Contrast medium reaction

Author: Mikael Häggström

This page in a nutshell: In a more severe reaction: Adrenaline shot, 0.3-0.5mg in adults, given intramuscularly. Summon an anesthesiologist

In case of a allergic reaction to contrast media, anaphylaxis is a more severe allergic reaction whose diagnostic criteria generally include low blood pressure and/or respiratory distress. In anaphylaxis, intramuscularly administered adrenaline is the most important initial therapy. Also, an anesthesiologist or corresponding clinician on duty should be summoned. A peripheral venous catheter is needed for the administration of IV fluids. Oxygen saturation, pulse and blood pressure are monitored.

Document the incident to avoid repeat reactions.

Evaluation

Hives

Initial evaluation can be done according to an ABCDE approach:

• Airway: Stridor? Swollen tongue?
• Breathing: Cyanosis? Use pulse oximeter if available.
• Circulation: Palpable pulse over radial, femoral and carotid artery? Heart rate? Blood pressure? Difficulty in taking blood pressure must not delay adrenaline administration.
• Disability: Altered level of consciousness?
• Exposure: Hives?

Severity grading

Severity	Skin	Eyes and nose	Mouth and GI tract	SkinAirways	Circulatory	Mental
Non-anaphylactic allergic reaction	Itching Flushing Hives Angioedema	Conjunctivitis Rhinitis	Itching mouth Lip swelling Feeling of swollen mouth and throat Nausea Mild abdominal pain Single vomiting			Fatigue
Anaphylaxis, grade 1			Increasing abdominal pain Repeated vomiting Diarrhea	Hoarseness Mild bronchial constriction		Substantial fatigue Restlessness Anxiety
Anaphylaxis, grade 2				Barking cough Difficulty swallowing Moderate bronchial constriction		Feeling like fainting Sense of impending doom
Anaphylaxis, grade 3			Passing urine or feces	Hypoxia/cyanosis Severe bronchial constriction Complete airway obstruction	Hypotension Bradychardia Arythmia Cardiac arrest	Confusion Loss of consciousness

In severe hives and progressive angioedema

Angioedema

• 0,3-0,5 mg adrenaline intramuscularly on the anterolateral part of the mid-thigh. It is repeated if needed every 3–5 minutes.
• Corticosteroid (see Table of medications below)
• Observation at least 30 minutes

Anaphylaxis

• 0,3-0,5 mg adrenaline intramuscularly on the anterolateral part of the mid-thigh. It is repeated if needed every 3–5 minutes.
• Summon anesthesiologist or corresponding clinician on duty
• Oxygen, 10 L/min on mask. Attach a pulse oximeter.
• In asthma or bronchospasm: Inhalations of bronchodilator (see Table of medications below)
• In hypotension: Tilt the table to lower the head of the patient and give volume expander
• Corticosteroid (see Table of medications below)

Cardiac arrest (unconscious and no breathing)

Chest compressions.

• Start CPR: 100 chest compressions per minute and ventilate x2 every 30 compressions
• Connect a defibrillator
• If ventricular fibrillation or tachycardia: defibrillate at 200 Joule
• If asystole or pulseless electrical activity (PEA): 1 mg adrenaline 0,1 i.v. bolus
• Continue CPR

Itching hives

If ABCDE is otherwise normal:

• Antihistamine (see Table of medications below)
• Observation at least 30 minutes

Table of medications

Symptoms	Medication		Route	Dosage		Time to effect	Repeat
	Class	Example		Adults	Children
Severe hives Respiratory distress Hypotension Altered level of consciousness Severe abdominal pains and vomiting	Injection of adrenaline		Intramuscular in lateral thigh	0.3 - 0.5 mg	0.01 mg/kg, up to 0.5 mg 10-20kg: 0.15 mg ≥20kg: 0.3 mg	Less than 5 min	Every 5-10 min if needed
Asthma	Bronchodilator	Salbutamol (Ventolin) or own bronchodilator	Inhalation	5 mg Usually 4-6 doses	2-6 doses	Less than 5 min	Every 10 mins if needed
Hypoxia	Oxygen		Mask	>5 l/min		Almost immediate	Continuous
Altered level of consciousness or hypotension	Volume expander	Ringer's	IV with pressure	20mg/kg		Fast	As needed
All anaphylaxis cases	Antihistamine	Desloratadine (Clarinex/Aerius)	Oral	10mg	<6 years: 2.5mg 6 - 12 years: 5 mg	Within 30-60 minutes
		Chlorphenamine	IM or slow IV	10mg	<6 months: 250μg/kg 6 months - 6 years: 2.5mg 6 - 12 years: 5mg
All anaphylaxis cases	Glucocorticoid	Betamethasone	Oral or IV	5-8 mg	<6 years: 3-4 mg ≥6 years: 5-8 mg	2-3 hours
		Hydrocortisone	IM or slow IV	200mg	<6 months: 25mg 6 months - 6 years: 50mg 6 - 12 years: 100mg

Documentation

All allergic reactions should be documented, and anaphylactic reactions should be documented so that it shows clearly when planning subsequent exams:

• Brand or type of contrast agent.
• Symptoms and their severity, or overall severity grading and most worrisome symptoms.
• Treatment if given (treated symptoms may have become worse without treatment)

Prevention

Main article: Prevention of contrast medium reaction

Before a contrast CT of a patient with known allergic-like or unknown-type of contrast reaction to the same class of contrast medium (such as iodinated), the American College of of Radiology recommends premedication with a glucocorticoid, preferably starting 12 or 13 hours before contrast administration.