Neck-Worn Monitoring Sensor for – A Study for Monitoring Subjects With Fluid-Management Issues During Dialysis

The investigators propose a study for validating the test device's measurement of a parameter called 'sternal fluid index' (SFI) in patients with diagnosed medical conditions related to fluid management, e.g. end-stage renal disease (ESRD), that are undergoing dialysis. The reference device for the study measures the averaged amplitude of a thoracic bio-impedance signal (Z) and a parameter called 'thoracic fluid content' (TFC), which is equal to 1000/Z. The test device measures SFI from a localized region near the sternum, whereas the reference device measures Z and TFC from the entire thoracic cavity. This means Z (or TFC) and SFI, if measured at approximately the same time, will likely correlate but have different absolute values. Thus, the statistical analysis will investigate the ability of SFI to track fluids, as well as the agreement between fluid-dependent trends displayed by SFI and Z (or TFC), as described below.

During the study the investigators will collect multiple samples, each containing a value of SFI from the test device, and values of TFC and Z from the reference device. The investigators will enroll approximately 20-50 subjects, with the goal of at least 20 subjects completing the study. The statistical analysis will include data from all subjects that complete the study. All subjects will undergo dialysis in a clinic. Approximately half to a third will have both ESRD and Heart Failure (HF). The investigators will measure a sample from each subject every 15 minutes during a standard dialysis session, which typically lasts about 3 to 4 hours. Levels of extracted fluids, determined by the dialysis machine, will be recorded at the time each sample is measured.

The statistical model compares time-dependent changes in SFI and Z values collected during dialysis. It is designed is to demonstrate: 1) that the test device is effective in characterizing fluid levels when used as intended; and 2) that the test and reference devices' measurements of trends in fluids are substantially equivalent, since they sense different physiological regions which are expected to yield different values of impedance.