Stenberg Jenny, Melin Jan, Lindberg Magnus, Furuland Hans
Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
Department of Health and Caring Sciences, University of Gävle, Gävle, Sweden.
Hemodial Int. 2019 Jul;23(3):402-413. doi: 10.1111/hdi.12751. Epub 2019 Mar 7.
Fluid management in hemodialysis patients is a controversial topic. Brain natriuretic peptide (BNP) is secreted from the heart in response to volume overload, and may be a marker of overhydration in hemodialysis patients. Our aim was to investigate the correlation between BNP and overhydration in a cohort of hemodialysis patients, and to find out whether BNP and overhydration correlate in repeated measurements within individuals with elevated BNP.
The study was prospective, observational, and had a cross-sectional part and a longitudinal follow-up. The distribution of BNP was investigated in a cohort of 64 hemodialysis patients. Blood samples and bioimpedance spectroscopy measurements were performed before midweek dialysis. Subsequently, 11 study participants with elevated BNP concentrations (>500 pg/mL) were assessed in another nine dialysis sessions each. These individuals also had their cardiac function and heart rate variability (HRV) examined.
BNP was above 500 pg/mL in 38% of the participants, and correlated positively with overhydration (r = 0.381), inflammation and malnutrition, but not with systolic blood pressure. In comparison to participants with BNP below 500 pg/mL, participants with elevated BNP were older, had lower muscle strength, lower bodyweight and lower levels of hemoglobin and albumin. Echocardiography revealed cardiac anomalies in all 11 participants in the longitudinal follow-up, and HRV, as measured by SDNN, was pathologically low. In repeated measurements, the between-individuals variation of BNP in relation to overhydration was greater (SD = 0.581) than the within-person variation (SD = 0.285).
BNP correlates positively to overhydration, malnutrition, and inflammation. In a subgroup of patients with elevated BNP, who are mainly elderly and frail, BNP reflects individual variation in hydration status, and hence seems to be a modifiable marker of overhydration. These data suggest that BNP is best applied for measuring changes in hydration status within an individual over time.
血液透析患者的液体管理是一个有争议的话题。脑钠肽（BNP）是心脏在容量超负荷时分泌的，可能是血液透析患者水合过多的一个标志物。我们的目的是研究一组血液透析患者中BNP与水合过多之间的相关性，并查明在BNP升高的个体中，重复测量时BNP与水合过多是否相关。
本研究为前瞻性观察性研究，包括横断面部分和纵向随访。对64名血液透析患者队列中的BNP分布进行了研究。在周中透析前采集血样并进行生物电阻抗光谱测量。随后，对11名BNP浓度升高（>500 pg/mL）的研究参与者在另外9次透析过程中分别进行了评估。这些个体还接受了心脏功能和心率变异性（HRV）检查。
38%的参与者BNP高于500 pg/mL，且与水合过多（r = 0.381）、炎症和营养不良呈正相关，但与收缩压无关。与BNP低于500 pg/mL的参与者相比，BNP升高的参与者年龄更大，肌肉力量更低，体重更低，血红蛋白和白蛋白水平更低。超声心动图显示，纵向随访的所有11名参与者均有心脏异常，通过SDNN测量的HRV在病理上较低。在重复测量中，BNP与水合过多的个体间变异（SD = 0.581）大于个体内变异（SD = 0.285）。
BNP与水合过多、营养不良和炎症呈正相关。在BNP升高的患者亚组中，这些患者主要是老年人且身体虚弱，BNP反映了水合状态的个体差异，因此似乎是水合过多的一个可改变的标志物。这些数据表明，BNP最适合用于测量个体随时间的水合状态变化。
