 Using conventional ionic contrast agents, total adverse reactions can be expected with a frequency of ~5-8%  Adverse reactions from intravascular contrast media may be classified as either anaphylactoid or chemotoxic  The Registry of the SCAI reported 519 major contrast media complications (0.23%) with four deaths (1 in 55,000) in 222,553 patients undergoing selective coronary cineangiography systemic reaction to contrast media occurring in one of every 500 Guidelines for Prevention, Diagnosis, and Treatment Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

Severity Classification for Contrast-Induced Anaphylactoid Reactions MinorModerateSevere Urticaria (limited)Urticaria (diffuse)Cardiovascular shock PruritusAngioedemaRespiratory arrest ErythemaLaryngeal edemaCardiac Arrest Bronchospasm Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Guidelines for Prevention, Diagnosis, and Treatment Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

PATHOPHYSIOLOGY  Anaphylactoid reaction differs from an anaphylactic reaction in its pathophysiology but not in its clinical manifestations or treatment  Anaphylactic reaction is an IgE-medicated hypersensitivity reaction requiring prior sensitization Complex combines on the surface of mast cellsand basophils stimulating histamine release  The exact mechanism of the nonimmune-mediated anaphylactoid reaction is not well worked out, but is most likely histamine mediated  Contrast media can stimulate histamine release not only as a result of an anaphylactoid reaction, but additionally can activate directly or indirectly the complement, coagulation, fibrinolytic, and kinin systems Guidelines for Prevention, Diagnosis, and Treatment Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

 Pretreatment reduces the incidence of anaphylactoid reactions  Prophylaxis is not completely protective  Anaphylactoid reactions are neither dose related nor always immediate  Patients who have experienced an anaphylactoid reaction to prior contrast media administration have traditionally been considered at increased risk for recurrent reactions  Repeat anaphylactoid reactions to conventional ionic contrast media have been reported to occur in 16-44% of patients with prior contrast reactions A second category for potential prophylaxis is the patient with a history of atopy and asthma  History of allergy to food containing iodine, such as seafood, is of no predictive value Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Guidelines for Prevention, Diagnosis, and Treatment Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

 Steroids and H1 blockers are the basic components of most premedication regimens  Prednisone 50 mg p.o. should be administered 13, 7, and 1 hr before procedure together with diphenhydramine 50 mg p.o. 1 hr before procedure  Addition of an H2 blocker to the above standard regimen would be logical if an IgE-mediated antigen/antibody reaction were involved Not as clear with the nonimmune-mediated anaphylactoid reaction Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Guidelines for Prevention, Diagnosis, and Treatment Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

 Nonionic contrast media  Overall recurrence rate was only 0.5% compared to a 10% recurrence rate for patients treated only with medical pretreatment regimens  In patients with known previous severe anaphylactoid reactions, nonionic contrast media is recommended in combination with medical pretreatment regimens  Patients with known prior anaphylactoid reactions to contrast media who present for emergency cardiac angiography Steroids given just 1 hr prior to contrast administration are likely ineffective in the prevention of anaphylactoid reactions Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Guidelines for Prevention, Diagnosis, and Treatment Patients With Known Anaphylactoid Reactions to Contrast Agents Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

CLINICAL PRESENTATION AND DIFFERENTIAL DIAGNOSIS  An anaphylactoid reaction must be considered with hypotension during catheterization  Distinguished from a vagal reaction by the absence of bradycardia  Anaphylactoid reaction without classic tachycardia may occur in the patient receiving beta blockers and in patients with VVI pacemakers  Central venous pressure monitoring demonstrates low pressures  Low systemic vascular resistance due to massive vasodilatation  The majority of anaphylactoid reactions occur within 20 min  64% of patients who develped severe/ fatal reactions did so within 5 min after injection  Severe anaphylactoid reactions may begin with very mild symptoms but progress rapidly in a matter of minutes  Rapid diagnosis, cessation of contrast administration, and appropriate therapy are essential Guidelines for Prevention, Diagnosis, and Treatment Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

Condition: Urticaria and Skin Itching Diaphenhydramine mg IV Unresponsive: Epinephrine 0.3 cc of 1:1,000 solution sub-Q q 15 min up to 1 cc Cimetidine 300 mg or ranitidine 50 mg in 20 cc NS IV over 15 min. Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Guidelines for Management of Anaphylactoid Reactions in the Cardiac Catheterization Laboratory Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

Condition: Bronchospasm 1)O 2 by mask, Oximetry 2)Mild: Albuterol inhaler-2 puffs Moderate: Epinephine 0.3 cc of 1:1,000 solution sub-Q q 15 min up to 1 cc Severe: Epinephrene IV as a bolus(es) of 10 µg/min, then an infusion of 1 to 4 µ g/min; observe for desired effect with BP and EKG monitoring Preparation: Bolus dose: (0.1 cc of 1:1,000 solution or 1 cc of 1:10,000) diluted to 10 cc (10 µg/cc) Infusion dose: (1 cc of 1:1000 or 10 cc of 1:10,000) in 250 cc NS (4 µg/cc) 3)Diphenyhydramine 50 mg IV 4)Hydrocortisone mg IV 5)Optional: H2 blocker as outlined Guidelines for Management of Anaphylactoid Reactions in the Cardiac Catheterization Laboratory Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

Condition: Facial Edema and Laryngeal Edema 1)Call anesthesia 2)Assess airway (a) 0 2 by mask (b) Intubation (c) Tracheostomy tray 3)Mild: Epinephrine sub-Q as outlined Moderate/Severe: Epinephrine IV as outlined 4)Diphenhydramine 50 mg IV 5)Oximetry / ABG 6)Optional: H2 blocker as outlined Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Guidelines for Management of Anaphylactoid Reactions in the Cardiac Catheterization Laboratory Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)

Condition: Hypotension/Shock 1)Simultaneous administration (a) Epinephrine IV, Bolus(es) 10 µg/min IV until desired BP response obtained, then infuse 1-4µg/min to maintain desired BP (b) Large volumes of 0.9% NS (1-3 liters in first hr) 2)O2 by mask, Intubation 3)Diphenhydramine mg IV 4)Hydrocortisone 400 mg IV 5) CVP/Swan-Ganz, Oximetry/ABG Unresponsive: 7)H2 blocker as outlined, Dopamine 2 to 15 µg/Kg/min IV, ACLS support Anaphylactoid Reactions to Iodinated Contrast Media During Cardiac Catheterization Procedures: Guidelines for Management of Anaphylactoid Reactions in the Cardiac Catheterization Laboratory Catheterization and Cardiovascular Diagnosis. 34:99-104(1995)