Ladislav Vít

A clinical study to assess the effect of heparin in dialyzer rinsing solutions.

The solution usually recommended for rinsing the blood side, which is an indispensable step in preparing a dialyzer for hemodialysis (HD), contains saline and heparin. The heparin used for rinsing is said to reduce the thrombogenic properties of the dialysis membrane and, hence, also the need for systemic heparinization during the whole procedure. The aim of our study was to establish whether this postulate also applies to polysulphone steam-sterilized dialyzers. To do so, 16 patients on long-term dialysis were randomized into two groups of eight. One group was subsequently treated with polysulphone low-flux dialyzers (F6HPS), the other with polysulphone high-flux dialyzers (F60S). Both groups were examined, in a crossover manner during HD using a dialyzer previously rinsed with 1000 ml of saline plus 2,000 IU of heparin, and during HD using a dialyzer previously rinsed with 500 ml of saline without heparin. Except for the rinsing, HD conditions were completely identical. Blood obtained before HD, and at 15, 60 and 240 min of HD at the dialyzer inlet, was used to determine the activated partial thromboplastin time (to test heparinization control), the thrombin-antithrombin III complex (ELISA, to evaluate coagulation system activation), platelet factor 4 (ELISA, a substance with antiheparin activity), and platelet count. None of the above parameters showed, at any of the collecting intervals, a statistically significant difference between HD with and without heparin with a reduced volume of rinsing solution, or between HD using low- and high-flux dialyzers. It is concluded that heparin used to rinse polysulphone dialyzers before HD has no effect on blood coagulation or on the need for heparin during the procedure.

Tissue-Type Plasminogen Activator (tPA) and Its Inhibitor (PAI-1) in Patients Treated with Continuous Ambulatory Peritoneal Dialysis

Aim: To establish whether the values of two key enzymes of fibrinolysis, tissue-type plasminogen activator (tPA) and its inhibitor (PAI-1), differ between patients treated with continuous ambulatory peritoneal dialysis (CAPD) and healthy volunteers and whether plasma and dialysate tPA and PAI-1 values vary during one exchange of dialysis solution. Methods: A total of 11 patients with chronic renal failure, treated with CAPD during the peritoneal equilibration test (in addition with blood sampling at time 0), and a control group of 11 healthy volunteers were examined. To identify the factors involved in the changes in tPA and PAI-1, 9 CAPD patients were subsequently monitored, in a crossover manner, during dialysis with solutions of 1.36 and 3.86% dextrose and off dialysis. Results: Compared with healthy individuals, CAPD-treated patients showed a significantly lower tPA activity (0.39 vs. 0.81 IU/ml, p < 0.05). Changes in plasma fibrinolysis during one exchange of dialysis solution were characterized mainly by a decrease in PAI-1 concentrations and activities caused by the circadian rhythm of fibrinolysis. To explain, in the crossover part of the study, the values of plasma PAI-1 antigen at time 0 (07.00 h) and at time 2 (09.00 h) were 9.4 versus 6.5 ng/ml with the 1.36% solution (p < 0.05), 8.2 versus 4.9 with the 3.86% solution (p < 0.05), and 14.1 versus 9.1 ng/ml off dialysis (p < 0.01). Compared to baseline (0 ng/ml with 1.36 as well as 3.86% solutions), the levels of PAI-1 antigen in dialysis solution rose, apparently due to local production in the peritoneal cavity, to 0.5 ng/ml (p < 0.05) with the 1.36% solution, to 0.7 (p < 0.05) with the 3.86% solution after a 2-hour dwell time, and to 1.6 (p < 0.05) and 1.3 ng/ml (p < 0.05) after a 4-hour dwell time, respectively. Hence, the different dextrose levels in the dialysis solutions had no effect on the monitored parameters of fibrinolysis. Conclusion: The lower activity of plasma tPA, and the increase in PAI-1 levels in dialysis solutions may contribute to the development of thromboses in CAPD patients and to fibrin formation on the peritoneal surface with consequences such as peritoneal fibrosis.

Fibrinolysis Defect in Long-Term Hemodialysis Patients with Type 2 Diabetes mellitus and Its Relation to Metabolic Disorders

