Gabutti Luca, Bianchi Giorgia, Soldini Davide, Marone Claudio, Burnier Michel
Division of Nephrology, Ospedale la Carità, Locarno, Switzerland.
Nephrol Dial Transplant. 2009 Mar;24(3):973-81. doi: 10.1093/ndt/gfn541. Epub 2008 Oct 8.
In a previous study we demonstrated that mild metabolic alkalosis resulting from standard bicarbonate haemodialysis induces hypotension. In this study, we have further investigated the changes in systemic haemodynamics induced by bicarbonate and calcium, using non-invasive procedures.
In a randomized controlled trial with a single-blind, crossover design, we sequentially changed the dialysate bicarbonate and calcium concentrations (between 26 and 35 mmol/l for bicarbonate and either 1.25 or 1.50 mmol/l for calcium). Twenty-one patients were enrolled for a total of 756 dialysis sessions. Systemic haemodynamics was evaluated using pulse wave analysers. Bioimpedance and BNP were used to compare the fluid status pattern.
The haemodynamic parameters and the pre-dialysis BNP using either a high calcium or bicarbonate concentration were as follows: systolic blood pressure (+5.6 and -4.7 mmHg; P < 0.05 for both), stroke volume (+12.3 and +5.2 ml; P < 0.05 and ns), peripheral resistances (-190 and -171 dyne s cm(-5); P < 0.05 for both), central augmentation index (+1.1% and -2.9%; ns and P < 0.05) and BNP (-5 and -170 ng/l; ns and P < 0.05). The need of staff intervention was similar in all modalities.
Both high bicarbonate and calcium concentrations in the dialysate improve the haemodynamic pattern during dialysis. Bicarbonate reduces arterial stiffness and ameliorates the heart tolerance for volume overload in the interdialytic phase, whereas calcium directly increases stroke volume. The slight hypotensive effect of alkalaemia should motivate a probative reduction of bicarbonate concentration in dialysis fluid for haemodynamic reasons, only in the event of failure of classical tools to prevent intradialytic hypotension.
在之前的一项研究中，我们证明了标准碳酸氢盐血液透析导致的轻度代谢性碱中毒会引发低血压。在本研究中，我们使用非侵入性程序进一步研究了碳酸氢盐和钙引起的全身血流动力学变化。
在一项采用单盲、交叉设计的随机对照试验中，我们依次改变透析液中碳酸氢盐和钙的浓度（碳酸氢盐浓度在26至35 mmol/l之间，钙浓度为1.25或1.50 mmol/l）。21名患者共进行了756次透析治疗。使用脉搏波分析仪评估全身血流动力学。采用生物阻抗和脑钠肽来比较液体状态模式。
使用高钙或高碳酸氢盐浓度时的血流动力学参数及透析前脑钠肽如下：收缩压（分别升高5.6 mmHg和降低4.7 mmHg；两者P均<0.05）、每搏输出量（分别增加12.3 ml和5.2 ml；P<0.05和无显著差异）、外周阻力（分别降低190和171达因·秒·厘米⁻⁵；两者P均<0.05）、中心动脉增强指数（分别增加1.1%和降低2.9%；无显著差异和P<0.05）以及脑钠肽（分别降低5和170 ng/l；无显著差异和P<0.0）。所有模式下工作人员干预的需求相似。
透析液中高碳酸氢盐和高钙浓度均可改善透析期间的血流动力学模式。碳酸氢盐可降低动脉僵硬度，并改善透析间期心脏对容量超负荷的耐受性，而钙可直接增加每搏输出量。碱血症的轻微降压作用仅在传统方法未能预防透析中低血压的情况下，才应基于血流动力学原因促使对透析液中碳酸氢盐浓度进行试探性降低。
