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Renal replacement therapy in acute renal failure
Renal replacement therapy in acute renal failure In their randomised study, C Vinsonneau and colleagues (July 29, p 379)1 found that continuous venovenous haemodiafiltration was no better than intermittent haemodialysis for patients with acute renal failure. Previous studies2,3 suggested a better haemodynamic stability by use of the continuous technique. Vinsonneau and colleagues claim that all treatments were done with the same membrane polymer (polyacrylonitrile AN69). However, during the study, the manufacturer (Hospal, France) provided a new membrane: the AN69ST. This membrane differs from the AN69 membrane in that it is coated with polyethyleneimine, which neutralyses its surface electronegativity. This process strongly modifies the membrane’s adsorptive properties, decreasing blood generation of kinins4 and allowing binding of heparin.5 According to the manufacturer’s information, intermittent dialysers equipped with this new membrane were available on March 1, 1999, and the AN69 manufacturing process was stopped on Sept 1, 2001. The production of AN69 filters for continuous haemodiafiltration was maintained throughout. This information suggests that about half the intermittent dialysers in Vinsonneau and colleagues’ study were equipped with the AN69ST, particularly in the late phase of the study. Thus, the homogeneity of the group of patients treated with intermittent haemodialysis is questionable. Vinsonneau and colleagues indicate that “during the study, the survival rate in the intermittent haemodialysis group increased progressively and significantly”, which could be explained by hypothetical “improvements in standards of care during the study”. This hypothesis seems very weak. We wonder whether the change in www.thelancet.com Vol 368 October 28, 2006
intermittent haemodialysis membrane could be a more rational explanation: stratification analysis of subgroups of patients (AN69 vs AN69ST) could shed some light on this question. We declare that we have no conflict of interest.
*Jacques Chanard, Alain Wynckel, Philippe Rieu [email protected] Service de Néphrologie, Centre Hospitalier Universitaire, 51092 Reims, France 1
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Vinsonneau C, Camus C, Combes A, et al. Continuous venovenous haemodiafiltration versus intermittent haemodialysis for acute renal failure in patients with multiple-organ dysfunction syndrome: a multicentre randomised trial. Lancet 2006; 368: 379–85. Mehta RL, McDonald B, Gabbai E, et al. Continuous versus intermittent dialysis for acute renal failure (ARF) in the ICU: results from a randomized multicenter trial. Kidney Int 2001; 60: 1154–63. Augustine JJ, Sandy D, Seifert TH, Paganini EP. A randomized controlled trial comparing intermittent with continuous dialysis in patients with ARF. Am J Kidney Dis 2004; 44: 1000–07. Renaux JL, Thomas M, Crost T, Loughraieb N, Vantard G. Activation of the kallikrein-kinin system in hemodialysis. Role of membrane electronegativity, blood dilution and pH. Kidney Int 1999; 55: 1097–103. Chanard J, Lavaud S, Paris B, et al. Assessement of heparin binding to the AN69 ST hemodialysis membrane, I—preclinical studies. ASAIO J 2005; 51: 342–47.
The study by C Vinsonneau and colleagues1 shows that the mere extrapolation of dialysis prescription from end-stage renal disease to severe acute renal failure results in underdialysis of critically ill patients, who are not adapted to acute uraemia or hypervolaemia. Vinsonneau and colleagues also show that advanced intermittent haemodialysis techniques might improve survival of critically ill patients, if provided on a daily basis. By excluding moribund patients and patients with low severity scores, Vinsonneau and colleagues preselected a population that was more likely to benefit from more intensive intermittent haemodialysis. The data corroborate a relation between dialysis dose and mortality in patients with acute renal failure.2 The question of superiority of one mode over the other cannot be
answered by Vinsonneau and colleagues’ trial, given the lack of strict treatment prescription (possible confounders) and given its limited power. Ronco and colleagues3 showed lower mortality rates in non-septic or septic patients with much higher filtration volumes than those reported by Vinsonneau and colleagues. Whereas Ronco and colleagues treated their patients in intensive care with postdilution haemofiltration, Vinsonneau and colleagues did predilution haemodiafiltration, resulting in a lower urea clearance at the same filtration volume. Vinsonneau and colleagues based the decision to start renal replacement therapy mainly on biochemical variables. However, overreliance on surrogate markers of glomerular filtration rate can lead to delayed recognition of acute renal failure and underestimation of its severity, particularly in non-oliguric patients. It has been suggested that early initiation of renal replacement therapy could reduce mortality in patients with acute renal failure.4 As shown by Vinsonneau and colleagues, advanced intensive care techniques should be tailored to patients’ needs.
The printed journal includes an image merely for illustration
We declare that we have no conflict of interest.
