrotic sy., Transplant rejection, Renal contusion.


(Text main source: Differential diagnosis in Abdominal US-Saunders)


The transplanted kidney


Renal calcifications

Types of calcifications:

- Medullary calcifications (95% of all parenchymal calcifications)

- Cortical calcifications

- Calcifications in a cyst wall, usually a complicated cyst (3%)

- Calcification in a renal tumour is usually amorphous but can be ring like and mimic cyst wall calcification (6% of renal tu.'s)

Medullary Ca:

Due to any cause of hypercalcemia, hypercalciuria. Pyramid margins are echogenic while the center remain echolucent. The pyramids may be echogenic and may shadow.

Cortical Ca:

5% of parenchymal calcification. Secondary pyramidal calcification may occure.