Effects of different modes of dilution during CVVHDF on the removal of different solutes with different molecular weights

Abstract

Objective To compare the rates of clearance of different solutes during continuous veno-venous haemodiafiltration (CVVHDF) between pre-dilution and post-dilution.Methods A study in vitro was carried out using model CRRT system with AN69 filter used,which was applied to perform CVVHDF for solutes clearance.The removed amounts of different solutes including potassium ion (K +),creatinine (Cr),vancomycin,insulin,and interleukin-6 (IL-6) were determined in the groups of control (without dilution),pre-dilution and post-dilution during CVVHDF at the same substitution fluid amount.Each group was repeated 4 times (n =4).Results Post-dilution mode increased K +,Cr,vancomycin and insulin clearances significantly.There was no difference in clearance of IL-6 between the pre-and post-dilution groups.In the control group,insulin and IL-6 levels were decreased extremely.Conclusions In general,the rate of clearance using post-dilution of CVVHDF is higher than that using pre-dilution.Among high molecular weight solutes,the difference in clearance is not significant.The control group demonstrates insulin and IL-6 adsorbed by the filter. Key words: Continuous renal replacement therapy; Continuous veno-venous haemodiafiltration; Solutes; Clearance ; Predilution; Postdilution; Molecular weight; Hemofilter