Potential role for clinical calibration to increase engagement with and application of home telemonitoring: a report from the HeartCycle programme

Aims: There is a need for alternative strategies that might avoid recurrent admissions in patients with heart failure. home telemonitoring (HTM) to monitor patient's symptoms from a distance may be useful. This study attempts to assess changes in HTM vital signs in response to daily life activities (variations in medication, salt intake, exercise, and stress) and to establish which variations affect weight, blood pressure, and heart rate. Methods and results: We assessed 76 patients with heart failure (mean age 76 ± 10.8 years, 75% male, mainly in NYHA class II/III and from ischaemic aetiology cause). Patients were given a calendar of interventions scheduling activities approximately twice a week before measuring their vital signs. Eating salty food or a large meal were the activities that had a significant impact on weight gain (+0.3 kg; P < 0.001 and P = 0.006, respectively). Exercise and skipping a dose of medication other than diuretics increased heart rate (+3 bpm, P = 0.001 and almost +2 bpm, P = 0.016, respectively). Conclusions: Our HTM system was able to detect small changes in vital signs related to these activities. Further studies should assess if providing such a schedule of activities might be useful for patient education and could improve long-term adherence to recommended lifestyle changes

Detecting Heart Failure Decompensation by Measuring Transthoracic Bioimpedance in the Outpatient Setting: Rationale and Design of the SENTINEL-HF Study

BACKGROUND: Recurrent hospital admissions are common among patients admitted for acute decompensated heart failure (ADHF), but identification of patients at risk for rehospitalization remains challenging. Contemporary heart failure (HF) management programs have shown modest ability to reduce readmissions, partly because they monitor signs or symptoms of HF worsening that appear late during decompensation. Detecting early stages of HF decompensation might allow for immediate application of effective HF therapies, thereby potentially reducing HF readmissions. One of the earliest indicators of HF decompensation is intrathoracic fluid accumulation, which can be assessed using transthoracic bioimpedance. OBJECTIVE: The SENTINEL-HF study is a prospective observational study designed to test a novel, wearable HF monitoring system as a predictor of HF decompensation among patients discharged after hospitalization for ADHF. METHODS: SENTINEL-HF tests the hypothesis that a decline in transthoracic bioimpedance, as assessed daily with the Philips fluid accumulation vest (FAV) and transmitted using a mobile phone, is associated with HF worsening and rehospitalization. According to pre-specified power calculations, 180 patients admitted with ADHF are enrolled. Participants transmit daily self-assessments using the FAV-mobile phone dyad for 45 days post-discharge. The primary predictor is the deviation of transthoracic bioimpedance for 3 consecutive days from a patient-specific normal variability range. The ADHF detection algorithm is evaluated in relation with a composite outcome of HF readmission, diuretic up-titration, and self-reported HF worsening (Kansas City Cardiomyopathy Questionnaire) during a 90-day follow-up period. Here, we provide the details and rationale of SENTINEL-HF. RESULTS: Enrollment in the SENTINEL-HF study is complete and the 90-days follow-up is currently under way. Once data collection is complete, the study dataset will be used to evaluate our ADHF detection algorithm and the results submitted for publication. CONCLUSION: SENTINEL-HF emerged from our long-term vision that advanced home monitoring technology can improve the management of chronic HF by extending clinical care into patients\u27 homes. Monitoring transthoracic bioimpedance with the FAV may identify patients at risk of recurrent HF decompensation and enable timely preventive measures. TRIAL REGISTRATION: Clinicaltrials.gov NCT01877369: https://clinicaltrials.gov/ct2/show/NCT01877369 (Archived by WebCite at http://www.webcitation.org/6bDYl0dGy)

Bioimpedance-Based Heart Failure Deterioration Prediction Using a Prototype Fluid Accumulation Vest-Mobile Phone Dyad: An Observational Study

