Clinical implications of remote dielectric sensing system to estimate lung fluid levels

Effect of measurement procedure errors on assessing lung fluid via remote dielectric sensing system

The study assessed the impact of procedural errors on the remote dielectric sensing system (ReDS), a non-invasive lung fluid assessment technology, in an Asian cohort. Healthy volunteers underwent ReDS measurements following manufacturer's instructions, with two consecutive measurements one minute apart. A subset of 20 participants had modified procedure settings. Reliability was measured using intraclass correlation coefficient (ICC). The study included 86 healthy volunteers, and all ReDS measurements fell within the recommended normal range. The intra-rater reliability of ReDS measurements was excellent, with an ICC of 0.968. Among the subset of 20 subjects, deviations in height and weight did not significantly affect ReDS values. However, deviations in chest size by ± 3 cm had a noticeable impact on ReDS measures, and incorrect station selection led to fluctuations in ReDS readings. In conclusion, the ReDS system demonstrated excellent intra-rater reliability and applicability in an Asian cohort. Procedural errors, such as chest size measurement and station selection, significantly influenced ReDS measurements. Adherence to standardized operating procedures is crucial to ensure accurate and consistent results. These findings highlight the importance of adherence to manufacturer instructions when utilizing ReDS for lung fluid assessment, thereby enhancing its reliability and clinical applicability.

A Lower Remote Dielectric Sensing Value Was Associated with Hypovolemia and Worse Clinical Outcomes

Background: Remote dielectric sensing (ReDS) systems can estimate the amount of lung fluid non-invasively and easily without expert techniques. The correlation between the elevated ReDS value and other modalities that estimate pulmonary congestion has been validated. The clinical implications of lower ReDS values, which may indicate hypovolemia, remain unknown. Methods: A total of 138 patients who were hospitalized for various cardiovascular-related problems and underwent ReDS value measurements at the index discharge in a blinded manner to the attending clinicians were eligible for inclusion. Patients with ReDS values > 30%, indicating the presence of pulmonary congestion, were excluded. The prognostic impact of lower ReDS values on all-cause readmission after index discharge was evaluated. Results: A total of 97 patients were included. The median age was 78 years, and 48 were men. The median ReDS value at index discharge was 26% (23%, 27%). A lower ReDS value correlated with smaller inferior vena cava maximum diameters (r = 0.46, p < 0.001) and higher blood urea nitrogen/creatinine ratios (r = -0.35, p < 0.001). A lower ReDS value (≤25%) was associated with a risk of all-cause readmissions with an unadjusted hazard ratio of 2.68 (95% confidence interval 1.09-6.59, p = 0.031) and an adjusted hazard ratio of 2.30 (95% confidence interval 0.92-5.78, p = 0.076). Its calculated cutoff of 25% significantly stratified the cumulative incidence of the primary outcome (36% versus 17%, p = 0.038). Conclusions: A lower ReDS value may indicate hypovolemia and be associated with the risk of all-cause readmission in patients hospitalized for cardiovascular diseases.

Clinical Implications of Remote Dielectric Sensing-Guided Management

Background: Remote dielectric sensing (ReDS) systems can quantify the degree of pulmonary congestion rapidly and non-invasively. However, the clinical implications of ReDS-guided medication adjustment remain uncertain. Methods: Patients hospitalized to treat cardiovascular diseases, including heart failure, valvular disease, and coronary artery disease, and underwent ReDS measurement before index discharge between 2021 and 2022 were included. According to our institutional protocol, ReDS values were blinded to the attending clinicians until February 2022 (blind period). After the period, ReDS values were timely opened to the attending clinicians, and medications such as diuretics were adjusted according to the ReDS values (target value between 20% and 35%) before index discharge (open period). A composite primary outcome of all-cause death and heart failure readmissions was compared between the two groups. Results: A total of 183 patients were included (median 79 years old, 101 men), consisting of 138 patients in the blind period and 45 patients in the open period. During a median of 646 (401, 818) days after the index discharge, 33 patients experienced the primary outcome of interest. Management during the open period, where medications were adjusted according to ReDS values, was independently associated with a lower incidence of the primary outcome with an adjusted hazard ratio of 0.22 (95% confidence interval 0.05-0.94, p = 0.041), as compared with those of the blind period. Conclusions: According to the findings of the present retrospective study, ReDS-guided management may have the potential to reduce the risk of mortality and heart failure admission in individuals hospitalized for cardiovascular diagnoses. Further prospective randomized control trials involving those with a variety of background etiologies and clinical scenarios are warranted to validate our findings and establish optimal ReDS-guided management.

