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The content below adapted from information provided by the University of Washington Radiology Department but the U.W. bears no responsibility for errors, outdated materials, or misinterpretations



Contrast Allergy: Reducing Risk of Allergic Like Reactions.

PROTOCOL FOR REDUCING RISK OF REPEAT ALLERGIC-LIKE REACTION TO CONTRAST MEDIA

A history of a prior allergic-like reaction to contrast media increases the likelihood of the patient experiencing a subsequent reaction. Additionally, an allergic history predisposes individuals to reactions. The relationship is a difficult one to define, since many individuals have at least a minor allergy, such as seasonal rhinitis, and do not experience reactions. True concern should be focused on patients with significant allergies, such as a prior anaphylactic response to one or more allergens. The predictive value of specific allergies, such as those to shellfish or dairy products, previously thought to be helpful, is now recognized to be unreliable. Any patient who describes an “allergy” to a food or contrast agent should be questioned further to clarify clearly the type and severity of the “allergy” or reaction. There seem to be “reactive” patients, and these patients have a greater chance of reacting to injected contrast media.

INDICATIONS FOR PREMEDICATION

The primary indication for premedication is pretreatment of “at risk” patients who require contrast media. Such regimens have been shown in clinical trials to decrease the frequency of contrast medium reactions. However, no regimen has eliminated repeat reactions completely. Pretesting is not predictive, may itself be dangerous, and is not recommended. Prior to administering contrast, consideration should be given to alternative imaging techniques which could answer the clinical question without intravenous contrast. These include non-contrast studies (CT & MR) and ultrasound.

When should a premedication regimen be used?

  1. History of a prior reaction to an intravascular contrast medium (e.g. iodinated, gadolinium) that required treatment.
    1. If the prior reaction was mild and required no treatment, pre-treatment is usually not necessary, although the option should be presented to the patient. This includes:
      • A few (< 12) scattered hives
    2. If the prior reaction was moderate, premedication is recommended. This includes:
      • Upper airway edema
      • Bronchospasm
      • Diffuse rash (> 12 hives)
    3. If the prior reaction was severe, then imaging studies that do not require contrast should be utilized. If a study with contrast is eventually deemed to be necessary, then informed consent of the patient must be obtained and anesthesia standby obtained.
  2. In addition, for patients with currently symptomatic asthma (“active asthma”) premedication is recommended because there is a higher rate of bronchospasm. Patients with a history of asthma which is not currently symptomatic do not require premedication.
  3. Patients with allergies to foods should be questioned about the type and severity of reaction. If the patient experienced diffuse (> 12) hives, or a moderate reaction (including bronchospasm, angioedema) or a severe reaction (e.g. anaphylaxis), or have allergies to more than four different allergens, premedication should be considered.
  4. Prior to ordering pre-medication, the physician should balance the risks of a reaction with the medical necessity, urgency and logistics of the study, as well as the patient’s own preferences. Potential risks include a delay of 13 hours prior to contrast imaging, worsening sepsis, hyperglycemia, psychosis, and impaired wound healing.

PREMEDICATION REGIMENS:

If it is necessary for the patient to have a contrast-enhanced exam:

Several premedication regimens have been proposed to reduce the frequency and/or severity of reactions to contrast media. Two frequently used regimens are:

  1. Corticosteroid/antihistamine
  2. Corticosteroid alone

Oral administration of steroids seems preferable to intravascular administration, and prednisone and methylprednisolone are equally effective. The two dose methylprednisolone regimen is more "patient friendly: particularly for outpatients, in that the patient does not need to awaken during the night for the middle dose of the prednisone regimen. If the patient is unable to take oral medication, 200 mg of hydrocortisone intravenously may be substituted for oral prednisone according to the Greenberger protocol (protocol no. 1 , above)

An interval of at least 6 hours between the initial corticosteroid administration and the injection of contrast medium is recommended, regardless of the route of steroid administration. Hence, an IV bolus of corticosteroid immediately prior to the contrast injection is not effective.

