EFFECT OF CONTRAST-MEDIA ON IN-VITRO BLEEDING-TIME - ASSESSMENT BY A HOLLOW-FIBER INSTRUMENT

Rationale and Objectives. We used a global screening device that opera tes under physiologic flow conditions to monitor the effects of ionic and nonionic contrast media (CM) on hemostasis. Methods. This flow dyn amic technique perfuses unanticoagulated whole blood through a hollow fiber. A leak in the fiber is created by a precision needle, and the r esulting pressure fluctuations within the fiber are monitored to exami ne the ability of the hemostatic system to close the leak by forming a stable platelet plug. Results. Both ionic and nonionic CM (25% CM/blo od, v/v) were shown to lengthen the mean in vitro bleeding times (IVBT s) compared with normal blood. Ionic CM (ioxaglate and diatrizoate) co nsistently produced IVBTs longer than 30 min. The nonionic CM iopamido l, iohexol, and ioversol gave mean IVBTs of 16.43, 17.63, and 19.84 mi n, respectively. Conclusion. Of the three nonionic CM tested, iopamido l had the greatest probability (31%) of producing an IVBT in the norma l range, with probabilities of 5% and 7% for iohexol and ioversol, res pectively. Thus, iopamidol offered the least anticoagulant effect amon g the ionic and nonionic CM are studied.