Validation of Noninvasive Remote Dielectric Sensing System to Quantify Lung Fluid Levels

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.

Prognostic impact of residual pulmonary congestion assessed by remote dielectric sensing system in patients admitted for heart failure

AIMS

Remote dielectric sensing (ReDS) represents a contemporary non-invasive technique reliant on electromagnetic energy to quantify pulmonary congestion. Its prognostic significance within the context of heart failure (HF) patients remains elusive. This study aimed to assess the prognostic implications of residual pulmonary congestion, as gauged by the ReDS system, among patients admitted due to congestive HF.

METHODS AND RESULTS

We enrolled hospitalized HF patients who underwent ReDS assessments upon admission and discharge in a blinded manner, independent of attending physicians. We evaluated the prognostic impact of the ReDS ratio between admission and discharge on the primary outcome, which encompassed all-cause mortality and HF-related re-hospitalizations. A cohort of 133 patients (median age 78 [72, 84] years, 78 male [59%]) was included. Over a median observation period of 363 days post-index discharge, an escalated ReDS group (ReDS ratio > 100%), determined through statistical calculation, emerged as an independent predictor of the primary outcome, exhibiting an adjusted hazard ratio of 4.37 (95% confidence interval 1.13-16.81, P = 0.032). The cumulative incidence of the primary outcome was notably higher in the increased ReDS group compared with the decreased ReDS group (50.1% vs. 8.5%, P = 0.034).

CONCLUSIONS

Elevated ReDS ratios detected during the index hospitalization could serve as a promising prognostic indicator in HF patients admitted for treatment. The clinical ramifications of ReDS-guided HF management warrant validation in subsequent studies.

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.

Construction of novel potentiometric sensors modified with biogenically synthesized metal oxide nanoparticles for sensitive detection of the opioid agonist-antagonist nalbuphine hydrochloride in its injection

Novel and sensitive potentiometric sensors were described for the assay of nalbuphine HCl (NBP) in authentic powder and injection samples. The developed sensors were modified with alumina nanoparticles (Al2O3NPs) and copper oxide nanoparticles (CuONPs). The nanoscale materials were synthesized using the extract of Salvia officinalis leaves in an environmentally friendly manner. The synthesized metal oxides were fully confirmed by various analytical techniques. Scanning electron microscope confirmed the morphology of nanosized materials with even distribution and particle size of 55.07 ± 4.15 and 59.48 ± 4.50 nm for Al2O3NPs and CuONPs, respectively. The modified sensors were prepared in three different steps. Nalbuphine hydrochloride was mixed with phosphomolybdic acid to prepare the sensor material nalbuphine phosphomolybdate (NBP-PM). It was then mixed with polyvinyl chloride in the presence of o-nitrophenyl ether and metal oxide nanoparticles to form the membrane matrix. Finally, a copper wire was coated with the sensing material. Excellent potentials of 1.0 × 10-8-1.0 × 10-2 and 1.0 × 10-9-1.0 × 10-2 mol L-1 were measured with lower assay limits of 4.8 × 10-9 and 5.0 × 10-10 mol L-1. The average detection % were 99.28 ± 0.58% and 99.52 ± 0.28% for NBP-PM-Al2O3NPs and NBP-PM-CuONPs, correspondingly. The suitability of the described sensors was investigated in terms of various validation criteria, and the modified sensors exposed excellent applicability and insurance for the quantification of nalbuphine hydrochloride in its bulk samples and injections compared with another standard sensor. It is obvious that the developed NBP-PM-Al2O3NPs and NBP-PM-CuONPs will serve as suitable sensors for the determination of NBP.

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.

How to Assess the Degree of Pulmonary Congestion in Patients with Congestive Heart Failure

With the introduction of several novel medications, including angiotensin receptor neprilysin inhibitors and sodium-glucose cotransporter 2 inhibitors, in addition to conventional beta-blockers and mineralocorticoid receptor antagonists, mortality and morbidity in patients with heart failure improved significantly [...].

