Supplementary Material for: Application of Remote Dielectric Sensing in Volumetric Evaluation for Maintenance Hemodialysis Patients

Background: Fluid overload increases the risk of cardiovascular events and all-cause mortality in hemodialysis patients. Remote dielectric sensing (ReDS) is a newly wearable device which can evaluate the volumetric status via the ratio of fluid and air in pulmonary tissue. In this study we explored whether ReDS can be used in evaluation of volume status in dialysis patients. Methods: We involved maintenance hemodialysis patients in the cross-sectional study and obtained both pre- and post-dialysis ReDS values. We also collected pre- and post-dialysis over hydration values by bioelectrical impedance analysis and biochemistry indicators like brain natriuretic peptide and analyzed their correlations with ReDS values to explore whether ReDS was feasible in fluid assessment for hemodialysis patients. Results: 115 maintenance hemodialysis patients were enrolled. The average pre-dialysis ReDS reading was 27.47% ± 4.88% (range from 16.00% to 39.00%), and the median post-dialysis ReDS value was 24% (range from 16% to 37%). ReDS can distinguish fluid overload patients (pre-dialysis over hydration value≥2.5L, p<0.001). ReDS value has a positive correlation with over hydration value (pre-dialysis: R=0.38, p<0.001) and a negative correlation with left ventricular ejection fraction (R=-0.333, p=0.018). ROC analysis showed that cut-off of pre-dialysis ReDS value to discriminate pre-dialysis over hydration value≥2.5L was 26.5%.Conclusion: ReDS has potential in fluid evaluation for maintenance hemodialysis patients and can serve as a useful tool to assist in clinical hydration status assessment.

背景：液体负荷过量会增加血液透析患者发生心血管事件及全因死亡的风险。远程介电传感（Remote Dielectric Sensing, ReDS）是一种新型可穿戴设备，可通过检测肺组织内液体与空气的比值评估机体容量状态。本研究旨在探讨ReDS能否用于评估透析患者的容量状态。
方法：本横断面研究纳入维持性血液透析患者，采集其透析前及透析后的ReDS检测值。同时通过生物电阻抗分析法获取患者透析前后的容量过负荷值，并检测脑钠肽等生化指标，分析上述指标与ReDS值的相关性，以探讨ReDS用于血液透析患者液体状态评估的可行性。
结果：本研究共纳入115例维持性血液透析患者。患者透析前ReDS检测值均值为27.47%±4.88%（范围16.00%~39.00%），透析后ReDS检测值中位数为24%（范围16%~37%）。ReDS可有效区分液体负荷过量患者（透析前容量过负荷值≥2.5L，p<0.001）。ReDS值与容量过负荷值呈正相关（透析前：R=0.38，p<0.001），与左心室射血分数呈负相关（R=-0.333，p=0.018）。受试者工作特征（Receiver Operating Characteristic, ROC）曲线分析显示，用于鉴别透析前容量过负荷值≥2.5L的透析前ReDS临界值为26.5%。
结论：ReDS在维持性血液透析患者的液体状态评估中具有应用潜力，可作为辅助临床评估患者容量状态的实用工具。