Conventional hemodialysis requires transient systemic anticoagulation to prevent blot clotting after contact with the extracorporeal circuit. However, low molecular weight heparin (LMWH) or unfractioned heparin are contra-indicated in dialysis patients at risk for hemorrhagic complications. In this setting, several procedures theoretically allow dialysis without systemic heparinization, but randomized studies to compare them are lacking. The gold standard is the use of iterative rises of the extra corporeal circuit with isotonic saline ( rises ). Two emerging procedures are increasingly used : continuous pre-dilution of the arterial line ( pre-dilution ) and the use of a specific dialysis membrane (NEPHRAL 400 ST) coated with heparin immediately before use ( heparin adsorption ).~We propose a monocentric prospective randomized open study to compare  rises ,  pre-dilution  and  heparin adsorption  in chronic hemodialysis patients with contra-indication to the use of LMWH. Main criteria will be extra-corporeal circuit clotting, with dialysis efficiency and tolerance as secondary criteria. Comparison will be made on grounds of  n-of-1  trial, i.e. series of randomized cross-over tests in individuals. We have planned to include 75 patients in this study, with 1050 LMWH-free dialysis sessions.~We hope to demonstrate chat by comparison wit rises, pre-dilution and heparin absorption techniques reduce the rate of extra-corporeal circuit by 30 and 50% respectively. We also hope to show that heparin adsorption (i) better preserves membrane integrity throughout the dialysis session, resulting in enhanced dialysis efficiency ; (ii) avoids extra fluid infusion and ultrafiltration, resulting in better dry weigh achievement and better clinical tolerance.
Conventional hemodialysis requires transient systemic anticoagulation to prevent blot clotting after contact with the extracorporeal circuit. However, low molecular weight heparin (LMWH) or unfractioned heparin are contra-indicated in dialysis patients at risk for hemorrhagic complications. In this setting, several procedures theoretically allow dialysis without systemic heparinization, but randomized studies to compare them are lacking. The gold standard is the use of iterative rises of the extra corporeal circuit with isotonic saline ( rises ). Two emerging procedures are increasingly used : continuous pre-dilution of the arterial line ( pre-dilution ) and the use of a specific dialysis membrane (NEPHRAL 400 ST) coated with heparin immediately before use ( heparin adsorption ).