多频生物电阻抗法在腹膜透析患者容量评估中的价值

Fluid status assessment in peritoneal dialysis patients by multifrequency bioelectrical impedance analysis

目的本研究旨在探讨应用多频生物电阻抗法评估腹膜透析（peritoneal dialysis,PD）患者容量负荷的临床价值。方法横断面研究。选择2014年1月～2016年1月稳定规律腹膜透析患者61例,记录临床资料,检测血清氨基末端前体脑钠肽（N-terminal pro brain natrinuretic peptide,NTpro BNP）水平,透析充分性及相应的生化参数,同时应用Inbody 720行人体成分检测,记录细胞外液量（extracellular water,ECW）与身体总水量（total body water,TBW）的比值即浮肿指数（edema index）,同时根据公式获得腹膜透析患者理想干体质量,并推算水过多（Overyhydration,OH）值。结果本组患者浮肿指数为（0.402±0.010）,浮肿指数达标率为34.4%（21/61）,公式法计算理想干体质量的达标率为77.05%（47/61）。浮肿指数与年龄呈正相关（r=0.514,P=0.000）关系,与白蛋白水平呈负相关（r=-0.483,P=0.000）关系,年龄（β=0.426,P〈0.001）和白蛋白水平（β=-0.386,P〈0.001）是腹膜透析患者浮肿指数的独立影响因素（R2=0.385）。合并糖尿病（t=-3.488,P=0.001）、合并心血管疾病（t=-2.176,P=0.034）,存在显性水肿（t=-2.546,P=0.014）的腹膜透析患者的浮肿指数明显高于对照组。浮肿指数与NT-pro BNP水平（r=0.397,P=0.002）密切正相关,两者对显性水肿和水过多诊断的ROC曲线下面积分别为（0.740比0.665）和（0.818比0.630）。结论腹膜透析患者浮肿指数诊断正常值受年龄、白蛋白水平及合并疾病影响而有所不同。浮肿指数与NT-pro BNP密切相关,浮肿指数对于诊断容量超负荷的敏感性特异性更高。多频生物电阻抗法评估腹膜透析患者容量负荷简便易行,具有一定的临床应用价值。

Objective The aim of this study was to validate the multifrequency bioelectrical impedance analysis（MBIA） for assessment of fluid status and volume overload in peritoneal dialysis（PD） patients.Methods Sixty-one clinically stable patients undergoing PD were enrolled in the study. In addition to routine blood tests, various body fluid components were measured in PD patients by using the In Body 720 instrument. Dialysis adequacy, renal function and N- terminal pro brain natriuretic peptide（N- pro BNP） level were also assessed in these patients. Results In this cross-sectional study, the ratio of extracellular water（ECW） to total body water（TBW） was positively correlated with age（r=0.514, P=0.000） and negatively correlated with serum albumin concentration（r=- 0.483, P=0.000）. The ECW/TBW ratio was higher in diabetic patients（t=-3.488, P=0.001）, cardiovascular disease patients（t=-2.176, P=0.034） and edema patients（t=-2.546, P=0.014）than in other patients（P〈0.05）. Multiple stepwise regression model showed that lower serum Alb（β =- 0.386, P〈0.001） and older age（β =0.426, P〈0.001） were the independent influential factors for higher ECW/TBW ratio. ECW/TBW ratio was positively correlated with NT-pro BNP（r=0.397, P=0.002）. ROC analysis showed that ECW/TBW ratio and NT-pro BNP level could effectively predict volume overload, and ECW/TBW ratio may be better for the prediction. Conclusions Normal ECW/TBW ratio may be affected by age,albumin level and associated diseases. ECW/TBW ratio and serum NT- pro BNP level are closely correlated.Both of them can be used to diagnose volume overload in PD patients, and ECW/TBW ratio may be better than NT-pro BNP for the diagnosis. ECW/TBW ratio appears to be an easy and useful marker for the estimation of dry body weight in PD patients with various clinical backgrounds.