***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: The efficacy and safety of a low molecular weight heparin ( LMWH ) given as a single predialysis bolus injection was compared to st and ard heparin ( SH ) administered with a continuous infusion in a r and omized , 6 month , open follow-up study in 70 patients undergoing hemodialysis . No major bleeding or adverse events were encountered during a total of 4,000 dialysis procedures ( 2,000 with LMWH ) . Clot formation in the extracorporeal circuit was minimal and comparable between the groups at 4 , 13 , and 26 weeks after the start of the study . No accumulation of LMWH anticoagulant activity was noted . It is concluded that the use of LMWH is a safe , effective , and less complex alternative to SH Low molecular weight heparins ( LMWHs ) are used for prevention of clotting in the dialysis circuit . The aim of this trial was to define the optimal dose of a new LMWH and to test the efficiency of a single dose at the start of the session . Fifteen patients were treated according to a double blind and crossover design during 4 blocks of 5 consecutive reviparin doses assigned r and omly as 50 , 60 , 70 , 85 , and 100 IU anti-Xa/kg . Assessment was carried out on screening of fibrin rings or clots in the arterial and venous air traps and on visual detection of fiber in the dialyzer after rinsing . These clinical results were compared to plasmatic anti-Xa activity and thrombin-antithrombin ( TAT ) complex generation . A st and ard dose of 70 IU anti-Xa/kg of nadroparin was used as the control . After a bolus of 50 to 100 IU anti-Xa/kg , the occurrence of fibrin rings and clots in the air traps was dependent on three factors : dose of LMWH , time of the session , and patient status . A bolus of 85 IU anti-Xa/kg of reviparin was effective and safe for sessions of 4 h. For this dose , plasmatic anti-Xa activity was 0.96 + /- 0.28 IU/ml at Hour 2 and 0.82 + /- 0.22 IU/ml at Hour 4 . TAT complexes are good markers of the activation of the coagulation . They did not increase during a 4 h session after a reviparin bolus of 100 IU/kg . For the same LMWH dose , the trial shows a great variability of the clinical effect and anti-Xa activities from one patient to another . A single dose of 85 IU anti-Xa/kg of reviparin can be used at the start of the dialysis session as a loading dose . We advise adapting the dose during the subsequent sessions according to the appearance of the blood circuit . The benefit of monitoring anti-Xa activity and TAT complexes could be tested in a further trial We have performed a dose ranging study of a low MW heparin , Kabi 2165 , during haemodialysis in humans ( n = 16 ) and compared it to a dose of unfractionated commercial heparin that has already been shown to inhibit fibrin formation . Low MW heparin administered as 5000 or 10,000 anti-factor Xa units , s.c . , half an hour prior to the initiation of dialysis was unable to prevent fibrin formation in the dialyser circuit . A single bolus injection of 5000 anti-factor Xa units of low MW heparin given i.v . inhibited fibrin formation , as determined by FPA generation , for up to 4 h and permitted dialysis for 6 h. Such a bolus injection may be useful for short frequent dialyses . Infusion of low MW heparin in the same dosage regimen as unfractionated heparin , 5000 anti-factor Xa units bolus plus 1500 anti-factor Xa units/h , result ed in a progressive rise in heparin , caused by its longer half-life of elimination from the circulation , and almost completely suppressed both FPA generation and fibrin clot formation for 6 h dialysis . From these studies we calculate that infusion of this low MW heparin at a dose of approximately 4000 anti-factor Xa units bolus plus 750 anti-factor Xa units/h should be a useful regimen that will be effective in suppressing fibrin formation during prolonged dialysis , and the plasma anti-factor Xa level of low MW heparin may reflect its ability to inhibit fibrin formation , although exactly comparable anti-factor Xa levels of unfractionated commercial heparin and low MW heparins may not have identical inhibitory effects Ten patients on chronic intermittent hemodialysis treatment received either unfractionated heparin or low molecular weight ( LMW ) heparin K 2165 in a single-blinded r and omized cross-over study to assess : effects on hemostasis and ex vivo platelet functions , and effectiveness , i.e. prevention of fibrin formation in the extracorporeal circuit . The 20 dialysis treatments were without untoward side effects , for both drugs used . The variation in the plasma anti-Xa activities was significantly less during K 2165 treatment than during heparinization . No differences between the drugs were observed regarding the Ivy bleeding time , platelet count and platelet aggregation ( spontaneous , and induced by ADP and collagen ) . Plasma platelet factor 4 levels did not increase under K 2165 to such an extent as under heparin . Both drugs did not influence the plasma levels of beta-thromboglobulin , thromboxane B2 and platelet serotonin content .  K 2165 did not affect platelet adhesion to collagen , in contrast to heparin which substantially inhibited platelet adhesion . Under both treatments , 4 minor clots were observed in 4 artificial kidneys , despite plasma anti-Xa levels in between 0.19 and 0.46 U/ml . K 2165 may therefore be considered as effective an anticoagulant as heparin , with less effects on ex vivo platelet functions BACKGROUND Increased platelet reactivity presages adverse cardiac events . Because both haemodialysis and unfractionated heparin ( UFH ) can increase platelet reactivity , we compared platelet reactivity during haemodialysis when patients were anticoagulated with UFH or enoxaparin . METHODS Patients ( n = 20 ) underwent consecutive haemodialysis sessions with either UFH or enoxaparin in a r and om order . Blood was taken from the arterial end of the haemodialysis circuit at the initiation of haemodialysis before anticoagulation . Subsequently , blood was taken during dialysis from the venous end of the circuit 10 min after treatment with UFH or enoxaparin .  