Dialysate bicarbonate variation in maintenance hemodiafiltration patients: Impact on serum bicarbonate,intradialytic hypotension and interdialytic weight gain

Introduction: The dialysate bicarbonate (DB) influences the acid‐base balance in dialysis patients. Very low and high serum bicarbonate (SB) have been related with a higher mortality. Acid‐base balance also has been associated with hemodynamic effects in these patients. The trial aim was to compare the effect of DB concentration variation on SB levels in maintenance hemodiafiltration (HDF) patients and the effect on intradialytic hypotension and interdialytic weight gain. Methods: A prospective study, with 9 months of follow‐up, involving 93 patients, divided in two groups: group 1 and group 2 with a DB of 34 mmol/L and 30 mmol/L, respectively, with monitoring of pre and post HDF SB, intradialytic hypotension, and interdialytic weight gain. Findings: Pre dialysis SB was higher in group 1: median concentration of 22.7 mmol/L vs. 21.1 mmol/L (P < 0.001). Post dialysis SB levels were higher in group 1: median concentration of 28.0 mmol/L vs. 25.3 mmol/L (P < 0.001). Post dialysis SB in alkalotic range was only detected in group 1 (51.2% of the patients). No significant differences were detected in intradialytic hypotension rate [28.0 vs. 27.4 episodes per 1000 sessions in group 1 and 2, respectively, (P = 0.906)] or in average interdialytic weight gain [2.9% vs. 3.0% in group 1 and 2, respectively, (P = 0.710)]. Discussion: DB of 30 mmol/L appears to be associated with SB levels closer to physiological levels than 34 mmol/L. The bicarbonate dialysate, in the tested concentrations, did not appear to have a significant impact on intradialytic hypotension and interdialytic weight gain in maintenance HDF patients.     

On‐line hemodiafiltration at home

Survival with online hemodiafiltration (OL‐HDF) is higher than with hemodialysis; frequent hemodialysis has also improved survival and quality of life. Home hemodialysis facilitates frequent therapy. We report our experience with 2 patients with stage 5 CKD who started home hemodialysis with OL‐HDF in November 2016. After a training period at the hospital, they started home hemodialysis with OL‐HDF after learning how to manage dialysis monitors and how to administer water treatment. We used the “5008‐home” (FMC^©) monitor, and the Acqua C^© (Fresenius Medical Care) for water treatment. Water conductivity was always checked before and during dialysis sessions and was always 2.5 to 3 mS/cm. Water cultures always fulfilled the criteria for ultrapurity. As far as we know, this is the first report on patients receiving OL‐HDF at home. The technique proved to be safe and valid for renal replacement therapy and transfers the benefits of hospital convective therapy to the home setting. Future data will enable us to determine whether survival has also improved.     

Citrate anticoagulation for pediatric continuous venovenous hemodiafiltration

Objective: To describe the use of argatroban in a post‐cardiac operation patient with heparin‐induced thrombocytopenia requiring hemodialysis and continuous veno‐veno hemodialysis (CVVH). Case Summary: A 23‐year-old Caucasian female with heparin‐induced thrombocytopenia developed acute renal failure after cardiovascular surgery. Argatroban was used as a substitute for heparin during hemodialysis and CVVH. Both activated partial thromboplastin time (aPTT) and activated clotting time (ACT) were used to guide the dosage of argatroban. The patient was successfully dialyzed without clotting of the circuit. The dosage required in our patient was much lower than the manufacturer's recommendation. Discussion: Argatroban is a thrombin inhibitor that does not cross react with heparin. It is metabolized by the liver, and dosage adjustment is recommended in patients with severe hepatic impairment. The correct dosage for patient with unstable hemodynamics is not known. Our patient had apparently normal hepatic function at the initiation of dialysis, but the dosage of argatroban recommended by the manufacturer resulted in prolonged elevation of the aPTT and ACT with associated gastrointestinal bleeding. This may be related to hepatic congestion secondary to poor cardiac function and/or severe anasarca. And the dosage of argatroban required during dialysis was much lower than the recommendation. Conclusions: Argatroban is an effective alternative of heparin for CVVH. The correct initial dosage in patients with mild hepatic impairment and unstable hemodynamics is still unclear.     

