Adverse reactions to nonionic iodine in contrast-enhanced computed tomography: usefulness of monitoring vital signs

Objectives: To report on adverse reactions to intravenous nonionic iodine contrast media and evaluate the usefulness of monitoring vital signs. Materials and methods: A prospective study of 1537 consective patients who received contrast-enhanced CT with nonionic iodine was performed. Systolic and diastolic arterial blood pressure, pulse rate and arterial blood oxygen saturation were monitored. Severity of adverse reactions was classified as minor, intermediate and severe. Results: A total of 64 adverse reactions developed in 57 patients. The overall prevalence was 3.7% (57/1537). The most common symptom was nausea (18/64) followed by pharyngeal discomfort (11/64). One patient had a severe reaction consisting of prolonged hypotension. Four patients had an intermediate reaction, three transient hypotension or hypertension and one extensive urticaria and facial edema. In two out of four patients who became hypotensive or hypertensive, the reactions developed without any obvious clinical symptoms. Conclusion: Severe or life-threatening acute adverse reactions to intravenous nonionic iodine contrast media may develop without any obvious clinical symptoms. Monitoring vital signs is very helpful for early detection.