Radiocontrast reactions

Acute and Late Adverse Reactions to Low-Osmolal Contrast Media

A prospective study of acute and late reactions to low-osmolal contrast media was conducted in 4 875 patients. The contrast medium was injected intravenously in 4 417 patients and intraarterially in 458 for CT, urography or angiography. In the i.v. group only nonionic contrast media, iohexol or iopamidol, were used and in the intraarterial group both ionic and nonionic contrast media, ioxaglate and iohexol, were used. The patients completed 2-phase questionnaires, the rate of reply being 88%. In the i.v. group the incidence of acute reactions was 1.2% and that of late reactions was 4.7%. In the intraarterial group the incidence of acute reactions was 7.4% and the incidence of late reactions was 4.8%. Women and patients from under 40 to 60 years of age were the most susceptible to late reactions. The risk factors for late reactions are allergy, medicine allergy, previous adverse reaction to contrast medium and other diseases including diabetes mellitus, heart-, liver- and kidney diseases.

The possible role of factor H in complement activation-related pseudoallergy (CARPA): a failed attempt to correlate blood levels of FH with liposome-induced hypersensitivity reactions in patients with autoimmune disease

Factor H (FH) is a natural inhibitor of the alternative pathway (AP) of complement (C) activation, an abundant protein in blood whose reduced level has been associated with proneness for increased C activation. There are also 5 FH-related proteins (FHR), which have different impacts on C function. After brief outlines of the C system and its activation via the AP, this review focuses on FH and FHR, collecting data from the literature that suggest that reduced levels or function of FH is associated with C activation-related hypersensitivity reactions (HSRs), called C activation related pseudoallergy (CARPA). Based on such observations we initiated the measurement of FH in the blood of patients with inflammatory bowel disease (IBD) and rheumatoid arthritis (RA), and examined the correlation between FH levels and HSRs following i.v. administration of PEGylated liposomal prednisolone phosphate (PLPP). ELISA assay of FH was conducted on plasma samples before treatment, immediately after treatment and at follow-up visits up to 7 weeks, and an attempt was made to correlate the FH levels obtained with the presence or absence of HSR that occurred in five of twenty patients. However, the initial data presented here on three reactive and three non-reactive patients showed FH levels >600 μg/mL, while the normal range of FH is 2–300 μg/mL. This unexpected outcome of the test led us to realize that the ELISA we used was based on antibodies raised against the short consensus repeats (SCR) in FH, which are also present in FHR. Thus the kit cannot distinguish these proteins and we most likely measured the combined levels of FH and FHR. These initial data highlighted an unforeseen technical problem in assessing FH function when using a FH ELISA that cross reacts with FHR, information that helps in further studies exploring the role of FH in CARPA.

Hypersensitivity reactions to radiocontrast media: the role of complement activation

Although intravenous use of radiocontrast media (RCM) for a variety of radiographic procedures is generally safe, clinically significant acute hypersensitivity reactions still occur in a significant percentage of patients. The mechanism of these anaphylactoid, or "pseudoallergic," reactions is complex, involving complement activation, direct degranulation of mast cells and basophils, and modulation of enzymes and proteolytic cascades in plasma. In this review, basic information on different RCMs and their reactogenicity is summarized and updated, and the prevalence, pathomechanism, prediction, prevention, treatment, and economic impact of hypersensitivity reactions are discussed. Particular attention is paid to the in vitro and in vivo evidence supporting complement activation as an underlying cause of RCM reactions.

Late and acute adverse reactions to iohexol in a pediatric population

The purpose of this study was to determine the incidence of acute and late reactions after contrast-medium injection in the Finnish paediatric population. From March 1989 to November 1990, 321 children under 19 years of age were examined with a nonionic contrast medium, iohexol, for urography and CT. The follow-up time for late reactions was up to 24 h after the contrast-medium injection. The return rate for the questionnaires given to patients to record their reactions was 73.2%. Acute adverse reaction was noted in 1.9% of the patients, with the most frequent reactions being in the weight range 24-40 kg. Asthma and previous reaction to contrast medium are risk factors for acute reaction. Late reactions were found in 6.2% of the patients, most frequently in children weighing under 24 kg.

Anaphylaxis

The syndrome of anaphylaxis is a life-threatening event in which the potential for patient morbidity and mortality is high. An understanding of the pathophysiology of anaphylaxis, the most serious of the allergic disorders, is paramount for its diagnosis. In addition to these elements, this article discusses newly recognized causes of anaphylaxis and reviews its treatment.

Drug allergy

Adverse reaction to drugs is a common problem in the pediatric population. This article discusses the different types of adverse drug reactions and their mechanisms. Also included are representative clinical syndromes of drug hypersensitivity reactions, as well as certain organ systems syndromes. Finally, diagnosis and management of allergic reactions to particular drugs such as penicillin, iodinated contrast dye, insulin, and others are discussed.