[Comparative study of heparin and a very low molecular-weight heparin in hemodialysis in chronic renal insufficiency].

In the course of dialysis sessions, we have compared the antithrombotic effect of two heparinization regimens: low molecular weight heparin (CY 222, mean molecular weight: 2,500, Institute Choay, France): 90 anti-Xa units/kg bodyweight as a bolus injection followed by a continuous infusion of 1,000 anti-Xa units/hour (regimen 1); or 300 anti-Xa units/kg as a bolus injection (regimen 3), with a standard heparinization regimen (100 IU/kg regimen 2). Eight patients received the 3 regimens successively. Factor IIa and factor Xa inactivation was measured by a method that uses chromogenic substrates. The frequency of adverse effects, ultrafiltration rates, creatinine and BUN clearances of the 3 regimens were similar, whereas dialyser blood loss was higher in the first regimen. At the dose of 300 anti-Xa units of CY 222 (regimen 3), inactivation of factor Xa was similar to Xa inhibition reached through the conventional treatment (regimen 2) but IIa inhibition was less pronounced.