Supplemental administration of an H-1 antihistamine (e.g., diphenhydramine), orally or intravenously, mildly reduce the frequency of urticaria, angioedema, and respiratory symptoms.

In emergency situations, intravenous corticosteroid (e.g., 200 mg hydrocortisone) begun 6 hours before the study and repeated at 4 - 6 hours, plus an H-1 antihistamine (e.g., 50 mg diphenhydramine) 1 hour before the procedure, has been used.

Corticosteroids are the essential component and should be included in any premedication protocol, unless there are very clear contraindications to their use.

W. Bush, MD; M. Gunn MD; J. Jarvik, MD; D. Shibata, MD. Department of Radiology, University of Washington

February 1, 2006; modified October 17, 2008

Addendum (November 2009)

Patients who have had prior severe reactions to iodinated contrast media (oral or iv) should not receive oral iodinated contrast media whenever possible. Alternatively, a barium based oral contrast agent should be considered.



Contrast Allergy: Treatment

URTICARIA

BRONCHOSPASM (ISOLATED)

HYPOTENSION (ISOLATED)

If hypotension unresponsive

VAGAL REACTION (HYPOTENSION AND BRADYCARDIA)

ANAPHYLACTOID REACTION (GENERALIZED SYSTEMIC REACTION)

ANGINA

HYPERTENSION

SEIZURES

HYPOGLYCEMIA



Serum Creatinine Levels before Intravenous Contrast

PURPOSE:

To establish Serum Creatinine testing guidelines prior to patients receiving contrast media agents intravascularly.

POLICIES:

Intravenous Iodinated Contrast Media

  1. All Inpatients must have a serum creatinine level within 24 hours of receiving IV contrast.
  2. All Outpatients, who answer yes to any of the risk factors for renal insufficiency (see below), must have a normal serum creatinine level within 14 days.
  3. Risk Factors
  4. If an outpatient has had an acute illness, recent major surgery, or is taking metformin; they must have a serum creatinine within 24 hours
  5. Normal Value Range is 0.6-1.2 mg/dl; but must be correlated with body muscle mass. An estimated Glomerular Filtration Rate (GFR) will be calculated if the patient is over age 70 or has a creatinine of > 1.2 mg/dl
  6. In medical emergencies (for example in the medically unstable or non-responsive multi-trauma patient), the delay caused by obtaining a comprehensive medical history and / or a serum creatinine level may put the patient at higher risk of an adverse outcome than administering contrast without a full history or serum creatinine level. In these circumstances, a supervising physician can elect to administer contrast without a full history or serum creatinine level
  7. Time between IV iodinated contrast scans should be as follows

Intravenous Gadolinium Based Contrast Media

  1. All inpatients, and all patients with prior liver transplantation or severe liver disease who will receive gadolinium should have a serum creatinine level within 24 hours
  2. All outpatients with a history of renal disease (including kidney tumors, solitary kidney, and renal transplantation), or who are over age 70, or who have hypertension or diabetes mellitus should receive a serum creatinine within six weeks of receiving gadolinium


Renal Impairment: Mucomyst

Mucomyst® Protocol

Dosing

One dose

600mg (3 ml of the solution) 20% Mucomyst® by mouth or feeding tube

Give 4 doses total
  1. Give 2 doses prior to the exam, @ 24 hrs. and 12 hrs.
  2. Give 2 doses following the exam, @ l hr. and 12 hrs.

Note

The evidence supporting the reno-protective effects of mucomyst is weak. The mainstays of prevention of contrast nephropathy remain reduced contrast load and hydration.



Renal Impairment: Sodium Bicarbonate

Use 154 meq/L of sodium bicarbonate in D5W (5% Dextrose/Water); the pharmacy provides 1 liter bags of D5W mixed with 3 amps of sodium bicarbonate.

