The Clinical And Experimental Study Of Volume Kinetics To Optimize Fluid Therapy

Objective: To study the time course of distribution and elimination with model of volume kinetics and mass balance during fluid infusion in different situation, and to try to design and optimize fluid therapy in a more scientific fashion.Methods: There are three parts in our study. Part I is the clinical part, and part II,III are the animal part. The following is the method of every part. (1) Fourty patients undergoing elective surgery were randomly divided into four groups (Group I , II ,III,IV) according to the different method or the starting time of hemodilution. Group I : 30ml/kg of Lactated Ringer's solution (LR) was administered at a constant rate over 30 min. Group II :The same amount of LR was administered over 30 min at 10 min after induction of anesthesia. Group III: Before induction of anesthesia, 10ml/kg of blood was withdrawn before 30ml/kg of LR was administered. GroupIV: After induction of anesthesia, the same amount of blood was withdrawn before 30ml/kg of LR was administered. Hemoglobin (Hb) concentration and hematocit (Hct) were measured every 5 min during and after infusion for 90 min. Haemodynamic parameters were recorded in the same time. (2) Twenty dogs were randomly divided into four groups: CL group, CG group, BL group, BG group. Each animal was subjected to two randomly ordered experiments that separated by at least 1 week. In the first phase, in which plasma volume expansion was studied in the state of anesthesia, animals received 30ml/kg of LR (CL group) or lOml/kg of gelatin (CG group) over 30 min. In the second phase, in which plasma volume expansion was studied in the state of hemorrhagic shock, animals received 30ml/kg of LR (BL group) or 10ml/kg of gelatin (BG group) over 30 min. Hb concentration andHct were measured every 5min during and after infusion for 90 min. Hemodynamic parameters were recorded in the same time. (3) Twenty dogs were randomly divided into four groups: CL group, CG group, LL group, LG group. Each animal was subjected to two randomly ordered experiments that separated by at least one week. In the first phase, in which plasma volume expansion was studied in the state of anesthesia, animals received 30ml/kg of LR (CL group) or lOml/kg of gelatin (CG group) over 30 min. In the second phase, in which plasma volume expansion was studied in the state of septic shock,animals received 30ml/kg of LR (LL group) or lOml/kg of gelatin (LG group) over 30 min. Hemoglobin (Hb) concentration and hematocit (Hct) were measured every 5min during and after infusion for 90 min. Haemodynamic parameters were recorded in the same time.The distribution and elimination of infused fluid were studied by volume kinetics based on serial analysis of hemoglobin dilution in arterial blood and by mass balance that incorporated volume calculations derived from volume kinetic analysis and measurements of urinary volumes.Results: (1) The mass balance calculations indicated the Volume increase , fluid retained and volume expandsion efficacy ( VEE) in group II,III,IV were significantly greater than those in group I , and those in group IV were more significantly (P<0.05) . The Volume expansion predicted by volume kinetics corresponded to the calculations based on mass balance. The value of V and Kr in group I was significantly greater than this in other groups, while this in group IV was significantly smaller this in other groups. The value of Vl, Kr and Kt in group IV was significantly smaller than this in group II ,III(P<0.05) .(2) When a one-volume kinetic model was fitted to the data, the value of V and Kr in CG, BL, BG group was significantly smaller than this in CL group. These can be found from the computer-generated curves .When a two-volume kinetic model was fitted to the data, the value of V1 , Kr, Kt in BL group was significantly smaller than this in CL group (P<0.05) . The calculations based on mass balance corresponded to the predicted based on volume kinetics. The change of central volume (CCV) in BL, BG, CG group was significantly greater than those in CL group. The VEE i...