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European Journal of Heart Failure Jul 2021
Topics: Blood Volume; Heart Failure; Humans; Stroke Volume; Ventricular Function, Left
PubMed: 34118181
DOI: 10.1002/ejhf.2268 -
Sensors (Basel, Switzerland) Feb 2022This paper presents a novel computational algorithm to estimate blood volume decompensation state based on machine learning (ML) analysis of multi-modal...
This paper presents a novel computational algorithm to estimate blood volume decompensation state based on machine learning (ML) analysis of multi-modal wearable-compatible physiological signals. To the best of our knowledge, our algorithm may be the first of its kind which can not only discriminate normovolemia from hypovolemia but also classify hypovolemia into absolute hypovolemia and relative hypovolemia. We realized our blood volume classification algorithm by (i) extracting a multitude of features from multi-modal physiological signals including the electrocardiogram (ECG), the seismocardiogram (SCG), the ballistocardiogram (BCG), and the photoplethysmogram (PPG), (ii) constructing two ML classifiers using the features, one to classify normovolemia vs. hypovolemia and the other to classify hypovolemia into absolute hypovolemia and relative hypovolemia, and (iii) sequentially integrating the two to enable multi-class classification (normovolemia, absolute hypovolemia, and relative hypovolemia). We developed the blood volume decompensation state classification algorithm using the experimental data collected from six animals undergoing normovolemia, relative hypovolemia, and absolute hypovolemia challenges. Leave-one-subject-out analysis showed that our classification algorithm achieved an F1 score and accuracy of (i) 0.93 and 0.89 in classifying normovolemia vs. hypovolemia, (ii) 0.88 and 0.89 in classifying hypovolemia into absolute hypovolemia and relative hypovolemia, and (iii) 0.77 and 0.81 in classifying the overall blood volume decompensation state. The analysis of the features embedded in the ML classifiers indicated that many features are physiologically plausible, and that multi-modal SCG-BCG fusion may play an important role in achieving good blood volume classification efficacy. Our work may complement existing computational algorithms to estimate blood volume compensatory reserve as a potential decision-support tool to provide guidance on context-sensitive hypovolemia therapeutic strategy.
Topics: Algorithms; Animals; Blood Volume; Hemorrhage; Hypovolemia; Machine Learning; Wearable Electronic Devices
PubMed: 35214238
DOI: 10.3390/s22041336 -
The American Journal of Cardiology Aug 2021Heart failure (HF) commonly progresses over time and identifying differences in volume profiles may help stratify risk and guide therapy. The aim of this study was to...
Heart failure (HF) commonly progresses over time and identifying differences in volume profiles may help stratify risk and guide therapy. The aim of this study was to assess the pathophysiologic and prognostic roles of volume profiles for HF progression in stable ambulatory and hospitalized patients. HF patients who had undergone quantitative intravascular volume analysis (185 outpatients and 139 inpatients) were retrospectively assessed for the combined end point of HF-related hospital admissions (outpatients), HF-readmissions (inpatients), and overall all-cause mortality. After multivariate Cox regression analysis, greater total blood volume expansion was associated with higher risk of HF-admission in previously stable outpatients (HR: 1.023, CI 1.005 to 1.043; p = 0.013) while in more advanced HF (inpatients) total blood volume expansion was associated with lower risk for HF-readmission and mortality (HR: 0.982, CI 0.967 to 0.997; p = 0.017). Secondary analysis suggests that subclinical plasma volume expansion was a driving factor for the detrimental association in outpatients (HR: 1.018, CI 0.997 to 1.036; p = 0.054), while an increase in red blood cell mass was central to the beneficial association in advanced HF (HR: 0.979, CI 0.968 to 0.991; p <0.001). In conclusion, understanding differences in plasma volume and red blood cell mass profiles can provide insight into the pathophysiology and progression of HF.
Topics: Aged; Aged, 80 and over; Blood Volume; Blood Volume Determination; Disease Progression; Erythrocyte Volume; Female; Heart Failure; Hospitalization; Humans; Male; Middle Aged; Patient Readmission; Plasma Volume; Prognosis; Proportional Hazards Models; Retrospective Studies; Severity of Illness Index
PubMed: 34215355
DOI: 10.1016/j.amjcard.2021.05.020 -
JACC. Heart Failure Nov 2018
Topics: Blood Volume; Heart; Heart Failure; Humans; Natriuretic Peptide, Brain; Stroke Volume
PubMed: 30316940
DOI: 10.1016/j.jchf.2018.08.003 -
JACC. Heart Failure Nov 2018This study performed a retrospective outcome analyses of a large cohort of mixed ejection fraction patients admitted for acute heart failure (HF), whose inpatient care...