Online hemodiafiltration: 4 years of clinical experience

Online hemodiafiltration (online HDF) is a new hemodialysis technique combining convection and diffusion and thus also enabling the purification of large molecules. As yet, only a small number of clinical experiences have been published about the effectiveness and safety of online HDF. We present a prospective and observational study conducted on 31 patients treated with online HDF in our center in the last 4 years. The purpose of the study is to compare the evolution of the following aspects before and after starting online HDF: dose of dialysis, purification of medium-sized/large molecules, inflammation, nutrition, Ca-P metabolism, anemia, and intradialytic complications. Online HDF increased Kt/V to 31.0% (p > 0.001) and reduced postdialysis beta(2)-M to 66.4% (p > 0.001). The rest of the parameters analyzed did not vary significantly. During online HDF, episodes of symptomatic hypotension fell by 45% in relation to conventional hemodialysis, and no relevant complication occurred. Online HDF is very useful in patients in whom we need to increase replacement therapy, such as patients with a large body surface, those in whom we suspect a residual syndrome or those who have been receiving dialysis for a long time and for whom we wish to prevent amyloidosis. Online HDF is safe and better tolerated than conventional hemodialysis.     

Convection with conviction-online hemodiafiltration for all: single center clinical observations

Online hemodiafiltration (HDF) has recently become an alternative to conventional hemodialysis for treatment of end-stage renal disease with superior results. Clinical experience with HDF in unselected populations has not been widely published and a longitudinal study on such a group of patients is presented here.     

The anticoagulant activity of enoxaparin sodium during on-line hemodiafiltration and conventional hemodialysis

To study and compare the anticoagulant activity of enoxaparin sodium during on-line hemodiafiltration (OL-HDF) and conventional hemodialysis (C-HD). Enoxaparin was administered as an anticoagulant to 21 hemodialysis patients at the beginning of a single 4-hour OL-HDF session as an intravenous bolus dose of 80 mg/kg. On-line hemodiafiltration was performed using a high-flux polyester polymer alloy dialyzer and a total of 18 L replacement fluid (session A). One week later, the study was repeated in the same patients during a single 4-hour session of C-HD using a low-flux polysulfone dialyzer (session B). Blood samples for the measurement of Hb, blood urea and nitrogen (BUN), activated partial thromboplastin time (APTT), and anti-Xa levels were taken before each study session and 5-minute postdialysis. In 13 more patients, the same study was performed during OL-HDF using a high-flux polysulfone dialyzer (session C). No differences were found between sessions A, B, and C when predialysis values for Hb, BUN, APTT, and anti-Xa were compared. The mean postdialysis APTT and anti-Xa values were 32.5±3.8 seconds and 0.19±0.11 IU/mL, respectively, in session A, 39.0±5.0 seconds and 0.71±0.17 IU/mL in session B, and 33.8±3.1 seconds and 0.35±17 IU/mL in session C (A vs. B, P<0.0001, for both parameters, A vs. C, P<0.003 for anti-XA, and B vs. C, P<0.005, for both parameters). The anticoagulant activity of enoxaparin sodium is decreased significantly during a 4-hour OL-HDF session compared with to a similar session of C-HD. The degree of the reduction seems to depend on the dialyzer's membrane.     

Pharmacokinetics of meprobamate in overdose treated with continuous venovenous hemodiafiltration (CVVHDF)

We report a case of massive suicidal overdose of meprobamate leading to cardiovascular collapse, respiratory failure, and severe central nervous system depression. We observed first‐order elimination kinetics despite significant overdose, and demonstrated effectiveness of continuous venovenous hemodiafiltration (CVVHDF) for extracorporeal removal of meprobamate in this patient. Total body clearance was calculated to be 87 mL/minute, with 64 mL/minute (74%) due to CVVHDF. CVVHDF was stopped after 36 hours, and the patient made an uneventful recovery.     

