Effects of different modes of dilution during CVVHDF on the removal of different solutes with different molecular weights / 中华急诊医学杂志

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.

Comparison between predilution and postdilution continuous renal replacement therapy (CRRT) for patients with MODS / 中华急诊医学杂志

Objective To comparie the effects of pre-dilution with post-dilution continuous renal replacement therapy (CRRT) for patients with MODS. Method Thirty-two MODS patients admitted to ICU (Intensive Care Unit ) were randomized and treated with different modes of CRRT. The results of creatinine clearance, acid-base equilibrium, haemodynamic variables before and post therapy were recorded.The maximal pre-filter pressure, the duration of filter unworn out and mortality of patients treated with different modes of CRRT were also recorded. Results Seventeen patients were treated with pre-dilution mode of CRRT and 15 patients treated with post-dilution mode of CRRT. After 24 hours of pre- and postdilution modes of CRRT, the net increase in Ccr (namely the rate of replacement creatinine clearance) were (15.6±4.6) vs. (22.7 ±4. 1) mL/min respectively (P＜0.01); after 48-hour, they were (14.9±3.3)vs. ( 18. 9 ±2. 3) mL/min (p ＜0. 05) . Both dilution modes could improve the blood PH、 HCO3- and BE( P ＜ 0. 05 ) without significant differences between two groups after CRRT therapy ( P ＞ 0. 05 ) . The MAP of patients treated with pre-dilution modes of CRRT therapy for 24 hours and the MAP of patients before therapy were 69. 2 ± 4. 6 and 56. 7 + 9. 1 mmHg respectively ( P ＜ 0. 05 ), and dosage of dopamine used in patients before CRRT therapy and that after CRRT for 24 hours were ( 11.20 +3.45 ) vs (6. 12 +3.41 ) μg ·kg-1 min -1(P＜0.05).The maximal pre-filter pressures of pre-and post-dilution modes were (82.23+9.11) cm H2O, (110.56 +28. 14) cmH2O respectively (P＜0.05), and the durations of lasting effect of filter used in two modes of CRRT were ( 39 + 28. 12 ) vs. ( 25 + 14. 45 ) h respectively ( P ＜0. 05) . Both dilution modes could improve APACHE Scores. There were no significant differences in APACHE Scores and mortalities between two groups after CRRT therapy. Conclusions Post-dilution mode of CRRT has higher filtration rate, but have higher maximal pre-filter pressure and shorter longevity of filter.Pre-dilution mode of CRRT has better effect on improving hemodynamics, reducing usage of vasopressor.Both modes of CRRT can correct acid base equilibrium disorder rapidly. There are no differences in the results of blood gas analysis improved、 APACHE scores and mortality between the two groups.