A low molecular weight heparin ('fragmin') for routine hemodialysis: A crossover trial comparing three dose regimens with a standard regimen of commercial unfractionated heparin

In 20 hemodialysis patients using mainly flat plate dialyzers, we have conducted a controlled randomized crossover trial of three dose regimens of a low molecular weight heparin (LMWH), 'Fragmin' (Kabi 2165), in comparison with a standard dose regimen of commercial unfractionated heparin (UFH) that had previously been shown to provide effective anticoagulation. The aim of the present study was to find the lowest dosage regimen of the LMWH which would be as effective as the standard UFH regimen. The UFH regimen comprised a prime with heparinized saline, an initial intravenous bolus of 5,000 international units (IU) and an infusion of 1,500 IU/h. The three LMWH regimens comprised a LMWH-saline prime, an infusion of 750 anti-factor Xa (aXa) U/h and three different bolus doses: 1) LMWH-low: 3,000 aXa U. 2) LMWH-medium: 4,000 aXa U. 3) LMWH-high: 5,000 aXa U. With the UFH regimen, plasma heparin levels of around 1.0 IU/ml were maintained during the heparin infusion, declining to 0.71 IU/ml an hour after the infusion was terminated. The LMWH-medium regimen produced very similar plasma aXa levels. The LMWH-high regimen also produced similar plasma aXa levels: therefore, it had no advantage over the LMWH-medium regimen. The LMWH-low regimen produced significantly lower levels than the other regimens during the heparin infusion (0.81-0.85 aXa U/ml, p < 0.025). Dialysis proceeded uneventfully at all times and plasma levels of fibrinopeptide A (FPA) were suppressed well with all 4 regimens (2.77-5.74 pmol/ml) but tended to rise after the infusion was switched off (5.52-8.45 pmol/ml). Plasma FPA levels with the LMWH-low regimen tended to be higher but were statistically indistinguishable from those obtained with the other regimens. We conclude that a LMWH dose regimen comprising a LMWH-saline prime, an initial bolus of 3,000-4,000 aXa U and an infusion of 750 aXa U/h provided effective anticoagulation for patients on maintenance hemodialysis, comparable to that provided by a standard regimen of UFH.