Trajectory of pulmonary congestion during TAVR

Patients with severe aortic stenosis often experience pulmonary congestion due to incremental afterload. The trajectory of pulmonary fluid volume during transcatheter aortic valve replacement (TAVR) remains uncertain. Remote dielectric sensing (ReDS) is a recently introduced device for non-invasive quantification of lung fluid volume without expert techniques. We evaluated the trajectory of ReDS values during TAVR and its prognostic implications. Patients with severe aortic stenosis who underwent ReDS measurements upon admission and at the index discharge after TAVR between 2021 and 2022 were eligible. They were followed up until August 2023. The primary focus was on the trajectory of ReDS values during TAVR, with secondary consideration given to its impact on the composite of death or all-cause readmission after TAVR. A total of 57 patients were included. Median age was 84 years and 24 were male. ReDS value remained unchanged after TAVR, changing from 27% (IQR 24%, 29%) to 26% (IQR 24%, 30%) (p = 0.65). ReDS value did not decrease in 23 (40%) patients. The presence of coronary artery disease and atrial fibrillation were associated with no decrease in ReDS value. This lack of decrease in ReDS value was linked to death or all-cause readmission after TAVR, with an age-adjusted hazard ratio of 3.40 (95% confidence interval 1.01-11.4, p = 0.048). The degree of lung fluid amount did not decrease in 40% of TAVR candidates during the procedure. The lack of decrease in lung fluid amount was associated with mortality and morbidity after TAVR. The next concern is to establish therapeutic strategy for patients with residual pulmonary congestion after TAVR.

Systemic Congestion as a Determinant of Efficacy in Adaptive Servo-Ventilation Therapy: A Retrospective Observational Study

BACKGROUND

The optimal criteria for patient selection in the context of adaptive servo-ventilation (ASV) therapy remain a subject of ongoing investigation. We postulate that baseline plasma volume, assessable through several straightforward clinical parameters, might be correlated with a more pronounced reduction in plasma B-type natriuretic peptide (BNP) levels following mid-term ASV therapy.

METHODS

We included patients diagnosed with congestive heart failure who had received continuous ASV therapy for a minimum of three months. The primary outcome of interest was the extent of decline in logarithmically transformed plasma BNP levels, defined as a decrease of more than 0.10 during the 3-month ASV treatment period.

RESULTS

A total of 66 patients were included in the study. The median age of the cohort was 66 years, with 53 patients (80%) being male. The median plasma volume status at baseline was -16.9%, and patients were categorized into two groups based on this median value. Patients with elevated baseline plasma volume status experienced a statistically significant reduction in plasma BNP levels (p = 0.016), whereas those with lower plasma volume exhibited no significant change in BNP levels (p = 0.23). A higher baseline plasma volume status was independently associated with a significant reduction in plasma BNP levels, with an adjusted odds ratio of 1.036 (95% confidence interval: 1.01-1.07, p = 0.032).

CONCLUSIONS

The presence of systemic congestion at baseline, quantified by the estimated plasma volume status, may serve as a crucial determinant of the efficacy of ASV therapy, leading to improvements in plasma BNP levels among patients suffering from congestive heart failure.

Prognostic impact of remote dielectric sensing value following TAVR

Remote dielectric sensing (ReDS) system non-invasively quantifies pulmonary congestion. Re-admission following trans-catheter aortic valve replacement (TAVR) remains an unsolved matter. Residual pulmonary congestion is a strong risk factor of worse clinical outcomes in patients with heart failure. ReDS system may have a prognostic impact in patients undergoing TAVR. Patients who received TAVR and ReDS measurements during index hospitalization between 2021 and 2022 were included. The prognostic impact of ReDS value on the composite endpoint of death or re-admission following index discharge was investigated. Totally, 42 patients (median 84 years, 14 men) were included. Median ReDS value at index discharge was 27% (24%, 30%) and 10 patients had ReDS values > 30%. During a median of 316 (282, 354) days following index discharge, a higher ReDS value at baseline was independently associated with the incidence of composite endpoint with an adjusted hazard ratio of 1.32 (95% confidence interval between 1.10 and 1.58) with a calculated cutoff of 30%, which significantly stratified the cumulative incidence of the composite endpoint (78% in the high ReDS group [N = 10] and 36% in the normal ReDS group [N = 32], p = 0.002). ReDS technology may be a promising tool to predict future clinical outcomes following TAVR by quantifying residual pulmonary congestion. The clinical implication of ReDS-guided aggressive intervention following TAVR remains the next concern.

