[Testify patient's blood electrolyte concentration a tendency to approach that of replacement-fluid in continuous renal replacement therapy].

Objective To prove with mathematical formula that the patient's blood electrolyte concentration shows a tendency to approach that of replacement-fluid after continuous renal replacement therapy (CRRT).Methods Electrolyte concentration of plasma,replacement-fluid and returning fluid were compared,and they were labeled as Cblood,Cnom,and Creturn respectively.The "Creturn" was calculated,and the relationship among them was demonstrated with comparison by mathematical formula.At last,according to their relationship,plasma change towards to the replacement fluid was analyzed.Results It was showed that "Cblood＜Creturn＜Cnom" or "Cblood＞Creturn＞ Cnom",and according the relationship,it was derive that the trend of change in "Cblood" after circulation for m unit time was "Cblood1 ＞Cblood2 ＞Cblood3 ＞ … ＞Cbloodm ＞Cblood" or "Cblood1 ＜ Cblood2 ＜Cblood3 ＜ … ＜Cbloodm ＜Cnom".The plasma electrolyte concentration would close to that of replacement fluid infinitely with the continue of CRRT.Conclusions With mathematical model,it is proved that the replacement fluid electrolyte concentration is the final target of the plasma.We must make up the replacement fluid correctly.And this results provide the basis for CRRT treatment of electrolyte disorder. Key words: Continuous renal replacement therapy;  Replacement fluid;  Electrolyte disorder;  Hyponatremia;  Hypernatremia