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Dialysis Time (dialysis + time)

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Medical Sciences	100%

Selected Abstracts

Tandem dialyzers with dual monitors to meet Kt/V targets

HEMODIALYSIS INTERNATIONAL, Issue 1 2005
N. Sridhar
Objective:,A large body mass and/or a poorly functioning vascular access predispose to inadequate Kt/V. Double dialyzers in parallel and tandem have been shown to enhance Kt/V to levels recommended by K/DOQI. We experienced difficulties with unintended excessive ultrafitration (UF), positive transmembrane pressure (TMP)-triggered pump stoppage, need for large volume saline infusion (inflating Kt/V), and a high incidence of clotting of the second dialyzer in tandem. Since blood and dialysate flow rates are higher in the tandem configuration, Kt/V should be theoretically higher. We developed a technique of using the tandem configuration with two monitors in which all the UF could be limited to the second dialyzer, the TMP of the two dialyzers independently controlled, TMP reversal eliminated, and saline infusion and unintended UF minimized. Methods:,3 large male patients with AV grafts (AVG) and 2 with tunneled catheters (TC) had 7 treatments (with Kt/V and URR calculated using the stop-flow technique in the last 5) sessions of each of single, double parallel, and tandem configurations. Blood (Qb) and dialysate-flow (Qd) were halved with Y-connectors in the parallel configuration. Qb through both dialyzers and Qd through the second were controlled with the first monitor and Qd (TMP set to near zero) through the first dialyzer controlled with the second monitor using recirculating saline through its blood pump (with the "venous" pressure adjusted using an air-filled syringe) in the tandem configuration. The patient's blood did not circulate through the blood-pump of the first machine. Qd was 500 ml/min through each dialyzer in the single and tandem and 250 ml/min in the parallel configurations. Processed blood volume (dialysis time) was exactly 85 L with AVG and 60 L with TC. Heparin dosage was constant. ANOVA, 2 × k tables, and Neuman-Keuls test were used in analyzing data. Results:,Mean Kt/V (%URR) increased from 1.15 (62) with single to 1.35 (68) with parallel (p < 0.02) and 1.48 (71) with tandem (p < 0.001) dialyzers in patients with AVG but not TC [1.05 (58), 1.02 (55), and 1.25 (64) with single, parallel, and tandem, respectively]. Tandem dialyzers met targets for URR (p < 0.001) and Kt/V ( p < 0.05) more frequently than parallel with AVG but not TC. Conclusions:,Tandem dialyzers with 2 monitors are more successful than parallel dialyzers in delivering target Kt/V and URR when Qb is not compromised. [source]

Fallacies of High-Speed Hemodialysis

HEMODIALYSIS INTERNATIONAL, Issue 2 2003
Zbylut J. Twardowski
Chronic hemodialysis sessions, as developed in Seattle in the 1960s, were long procedures with minimal intra- and interdialytic symptoms. Financial and logistical pressures related to the overwhelming number of patients requiring hemodialysis created an incentive to shorten dialysis time to four, three, and even two hours per session in a thrice weekly schedule. This method spread rapidly, particularly in the United States, after the National Cooperative Dialysis Study suggested that time of dialysis is of minor importance as long as urea clearance multiplied by dialysis time and scaled to total body water (Kt/Vurea) equals 0.95,1.0. This number was later increased to 1.3, but the assumption remained unchanged that hemodialysis time is of minimal importance as long as it is compensated by increased urea clearance. Patients accepted short dialysis as a godsend, believing that it would not be detrimental to their well-being and longevity. However, Kt/Vurea measures only removal of low molecular weight substances and does not consider removal of larger molecules. Besides, it does not correlate with the other important function of hemodialysis, namely ultrafiltration. Whereas patients with substantial residual renal function may tolerate short dialysis sessions, the patients with little or no urine output tolerate short dialyses poorly because the ultrafiltration rate at the same interdialytic weight gain is inversely proportional to dialysis time. Rapid ultrafiltration is associated with cramps, nausea, vomiting, headache, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control, left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. Short, high-efficiency dialysis requires high blood flow, which increases demands on blood access. The classic wrist arteriovenous fistula, the access with the best longevity and lowest complication rates, provides "insufficient" blood flow and is replaced with an arteriovenous graft fistula or an intravenous catheter. Moreover, to achieve high blood flows, large diameter intravenous catheters are used; these fit veins "too tightly," so predispose the patient to central-vein thrombosis. Longer hemodialysis sessions (5,8 hrs, thrice weekly), as practiced in some centers, are associated with lower complication rates and better outcomes. Frequent dialyses (four or more sessions per week) provide better clinical results, but are associated with increased cost. It is my strong belief that a wide acceptance of longer, gentler dialysis sessions, even in a thrice weekly schedule, would improve overall hemodialysis results and decrease access complications, hospitalizations, and mortality, particularly in anuric patients. [source]

