目的  观察在线下调透析液碳酸氢盐浓度预防局部枸橼酸钠抗凝血液透析患者代谢性碱中毒的作用。 方法  将2022年4月～2022年8月中国人民解放军联勤部保障部队第九四〇医院血液净化中心高出血风险且符合局部枸橼酸抗凝的血液透析患者，按透析液碳酸氢盐浓度分为常规浓度组(31.3mmol/L)15例，低浓度组(29.3mmol/L)15例。2组均排除透析前存在代谢性酸中毒患者。比较2组透析结束时与透析开始时患者血pH值及碳酸氢根水平变化。 结果  2组患者临床资料、透析参数、透析开始时患者血pH值、碳酸氢根及钠离子水平均无统计学意义的差别(P＞0.05)。常规浓度组：透析结束时血pH值(t=6.971，P＜0.001)及碳酸氢根(t =5.407，P＜0.001)水平较透析开始时均升高，透析结束时33%的患者发生代谢性碱中毒。低浓度组：透析结束时血pH值较透析开始时升高(t=2.877，P=0.008)，碳酸氢根水平差异无统计学意义(t=0.956，P=0.347)，透析结束时没有患者发生代谢性碱中毒。2组患者透析结束时pH值增加值(t=3.223，P=0.003)及碳酸氢根水平增加值(t=7.756，P＜0.001)的差异均有统计学意义；低浓度组代谢性碱中毒发生率低于常规浓度组(χ2=4.375,P=0.036)。2组患者透析结束时与透析开始时血钠离子水平差异均无统计学意义(t=0.335、1.382，P=0.740、0.178)。 结论  对于透析前不伴酸中毒患者，下调透析液碳酸氢盐浓度可预防局部枸橼酸钠抗凝引起的代谢性碱中毒。

Objective  To investigate the effects of lower on-line bicarbonate concentration in dialysate to prevent metabolic alkalosis in hemodialysis (HD) patients using regional citrate anticoagulation (RCA).  Methods  The HD patients at a high risk of bleeding, having the criteria for RCA and treated in the 940th Hospital of Joint Logistics Support Force of Chinese PLA between April 2022 and August 2022 were enrolled in this study. Patients with metabolic acidosis before HD were excluded. They were then divided into two groups, conventional concentration group (dialysate bicarbonate=31.3mmol/L, n=15) and lower concentration group (dialysate bicarbonate=29.3mmol/L, n=15). The alterations of blood pH and HCO3- before and after HD were compared between the two groups.  Results  Before HD, there were no differences in clinical data, HD parameters, and levels of blood pH, HCO3- and Na+ between the two groups. In the conventional concentration group, blood pH and HCO3- were higher at the end of HD than those at the beginning of HD (7.48±0.03 vs. 7.39±0.04 and 27.50±1.93 vs. 23.57±1.13; t=6.971，5.407,P＜0.001), and 33% of the patients had metabolic alkalosis after HD. In the lower concentration group, blood pH was statistically different before and after HD (7.42±0.04 vs. 7.39±0.02, t=2.877, P=0.008), HCO3- had no difference (25.50±1.86 vs. 23.00±1.40, t=0.956，P=0.347), and no patient had the blood pH≥7.50 after HD. At the end of HD, the increased values of blood pH and HCO3- were significantly higher in the conventional concentration group than in the lower concentration group (0.07±0.02 vs. 0.04±0.03 and 4.00±1.1 vs. 1.10±0.88; t=3.223，7.756,P=0.003,＜0.001); the presence of metabolic alkalosis was significantly different between the two groups (33% vs. 0, χ2=4.375,P=0.036). The changes of blood Na+ level before and after HD had no statistical difference between the two groups (136.82±1.78 vs. 136.46±3.76 and 137.69±1.68 vs. 138.60±1.92;t=0.335、1.382，P=0.740、0.178).  Conclusions  For patients without metabolic acidosis before HD, down-regulation of bicarbonate concentration in dialysate may prevent the HD patients with RCA from metabolic alkalosis.