Miscellaneous adverse effects of low-versus high-osmolality contrast media: a study revised
Article Abstract:
Contrast media are materials ingested or injected into patients to facilitate imaging techniques. They help define and delineate tissues and organs being examined for abnormalities. There are several types of contrast media, one of which is based on osmolality, or the physical property of attracting fluids through a semipermeable membrane. High-osmolality contrast media (HOM) have generally been used for imaging. Recently, low-osmolality contrast media (LOM) have begun to be used. LOM are much more expensive than HOM, and justification for a general switch to LOM is necessary. Contrast media can cause side effects when introduced into the body. HOM may result in nausea, vomiting, and urticaria (hives and severe itching). It has been thought that one advantage of LOM may be a reduction in side effects. In the February 1989 issue of Radiology, articles by Powe et al. and Kinnison et al. reported the results of studies comparing HOM with LOM. They concluded that there were no significant differences in the side effects produced by HOM and LOM. This study re-examined the data used by these researchers. The original studies placed all LOM data in the same group. In this study, the LOM data were divided into two groups, based upon the ionic (containing electrically charged particles) properties of the media. Nonionic LOM (NIM) included the contrast media iohexol. The original data were also pooled because the small groups used made statistical differences hard to measure. The results of this re-evaluation found that iohexol caused significantly fewer side effects than did HOM. These findings differ from the previous results because of the difference in the way groups were pooled and the relatively small size of the groups. To examine the frequency of serious side effects caused by the nonionic and ionic LOM and HOM, a much larger sample size is needed. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Radiology
Subject: Health
ISSN: 0033-8419
Year: 1991
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Thrombogenic potential of nonionic contrast media?
Article Abstract:
Nonionic contrast agents were introduced for use in radiology as a safer alternative to ionic contrast agents. Some reports have indicated that nonionic contrast agents may cause thrombogenic complications (blood clots) in some patients. Regulatory agencies have stated that nonionic agents should be used with caution, even though no studies have conclusively shown that these agents can cause blood clots to develop. Two major studies, one performed in Australia and the other in Japan, explored potential complications from using nonionic contrast media, but neither study examined the potential thrombogenic complications of these agents. In the February 1990 issue of Radiology, a study by Kopko et. al reports that when blood was mixed with nonionic contrast agents of varying types and concentrations, thrombin, a protein involved in blood clotting, was generated. This reaction depended on the type and concentration of the agent used, and varied with the blood type of the patient. The elderly, the obese, and smokers appear to have increased risks for developing blood clots. A report by Hwang et. al suggested that blood clot formation when using nonionic contrast agents can be prevented by heparin, an anticoagulant drug. In our own studies, nonionic contrast agents caused thrombin formation in blood, but no clot formation was observed. These findings were similar to those of Kopko. The rate of thrombin formation was much greater when glass syringes were used than when plastic syringes were used. This finding could be important to the clinical use of these agents. Further studies are needed to assess the extent of the risks involved with using nonionic contrast agents. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Radiology
Subject: Health
ISSN: 0033-8419
Year: 1990
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