Early venovenous haemodiafiltration for sepsis-related multiple organ failure

Abstract

In a prospective observational study that included 60 consecutive patients over a 10-year period, Page and coworkers [1] studied the effects of early continuous venovenous haemodiafiltration (CVVHDF) during sepsis-induced multiple organ failure. In two-thirds of the patients rapid metabolic improvement during CVVHDF was associated with circulatory improvement and a low mortality rate, whereas lack of metabolic improvement after 12 hours of CVVHDF (mainly based on changes in base excess) was associated with a 100% mortality rate. The authors concluded that early CVVHDF may improve the prognosis of sepsis-related multiple organ failure, and that failure to correct metabolic acidosis rapidly during the procedure is a strong predictor of mortality. In that study, metabolic acidosis was assessed using base excess values, and the authors highlighted the influence of individual changes 6-12 hours after initiation of CVVHDF on predicted outcome. However, despite the findings reported, the usefulness of base excess is questionable. First, because of the high incidence of circulatory failure occurring after several days of hospitalization, base excess may be influenced by large volume crystalloid infusion, resulting in altered protein status. Second, the link between base excess and lactate concentration was weak (r 2 = 0.36 for the patients studied). We believe that lactate values may be more important in predicting outcome than base excess. Indeed, it is widely accepted that early lactate clearance is associated with improved outcomes in septic shock [2] and that lactate levels are not affected by CVVHDF [3]. In the study by Page and coworkers [1] one cannot exclude the possibility that the lack of improvement in base excess in the nonresponder group was linked to persistent lactate production, and so metabolic improvement during the procedure is not necessarily superior to the trend in blood lactate as a predictive tool.