Current worldwide practice of dialysis dose prescription in acute renal failure

PURPOSE OF REVIEW

The practice of renal replacement therapy for acute renal failure varies greatly around the world. This is especially true for the dose of renal replacement therapy. This review describes the epidemiology of dialysis prescription and delivery around the world based on recent observational studies and international surveys. Furthermore, a brief speculation on the concept of adequacy of therapy is provided.

RECENT FINDINGS

Following the publication of the first large prospective randomized trial on the effects of treatment dose on outcome of patients with acute renal failure a certain consensus has been achieved on the adequacy of 35 ml/kg/h of clearance in continuous therapies. Surveys conducted in 1998 had demonstrated that such adequate therapy was only prescribed in a minority of patients. Recent observations based on questionnaires and surveys confirm that the number of centers prescribing adequate dialysis dose is increasing, but there is still a large number of institutions where prescription is made with no specific adequacy targets and effective delivery is not measured. Several barriers have been identified to reach adequacy targets including logistics, costs, personnel and others.

SUMMARY

The analysis of the epidemiology of dialysis dose around the world shows a complex picture. Wide variations in practice are present although a significant effort has been made to standardize the prescription and delivery of therapy.

Renal replacement II: dialysis dose

Improved survival of critically ill acute renal failure patients can be correlated with therapy dose. The overall solute elimination can be measured by the product of clearance and time (Kt), which is usually normalized for the volume of distribution (V) of the solute as "Kt/V." Setting a Kt/V threshold of 1.4 can guide clinicians toward adequate treatment. This is a slightly higher prescription than the current value for chronic dialysis. However, the true uraemic toxins probably diffuse among body compartments less readily than urea and, as such, the frequency of renal replacement therapy should be more important to its efficiency, and should be optimal with continuous therapy. In the absence of an optimal dialysis dose, it can only be recommended that the prescription should exceed that calculated to be "adequate."

Outcomes research in acute renal failure

Acute renal failure (ARF) is associated with morbidity and mortality in excess of 50% in the intensive care unit (ICU) setting. A variety of outcome measures have been described in published reports of ARF, however, the studies often do not distinguish between clinical outcomes and surrogate endpoints. Multiple factors can influence these outcomes, including variations in practice. It is important to be aware of the potential effects of these factors when clinical trials are planned and executed for ARF patients. For any intervention trial, knowledge of the natural history of the disease and process of care informs the design and conduct of the trial. Standardization of a definition for ARF and of the criteria for initiation, frequency, duration, and withdrawal of dialysis support would be of great benefit. This article provides a critical appraisal of outcomes research in ARF and describes an approach for selecting appropriate endpoints for future clinical research in ARF.

The first international consensus conference on continuous renal replacement therapy

BACKGROUND

Management of acute renal failure (ARF) in the critically ill is extremely variable and there are no published standards for the provision of renal replacement therapy in this population. We sought to review the available evidence, make evidence-based practice recommendations, and delineate key questions for future study.

METHODS

We undertook an evidence-based review of the literature on continuous renal replacement therapy (CRRT) using MEDLINE searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated practice guidelines and/or directions for future research.

RESULTS

Of the 46 questions considered, we found consensus for 20. We found inadequate evidence for 21 questions and for the remaining five we found data but no consensus. Full versions of workgroup findings are available on the Internet at http://www.ADQI.net.

CONCLUSIONS

Despite limited data, broad areas of consensus exist for use of CRRT and guideline development appears feasible. Equally broad areas of disagreement also exist and additional basic and applied research in acute renal failure is needed.

The Acute Dialysis Quality Initiative--part III: solute control (treatment dose)

One of the most important advances in chronic dialysis therapy was the establishment of a method for determining delivered dose. There has been a meaningful relationship between higher delivered dialysis dose and improved outcome in the end-stage renal disease (ESRD) patient. The question of establishing a similar dialysis dose method in the patients with acute renal failure (ARF) is hampered with several specific issues to the ARF patient. The state of catabolism in ARF is not eubolic, but rather catabolic. Patient volume or urea space is highly variable among ARF patients and even within the same patient over very short periods of time. Finally, there are comorbidities that play a major role in both the ultimate patient outcome and the generation of many of the indicators used in dialysis dose generation. Thus, the mere transition from the ESRD dose methodology, where these issues are quite stable, to the ARF population is not an easy process. It is, however, of utmost importance that a dose methodology be established. Only after will we be able to address the dose/outcome relationship. The current article reviews what is known, what is theorized and what needs to be established in an effort to determine a dialysis dose methodology in ARF patients.

Acute renal failure in severely burned patients

Acute renal failure (ARF) is a well known complication of severe burns and is an important factor leading to an increase in mortality. In order to analyze possible pathogenetic and prognostic factors associated with ARF in burned patients we reviewed in a retrospective study the files of 328 patients with burns > 10% body surface area (BSA), admitted to our burn unit between 01.01.94 and 01.05.98. We found 48 patients with acute renal failure corresponding with an incidence of 14.6%. Patients with ARF had a mean burned surface area of 48% (13-95) and an abbreviated burn severity index score (ABSI) of 9.8 (4-15). Thirty eight (79%) of these patients had an inhalation injury diagnosed. Renal insufficiency was divided in a late and an early form depending on its time of onset and we found 15 (31%) patients with ARF occurring within the first 5 days of the hospital stay and 33 (69%) patients with ARF developing >5 days following the thermal injury. The incidence of myoglobinuria and hypotension during the resuscitation phase was significantly higher in the group with early ARF, whereas patients with late ARF presented sepsis more frequently than patients with early occurring renal failure. Accordingly, potential nephrotoxic antibiotics were administered more often in patients with late ARF. Patients with ARF were treated by continuous arteriovenous hemofiltration (CAVH) for a mean period of 10.5 days (1-47) and CAVH was associated with a complication rate of 10%. Most of the complications were associated with the vascular access in the femoral artery. The mortality rate in patients with ARF was 85% and death was due to multiple organ failure in 83% of the cases. Only burned BSA and inhalation injury proved to be significantly correlated with the development of ARF, whereas age, third degree burn or electric injury were not significantly different between the two groups. Neither age, TBSA, day of onset of ARF nor duration of the renal replacement therapy proved to be significantly different comparing survivors with non-survivors, and thus predictive for the survival rate.