Sustained low-efficiency dialysis in surgical acute kidney injury - really useful?

the article by Schwenger and colleagues [1] on sustained low-effi ciency dialysis (SLED) versus continuous venovenous hemofi ltration (CVVH) in surgical patients with acute kidney injury. Th e authors have to be congratulated for their eff orts to shed some light on the clinical usefulness of the SLED technology as an alternative to conventional renal replacement therapy (RRT) modalities. However, in our opinion, the study has some important limitations: According to the protocol (NCT00322530), the authors aimed to enroll 100 patients per group, a sample size that may be justifi ed only for an anticipated (but unlikely) mortality diff erence of roughly 20%. Th us, the present study is clearly underpowered to detect diff erences in the primary outcome (90-day mortality). Unfortunately, neither baseline pulmonary function nor indications for respiratory support are presented. Th is leaves ample room for speculation that – in such a small population with a high percentage of patients for whom severe pulmonary complications are common – the shorter duration of ventilator support in the SLED group may be related to factors other than the RRT modality. Despite the protocol (NCT00322530), the authors do not present renal recovery at 90 days. ‘Time after RRT initiation’ is a questionable renal outcome taking into account the lack of clearly defi ned RRT stop criteria and the unusual use of high-dose diuretics during (!) RRT. With respect to these and other [2] limitations of the present study and the continuous RRT benefi ts shown in a recent meta-analysis [3], adequately powered studies comparing SLED and continuous venovenous hemo diafi ltration are still urgently needed.