Who Should Be Premediciated for Contrast-Enhanced Exams?

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1 Who Should Be Premediciated for Contrast-Enhanced Exams? Jeffrey C. Weinreb, MD,FACR Yale University School of Medicine

2 Types of Intravenous Contrast Media Iodinated Contrast Agents Charge ionic vs nonionic Osmolality high(hocm), low (LOCM), iso (IOCM) Gadolinium-Based Agents Charge ionic vs nonionic Chemical Structure linear vs cyclic

3 Acute Systemic Contrast Reactions Anaphylactic (allergic) due to antigen/ige induced mast cell and basophil degranulation with release of their mediators (eg. histamine) Anaphylactoid (allergic-like): due to mast cell and basophil degranulation but not involving IgE. These are usually clinically indistinguishable

4 Some Mediators and Their Activities Mediator Histamine AA met PAF Kinins Pathophysiology Vascular permeability Vasodilation Contraction of smooth muscle Glandular secretion Sensory nerve stimulation Clinical Flush Urticaria Angioedema Hypotension Itch Wheeze Lieberman P. Allergy Principles and Practice

5 Mild Signs and symptoms are self-limited without evidence of progression Nausea, vomiting Cough Warmth Headache Dizziness Shaking Altered taste Itching Pallor Flushing Chills Sweats Rash, hives Nasal stuffiness Swelling;eyes,face Anxiety Observation to confirm stability or resolution, but usually no treatment American College of Radiology: Manual on contrast media, 7 th ed. Reston VA: American College of Radiology 2010

6 Moderate Signs and symptoms are more pronounced Tachycardia/bradycardia Hypertension Generalized or diffuse erythema Dyspnea Bronchospasm, wheezing Laryngeal edema Mild hypotension Prompt treatment frequently requiring close, careful observation for progression American College of Radiology: Manual on contrast media, 7 th ed. Reston VA: American College of Radiology 2010

7 Severe Signs and symptoms are often life-threatening Laryngeal edema (severe or rapidly progressing) Unresponsiveness Cardiopulmonary arrest Convulsions Profound hypotension Clinically manifest arrhythmias Aggressive treatment frequently requiring hospitalization American College of Radiology: Manual on contrast media, 7 th ed. Reston VA: American College of Radiology 2010

8 Clinical Criteria for Diagnosing Anaphylaxis Acute onset of symptoms with involvement of the skin, mucosal tissue, or both AND AT LEAST ONE OF THE FOLLOWING OR 2 of the following that occur rapidly after exposure to a likely allergen (minutes to several hours): OR Reduced BP after exposure to known allergen (minutes to several hours): Respiratory compromise (eg, dyspnea, wheezebronchospasm) Reduced BP or associated symptoms of end-organ dysfunction a. Involvement of the skin-mucosal tissue (eg, generalized hives, itch-flush, swollen lips-tongue-uvula) b. Respiratory compromise c. Reduced BP or associated symptoms d. Persistent gastrointestinal symptoms (eg, crampy abdominal pain, vomiting) a. Infants and children: Low SBP (age specific) or >30% decrease in SBP* b. Adults: SBP of <90 mm Hg or >30% decrease from that person s baseline Sampson HA et al. J Allergy Clin Immunol. 2006;117:

9 Panic Attack vs Allergic-type Reaction The presence of one can impact the other Patients with a history of a previous reaction to drugs or contrast media may be more likely to panic Patients in a state of panic may be particularly prone to an allergic-type reaction Potential for confusion can lead to diagnostic difficulties An erythematous skin reaction associated with anxiety A mild or moderate allergy-like reaction that triggers panic Panic attacks are associated with breathlessness and hyperventilation, but not with hypotension, pallor, or wheezing

10 Risk Factors Allergy history Asthma Prior anaphylactic/anaphylactoid reaction to intravenous contrast injection ACR Manual on Contrast Media v Bettmann MA, et al. Radiology 1997;203: Katayama H, et al. Radiology 1990;175;

11 Risk Factors-Allergy Even though a history of severe allergies is thought to predispose individuals to adverse reactions, it is probably only by a small percent, and most of the reactions will be minor. Thus, an allergic history is not generally a reason to avoid injection of contrast media. Nevertheless, any patient who describes an allergy to a food or anything else should be questioned further to clarify the type and severity of the allergy or reaction. True concern should be focused on patients with a history of a major ( significant =moderate-severe?) reaction, regardless of the specific type of allergen. No evidence that a prior reaction to shellfish confers a greater risk for an adverse event following exposure to an iodinated contrast agent than any other type of allergen.

12 Risk Factors-Asthma Asthma is considered to be a predictor of increased risk. Asthma in and of itself, especially active asthma, increases the risk primarily of bronchospasm, not other adverse events. But, many asthmatics also have allergies

13 Prior allergy-like reaction to intravenous contrast injection Although there is no cross reactivity, patients who have had previous allergic-like reactions to iodinated contrast media are also at risk from GBCAs, albeit probably at a lower level. If a patient had a previous reaction to a GBCA, consider using a different GBCA for the next MRI exam.

14 Premedication Primary indication for premedication is pretreatment of at risk patients who require contrast media Premedication is probably most useful for patients who, in the past, have had moderately severe or severe reactions that required treatment Lowers incidence and severity of minor reactions, but proof that premedication decreases incidence of life-threatening reactions is lacking ACR Manual on Contrast Media, Version 7; 2010.

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16 Sample Premedication Policy for Iodinated Contrast The following patients require premedication; Any severe allergic reaction to any substance Currently taking daily either two medications or a single combination agent for asthma All prior allergic-like reactions to iodinated contrast material

17 Relative Contraindications to Corticosteroids Diabetes Peptic ulcer disease Diverticulitis Systemic fungal infections Active TB