BACKGROUND: Recurrent heart failure (HF) events are common in patients discharged after acute decompensated heart failure (ADHF). New patient-centered technologies are needed to aid in detecting HF decompensation. Transthoracic bioimpedance noninvasively measures pulmonary fluid retention. OBJECTIVE: The objectives of our study were to (1) determine whether transthoracic bioimpedance can be measured daily with a novel, noninvasive, wearable fluid accumulation vest (FAV) and transmitted using a mobile phone and (2) establish whether an automated algorithm analyzing daily thoracic bioimpedance values would predict recurrent HF events. METHODS: We prospectively enrolled patients admitted for ADHF. Participants were trained to use a FAV-mobile phone dyad and asked to transmit bioimpedance measurements for 45 consecutive days. We examined the performance of an algorithm analyzing changes in transthoracic bioimpedance as a predictor of HF events (HF readmission, diuretic uptitration) over a 75-day follow-up. RESULTS: We observed 64 HF events (18 HF readmissions and 46 diuretic uptitrations) in the 106 participants (67 years; 63.2%, 67/106, male; 48.1%, 51/106, with prior HF) who completed follow-up. History of HF was the only clinical or laboratory factor related to recurrent HF events (P=.04). Among study participants with sufficient FAV data (n=57), an algorithm analyzing thoracic bioimpedance showed 87% sensitivity (95% CI 82-92), 70% specificity (95% CI 68-72), and 72% accuracy (95% CI 70-74) for identifying recurrent HF events. CONCLUSIONS: Patients discharged after ADHF can measure and transmit daily transthoracic bioimpedance using a FAV-mobile phone dyad. Algorithms analyzing thoracic bioimpedance may help identify patients at risk for recurrent HF events after hospital discharge. Sert Kuniyoshi, Joseph Rock, Theo E Meyer, David D McManus. Originally published in JMIR Cardio (http://cardio.jmir.org), 13.03.2017

Monitoring thoracic fluid content using bioelectrical impedance spectroscopy and Cole modeling

Heart failure is a chronic disease marked by frequenthospitalizations due to pulmonary fluid congestion. Monitoringthe thoracic fluid status may favor the detection of fluidcongestion in an early stage and enable targeted preventivemeasures. Bioelectrical impedance spectroscopy (BIS) has beenused in combination with the Cole model for monitoring bodycomposition including fluid status. The model parameters reflectintracellular and extracellular fluid volume as well as cell sizes,types and interactions. Transthoracic BIS may be a suitableapproach to monitoring variations in thoracic fluid content.The aim of this study was to identify BIS measures, which canbe derived based on the Cole model, that are sensitive to earlystages of thoracic fluid accumulation. We simulated this medicalcondition in healthy subjects by shifting a part of the whole bloodfrom the periphery towards the thorax. The redistribution ofblood was achieved non-invasively through leg compression usinginflatable leg sleeves. We acquired BIS data before, during andafter compression of the legs and examined the effect of thoracicfluid variations on parameters derived based on the Cole modeland on geometrical properties of the impedance arc. Indicatordilution measurements obtained through cardiac magneticresonance imaging were used as a reference for the changes inpulmonary fluid volume.Eight healthy subjects were included in the study. The Colemodel parameters of the study group at baseline were: R0 = 51.4 ±6.7 Ω, R∞ = 25.0 ± 7.0 Ω, fc = 49.0 ± 10.5 kHz, α = 0.687 ± 0.027, theresistances of individual fluid compartments were RE = 51.4 ± 6.7Ω, RI = 50.5 ± 22.9 Ω, the fluid distribution ratio was K = 1.1 ± 0.3,and the radius, area and depression of the arc’s center were: R =15.7 ± 1.3 Ω, XC = −8.5 ± 1.5 Ω, A = 134.0 ± 15.6 Ω2. The effect ofleg compression was a relatively small, reversible increase inpulmonary blood volume of 90 ± 57 mL. We observed significantchanges in parameters associated with intracellular, extracellularand total fluid volume (R0: -1.5 ± 0.9 %, p < 0.01; R∞: −2.1 ± 1.1, p <0.01; RI: −2.6 ± 1.6 %, p < 0.01), and in the arc’s geometricalproperties (R: -1.6 ± 1.3 %, p < 0.05; XC: −1.7 ± 1.5 %, p < 0.05, A:−2.9 ± 1.2 %, p < 0.01). K and the parameters associated withtissue structure fc and α remained stable.Transthoracic BIS is sensitive to small variations in intrathoracicblood volume, in particular the resistances of fluidcompartments and the geometric properties of the impedancearc. Taken together with previous studies, our findings suggestthat R0 may be a suitable parameter to monitor congestion. Use ofadditional parameters such as RI, K, XC, fc and α may enable thediscrimination between different types and stages of thoracic fluidaccumulation and should be the focus of future research