Platelet activation and clotting cascade activation by dialyzers designed for high volume online hemodiafiltration

Introduction: Hemodialysis patients are pro‐thrombotic. Higher volume online postdilutional hemodiafiltration (OL‐HDF), with increasing hematocrit increases the risk of clotting in the extracorporeal circuit (ECC). We wished to determine whether OL‐HDF increased platelet activation and ECC clotting. Methods: Coagulation parameters, platelet, white cell, and endothelial activation markers were measured at the start and end of dialysis sessions in 10 patients and also pre‐ and post‐dialyzer after 15 minutes using two different dialyzers designed for high volume OL‐HDF; cellulose triacetate (TAGP) and polysulphone (PS), and polyvinylpyrrolidone (PVP). Patients were anticoagulated with a heparin bolus. Findings: At the start of OL‐HDF, D dimers, thrombin antithrombin complexes (TATs), and soluble adhesions molecules (sICAM‐1 and sVCAM‐1) were increased. Post‐treatment soluble P selectin (PS/PVP 26.7 ± 7.1 versus 36.6 ± 9.9; TAGP 28.7 ± 7.2 versus 43.5 ± 8.4 ng/ml, P < 0.001), and soluble CD40 ligand (PS/PVP 297 ± 228 versus 552 ± 272, TAGP 245 ± 187 versus 390 ± 205 ng/ml, P < 0.05) increased. Post‐dialyzer concentrations increased versus pre‐dialyzer for tissue factor (PS/PVP 117 ± 12 versus 136 ± 16, TAGP 100 ± 25 versus 128 ± 40 ng/ml, P < 0.05), factor VIIIc (PS/PVP 174 ± 54 versus 237 ± 83, TAGP 163 ± 60 versus 247 ± 102 IU/ml, P < 0.01), sVCAM‐1 (PS/PVP 782 ± 64 versus 918 ± 140, TAGP 722 ± 121 versus 889 ± 168 ng/ml, P < 0.01), and D‐dimers (PS/PVP 292 ± 132 versus 355 ± 167, TAGP 300 ± 129 versus 391 ± 171 ng/ml, P < 0.001). There was no macroscopic thrombus noted in the ECC, and no increase in microparticles, platelet factor‐4, or TATs. Discussion: Despite being pro‐thrombotic, with activation of platelets, and lymphocytes during passage through ECC, no macroscopic clotting, or increased TATs were noted during OL‐HDF, and no major differences between cellulosic and polysulphone dialyzers.     

Severe carbamazepine intoxication unresponsive to albumin‐enhanced continuous venovenous hemodiafiltration with low dialysate flow

Carbamazepine (CBZ) intoxication can be associated with severe toxicity, including neurological and cardio‐respiratory abnormalities. Highly protein‐bound, CBZ is not removed efficiently through conventional hemodialysis. Charcoal hemoperfusion is the most effective extracorporeal elimination therapy for CBZ intoxication. Recent reports have indicated that continuous venovenous hemodiafiltration (CVVHDF), albumin‐enhanced continuous venovenous hemodialysis, high‐flux hemodialysis and plasma exchange can be as effective as charcoal hemoperfusion. In contrast to recent reports, which demonstrated the effectiveness of CVVHDF with high dialysate flow in CBZ intoxication, we observed that serum CBZ level was decreased minimally by albumin‐enhanced CVVHDF with low dialysate flow. Therefore, albumin‐enhanced CVVHDF with high dialysate flow should be considered in severe CBZ intoxication, if hemoperfusion is unavailable because of the lack of facilities or if it cannot be performed.     

Infective spondylodiscitis in patients on high‐flux hemodialysis and on‐line hemodiafiltration

Infective spondylodiscitis (ISD) is a rare but potentially devastating condition in hemodialysis (HD) patients. Reports are limited especially in patients receiving high‐flux HD and hemodiafiltration (HDF). In a retrospective analysis, 13 patients on our maintenance high‐flux HD/HDF program were identified as having has infective spondylodiscitis over a 10‐year period (1997–2006), an incidence of approximately 1 episode every 215 patient‐years. The incidence was around 3 times higher in patients dialyzing with tunnelled central venous catheters (TCVC) than in those with arteriovenous fistulae. Affected patients were elderly (mean age 70 years) and had multiple comorbidities. Access problems, particularly TCVC infection, were common in the months preceding it's onset. Tunnelled central venous catheter removal during these episodes did not necessarily prevent it. Diagnosis was based on a history of back pain, raised C‐reactive protein, positive blood cultures, and characteristic magnetic resonance findings. Many patients were apyrexial and had normal white cell counts. In our patients on high‐flux HD/hemodiafiltration, its incidence appears comparable to that in conventional HD settings. No patients had infection with waterborne organisms. Blood cultures were positive in 77%. Gram‐positive organisms predominated, particularly Staphylococcus aureus. The major route of infection was hematogenous, with the most likely source the venous access. All received antibiotics for 6 to 12 weeks or until death. Only 2 patients underwent surgical drainage. Mortality was high (46%) and predicted by the development of complications, and by pre‐existing cardiovascular comorbidity. Prevention, using strategies to reduce the prevalence of bacteremia, including limiting the use of TCVC, should be an overriding aim.     