Remote dielectric sensing and lung ultrasound to assess pulmonary congestion

We investigated the agreement between remote dielectric sensing (ReDS) system, which is a recently introduced non-invasive technology to quantify the degree of pulmonary congestion, and lung ultrasound (LUS), which is a gold standard to assess the existence of severe pulmonary congestion. Consecutive patients who were hospitalized to examine the cause of heart failure and treat their heart failure in our institute were prospectively included. They received LUS and simultaneous ReDS measurements. Three or more B-lines at each LUS zone was assigned to B-profile positive, indicating the existence of significant pulmonary congestion. ReDS values ≥ 35% were defined as significant pulmonary congestion. A total of 19 heart failure patients were included (77 years, 13 men). Plasma B-type natriuretic peptide level was 131 (36, 416) pg/ml. Three patients had B-profile, indicating significant pulmonary congestion, and two of them had ≥ 35% of ReDS (sensitivity 66.7%, specificity 87.5%, and negative predictive value 93.3%). Most of the patients (79%) had lower B-lines below 3 and did not satisfy the criteria of B-profile, irrespective of wide ranges of ReDS values. ReDS system had as acceptable predictability as LUS in assessing the existence of significant pulmonary congestion. ReDS would be recommended to rule out significant pulmonary congestion or quantify the degree of less significant pulmonary congestion.

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

The reduction of pulmonary congestion is an essential clinical target in the management of chronic heart failure. This proves to be challenging given the lack of a gold standard method to quantify the degree of pulmonary congestion both quickly and non-invasively. Remote dielectric sensing (ReDS) is a non-invasive electromagnetic energy-based technology to quantify lung fluid levels as a percentage within minutes. This technique, due to its high negative predictive value, may be a useful tool particularly to rule out primarily cardiac causes of dyspnea in ambulatory patients when the values are normal. Further studies are warranted to establish ReDS-guided management of congestive heart failure patients.

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.

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.

Change in Lung Fluid Volume during Exercise in Patients with Exercise-Induced Mitral Regurgitation

Exercise-induced mitral regurgitation (MR) can be diagnosed during stress echocardiography testing. Remote dielectric sensing (ReDS^TM) is a noninvasive electromagnetic-based modality to measure lung fluid levels. The change in lung fluid levels in patients with MR during stress echocardiography remains unknown. Patients with symptomatic MR at baseline and suspected worsening exercise-induced MR underwent stress echocardiography. ReDS values were measured before and after the tests. A total of four patients (ages ranging between 74 and 84 years old, three women) underwent stress echocardiography testing using a bicycle ergometer. In patient A, MR effective regurgitant orifice area (EROA) remained unchanged and ReDS values decreased. EROA increased significantly with a small incremental change in ReDS values in patient B and patient C, who underwent valve repair with MitraClip later. Patient D had a mild increase in MR EROA but a considerable increase in ReDS values (from 22% to 32%), and eventually received valve repair with MitraClip. The ReDS system may be a complementary tool to conventional stress echocardiography in the evaluation of clinically significant MR and considering mitral valve intervention.

Lung Fluid Volume during Cardiopulmonary Exercise Testing

Background and Objectives: Cardiopulmonary exercise testing can be used to quantify exercise capacity in patients with heart failure with reduced ejection fraction (HfrEF). Lung fluid levels as measured non-invasively by remote dielectric sensing (ReDSTM), often correlate with intracardiac filling pressures. The change in lung fluid levels in patients with HfrEF during cardiopulmonary exercise testing is unknown. Materials and Methods: Patients with chronic HfrEF who underwent cardiopulmonary exercise testing between October 2021 and March 2022 were prospectively included in this proof-of-concept study, with ReDS values measured before and after testing. Results: Thirteen patients (median age 41 (37, 52) years, 69% men, plasma B-type natriuretic peptide 141 (57, 368) pg/mL) were included. Median peak oxygen consumption was 11.4 (10.7, 14.0) mL/kg/min. During the test, ReDS values increased from 25% to 32% only in one patient on inotropic support, whereas ReDS values remained unchanged in the other 12 patients. The former patient remained hospitalized, whereas the other patients were dischargeable without any new incidence of clinical events during the observational period (median duration 69 (33, 112] days). Conclusions: The ReDS system may be a feasible complementary tool to noninvasively assess the changes in lung fluid levels during cardiopulmonary exercise testing. The clinical implications of ReDS values during exercise needs further investigation.