Monitoring thoracic fluid content using bioelectrical impedance spectroscopy and Cole modeling

Heart failure is a chronic disease marked by frequenthospitalizations due to pulmonary fluid congestion. Monitoringthe thoracic fluid status may favor the detection of fluidcongestion in an early stage and enable targeted preventivemeasures. Bioelectrical impedance spectroscopy (BIS) has beenused in combination with the Cole model for monitoring bodycomposition including fluid status. The model parameters reflectintracellular and extracellular fluid volume as well as cell sizes,types and interactions. Transthoracic BIS may be a suitableapproach to monitoring variations in thoracic fluid content.The aim of this study was to identify BIS measures, which canbe derived based on the Cole model, that are sensitive to earlystages of thoracic fluid accumulation. We simulated this medicalcondition in healthy subjects by shifting a part of the whole bloodfrom the periphery towards the thorax. The redistribution ofblood was achieved non-invasively through leg compression usinginflatable leg sleeves. We acquired BIS data before, during andafter compression of the legs and examined the effect of thoracicfluid variations on parameters derived based on the Cole modeland on geometrical properties of the impedance arc. Indicatordilution measurements obtained through cardiac magneticresonance imaging were used as a reference for the changes inpulmonary fluid volume.Eight healthy subjects were included in the study. The Colemodel parameters of the study group at baseline were: R0 = 51.4 ±6.7 Ω, R∞ = 25.0 ± 7.0 Ω, fc = 49.0 ± 10.5 kHz, α = 0.687 ± 0.027, theresistances of individual fluid compartments were RE = 51.4 ± 6.7Ω, RI = 50.5 ± 22.9 Ω, the fluid distribution ratio was K = 1.1 ± 0.3,and the radius, area and depression of the arc’s center were: R =15.7 ± 1.3 Ω, XC = −8.5 ± 1.5 Ω, A = 134.0 ± 15.6 Ω2. The effect ofleg compression was a relatively small, reversible increase inpulmonary blood volume of 90 ± 57 mL. We observed significantchanges in parameters associated with intracellular, extracellularand total fluid volume (R0: -1.5 ± 0.9 %, p &lt; 0.01; R∞: −2.1 ± 1.1, p &lt;0.01; RI: −2.6 ± 1.6 %, p &lt; 0.01), and in the arc’s geometricalproperties (R: -1.6 ± 1.3 %, p &lt; 0.05; XC: −1.7 ± 1.5 %, p &lt; 0.05, A:−2.9 ± 1.2 %, p &lt; 0.01). K and the parameters associated withtissue structure fc and α remained stable.Transthoracic BIS is sensitive to small variations in intrathoracicblood volume, in particular the resistances of fluidcompartments and the geometric properties of the impedancearc. Taken together with previous studies, our findings suggestthat R0 may be a suitable parameter to monitor congestion. Use ofadditional parameters such as RI, K, XC, fc and α may enable thediscrimination between different types and stages of thoracic fluidaccumulation and should be the focus of future research

Potential role for clinical calibration to increase engagement with and application of home telemonitoring: a report from the HeartCycle programme