Nocturnal Hemodialysis Is Better Than Quotidian Hemodialysis

HEMODIALYSIS INTERNATIONAL, Issue 1 2003
MP Kooistra
Background. It is unknown whether long nocturnal (6,7 times weekly 6,8 hours) hemodialysis (NHD) is better than frequent short hemodialysis (,daily', quotidian hemodialysis, QHD). Methods. A Dutch NHD pilot study (,Nocturne') started in December 2001. We can now evaluate effects of 4 months NHD in 14 patients. Baseline dialysis frequency was 3.5 or less (3.13 ± 0.23, M ± SD) in group A (n = 8), and 4 or more (5.0 ± 0.89) in group B (n = 6), weekly dialysis time was equal in both groups. Results. Single pool Kt/V, being higher in group B at baseline, increased in both groups (A: 3.1 ± 0.8/week to 9.5 ± 2.3, B: 3.8 ± 1.0 to 10.9 ± 4.1). Baseline nPCR, being higher in group B, increased in both groups (A: 1.0 ± 0.3 g/kg/week to 1.4 ± 0.3, and B: 1.2 ± 0.5 to 1.8 ± 0.5). Baseline albumin was higher in group B, and increased in group A (39.6 ± 3.7 g/l to 43.2 ± 1.5), not in B (41.4 ± 2.3 to 42.8 ± 2.3). Target weight increased only in group A (71.8 ± 10.5 kg to 75.3 ± 11.9), not in B (71.4 ± 25.5 to 71.3 ± 26.7). NHD resulted in normophosphatemia in both groups despite phosphate supplementation and cessation of phosphate binders. PTH decreased in both groups (A: 40.6 ± 38.0 pmol/l to 14.4 ± 11.7, B: 35.6 ± 37.7 to 22.4 ± 41.5). In both groups, pre- and postdialysis mean arterial pressure decreased (A: 106.8 ± 7.9 mmHg to 94.4 ± 12.1 and 97.3 ± 9.5 mmHg to 86.3 ± 8.2, B: 102.2 ± 28.4 to 89.4 ± 9.5 and 90.3 ± 26.8 to 82.7 ± 12.9). Antihypertensives were discontinued or markedly reduced. Fatigue, insomnia, prurigo, restlessness, appetite, physical condition, working ability and quality of life (SF36) improved significantly in both groups. Conclusion. This small pilot study suggests that phosphate and PTH control, blood pressure, uremic symptoms and quality of life improve when conventional hemodialysis or QHD patients switch to NHD. Nutritional parameters improve only in the previously conventionally treated group. [source]

Moving Kidney Allocation Forward: The ASTS Perspective

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2009
R. B. Freeman
In 2008, the United Network for Organ Sharing issued a request for information regarding a proposed revision to kidney allocation policy. This plan described combining dialysis time, donor characteristics and the estimated life years from transplant (LYFT) each candidate would gain in an allocation score that would rank waiting candidates. Though there were some advantages of this plan, the inclusion of LYFT raised many questions. Foremost, there was no clear agreement that LYFT should be the main criterion by which patients should be ranked. Moreover, to rank waiting candidates with this metric, long-term survival models were required in which there was no incorporation of patient preference or discounting for long survival times and for which the predictive accuracy did not achieve accepted standards. The American Society of Transplant Surgeons was pleased to participate in the evaluation of the proposal. Ultimately, the membership did not favor this proposal, because we felt that it was too complicated and that the projected slight increase in overall utility was not justified by the compromise in individual justice that was required. We offer alternative policy options to address some of the unmet needs and issues that were brought to light during this interesting process. [source]

The Expanded Criteria Donor Policy: An Evaluation of Program Objectives and Indirect Ramifications

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 7 2006
J. D. Schold
The expanded criteria donor (ECD) policy was formalized in 2002, which defined higher-risk deceased donor kidneys recovered for transplantation. There has not been a comprehensive examination of the impact of policy on the allocation of ECD kidneys, waiting times for transplant, center listing patterns or human leukocyte antigen (HLA) matching. We examined transplant candidates from 1998 to 2004 utilizing a national database. We constructed models to assess alterations in recipient characteristics of ECD kidneys and trends in waiting time and cold ischemia time (CIT) associated with policy. We also evaluated the impact of the proportion of center candidate listings for ECD kidneys on waiting times. Elderly recipients were more likely to receive ECDs following policy (odds ratio = 1.36, p < 0.01). There was no association of decreased CIT or pretransplant dialysis time while increasing HLA mismatching with policy inception. Over one quarter of centers listed <20% of candidates for ECDs, while an additional quarter of centers listed >90%. Only centers with selective listing for ECDs offered reduced waiting times to ECD recipients. The ECD policy demonstrates potential to achieve certain ascribed goals; however, the full impact of the program, reaching all transplant candidates, may only be achieved once ECD listing patterns are recommended and adopted accordingly. [source]