Haemostatic effects of low osmolar non-ionic and ionic contrast media: a double-blind comparative study.

In this prospective, double-blind, randomized study the effects of a non-ionic contrast medium (Iopromide) on the haemostatic system were compared with those of a low osmolar ionic medium (Ioxaglate). The aim was to investigate in vivo whether a non-ionic contrast agent is less anticoagulant or more pro-thrombotic than an ionic medium. A large number of haemostatic parameters, including activation markers, were measured. Either Iopromide (n = 16; median volume 102 ml; 95% confidence interval 90-108 ml) or Ioxaglate (n = 15; median 105 ml; 95% confidence interval 95-114 ml) was given to 31 patients scheduled for abdominal and femoral arteriography. Blood for laboratory investigations was collected before, and 5 and 30 min after, administering the contrast medium. Indications for activation of coagulation and platelets were already found in nearly 50% of the patients before any contrast medium was given. Both Iopromide and Ioxaglate caused further increases in thrombin-antithrombin complex, prothrombin fragments 1 + 2 and beta-thromboglobulin. The degree of activation was similar for both agents. Anticoagulant effects were not observed. The haemorheological effects were compatible with haemodilution by 5-8%, again without differences between the contrast agents. Contrary to the findings from in vitro studies, we found no significant differences between the effects of the non-ionic Iopromide and the ionic Ioxaglate on coagulation and platelets. Both agents activated these systems to a limited, but identical, degree. Our results support the notion that the catheterization procedure per se may represent a source of haemostatic activation and that the ionic contrast agent studied has insufficient anticoagulant effect to prevent clotting activation being induced by the contrast medium.