Immediate and nonimmediate reactions induced by contrast media: incidence, severity and risk factors

The pattern of the contrast media-induced adverse reactions has not been investigated extensively in Mexico.

To estimate the incidence and the degree of severity of the adverse reactions to contrast media, administered for the first time, in hospitalized subjects.

We studied 99 patients longitudinally on whom computed tomography with contrast media (iopamidol) was carried out. The adverse reactions were identified by clinical examination; subsequently, they were classified as mild, moderate and severe, following the Manual on Contrast Media version 9 guides, and as immediate and nonimmediate. In addition, the vital functions, oxygen saturation, serum creatinine levels and the total number of eosinophils were measured before and after the procedure.

The incidence of immediate and nonimmediate adverse reactions was of 26.3% and 10.1%, respectively. The mild immediate reactions were 18 (69.2%), the most common being the sensation of warmth, nausea and pruritus; among the more delayed reactions, nephrotoxicity stood out (5.1%). The serum creatinine median showed no difference either before or after the intravenous injection of contrast media (p = 0.13); in contrast, there was a significant difference in the total number of eosinophils (p ≤ 0.001). The values of high baseline systolic blood pressure and the diminished baseline amounts in pulse oximetry were significantly related with any type of the adverse reactions to contrast media.

The incidence of the adverse reactions to contrast media was greater with respect to previous reports; the majority of these reactions were of the immediate type and of a mild nature. The risk factors that have mostly been implicated in the adverse reactions to contrast media could not be identified in our cohort.