Background/Aims: Patients with chronic renal failure (CRF) secondary to diabetes mellitus show a high incidence of atherosclerosis with its thrombotic complications. Both CRF and type 2 diabetes mellitus (DM2) results in fibrinolysis defects causally related to atherogenesis and thrombogenesis. It is not well known whether or not and, if so, how fibrinolysis is altered in patients with both CRF and DM2. Our study was designed (1) to identify the fibrinolysis defect present in patients with DM2-mediated CRF and treated by long-term hemodialysis (DM2HD), and (2) to establish whether the fibrinolysis defect is related to the metabolic abnormalities observed in CRF or DM2. Methods: Sixteen DM2HD patients and 23 healthy individuals (HI) had their euglobulin clot lysis time (ECLT), and tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) activities (act) and concentrations (ag) assessed before and after standard fibrinolytic stimulus (i.v. administration of 0.4 µg/kg BW 1-deamino-8-D-arginine vasopressin, DDAVP) along with metabolic status markers. Results: DDAVP caused a significant shortening of ECLT, rises in tPA act and ag, and a significant decrease in PAI-1 act. PAI-1 ag declined significantly in HI, but not in DM2HD. A comparison of responses to DDAVP revealed the groups differed significantly in the change in PAI-1 ag. Whereas, in HI, PAI-1 ag decreased by 11.8 ng/ml, no decrease was seen in DM2HD (0.0 ng/ml) (p < 0.0001; medians given; unpaired Wilcoxon’s test). Stepwise regression analysis showed the change in PAI-1 ag was highly group-specific (DM2HD vs. HI, regression coefficient 21.22; partial correlation 0.58; p < 0.0001) and, also dependent on the serum concentrations of apolipoprotein A-I (–32.41; –0.46; p < 0.01) and homocysteine (0.35; 0.36; p < 0.05). Conclusions: Patients with type 2 DM and CRF on long-term hemodialysis have a fibrinolysis defect manifesting itself after standard fibrinolytic stimulus by an insufficient decrease in PAI-1 concentrations. The defect is related to decreased serum levels of apolipoprotein A-I and increased serum levels of homocysteine. The defect might be a factor contributing to accelerated atherosclerosis and thrombotic complications in these patients.

Tissue Factor, Its Pathway Inhibitor, and Metabolic Disturbances in Long-Term Peritoneal Dialysis

Background/Aim: The tissue factor (TF) plays a key role in triggering the coagulation system in vivo. Our study was designed to determine whether or not the plasma levels of TF and its pathway inhibitor (TF pathway inhibitor; TFPI) in patients with chronic renal failure (CRF) treated by peritoneal dialysis (PD) (1) are pathologically altered; (2) differ between diabetics and nondiabetics, and (3) depend on the metabolic disorders associated with CRF and/or diabetes. Methods: Using ELISA, plasma TF and TFPI levels were measured once in 21 PD patients (10 with diabetes, 11 without diabetes) and in 21 healthy subjects. Results: As compared with healthy subjects (TF 282 pg/ml; TFPI 73 ng/ml), both TF and TFPI levels were significantly higher in PD patients with diabetes (485 pg/ml, p < 0.001, and 106 ng/ml, p < 0.01, respectively) and in PD patients without diabetes (480 pg/ml, p < 0,001, and 121 ng/ml, p < 0.001, respectively). The difference between diabetics and nondiabetics was not significant. In stepwise regression analysis, the TF levels depended on serum creatinine (partial correlation 0.39, p < 0.05), glycemia (0.43, p < 0.01), and insulin (–0.43, p < 0.05), and the TFPI levels depended on creatinine (partial correlation 0.67, p < 0.001), apolipoprotein B (0.46, p < 0.01), and plasma fibrinogen (0.43, p < 0.01). Conclusions: CRF patients on PD show increased plasma TF and TFPI levels. There is no difference between diabetics and nondiabetics. The TF and TFPI levels depend significantly on the renal function, as assessed by serum creatinine, and on some metabolic disorders. Elevated TF and TFPI levels may be related to thrombosis and atherosclerosis in CRF patients on PD.

The effect of heparin rinse on the biocompatibility of continuous veno-venous hemodiafiltration.

The aims of our cross-over randomized study were (1) to assess hemostasis in patients with acute renal failure (ARF) and (2) to determine whether or not the generally recommended heparin rinse of the extracorporeal circuit (ECC) prior to the procedure affects thrombogenicity, complement activation, and leukocyte count in blood during continuous venovenous hemodiafiltration (CVVHDF). Eleven critically ill ARF patients were treated, in random order, using CVVHDF in postdilution setup following ECC rinse with saline (A) with heparin at a concentration of 2,000 IU/L (10 procedures), (B) with heparin at a concentration of 10,000 IU/L (7 procedures), and (C) without heparin (9 procedures). Except for the rinse, anticoagulation therapy did not differ in individual patients during the procedures. Blood was withdrawn before, and at minutes 15, 60, and 360, invariably at diafilter inlet and outlet. Compared with healthy individuals, patients showed lower blood thrombocyte counts (153 vs 233*109/L, p<0.01, arithmetic means, Students t test), longer aPTT (44 vs 36 s, p<0.05), higher plasma levels of heparin (0.1 vs 0.0 U/mL, p<0.05), D-dimer (1129 vs 36 ng/mL, p<0.001) and beta-thromboglobulin (BTG) (159 vs 37 U/mL, p<0.001) prior to CVVHDF. The comparison of procedures with different rinsing technique did not reveal any significant difference in their effects on blood thrombocyte and leukocyte counts, aPTT, plasma levels of heparin, BTG, thrombin-antithrombin III complexes, D-dimer, or the C5a complement component. Conclusions: (1) Patients indicated for CVVHDF show impaired hemostasis involving thrombocytes, coagulation, and fibrinolysis, (2) no beneficial effect of heparin rinse on CVVHDF ECC thrombogenicity, complement activation or blood leukocyte counts was demonstrated.