MUNICH—The current thinking on hemodialysis for acute renal failure has been challenged by new data showing that daily treatment may be better than conventional alternate-day therapy. Schiffl et al[1] compared the two approaches in 160 critically ill patients with acute renal failure and found that mortality was lower with daily hemodialysis.

Daily hemodialysis was also associated with quicker recovery from acute renal failure, more effective control of uremia, and fewer hypotensive episodes. In addition, the conventional dialysis group had a higher incidence of systemic inflammatory response syndrome (SIRS) or sepsis, respiratory failure, gastrointestinal (GI) bleeding, or progression to oliguric acute renal failure than did the daily dialysis group.

Although these findings bolster the argument of those in favor of more hemodialysis, several factors in the study’s design limit the applicability of its results to many intensive care units (ICUs). Among these, says Joseph V. Bonventre, MD, PhD, in an editorial that accompanies the report by Schiffl et al, are the study’s nonrandom allocation of patients, the comparatively mild severity of the patients’ illnesses, and the inadequacy of the dialysis regimen in the conventional group.[2] Dr. Bonventre is not yet ready to recommend a daily regimen instead of conventional therapy for the critically ill patient with acute renal failure.

“The study is important, but it was small and may not truly reflect this population,” Dr. Bonventre, the Robert H. Ebert Professor of Molecular Medicine at Harvard University, told PULMONARY REVIEWS. The typical ICU patient with acute renal failure is much more severely ill and often requires continuous hemodialysis, rather than the intermittent methods used in the Schiffl study, he explained. “Those who received alternate-day therapy were not terribly well dialyzed,” he added, “so the study may only be comparing inadequate to adequate hemodialysis.”

Nevertheless, the study is useful in that it raises an important question: Can better approaches to dialysis lower the high mortality rates associated with acute renal failure? The results of Schiffl et al suggest that they can.

To be included in the Schiffl study, which was conducted at the University of Munich, patients had to have a diagnosis of severe acute tubular necrosis due to recent ischemia or nephrotoxicity. It also had to be expected that they would need at least one week of intermittent hemodialysis. Subjects were enrolled consecutively and assigned to daily or conventional hemodialysis in alternating order.

The hemodialysis indications were volume overload, electrolyte imbalance, uremic symptoms, acid-base disturbances, and, for some, a blood urea nitrogen level higher than 100 mg/dL. Hemodialysis was discontinued after partial recovery of renal function (ie, restoration of diuresis, absence of uremia, and improved electrolyte and acid-base homeostasis).

Fourteen patients did not complete the study, leaving 74 in the daily hemodialysis group and 72 in the conventional treatment group. The two groups were similar in age, sex, cause and severity of acute renal failure, APACHE III score, and proportion of patients in a medical (vs a surgical) ICU. Both groups received significantly smaller hemodialysis doses than were prescribed.

The mean time-averaged blood urea nitrogen and serum creatinine levels were 60 and 5.3 mg/dL, respectively, in the daily hemodialysis group and 104 and 9.5 mg/dL, respectively, in the conventional treatment group, demonstrating better uremia control with daily hemodialysis. On average, hypotension occurred during only 5% of daily hemodialysis sessions but during 25% of conventional treatment sessions.

In comparison to conventional treatment, daily hemodialysis was also associated with lower rates of SIRS or sepsis (22% vs 46%), respiratory failure (35% vs 69%), mental status changes (38% vs 69%), and GI bleeding (15% vs 36%). Among patients who had normal urine output initially, only 21% of those who received daily hemodialysis developed oliguria, compared with 73% of those given conventional treatment. The average time to recovery of renal function was significantly shorter with daily hemodialysis—nine days vs 16 days with conventional treatment.

When the investigators calculated mortality at 14 days after the completion of hemodialysis using the intention-to-treat approach, they found rates of 28% in the daily treatment group and 46% in the conventional treatment group. Among patients who completed the study, 26% of those who received daily hemodialysis died, compared with 43% of those given conventional treatment. In a multiple logistic regression analysis, sepsis at enrollment and greater illness severity demonstrated a negative effect on survival, whereas normal urine output at enrollment and daily hemodialysis showed a positive effect.

“We suggest that daily hemodialysis be prescribed for the treatment of hypercatabolic or oliguric or anuric acute renal failure,” the investigators conclude. However, larger and more representative studies in which both groups are adequately dialyzed are necessary before such a recommendation can be made, Dr. Bonventre said.

—Timothy Begany

References
1. Schiffl H, Lang SM, Fischer R. Daily hemodialysis and the outcome of acute renal failure. N Engl J Med. 2002;346:305-310.
2. Bonventre JV. Daily hemodialysis—will treatment each day improve the outcome in patients with acute renal failure? N Engl J Med. 2002;346:362-364.

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