Platelet reactivity was assessed with the use of flow cytometry by determining the capacity of platelets to bind fibrinogen and the surface expression of P-selectin in response to adenosine diphosphate ( ADP , 0 and 0.2 microM ) . Results were compared with the use of two-way repeated measure ANOVA . RESULTS Platelet reactivity in arterial blood obtained at the beginning of dialysis prior to patients being treated with either UFH [ 0.2 microM ADP-induced capacity to bind fibrinogen = 28+/-15 % ( SD ) ] or enoxaparin ( 30+/-18 % ) was similar ( P = 0.15 ) . In contrast , platelet reactivity was less after treatment with enoxaparin compared with UFH ( P = 0.006 ) . The 0.2 microM ADP-induced capacity to bind fibrinogen in venous blood obtained 10 min after anticoagulation was 34+/-11 % after treatment with UFH and 22+/-11 % after treatment with enoxaparin . CONCLUSIONS Anticoagulation with enoxaparin during haemodialysis is associated with less platelet reactivity compared with UFH . Accordingly , enoxaparin use may contribute to a lesser risk of cardiac events in patients with end-stage renal disease treated with haemodialysis Background : Low-molecular-weight heparins offer several advantages over st and ard heparins , but their use for maintenance hemodialysis has been limited in North America because of their higher cost . Our objective was to compare tinzaparin to st and ard heparin during maintenance hemodialysis over an 8-week period , in regard to the visual aspect of the extracorporeal circuit , filter reuse , bleeding and time for compression of vascular access at the end of hemodialysis session , nursing time devoted to anticoagulation administration , level of satisfaction of patients and nurses , and relative cost . Methods : Thirty-two chronic hemodialysis adult patients with peripheral accesses were r and omly divided into two groups in a cross-over design : tinzaparin for 4 weeks followed by st and ard heparin for 4 weeks , or vice versa . Hemodialysis was performed thrice weekly over 3.5–4 h using large surface reused filters . St and ard heparin was administered as an initial bolus of 50–75 units per kilogram followed by an infusion to maintain an activated clotting time ( ACTESTER ) between 150 and 200 s and discontinued 30–45 min before the end of the session . The initial dose of tinzaparin was 3,500 IU anti-Xa for patients usually receiving 7,500 units or less of st and ard heparin , or 4,500 IU anti-Xa for patients receiving more than 7,500 units of st and ard heparin , and it was injected as a bolus in the arterial line at the beginning of hemodialysis . Dosage adjustments were made by increments or decrements of 500 IU . Results : A total of 6 patients did not require any adjustment in their dose of tinzaparin and remained at the initial dose , while the remaining 26 necessitated adjustments of the initial dose of tinzaparin : 20 patients required increments from the initial dose whereas 6 required reductions . For most patients , 27 of them , the st and ard heparin dose was kept at the same level throughout the study period ( since it was their usual regimen and they were in stable medical conditions ) . According to the monitoring scale , the visual aspects of the tubing of the extracorporeal circuit and of the dialyzers at the end of the session were similar for both tinzaparin and st and ard heparin .  The time of compression of the vascular access at the end of the hemodialysis sessions was not significantly different with tinzaparin than with st and ard heparin . However , as indicated below , most patients noted less bleeding ( or oozing ) from their access ( during compression and thereafter , in the few hours after hemodialysis ) with tinzaparin than with st and ard heparin . Clotting was observed more frequently in the arterial and venous bubble traps with tinzaparin than with st and ard heparin . The presence of clot(s ) was observed in the arterial and venous bubble traps in , respectively , 18 ± 12 and 10 ± 6 % of the sessions with tinzaparin , while in , respectively , 3 ± 4 and 2 ± 4 % of the sessions with st and ard heparin ( p < 0.005 ) . Despite a tendency for a reduced reuse number of the dialyzers , the difference did not reach statistical significance . Among the 30 patients who completed the study , 2 reported excessive bleeding from their vascular access with tinzaparin whereas 8 reported such an excessive bleeding  with st and ard heparin .  The level of satisfaction of patients and nurses for tinzaparin was extremely good . The main reasons stated by the patients was reduced bleeding from their access after dialysis . The nurses preferred tinzaparin because of the simplicity and the rapidity of its administration , the lack of monitoring required , and the decreased bleeding/oozing tendency from the vascular access sites . The time spent for anticoagulation during a hemodialysis session was reported as 5 min with st and ard heparin ( if no ACTESTER monitoring ) , 25–30 min with st and ard heparin ( if ACTESTER monitoring required ) , and 1 min with tinzaparin . The cost analysis revealed that although tinzaparin is more than six times more expensive than st and ard heparin , the use of tinzaparin becomes similar to the use of st and ard heparin ( USD 7.33 vs. USD 7.62 Canadian dollars for one hemodialysis session ) if ACTESTER monitoring is performed ( assuming that 22 % of the sessions are routinely monitored and that one ACTESTER device is necessary for 8–10 dialysis stations , as applied in our unit ) . Conclusion : Our experience with tinzaparin was positive : it represents a simple and easy way to offer anticoagulation during maintenance hemodialysis , it seems associated with less postdialysis bleeding , it saves precious nursing time and is widely appreciated by patients and staff In haemodialysis  low-molecular-weight ( LMW ) heparin is increasingly used for anticoagulation . The advantages over unfractionated ( UF ) heparin are the lower bleeding risk and the lack of influence on lipid metabolism . However , no reliable and rapid method is available so far to control the efficacy and safety of LMW heparin during haemodialysis . The specific anti-factor Xa ( aXa ) chromogenic substrate assays are laborious and time consuming . In the present study we have compared chromogenic assay with a  coagulation assay ( heptest ) , which was performed from plasma and whole-blood sample s. The effects were compared with unfractionated heparin during haemodialysis . The aXa activity in the chromogenic S2222 assay ranged between 0.2 and 
    Output:
    
Conclusions .
LMWH is as safe and effective as UFH .