Association of remote dielectric sensing and six-minute walk distance among those with severe aortic stenosis

BACKGROUND

Remote dielectric sensing (ReDS) is a novel non-invasive electromagnetic energy-incorporated technology to quantify lung fluid levels. The six-minute walk test is an established method to assess exercise capacity among those with a variety of chronic conditions related to heart and pulmonary diseases. We aimed to understand the association between ReDS value and six-minute walk distance (6MWD) in patients with severe aortic stenosis being evaluated for valve replacement.

METHODS

Patients who were hospitalized to receive trans-catheter aortic valve replacement were prospectively included and simultaneous ReDS and 6MWD measurements were performed on admission. We attempted to correlate 6MWD with ReDS value.

RESULTS

A total of 25 patients (median 85 years, 11 men) were included. Median 6MWD was 168 (133, 244) meters and median ReDS value was 26 % (23 %, 30 %). 6MWD displayed a moderate inverse correlation with ReDS value (r = -0.516, p = 0.008) and significantly distinguished ReDS value ≥30 %, representing mild or greater pulmonary congestion, at a cut-off of 170 m (sensitivity 0.67 and specificity 1.00).

CONCLUSIONS

6MWD had a moderate inverse correlation with ReDS values among candidates for trans-catheter aortic valve replacement, indicating that patients with shorter 6MWD had increased pulmonary congestion as assessed by ReDS system.

Noninvasive assessment of pulmonary congestion in heart failure: Need of the hour

Early pulmonary congestion detection and surveillance in acute heart failure patients can prevent decompensation, minimize hospitalizations, and improve prognosis. In India, the warm and wet types of HF are still the most common types and residual congestion at discharge is still a significant concern. Thus, there is an urgent need for a reliable and sensitive means of identifying residual and subclinical congestion. Two such monitoring systems are available and approved by US FDA. These include CardioMEMS HF System (Abbott, Sylmar, California) and ReDS System (Sensible Medical Innovations, Ltd., Nanya, Israel). CardioMEMS is a wireless pressure-sensitive implantable device, while ReDS is a wearable noninvasive device for measurement of the lung fluid and hence direct detection of PC. This review discusses the role of noninvasive assessment in PC monitoring in patients with heart failure and its implications from an Indian perspective.

Presence of Pleural Effusion in the Assessment of Remote Dielectric Sensing

BACKGROUND

The remote dielectric sensing (ReDS) system is a recently introduced non-invasive technology used to easily estimate the degree of lung fluid volume without any expert techniques. In the previous literature, ReDS values had a moderate correlation with invasively measured pulmonary artery wedge pressure (PAWP), the gold standard for representing left heart preload. Considering the mechanism of ReDS technology, ReDS values may be inappropriately elevated in the presence of pleural effusion (PE), and the ability of the ReDS system to estimate PAWP may decrease in such a situation.

METHODS

In-hospital patients with cardiovascular diseases underwent computed tomography, and the presence of pleural effusion (PE) was evaluated. The measurement of ReDS values using the ReDS system and the measurement of PAWP using invasive right heart catheterization were also performed simultaneously. The impact of the presence of PE on the relationship between the ReDS values and PAWP was evaluated.

RESULTS

A total of 59 patients (79 years, 30 male) were included. The median ReDS value was 25% (IQR: 22%, 30%) and the median PAWP level was 13 (IQR: 10, 18) mmHg. Of these patients, 11 had PE. PAWP was not significantly different between the two groups, whereas the ReDS values in the PE group were significantly higher than in the no-PE group. The impact of the presence of PE on the ReDS values was significant, with a beta value of 6.61 (95% confidence interval: 4.80-8.42, p < 0.001) upon adjusting for the levels of PAWP.

CONCLUSIONS

We should pay attention to interpreting ReDS values when assessing the degree of pulmonary congestion in patients with PE, because ReDS values may be inappropriately elevated in this cohort.

Correlation between Remote Dielectric Sensing and Chest X-Ray to Assess Pulmonary Congestion

Background: Chest X-ray is a practical tool to semi-qualify pulmonary congestion. Remote dielectric sensing (ReDS) is a recently introduced, non-invasive, electromagnetic energy-based technology to quantify pulmonary congestion without expert technique. We compared these two modalities to clarify appropriate clinical situations for each modality. Methods: ReDS and chest X-ray measurements were prospectively performed on admission in consecutive hospitalized patients with cardiovascular diseases. In the chest X-ray, the congestive score index (CSI) was calculated blindly by two independent experts and averaged. CSIs were correlated with ReDS values. Results: A total of 458 patients (76 (69, 82) years old, 267 men, and 130 heart failure) were included. Median ReDS value was 28% (25%, 33%). There was a mild correlation between ReDS values and CSIs (r = 0.329, p < 0.001). The correlation between ReDS values and CSIs became stronger in the heart failure cohort (r = 0.538, p < 0.001). In patients with mild congestion (ReDS < 35%), ReDS values, instead of CSI, stratified the degree of congestion. In patients with severe congestion (ReDS > 35%), both modalities stratified the degree of congestion. Conclusions: Both chest X-ray and ReDS are useful for assessing severe pulmonary congestion, whereas ReDS would be preferred to chest X-ray in stratifying the severity of mild pulmonary congestion.

