Background: The accuracy of the remote dielectric sensing (ReDSTM) system, which is a noninvasive electromagnetic-based technology to quantify lung fluid levels, particularly among those with small body size, remains uncertain. Methods: Hospitalized patients with and without heart failure underwent assessment of lung fluid levels with ReDS and successive chest computed tomography imaging. We performed a correlation analysis of the ReDS measurement, representing lung fluid levels, and computed tomography-derived high attenuation area percentage, which also provides a spatial quantification of lung fluid level. Results: A total of 46 patients (median 76 years old, 28 men), including 28 patients with heart failure, were included. The median ReDS value was 28% (interquartile: 23%, 33%), and the median percentage of high attenuation area was 21.6% (14.4%, 28.5%). ReDS values and percentage of high attenuation area were moderately correlated (r = 0.65, p < 0.001), irrespective of the existence of heart failure. ReDS value independently predicted the percentage of high attenuation area seen on computed tomography (p < 0.001). Conclusions: The ReDS system may be a promising, noninvasive tool to quantify fluid lung levels, as validated by comparison with chest computed tomography imaging. Further studies are warranted to validate the utility and applicability of this technology to a variety of clinical scenarios.

Background: Remote dielectric sensing (ReDS™) is an electromagnetic-based technology used to noninvasively measure lung fluid levels. The association between ReDS values and invasively measured hemodynamics, particularly among those with small physics, remains unknown. Methods: Consecutive patients with chronic heart failure who were admitted to our institute and underwent invasive right heart catheterization as well as simultaneous ReDS measurement at clinically stable conditions between September and November 2021 were prospectively included. The colinearity between ReDS values and pulmonary capillary wedge pressure was studied. Results: In total, 30 patients (median 79 (73, 84) years old, 13 men) were included. Median ReDS value was 26% (22%, 28%). ReDS values had a moderate collinearity with pulmonary capillary wedge pressure (r = 0.698, p < 0.001), even among those with a body height <155 cm. ReDS values with a cutoff of 28% predicted a pulmonary capillary wedge pressure >15 mmHg with sensitivity 0.70 and specificity 0.75. Conclusions: An electromagnetic-based engineering ReDS might be a potential tool to estimate cardiac pressure in patients with heart failure, including those with small physics.

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demonstrated a correlation between ReDS values and lung fluid levels, 8,9 as well as the clinical implications of ReDSguided heart failure management. 10, 11 The Second Department of Internal Medicine, Toyama University received permission to use the device for the first time in Japan before commercial marketing. The device itself will soon be clinically available in Japan.In the present proof-of-concept study, we investigated the relationship between body posture and ReDS values in healthy volunteers to clarify the physiological proof of fluid shift depending on different body postures. Methods Participant SelectionHealthy volunteers aged >20 years without any past medical history were prospectively included in this single-center proofof-concept study between August and September 2021. This study was approved by the Clinical Research Review Board, University of Toyama (IRB no. MTK2020007), and written informed consent was obtained from all participants.

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