A Novel Radiofrequency Device to Monitor Changes in Pulmonary Fluid in Dialysis Patients

BACKGROUND AND OBJECTIVES: Fluid monitoring is an important management strategy in patients with chronic kidney disease (CKD) and heart failure (HF). The µCor™ Heart Failure and Arrhythmia Management System uses a radiofrequency-based thoracic fluid index (TFI) to track pulmonary edema. During hemodialysis, the acute removal of fluid through ultrafiltration offers a model for measuring a patient’s fluid status. The objective of the study was to assess the relationship between the device measured TFI and ultrafiltration volume (UFV). DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: Patients undergoing chronic dialysis with and without heart failure were enrolled in the study. The relationship between TFI and UFV in each individual subject was assessed by calculating the Pearson correlation coefficient (r). The average correlation across all subjects was calculated through the use of the Fisher’s z transform. Responder analysis was performed to assess the magnitude of change in TFI before and after dialysis. RESULTS: Twenty subjects were enrolled in the trial. The mean volume of fluid removal was 3.63 L (SD 0.88 L). The mean correlation based on Fisher’s transform was 0.95 CI (0.92–0.99). Responder analysis showed that the mean reduction of TFI after dialysis was 5.5% ± 3.8. CONCLUSION: The µCor system provides radiofrequency-based measurements of thoracic fluid which correlate well with total body fluid removal in a real-world setting. Fluid management based on the radar-derived TFI may provide benefits to dialysis patients and serves as a potential model for pulmonary edema common to the clinical course of heart failure.