Nutrition in Acute Renal Failure. In: Bellomo R, Ronco C, editors. Acute Renal Failure in the Critically Ill. Berlin: Springer Berlin Heidelberg; 1995. pp. 324-45. [DOI: 10.1007/978-3-642-79244-1_16]

Changing Acute Renal Failure Treatment from Intermittent Hemodialysis to Continuous Hemofiltration: Impact on Azotemic Control

Background

Continuous renal replacement therapy is increasingly used in the management of acute renal failure in critically ill patients. The advantages of continuous renal replacement therapy (CRRT) over intermittent hemodialysis (IHD), however, are not yet fully documented. In particular, it is unknown whether continuous veno-venuous hemodiafiltration (CVVHDF) provides better control of azotemia than IHD.

Objectives

To study the effect on azotemic control of changing acute renal failure treatment from IHD to CVVHDF.

Settings

Tertiary intensive care unit.

Patients

Forty seven consecutive critically ill patients with multiorgan failure and acute renal failure treated with IHD and 47 similar patients treated with CVVHDF.

Methods

Analysis of daily morning urea and creatinine concentrations over the period of renal replacement therapy in the ICU. Statistical comparison of data.

Results

The two groups of patients were comparable for mean age (55 years for IHD vs. 60 years for CVVHDF; NS) and number of failing organs prior to therapy (mean of 4.2 for IHD vs. 3.7 for CVVHDF; NS). Severity of illness at admission as assessed by APACHE II score, however, was greater for patients receiving CVVHDF (29.4 vs 25.7; p<0.003). CVVHDF was associated with a significantly lower plasma urea (p< 0.0001) and serum creatinine (p<0.01) level at 24 hours of treatment despite similar levels at the start of therapy. Throughout the duration of therapy, mean urea levels (35.0 mmol/L for IHD vs 23.4 mmol/L for CVVHDF) and mean serum creatinine levels (513 micromoles/L for IHD and 263 micromoles/L for CVVHDF) showed significantly (p <0.0001) better control of uremia with CRRT.

Conclusions

Changing the form of renal replacement therapy from intermittent hemodialysis to continuous hemofiltration is associated with improved control of azotemia. The superior adequacy of small solute clearance achieved during CVVHDF provides additional support for its preferential use in the management of acute renal failure in the ICU.

Acute renal failure in hospitalized patients: part II

BACKGROUND

Acute renal failure (ARF) is a common condition in hospitalized patients. Research has been unable to identify the optimal target for therapeutic intervention; hence, effective prevention of and/or treatment for ARF remain elusive.

OBJECTIVE

To examine the usefulness of current and potential pharmacologic treatments in seriously ill, hospitalized patients.

DATA SOURCES

A MEDLINE search (1996-June 2002) was conducted using the search terms kidney (drug effects) and acute kidney failure (drug therapy). Bibliographies of selected articles were also examined to include all relevant investigations.

STUDY SELECTION AND DATA EXTRACTION

Review articles, meta-analyses, and clinical trials describing prevention of and treatment for hospital-acquired ARF were identified. Results from prospective, controlled trials were given priority when available.

CONCLUSIONS

Appropriate management of ARF includes prospective identification of at-risk patients, fluid administration, and optimal hemodynamic support. Drug treatments, including low-dose dopamine and diuretics, have demonstrated extremely limited benefits and have not been shown to improve patient outcome. Experimental agents influence cellular processes of renal dysfunction and recovery; unfortunately, relatively few drugs show promise for the future.

New CRRT systems: impact on dose delivery

The evolution of technology and biomaterials has permitted a parallel development of renal replacement therapies in the acute, critically ill patient. From the original description of continuous arteriovenous hemofiltration, new techniques such as continuous venovenous hemofiltration, hemodiafiltration, and high flux dialysis have been developed and clinically used. A parallel improvement in efficiency has been achieved with urea daily clearances as high as 50 L or more. The use of special highly permeable dialyzers has also permitted an increase in the clearances of larger solutes, thus leading to significant removals of chemical substances involved in acute inflammation and sepsis. In this field, recent observations have suggested using hemofiltration with high volumes of fluid exchange. The hardware and software of the newer CRRT systems are key in achieving these results and in safely performing such challenging techniques.