Short Duration-High Area Regular Dialysis Using Two UF 2 Coils in Series

2006

Blood Purif

Chronic hemodialysis sessions, as developed in Seattle in the 1960s, were long procedures with minimal intra- and interdialytic symptoms. Over the next three decades, dialysis duration was shorten to 4, 3, even 2 h in thrice weekly schedules. This method spread rapidly, particularly in the United States, after the National Cooperative Dialysis Study suggested that the time of dialysis is of minor importance as long as urea clearance multiplied by dialysis time and scaled to total body water (Kt/V_urea) equals 0.95–1.0. This number was later increased to 1.3, but the assumption that hemodialysis time is of minimal importance remained unchanged. However, Kt/V_urea measures only the removal of low molecular weight substances and does not consider the removal of larger molecules. Nor does it correlate with the other important function of hemodialysis, namely ultrafiltration. 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 leading to left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. Kt/V_urea should be abandoned as a measure of dialysis quality. The formula suggests that it is possible to decrease t as long as K is proportionately increased, but this is not true. Time of dialysis should be adjusted in such a way that patients would not suffer from symptoms related to rapid ultrafiltration, would not have other uremic symptoms and most patients would have blood pressure controlled without antihypertensive drugs.

Section: Justification For Short Dialysismentioning

confidence: 99%

Treatment Time and Ultrafiltration Rate Are More Important in Dialysis Prescription than Small Molecule Clearance

2006

Blood Purif

“…In the past, residual renal function was considered important for dialysis prescription . Twardowski reported that patients with urine output over 500 mL/24 hours could achieve clinically adequate dialysis in 12 hours per treatment based on twice‐weekly schedule; however, patients with lower urine output required three or more dialysis per week .…”

Section: Residual Renal Functionmentioning

confidence: 99%

“…In the past, residual renal function was considered important for dialysis prescription. 38,39 Twardowski reported that patients with urine output over 500 mL/24 hours could achieve clinically adequate dialysis in 12 hours per treatment based on twice-weekly schedule; however, patients with lower urine output required three or more dialysis per week. 23 The residual renal function measured by creatinine clearance was also correlated with clinical status in patients dialyzed twice weekly for 12 hours in each session, but the correlation was inferior to that found for simple urine output.…”

Section: Residual Renal Functionmentioning

confidence: 99%

A need for a paradigm shift in focus: From Kt/V_urea to appropriate removal of sodium (the ignored uremic toxin)

Hemodialysis International

Misra

2018

Hemodialysis for chronic renal failure was introduced and developed in Seattle, WA, in the 1960s. Using Kiil dialyzers, weekly dialysis time and frequency were established to be about 30 hours on 3 time weekly dialysis. This dialysis time and frequency was associated with 10% yearly mortality in the United States in 1970s. Later in 1970s, newer and more efficient dialyzers were developed and it was felt that dialysis time could be shortened. An additional incentive to shorten dialysis was felt to be lower cost and higher convenience. Additional support for shortening dialysis time was provided by a randomized prospective trial performed by National Cooperative Dialysis Study (NCDS). This study committed a Type II statistical error rejecting the time of dialysis as an important factor in determining the quality of dialysis. This study also provided the basis for the establishment of the Kt/Vurea index as a measure of dialysis adequacy. This index having been established in a sacrosanct randomized controlled trial (RCT), was readily accepted by the HD community, and led to shorter dialysis, and higher mortality in the United States. Kt/Vurea is a poor measure of dialysis quality because it combines three unrelated variables into a single formula. These variables influence the clinical status of the patient independent of each other. It is impossible to compensate short dialysis duration (t) with the increased clearance of urea (K), because the tolerance of ultrafiltration depends on the plasma‐refilling rate, which has nothing in common with urea clearance. Later, another RCT (the HEMO study) committed a Type III statistical error by asking the wrong research question, thus not yielding any valuable results. Fortunately, it did not lead to deterioration of dialysis outcomes in the United States. The third RCT in this field (“in‐center hemodialysis 6 times per week versus 3 times per week”) did not bring forth any valuable results, but at least confirmed what was already known. The fourth such trial (“The effects of frequent nocturnal home hemodialysis”) too did not show any positive results primarily due to significant subject recruitment issues leading to inappropriate selection of patients. Comparison of the value of peritoneal dialysis and HD in RCTs could not be completed because of recruitment problems. Randomized controlled trials have therefore failed to yield any meaningful information in the area of dose and or frequency of hemodialysis.

“…Barth [7] argued that at least three factors were necessary to make it possible: technical feasibility, economic incentives, and medical/scientific justification. Ari et al [9] compared 7-hr dialysis twice weekly or 6-hr thrice weekly dialysis on a UF 145 with 3.5-hr twice a week or 3-hr three times a week with two UF 2 coils in series (2 m 2 ), respectively. Shortly thereafter, more efficient dialyzers were designed.…”

Section: Justification For Short Dialysismentioning

confidence: 99%

“…Additionally, more efficient coil and parallel plate dialyzers were devel-oped in the early 1970s, so removal of uremic toxins seemed to be possible in short-duration dialysis. Ari et al [9] compared 7-hr dialysis twice weekly or 6-hr thrice weekly dialysis on a UF 145 with 3.5-hr twice a week or 3-hr three times a week with two UF 2 coils in series (2 m 2 ), respectively. They found no differences between the pairs.…”

Section: Justification For Short Dialysismentioning

confidence: 99%

Fallacies of High‐Speed Hemodialysis

Hemodialysis International

2003

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/V(urea)) 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/V(urea) 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.