*H Schiffl, S M Lang hschiffl@hotmail.com KfH Renal Centre Munich-Laim, Elsenheimerstrasse 63, 80687 Munich, Germany (HS); and Medizinische Klinik, University of Munich, Munich, Germany (SML) 1
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Vinsonneau C, Camus C, Combes A, et al. Continuous venovenous haemodiafiltration versus intermittent haemodialysis for acute renal failure in patients with multipleorgan dysfunction syndrome: a multicentre randomised trial. Lancet 2006; 368: 379–85. Schiffl H, Lang SM, Fischer R. Daily hemodialysis and the outcome of acute renal failure. N Engl J Med 2002; 346: 305–10. Ronco C, Bellomo R, Homel P, et al. Effects of different doses in continuous veno-venous haemofiltration on outcomes of acute renal failure: a prospective randomised trial. Lancet 2000; 356: 26–30. Liu KD, Himmelfarb J, Paganini E, et al. Timing of initiation of dialysis in critically ill patients with acute renal injury. Clin J Am Soc Nephrol 2006; 1: 915–19.
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Correspondence
intermittent haemodialysis membrane could be a more rational explanation: stratification analysis of subgroups of patients (AN69 vs AN69ST) could shed some light on this question. We declare that we have no conflict of interest.
*Jacques Chanard, Alain Wynckel, Philippe Rieu [email protected] Service de Néphrologie, Centre Hospitalier Universitaire, 51092 Reims, France 1
2
3
4
5
Vinsonneau C, Camus C, Combes A, et al. Continuous venovenous haemodiafiltration versus intermittent haemodialysis for acute renal failure in patients with multiple-organ dysfunction syndrome: a multicentre randomised trial. Lancet 2006; 368: 379–85. Mehta RL, McDonald B, Gabbai E, et al. Continuous versus intermittent dialysis for acute renal failure (ARF) in the ICU: results from a randomized multicenter trial. Kidney Int 2001; 60: 1154–63. Augustine JJ, Sandy D, Seifert TH, Paganini EP. A randomized controlled trial comparing intermittent with continuous dialysis in patients with ARF. Am J Kidney Dis 2004; 44: 1000–07. Renaux JL, Thomas M, Crost T, Loughraieb N, Vantard G. Activation of the kallikrein-kinin system in hemodialysis. Role of membrane electronegativity, blood dilution and pH. Kidney Int 1999; 55: 1097–103. Chanard J, Lavaud S, Paris B, et al. Assessement of heparin binding to the AN69 ST hemodialysis membrane, I—preclinical studies. ASAIO J 2005; 51: 342–47.
The study by C Vinsonneau and colleagues1 shows that the mere extrapolation of dialysis prescription from end-stage renal disease to severe acute renal failure results in underdialysis of critically ill patients, who are not adapted to acute uraemia or hypervolaemia. Vinsonneau and colleagues also show that advanced intermittent haemodialysis techniques might improve survival of critically ill patients, if provided on a daily basis. By excluding moribund patients and patients with low severity scores, Vinsonneau and colleagues preselected a population that was more likely to benefit from more intensive intermittent haemodialysis. The data corroborate a relation between dialysis dose and mortality in patients with acute renal failure.2 The question of superiority of one mode over the other cannot be
answered by Vinsonneau and colleagues’ trial, given the lack of strict treatment prescription (possible confounders) and given its limited power. Ronco and colleagues3 showed lower mortality rates in non-septic or septic patients with much higher filtration volumes than those reported by Vinsonneau and colleagues. Whereas Ronco and colleagues treated their patients in intensive care with postdilution haemofiltration, Vinsonneau and colleagues did predilution haemodiafiltration, resulting in a lower urea clearance at the same filtration volume. Vinsonneau and colleagues based the decision to start renal replacement therapy mainly on biochemical variables. However, overreliance on surrogate markers of glomerular filtration rate can lead to delayed recognition of acute renal failure and underestimation of its severity, particularly in non-oliguric patients. It has been suggested that early initiation of renal replacement therapy could reduce mortality in patients with acute renal failure.4 As shown by Vinsonneau and colleagues, advanced intensive care techniques should be tailored to patients’ needs.
The printed journal includes an image merely for illustration
We declare that we have no conflict of interest.
*H Schiffl, S M Lang hschiffl@hotmail.com KfH Renal Centre Munich-Laim, Elsenheimerstrasse 63, 80687 Munich, Germany (HS); and Medizinische Klinik, University of Munich, Munich, Germany (SML) 1
2
3
4
Vinsonneau C, Camus C, Combes A, et al. Continuous venovenous haemodiafiltration versus intermittent haemodialysis for acute renal failure in patients with multipleorgan dysfunction syndrome: a multicentre randomised trial. Lancet 2006; 368: 379–85. Schiffl H, Lang SM, Fischer R. Daily hemodialysis and the outcome of acute renal failure. N Engl J Med 2002; 346: 305–10. Ronco C, Bellomo R, Homel P, et al. Effects of different doses in continuous veno-venous haemofiltration on outcomes of acute renal failure: a prospective randomised trial. Lancet 2000; 356: 26–30. Liu KD, Himmelfarb J, Paganini E, et al. Timing of initiation of dialysis in critically ill patients with acute renal injury. Clin J Am Soc Nephrol 2006; 1: 915–19.
1491
Science Photo Library
Correspondence