探讨超滤液中钙的清除率，并明确在采用局部枸橼酸钠抗凝的连续性静脉-静脉血液滤过（CVVH）治疗期间，其是否可以作为患者补钙速度的参考指标。

55例需要连续性肾脏替代治疗（CRRT）的高危出血风险患者，均接受CVVH治疗模式，拟采取局部枸橼酸钠抗凝（4%枸橼酸钠200 ml/h）。第一阶段采用完全后稀释方式输入，检测血总钙及超滤液总钙浓度，观察超滤液中钙的清除率。第二阶段将正常组和低钙组患者均随机分为全后稀释组、前后1:1稀释组、全前稀释组。在CVVH期间，根据第一阶段实验得出的钙清除比例等量补充钙剂。常规每4 h监测体内血离子钙及滤器后离子钙浓度，并在上机前、上机后6 h和12 h分别检测患者血总钙、超滤液总钙及血离子钙的浓度。

（1）治疗时间：每例次平均治疗时间（21.2±5.6）h，无一例患者因体外回路凝血而终止CVVH治疗；（2）第一阶段15例患者超滤液总钙浓度与血总钙浓度比例为85%，其中正常组钙清除率为84.5%，低钙组钙清除率为85.5%，正常组和低钙组的钙清除率与总体钙清除率3组间无统计学差异（F=0.8484，P>0.05）；（3）第二阶段正常组30例患者理论计算所得超滤液钙浓度与实际检测所得超滤液钙浓度比较，全后稀释组、前后1:1稀释组、全前稀释组结果均无统计学差异（t=0.1637，1.103，0.04；P均>0.05），第二阶段低钙组10例患者理论计算所得超滤液钙浓度与实际检测所得超滤液钙浓度比较，全后稀释组、前后1:1稀释组、全前稀释组结果均无统计学差异（t=0.1968，2.402，0.1818；P均>0.05）；（4）第二阶段正常组30例患者CVVH模式治疗前、治疗后6 h和12 h的体内血总钙浓度比较和血离子钙浓度比较，结果均无统计学差异（F=2.5690，2.8930；P均>0.05），第二阶段低钙组10例患者CVVH模式治疗前、治疗后6 h和12 h的体内血总钙浓度比较和血离子钙浓度比较，结果均无统计学差异（F=0.7124，1.080；P均>0.05）；（5）CVVH模式治疗期间，正常组30例患者没有血钙异常发生，低钙组10例患者没有出现低钙血症的临床表现且治疗期间体内血离子钙水平正常。

在采取局部枸橼酸钠抗凝的CVVH治疗期间，可以根据患者血总钙浓度以及置换液前后补充方式的不同，计算出理论上患者的血钙清除率，并将其作为CVVH治疗时补钙速度的参考依据。

To investigate the clearance rate of calcium in ultrafiltrate and to determine whether it can be used as a reference indicator for calcium supplementation rate in patients during continuous venous-venous hemofiltration (CVVH) treatment with local sodium citrate anticoagulation.

Fifty-five patients at high risk for bleeding who required continuous renal replacement therapy (CRRT) were included. They underwent CVVH treatment with local anticoagulant sodium citrate, and the rate of 4% sodium citrate was 200 ml/h. In the first stage of the experiment, totally post-dilutional hemodiafiltration was used, and the total concentrations of calcium in blood and ultrafiltrate were tested to observe the calcium clearance rate in the ultrafiltrate. In the second stage, the patients who had normal and low calcium levels were randomly divided into a total post-dilution group, a pre-dilution to post-dilution ratio 1:1 group, and a total pre-dilution group. During CVVH, calcium was supplemented in the same amount according to the calcium clearance ratio obtained in the first stage of the experiment. The concentration of ionized calcium in the body and post-filter solution were monitored routinely every 4 h. The concentrations of total calcium in blood and ultrafiltrate and ionized calcium in the body were tested before CVVH, 6 h and 12 h after CVVH was stabilized.

The average treatment time per person was (21.2±5.6) h, and no patient terminated the CVVH due to extracorporeal circuit coagulation. In the first stage, the ratio of total calcium concentration in ultrafiltrate to the total calcium concentration in blood was 85% in 15 patients, of which the normal group had a calcium clearance rate of 84.5% and the low calcium group had a rate of 85.5%. There was no significant difference between the total calcium clearance rate and the calcium clearance rate in the normal group and low calcium (F=0.8484, P>0.05). In the second stage, for the 30 patients in the normal group, there was no significant difference in the theoretically calculated and actually measured ultra-filtrate calcium concentrations among the total post-dilution group, the pre-dilution to post-dilution ratio 1:1 group, and the total pre-dilution group (t=0.1637, 1.103, 0.04; P>0.05). For the 10 patients in the low-calcium group, there was also no significant difference in the theoretically calculated and actually measured ultra-filtrate calcium concentrations among the total post-dilution group, the pre-dilution to post-dilution ratio 1:1 group, and the total pre-dilution group (t=0.1968, 2.402, 0.1818; P>0.05). In both the normal and low-calcium groups, there was no significant difference in blood total calcium concentration or blood ion calcium concentration between before, 6 h and 12 h after CVVH treatment (normal group: F=2.5690, 2.8930, P>0.05; low-calcium group: F=0.7124, 1.080, P>0.05). During CVVH treatment, the normal group did not have abnormal blood calcium, and the low calcium group did not have clinical manifestation of hypocalcemia and had normal levels of ionized calcium in blood.

During the course of CVVH with regional citrate anticoagulation with calcium free replacement solution, the clearance of calcium can be calculated according to the total calcium in blood and the input method of replacement fluid, which can be used as an important reference for the calcium supplement during CVVH treatment.