Aims: There is a need for alternative strategies that might avoid recurrent admissions in patients with heart failure. home telemonitoring (HTM) to monitor patient's symptoms from a distance may be useful. This study attempts to assess changes in HTM vital signs in response to daily life activities (variations in medication, salt intake, exercise, and stress) and to establish which variations affect weight, blood pressure, and heart rate. Methods and results: We assessed 76 patients with heart failure (mean age 76 ± 10.8 years, 75% male, mainly in NYHA class II/III and from ischaemic aetiology cause). Patients were given a calendar of interventions scheduling activities approximately twice a week before measuring their vital signs. Eating salty food or a large meal were the activities that had a significant impact on weight gain (+0.3 kg; P<0.001 and P = 0.006, respectively). Exercise and skipping a dose of medication other than diuretics increased heart rate (+3 bpm, P = 0.001 and almost +2 bpm, P = 0.016, respectively). Conclusions: Our HTM system was able to detect small changes in vital signs related to these activities. Further studies should assess if providing such a schedule of activities might be useful for patient education and could improve long-term adherence to recommended lifestyle changes

Sensitivity of a wearable bioimpedance monitor to changes in the thoracic fluid content of heart failure patients

\u3cp\u3eIn the context of home telehealth, spectroscopic bioimpedance measurements have the potential to aid therapy guidance and health maintenance in patients at risk of abnormal fluid accumulation such as heart failure patients. To this aim, monitoring devices need to be sensitive to subtle changes in congestion and hemodynamics. In this study, we assess the sensitivity of a wearable trans-thoracic bioimpedance monitor (BIM) with textile electrodes to variations in the thoracic fluid content of heart failure patients induced by postural maneuvers and omission of medications such as diuretics. The results indicate that the BIM is able to follow these changes and that the largest effect size is accounted by the omission of heart failure medications.\u3c/p\u3

Comparison of cardiac magnetic resonance imaging and bio-impedance spectroscopy for the assessment of fluid displacement induced by external leg compression

\u3cp\u3eHeart failure is marked by frequent hospital admissions, often as a consequence of pulmonary congestion. Current gold standard techniques for thoracic fluid measurement require invasive heamodynamic access and therefore they are not suitable for continuous monitoring. Changes in thoracic impedance (TI) may enable non-invasive early detection of congestion and prevention of unplanned hospitalizations. However, the usefulness of TI to assess thoracic fluid status is limited by inter-subject variability and by the lack of reliable normalization methods. Indicator dilution methods allow absolute fluid volume estimation; cardiac magnetic resonance (CMR) has been recently proposed to apply indicator dilution methods in a minimally-invasive manner. In this study, we aim to compare bio-impedance spectroscopy (BIS) and CMR for the assessment of thoracic fluid status, and to determine their ability to detect fluid displacement induced by a leg compression procedure in healthy volunteers. A pressure gradient was applied across each subject's legs for 5 min (100-60 mmHg, distal to proximal). Each subject underwent a continuous TI-BIS measurement during the procedure, and repeated CMR-based indicator dilution measurements on a 1.5 T scanner at baseline, during compression, and after pressure release. The Cole-Cole and the local density random walk models were used for parameter extraction from TI-BIS and indicator dilution measurements, respectively. Intra-thoracic blood volume index (ITBI) derived from CMR, and extracellular fluid resistance (R \u3csub\u3eE\u3c/sub\u3e) from TI-BIS, were considered as thoracic fluid status measures. Eight healthy volunteers were included in this study. An increase in ITBI of 45.2 47.2 ml m\u3csup\u3e-2\u3c/sup\u3e was observed after the leg inflation (13.1 15.1% w.r.t. baseline, p &lt; 0.05), while a decrease of -0.84 0.39 Ω in R \u3csub\u3eE\u3c/sub\u3e (-1.7 0.9% w.r.t. baseline, p &lt; 0.05) was observed. ITBV and R \u3csub\u3eE\u3c/sub\u3e normalized by body mass index were strongly inversely correlated (r = -0.93, p &lt; 0.05). In conclusion, an acute fluid displacement to the thoracic circulation was induced in healthy volunteers. Significant changes were observed in the considered thoracic fluid measures derived from BIS and CMR. Good correlation was observed between the two measurement techniques. Further clinical studies will be necessary to prospectively evaluate the value of a combination of the two techniques for prediction of re-hospitalizations after admission for heart failure.\u3c/p\u3