Intermittent versus continuous renal replacement therapy for acute renal failure in adults: Cochrane systematic review

Abstract

Assessed as up to date: 2007/05/14

Background

Renal replacement therapy (RRT) for acute renal failure (ARF) can be applied intermittently (IRRT) or continuously (CRRT). It has been suggested that CRRT has several advantages over IRRT including better haemodynamic stability, lower mortality and higher renal recovery rates.

Objectives

To compare CRRT with IRRT to establish if any of these techniques is superior to each other in patients with ARF.

Search strategy

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL). Authors of included studies were contacted, reference lists of identified studies and relevant narrative reviews were screened. Search date: October 2006.

Selection criteria

RCTs comparing CRRT with IRRT in adult patients with ARF and reporting prespecified outcomes of interest were included. Studies assessing CAPD were excluded.

Data collection and analysis

Two authors assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as risk ratios (RR) for dichotomous outcomes or mean difference (MD) for continuous data with 95% confidence intervals (CI).

Main results

We identified 15 studies (1550 patients). CRRT did not differ from IRRT with respect to in-hospital mortality (RR 1.01, 95% CI 0.92 to 1.12), ICU mortality (RR 1.06, 95% CI 0.90 to 1.26), number of surviving patients not requiring RRT (RR 0.99, 95% CI 0.92 to 1.07), haemodynamic instability (RR 0.48, 95% CI 0.10 to 2.28) or hypotension (RR 0.92, 95% CI 0.72 to 1.16) and need for escalation of pressor therapy (RR 0.53, 95% CI 0.26 to 1.08). Patients on CRRT were likely to have significantly higher mean arterial pressure (MAP) (MD 5.35, 95% CI 1.41 to 9.29) and higher risk of clotting dialysis filters (RR, 95% CI 8.50 CI 1.14 to 63.33).

Authors' conclusions

In patients who are haemodynamically stable, the RRT modality does not appear to influence important patient outcomes, and therefore the preference for CRRT over IRRT in such patients does not appear justified in the light of available evidence. CRRT was shown to achieve better haemodynamic parameters such as MAP. Future research should focus on factors such as the dose of dialysis and evaluation of newer promising hybrid technologies such as SLED. Triallists should follow the recommendations regarding clinical endpoints assessment in RCTs in ARF made by the Working Group of the Acute Dialysis Quality Initiative Working Group.

Author(s)

Rabindranath Kannaiyan S, Adams James, MacLeod Alison M, Muirhead Norman

Summary

Intermittent versus continuous renal replacement therapy for acute renal failure in adults

Acute renal failure (ARF) is an abrupt reduction in kidney function with elevation of blood urea nitrogen (BUN) and plasma creatinine and a fall in urine output. In most cases correction of the underlying cause leads to recovery, however for many some form of renal replacement therapy (RRT - a treatment that removes waste products, salts and excess water form the body) may be required. RRT can either be intermittent (IRRT- performed for less than 24 hours in each 24 hour period, two to seven times per week) or continuous (CRRT- performed continuously without any interruption throughout each day). It has been suggested that CRRT has several advantages over IRRT including better haemodynamic stability (blood pressure control and blood circulation), improved survival and greater likelihood of renal recovery. Our systematic review identified 15 randomised studies with 1550 patients comparing CRRT with IRRT. We did not find any difference between CRRT and IRRT with respect to mortality, renal recovery, and risk of haemodynamic instability or hypotension episodes.

Reviewer's Conclusions

Implications for practice

In patients with ARF who are haemodynamically stable, the RRT modality does not appear to influence important patient outcomes and therefore the preference for CRRT over IRRT in such patients does not appear to be justified in the light of available evidence. In haemodynamically unstable patients, CRRT may however be preferable as patients on CRRT appear to achieve higher MAP and show a trend towards lesser need for escalation of vasopressor therapy and arrhythmias.

Implications for research

Future research should focus on factors such as the dose of dialysis and evaluation of newer promising hybrid technologies such as SLED. Triallists should also endeavour to follow the recommendations regarding clinical endpoints assessment in RCTs in ARF made by the Working Group of the Acute Dialysis Quality Initiative Working Group. All studies should endeavour to use common definitions for ARF and outcomes such as hypotension. The Acute Renal Failure Trial Network study aims to recruit 1164 patients with ARF the design of the study is intended to deliver data on comparison between low and high dose of dialysis using both IRRT and CRRT techniques. The Augmented Versus Normal Renal Replacement Therapy in Severe Acute Renal Failure study by The Australia and New Zealand Intensive Care Group will compare CVVHDF at a dose of 25 or 40 mL/kg/h in 1500 patients. These two large RCTs that are under way look very promising in providing clinicians with robust data that will help deliver the most appropriate RRT strategies for patients with ARF.

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