Association between Remote Dielectric Sensing and Estimated Plasma Volume to Assess Body Fluid Distribution

Background: Pulmonary congestion is quantified by a remote dielectric sensing (ReDSTM) system, while systemic congestion is estimated by calculated plasma volume. The type of clinical patient profile as defined by the ReDS system and calculated plasma volume remains uncertain. Methods: Hospitalized patients with or without heart failure were included in this prospective study. On admission, ReDS values were measured and plasma volume status (PVS) was estimated using their body weight at the same time. Cutoffs of ReDS value and PVS were defined at 34% and −2.7%, respectively. The association between the two parameters was assessed. Results: A total of 482 patients (median 76 years, 288 men) were included. The median ReDS value was 28% (25%, 32%) and median PVS was −16.4% (−26.3%, −5.9%). Of the patients, 64 had high ReDS value (and low PVS) and 80 had high PVS (and low ReDS value). The high ReDS group had a higher prevalence of clinical heart failure with a more elevated echocardiographic E/e’ ratio, whereas the high PVS group had a higher prevalence of chronic kidney disease (p < 0.05 for all). Four out of a total of six patients with high ReDS value and high PVS had both heart failure and chronic kidney disease profiles. Conclusion: The combination of ReDS value and PVS was able to clinically stratify the types of body fluid distribution and patient profiles. Utilizing these tools may assist the clinician in constructing a therapeutic strategy for the at-risk hospitalized patient.

Association Between Remote Dielectric Sensing and Body Mass Index

Remote dielectric sensing (ReDS) is a non-invasive, electromagnetic energy-based technology to quantify pulmonary congestion. However, the accuracy of ReDS values in patients with a variety of physiques has not been fully validated.Prospective successive measurements of ReDS values and body mass index (BMI) were performed on admission in consecutive hospitalized patients with cardiovascular diseases. Patients were stratified into 4 groups according to the WHO classification: underweight (BMI < 18.5), normal weight (18.5 ≤ BMI < 24.9), pre-obese (25.0 ≤ BMI < 29.9), and obese (30.0 ≤ BMI). The indexed ReDS value was defined as a ReDS value divided by the modified congestion score index (the severity of pulmonary congestion on chest X-ray). The indexed ReDS values were compared among the 4 stratified groups.A total of 436 patients (76 [69, 82] years old and 254 men) were included. The median indexed ReDS values were 21.3 (19.1, 23.8), 25.7 (21.0, 29.5), 25.7 (20.3, 31.0), and 28.0 (21.1, 34.0) in underweight, normal weight, pre-obese, and obese patients, respectively, highlighting the underweight group had the lowest values (P < 0.001).ReDS values may be underestimated and specific caution should be paid in its interpretation in underweight patients.

Remote Dielectric Sensing to Assess Residual Pulmonary Congestion Following Percutaneous Mitral Valve Repair

Background and Objectives: Percutaneous mitral valve repair using a MitraClip system is an established therapeutic strategy to treat severe mitral regurgitation, which is recommended by guidelines in Europe and in the United States, whereas residual mitral regurgitation is associated with mortality and morbidity. Accurate assessment of residual mitral regurgitation is crucial for risk stratification and further adequate intervention, whereas its quantification has technical limitations due to “double” regurgitation that is often encountered following valve clipping. Remote dielectric sensing (ReDS^TM) is a non-invasive electromagnetic-based technology to quantify lung fluid levels and might be a promising tool to assess the impact of residual mitral regurgitation following MitraClip. Materials and Methods: Following MitraClip, ReDS values measurements and right heart catheterization were performed and correlated. Results: We had 13 patients (median 74 years, 7 men) who underwent successful MitraClip. According to the visual estimation, eight patients had none or mild regurgitation, and five patients had moderate regurgitation. ReDS values were distributed widely between 16% and 33%, irrespective of the severity of regurgitation. ReDS values had a moderate correlation with invasively measured pulmonary artery wedge pressure (r = 0.73, p = 0.004). Conclusions: ReDS value might be a promising tool to assess residual pulmonary congestion following MitraClip, irrespective of the visually estimated severity of residual mitral regurgitation.