Dialysate saving by automated control of flow rates: comparison between individualized online hemodiafiltration and standard hemodialysis

Cost reduction and quality improvement seem to be conflicting issues. However, online hemodiafiltration (oHDF) with new automatic functions offers a cost‐efficient therapy compared to hemodialysis (HD). Seven dialysis centers conducted a randomized clinical trial with cross‐over design: high‐flux HD vs. postdilutional oHDF with functions coupling both dialysate and substitution flow rates to blood flow rates. During the 6 weeks of the study, all treatment parameters remained unchanged for HD and oHDF, apart from dialysate and substitution flow rate. Treatment data were recorded during each treatment, and predialytic and postdialytic concentrations of urea were recorded at the end of each study phase. The analysis involved 956 treatments of 54 patients. The mean dialysate consumption was 123.2 ± 6.4 l for HD and 113.4 ± 14.9 l for oHDF (p < 0.0001), the mean dialysis dose was 1.42 ± 0.23 for HD and 1.47 ± 0.26 for oHDF (p < 0.0001); oHDF resulted in a lower dialysate consumption (8.0% less) and a slightly increased dialysis dose (Kt/V 3.5% higher) compared to HD. oHDF with the investigated automatic functions offers substantial savings in dialysate consumption without decreasing dialysis dose.     

Experience with continuous venovenous hemodiafiltration in four newborns: A case series and review of the literature

When conventional methods for treating complicated problems such as acute and chronic renal failure or metabolic diseases fail, the therapy of choice is peritoneal dialysis (PD) in neonatal period. However, in cases that involve technical difficulties, such as bulky lesions in the abdomen or complications from previous abdominal surgeries, it is not always possible to place a peritoneal catheter. In such situations, continuous venovenous hemodiafiltration (CVVHDF) can be effective. This case series presents our experience in 2013 with the administration of CVVHDF to four patients in our neonatal intensive care unit who could not undergo PD for various reasons.     

Quantitative analysis of convective dose in hemofiltration and hemodiafiltration: "predilution" vs. "postdilution" reinfusion

In hemofiltration (HF) and hemodiafiltration (HDF), removal of medium and high-molecular-weight solutes is greatly enhanced by convective mechanisms as compared with simple diffusion; increasing convective flows may allow greater removal rates of these solutes. Use of "predilution" (pre-H[D]F) may allow higher ultrafiltration rates than the "postdilution" mode (post-H[D]F); yet, the dilution of plasma water may have unpredictable effects on "endogenous" water convection. We have applied a mathematical analysis to evaluate and compare endogenous water convective flow rates in pre-H(D)F vs. post-H(D)F. Endogenous plasma water recovered in ultrafiltrate was calculated according to patient (hematocrit, total protein level) and session parameters (blood flow, ultrafiltration rate, programmed weight loss), in absolute terms and as a fraction of endogenous plasma water delivery to the filter. Maximally efficient post-H(D)F was modelled according to a preset postfilter hematocrit or filtration fraction. Nomograms were constructed expressing endogenous water convective fluxes in relation to parameters of interest (ultrafiltration rate, blood flow, hematocrit) with both post-H(D)F and pre-H(D)F, and "efficiency" of pre-H(D)F vs. post-H(D)F (as the ratio of endogenous water convective flow rate with the 2 techniques) as a function of the ultrafiltration/reinfusion rate. In post-H(D)F, the model predicts maximal ultrafiltration rates within the limits of a preset hemoconcentration at the filter outlet; additionally, the model allows to calculate ultrafiltration/reinfusion quantities to be set in pre-H(D)F to equal and overcome maximal convective efficiency of post-H(D)F. This "equivalence" ultrafiltration rate may greatly vary according to patient's hematocrit and blood flow, so that the ultrafiltrate-reinfusate volume available in the system dictates, in any patient, which mode of reinfusion may attain higher "endogenous" convective flow rates. Pre-H(D)F may allow higher fractional and absolute "endogenous" convective flow rates as compared with post-H(D)F, provided that adequate amounts of reinfusate are available. For lower reinfusate volumes than "equivalence" values, post-H(D)F remains a better option.