General toxicity of water-soluble iodinated contrast media. Pathogenic concepts

Review article: Acute serious and fatal reactions to contrast media: our current understanding

Serious or fatal reactions to a contrast medium (CM) are unpredictable but fortunately rare. History of serious reaction to CM, bronchial asthma or multiple allergies increases the incidence of serious reactions by a factor of 5. Serious or fatal reaction to CM could be due to direct effect on basophils and mast cells or IgE mediated (type 1 hypersensitivity reaction). Activation of the kinin system leading to the formation of bradykinin could also be involved. Complement activation is unlikely to be a primary factor in initiating a serious reaction to CM. Avoiding CM administration in patients at high risk of serious reaction is advisable, but if the administration is deemed essential all precautions should be implemented and measures to treat serious reactions should be readily available. Oxygen supplementation, intravenous administration of physiological fluids and intramuscular injection of 0.5 ml adrenalin (1:1000) should be considered in the first line management of acute anaphylaxis. The ability to assess and treat serious CM reaction effectively is an essential skill that the radiologist should have and maintain.

Nephrotoxicity of low-osmolality contrast media

To evaluate renal function after the use of a low-osmolality radiological contrast medium (CM), we prospectively analyzed 39 patients submitted to the following examinations: arteriography (n = 32), phlebography (n = 3), computed tomography (n = 3), angioplasty (n = 1), and retrograde pyelography (n = 1). The patients were divided into three groups: group 1, control, formed by renal donors (CT, n = 11 and 11 exams); group 2, hypertensive patients (HYPT, n = 15 and 16 exams); and group 3, patients with diseases of multiple etiologies (MIX, n = 13 patients and 13 exams). Additionally, the patients were divided according to their renal function into: group 4, with a moderate deficit of renal function, creatinine clearance (CrCl) 25 to 60 mL/min (n = 15 patients and 15 exams); and group 5, with a mild deficit of renal function, CrCl > or = 60 mL/min (n = 14 patients and 14 exams). The CM utilized was ioxaglic acid (Hexabrix) the incidence of acute renal failure (ARF) among the patients studied was 12.5% (5/40), and CrCl was the best parameter to monitor the alterations in renal function, which occurred in 35% of the patients, although the changes were mild, reversible, and did not need any therapeutic interventions. The triggering of ARF in these patients may have been due to multiple factors presented at time of CM examination. Thus, it is not possible to identify a single risk factor. However, it is probable that previous important impairment of renal function was the most expressive risk factor.

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.

The adverse effects of angiographic radiocontrast media

Radiographic procedures which require the intravascular administration of water-soluble radiocontrast media are performed with increasing frequency. Each examination carries risks that are related either to the technique itself or to the opaque medium chosen. The pathogenesis of radiocontrast media-related adverse effects cannot be explained by a unique theory. The major factors implicated are direct chemotoxic effects and the physicochemical properties of contrast media, the latter being the basis for development of new contrast agents. With nonionic opaque media cardiovascular adverse effects, heat sensation and local pain are observed less frequently. However, it remains unclear whether the incidence of organ dysfunction or anaphylactic reactions with nonionic contrast media currently used can be reduced. This review compares ionic and nonionic contrast media, and current thoughts on the pathophysiology and treatment of adverse reactions are presented.