血液透析患者体液分布异常及透析对体液分布的影响

目的:血液透析(hemodialysis,HD)患者在透析前存在水潴留,且水分主要潴留于细胞外液(extra-cellular water,ECW).本文研究HD患者透析前后细胞内液(intra-cellular water,ICW),ECW和总体液量(total body water,TBW)与正常个体的差异,以及透析过程中的变化.方法:选择维持性HD治疗的终末肾功能衰竭患者80例,其中女性60例,男性20例.所有患者使用血仿膜或聚砜膜低通量透析器,透析液钠浓度138 mmol/L.所有患者无水肿,透析过程中无超滤量过大,临床判定干体重合适.利用生物电阻抗频谱分析方法分别于透析前、后测定ICW,ECW和TBW,并用体重标准化为nICW、nECW和nTBW,与69例性别、年龄和体重匹配的正常个体进行比较.结果:男性和女性HD患者的年龄、透析后体重和体重指数与正常对照没有明显差异.与对照组比较,HD患者透析前nICW男(0.28±0.05) vs (0.33±0.04),P＜0.01;女(0.22±0.03) vs (0.27±0.04),P＜0.01]和nTBW男(0.56±0.04) vs (0.58±0.05),P＜0.05;女(0.47±0.04) vs (0.50±0.03),P＜0.05]明显减少,nECW男(0.28±0.02) vs (0.25±0.02),P＜0.01;女(0.25±0.03) vs (0.23±0.01),P＜0.05]明显增加.透析后与透析前相比nICW明显增加男(0.28±0.05) vs (0.30±0.05),P＜0.001;女(0.22±0.03) vs (0.25±0.03),P＜0.001],nECW男(0.28±0.02) vs (0.26±0.03),P＜0.01;女(0.24±0.03) vs (0.21±0.03),P＜0.001]和ECW/ICW比值男(1.06±0.30) vs (0.89±0.25),P＜0.001;女(1.10±0.20) vs (0.88±0.17),P＜0.001]显著降低,接近正常个体水平.结论:(1)透析前HD患者存在显著体液分布异常,表现为nICW减少和nECW增加.(2)HD脱水主要来自细胞外液,进行传统的低通量透析时,体液自细胞外向细胞内转移.(3)HD患者透析后nECW和ECW/ICW比值接近正常对照,因此可以将之用来评价HD患者的干体重.

Fluid distribution abnormalities and influence of hemodialysis on fluid distribution in patients on maintenance hemodialysis

OBJECTIVE: To study the fluid distribution abnormalities in patients on hemodialysis and fluid shift between intracellular and extracellular compartment during hemodialysis (HD). METHODS: Eighty stable end stage renal disease patients on maintenance hemodialysis were selected. Conventional low flux dialyses at dialysate sodium concentration of 138 mmoL/L were performed for all of the patients. Fresenius polysulphons or Gambro hemophon dialyzers were used. All of the patients showed no clinical signs of over ultrafiltration during HD sessions and dry body weights were considered adequate. Intracellular water (ICW), extracellular water (ECW) and total body water (TBW) were measured and standardized by body weight (nICW, nECW, nTBW) before and after HD sessions. Sixty-seven cases of sex, age and body weight matched normal individuals were used as controls. Bio-impedance spectrum (BIS) analysis (Xitron, Technologies, San Diego, CA, USA) was used in body fluid measurement. Pre and post HD nICW, nECW, and nTBW were compared with these of the controls. RESULTS: There were no differences in age, post-dialysis body weight and body mass index between patients on hemodialysis and the controls. Patients on hemodialysis had less nICW male (0.28+/-0.05) vs (0.33+/-0.04), P<0.01; female (0.22+/-0.03) vs (0.27+/- 0.04), P<0.001], more nECW male (0.28+/-0.02) vs (0.25+/-0.02), P<0.001; female (0.25+/-0.03) vs (0.23+/-0.01), P<0.05], and less nTBW male (0.56+/-0.04) vs (0.58+/-0.05), P<0.05; female (0.47+/-0.05) vs (0.49+/-0.03), P<0.05] compared with the controls. The average ultra-filtration volume was (2.2+/-0.9)L. After dialysis, there was an increase in nICW male (0.28+/-0.05) vs (0.30+/-0.05), P<0.001; female (0.22+/-0.03) vs (0.25+/-0.03), P<0.001), an decrease in nECW male (0.28+/-0.02) vs (0.26+/-0.03), P<0.001; female (0.24+/-0.03) vs (0.21+/-0.03), P<0.001],and decrease of ECW/ICW ratio male (1.06+/-0.30) vs (0.89+/-0.25) P<0.001; female (1.10+/-0.17) vs (0.88+/-0.17) P<0.001] which reached the levels of the normal individuals (0.79+/- 0.10 for male, 0.86+/-0.10 for female]. CONCLUSION: Our results show that (1) Before HD sessions, patients on HD had less nICW and more nECW; (2) During conventional low flux HD sessions at dialysate sodium concentration of 138 mmoL/L, fluid shifted from extracellular space to intracellular space.(3) nECW and ECW/ICW ratio from normal population are reasonable for evaluation of dry weight in patients on hemodialysis, but nTBW and nICW are not.