Chronotype of Lung Fluid Levels in Patients with Chronic Heart Failure

Background: The variation in lung fluid levels dependent on chronotype in patients with chronic heart failure is unclear. Remote dielectric sensing (ReDS^TM) is a novel non-invasive system to quantify the lung fluids, which may correlate to intracardiac filling pressures. We aimed to understand the variation in ReDS measurements by chronotype in patients with chronic heart failure. Methods: The patients who were hospitalized for heart failure exacerbations between November 2021 and March 2022 were prospectively included. ReDS values were measured at clinically stable conditions at the following three time points during the day: 5:00 (morning), 12:00 (noon), and 21:00 (night) (manufacture-recommended reference of ReDS value: between 25% and 35%). Results: Twelve patients were included. The median age was 84 (75, 90) years and four patients (33%) were men. The median plasma B-type natriuretic peptide was 235 (178, 450) pg/mL. The median ReDS value was 38% (23%, 41%) in the morning. The ReDS value decreased significantly at the noon measurement, down to 28% (23%, 29%) (p = 0.005) and again increased significantly at the night measurement, up to 31% (27%, 42%) (p = 0.002). The patients were clinically stabilized during the observational period. Conclusions: the lung fluid level varied considerably in patients with chronic heart failure following clinical stabilization.

Initial Experience to Follow Lung Fluid Levels during Hemodialysis: A Possibility of Remote Dielectric Sensing-Guided Hemodialysis

Remote dielectric sensing (ReDS^TM) is a novel technology that noninvasively quantifies lung fluid levels. Trends in ReDS values following hemodialysis remain uninvestigated. In a 64-year-old man with clinically stable hemodynamics, 2.7 L of fluid was drained during hemodialysis whereas the ReDS value remained almost unchanged (from 32 to 30%). In a 60-year-old woman with unstable hemodynamics, only 1.8 L of fluid was drained during hemodialysis, whereas ReDS value decreased considerably from 37 to 27%. Given our initial experience measuring ReDS values during hemodialysis, the ratio of fluid removal by hemodialysis between systemic plasma and lung fluid might vary in each patient. ReDS value might be a promising marker to determine the degree of fluid removal in addition to the conventional multidisciplinary index, particularly for those with unstable hemodynamics. The implications of ReDS-guided hemodialysis remain a future concern.

Adaptive Servo-Ventilation as a Novel Therapeutic Strategy for Chronic Heart Failure

The introduction of new therapeutics for patients with chronic heart failure, including sacubitril/valsartan, sodium-glucose cotransporter 2 inhibitors, and ivabradine, in addition to beta-blockers, angiotensin converting enzyme inhibitors, and mineralocorticoid receptor antagonists, lends an opportunity for significant clinical risk reduction compared to what was available just one decade ago. Further clinical options are needed, however, for patients with residual clinical congestion refractory to these therapies. Adaptive servo-ventilation is a novel therapeutic option to address significant clinical volume in cases resistant to medical therapy. The aggregate benefit of these additional therapeutic strategies in addition to foundational medical therapy may be a promising option in the selected candidates who do not achieve acceptable clinical and quality-of-life improvements with oral medical therapy alone. Now is the era to reconsider the implication of an adaptive servo-ventilation-therapy-incorporated medical therapeutic strategy for patients with congestive heart failure.