Dosing

  1. Give 3ml/kg/hr for 1 hr prior to the exam (multiply 3 ml by body weight in kilos; infuse this volume over 1 hour).
  2. Give 1 ml/kg/hr during the exam and for 6 hours after the exam (1 ml per kilo per hour for 6 hours)

Example: The patient weighs 100 kilos; give 300 ml of solution 1 hour prior to exam, give 100 ml solution per hour for 6 hours following exam for a tota1 of 600 ml.

Note

The evidence supporting the reno-protective effects of bicarbonate is weak. It is of questionable value at best, and might make contrast nephropathy worse. The mainstays of prevention of contrast nephropathy remain reduced contrast load and hydration.



Renal Impairment: Repeat Doses of Contrast in 24 hours

Repeat doses of intravenous contrast in a short period of time may increase the risk of contrast nephropathy in patients with pre-existing renal impairment



Insulin Guidelines in Diabetics Undergoing Angiography

Type I Diabetes

Type II Diabetes

Considerations for Glucophage (Metformin)



Renal Impairment: Gadolinium Protocol

Background

It has been recognized recently that patients with severe renal in sufficiency/renal failure are at increased risk for the development of Nephrogenic Systemic Fibrosis (NSF) when given gadolinium agents for MRI imaging. The reported incidence varies from 1% to 7% in patients with severe chronic kidney disease (CKD), particularly those on chronic dialysis.

NSF has been reported with several gadolinium agents, although it is more strongly associated with some, specifically gadodiamide (Omniscan@). The occurrence of NSF increases with larger gadolinium doses (e.g. MRA) and repeat administration, in the higher risk categories.

NSF occurs primarily in patients on chronic dialysis (hemo-, peritoneal) for their renal failure; therefore, it is found primarily in patients whose GFR is less than 15 ml/min.

It has not been reported when the GFR is above 60 ml/min; and there is a theoretical risk when the GFR is between 60 and 30 ml/min. An increased number of cases have occurred in in patients with a GFR of less than 30 ml/min. Dialysis does clear gadolinium agents, but in renal failure patients on chronic dialysis, at least 3 treatments would be necessary to clear all of the gadolinium.

APPROACH TO IMAGING PATIENTS WITH GADOLINIUM

  1. If the GFR is greater than 60 ml/min, any agent may be utilized without risk.
  2. If the GFR is less than 60 ml/min but greater than 30 ml/min, gadodiamide (Omniscan@), gadopentetate dimeglumine (Magnevist@)and gadoversetamide (OptiMARK@)should be avoided; the exam can be done with minimal risk, but risk/benefit must always be considered.
  3. If the GFR is less than 30 but greater than 15 (e.g. patient is not on dialysis), the patient is at significant risk for NSF, but the risk is low with the "less risky" gadolinium agents. Risk-benefit should be discussed with the referring physician and the patient and informed consent of the patient should be obtained. (CT with iodinated contrast is not a good option in this group of patients since there is still residual renal function that may be severely damaged by a large dose of iodinated contrast).
  4. If the patient is on dialysis, gadolinium-enhanced MRI should be avoided. MR without gadolinium should be considered as an initial study. If a contrast-enhanced examination is indicated and the patient is on permanent dialysis, an iodinated contrast CT should be the imaging study of choice. If MR with gadolinium must still be done, this should be discussed in detail with the clinician and patient, and written informed consent obtained.
  5. Although dialysis can remove only a portion of the gadolinium, arranging for the gd-MR exam to be done immediately before a scheduled dialysis treatment might be beneficial, though this is not proven.


NSF and Gadolinium

What is Nephrogenic Systemic Fibrosis?

Who does it occur in?

How long after getting gadolinium does it take before NSF occurs?

Are we sure that NSF is caused by Gadolinium?

Is there any treatment available?

What is the risk of NSF?

Does dialysis prevent NSF?

Are certain gadolinium agents more likely to cause NSF?

Is Multihance OK?