Comparison Of Continuous Veno-Venous Hemofiltration And Continuous Veno-Venous Diafiltration In Solute Clearance Efficiency And Filter Life

Objective:Compare the solute removal efficiency and filter life of continuous veno-venous hemofiltration(CVVH)with continuous veno-venous hemodiafiltration(CVVHDF),and search for optimal indication for changing the circuit and filter.To provides a basis for rational selection of continuous renal replacement therapy(CRRT)treatment modality and timing of circuit and filter change in clinical decision-making,thereby improving treatment effect and lower treatment cost.Methods:This study complied a randomized crossover study design.Patients with acute renal injury requiring CRRT in the ICU were randomly assigned to receive either CVVH or CVVHDF treatment first,using the same prescribed dose,followed by the alternative treatment modality.Delivered dose acted as the surrogate of solute clearance efficiency,which was calculated with different molecular weight solute(urea nitrogen,creatinine,?2 microglobulin and cystatin C)at various time points(0.5h after treatment initiation,every 12h and right before the treatment ceased for circuit change).The difference between delivered doses of CVVH and CVVHDF were then compared,as well as the filter life span of the two modalities.The correlation between delivered dose and the pre-filter pressure(PPRE)as well as the transmembrane pressure(TMP)during CRRT treatment was studied.ROC curve was used to determine the optimal timing of circuit change.Result:The delivered dose of CVVH and CVVHDF for small molecule solutes(urea nitrogen and creatinine)showed no significant difference at each time point(p>0.05).For medium molecular solute(?2 microglobulin and cystatin C),the solute clearance efficiency of CVVH was superior than that of CVVHDF,but only exist at the 12h time point(p<0.05).The delivered doses of CVVH and CVVHDF for different molecular weight solutes all decreased significantly before the circuit change(p<0.01).In the late stage of treatment,and with the prolongation of treatment time,the likelihood of patients' serum solute level rebound was increasing.There was no significant difference in the ratio of rebound between CVVH mode and CVVHDF(p>0.05).There was no significant correlation between the small molecule solute delivered dose and PPRE,as well as TMP(p>0.05),and there was no significant correlation between PPRE and medium molecular solute delivered dose(p>0.05).There was a significant negative correlation between the TMP and the delivered dose of the medium molecular solute(p<0.01).The AUC of the ROC curve of ?2 microglobulin serum solute rebound prediction with TMP was 0.651,The AUC of the ROC curve of Cystatin C rebound prediction with TMP was 0.717.The filter life of the CVVHDF was significantly longer than that of the CVVH(p<0.01).Conclusion:The CVVH mode and CVVHDF mode have similar clearance efficiency for small molecule solutes.The advantage of CVVH for medium molecular solutes clearance only occurs at 12h after treatment initiation.TMP is significantly associated with the delivered dose of medium molecular solutes and can be used as a reference for solute clearance efficiency.When the medium molecular solute is set as the therapeutic target,TMP=146.5mmHg can be used as indication for the filter change.The CVVHDF has longer filter life.CVVHDF is according to our results a CRRT modality of choice for economical consideration.