OBJECTIVES
This study performed a retrospective outcome analyses of a large cohort of mixed ejection fraction patients admitted for acute heart failure (HF), whose inpatient care was guided by individual quantitative blood volume analysis (BVA) results.
BACKGROUND
Decongestion strategies in patients hospitalized for HF are based on clinical assessment of volume and have not integrated a quantitative intravascular volume metric.
METHODS
Propensity score control matching analysis was performed in 245 consecutive HF admissions to a community hospital (September 2007 to April 2014; 78 ± 10 years of age; 50% with HF with reduced ejection fraction [HFrEF]; and 30% with Stage 4 chronic kidney disease). Total blood volume (TBV), red blood cell volume (RBCV), and plasma volume (PV) were measured at admission by using iodine-131-labeled albumin indicator-dilution technique. Decongestion strategy targeted a TBV threshold of 6% to 8% above patient-specific normative values. Anemia was treated based on cause. Hematocrit (Hct) measurements were monitored to assess effectiveness of interventions. Control subjects derived from Centers for Medicare and Medicaid Services data were matched 10:1 for demographics, comorbidity, and year of treatment.
RESULTS
Although 66% of subjects had PV expansion, only 37% were hypervolemic (TBV >10% excess). True anemia (RBCV ≥10% deficit) was present in 62% of subjects. Treatment of true anemia without hypervolemia resulted in a rise in peripheral Hct of 2.7 ± 2.9% (p < 0.001), and diuretic treatment of hypervolemia in cases without anemia caused a 4.5 ± 3.9% (p < 0.001) increase in peripheral Hct at 11.3 ± 7.5 days after admission. Subjects had lower 30-day rates of readmission (12.2% vs. 27.7%, respectively; p < 0.001), of 30-day mortality (2.0% vs. 11.1%, respectively; p < 0.001), and of 365-day mortality (4.9% vs. 35.5%, respectively; p < 0.001) but longer lengths of stay (7.3 vs. 5.6 days, respectively; p < 0.001) than control subjects.
CONCLUSIONS
Retrospective outcomes using volume-guided HF therapy versus propensity-matched controls support the benefit of BVA in guiding volume management and reducing death and rehospitalization due to HF.
Topics: Aged; Blood Volume; Blood Volume Determination; Erythrocyte Volume; Female; Heart Failure; Humans; Male; Patient Readmission; Propensity Score; Retrospective Studies; Treatment Outcome
PubMed: 30316941
DOI: 10.1016/j.jchf.2018.06.017 -
Journal of Cardiovascular Translational... Aug 2020Volume management is an essential component of anti-hypertensive therapy. Different volume phenotypes have been proposed. We sought to study the total blood volume...
Volume management is an essential component of anti-hypertensive therapy. Different volume phenotypes have been proposed. We sought to study the total blood volume (TBV), plasma volume (PV), and red blood cell volume (RBV) in hypertensive patients. We included patients followed in an outpatient cardiology clinic from 1998 to 2003. Blood volume (BV) parameters were measured using radioisotope iodine-131-labeled albumin dilution technique. Values were expressed as percentage (%) deviation from ideal volumes. A total of 95 patients were included. The intravascular volume distribution as percent deviation from normal volume ranged from - 23 to + 28% for TBV, - 22 to + 36% for PV and - 29 to + 37% for RBV. There was no significant correlation between systolic BP and any of the BV parameters (TBV and SBP, r = - 0.03; PV and SBP, r = - 0.12; RBV and SBP, r = - 0.08). Patients with hypertension have a wide variation in BV parameters. BV does not correlate with SBP.
Topics: Blood Pressure; Blood Volume; Blood Volume Determination; Chronic Disease; Erythrocyte Volume; Female; Humans; Hypertension; Male; Middle Aged; Plasma Volume; Predictive Value of Tests; Radioisotope Dilution Technique; Retrospective Studies; Serum Albumin, Radio-Iodinated
PubMed: 31463701
DOI: 10.1007/s12265-019-09910-4 -
BioMed Research International 2014Arterial pulse pressure has been widely used as surrogate of stroke volume, for example, in the guidance of fluid therapy. However, recent experimental investigations...
Arterial pulse pressure has been widely used as surrogate of stroke volume, for example, in the guidance of fluid therapy. However, recent experimental investigations suggest that arterial pulse pressure is not linearly proportional to stroke volume. However, mechanisms underlying the relation between the two have not been clearly understood. The goal of this study was to elucidate how arterial pulse pressure and stroke volume respond to a perturbation in the left ventricular blood volume based on a systematic mathematical analysis. Both our mathematical analysis and experimental data showed that the relative change in arterial pulse pressure due to a left ventricular blood volume perturbation was consistently smaller than the corresponding relative change in stroke volume, due to the nonlinear left ventricular pressure-volume relation during diastole that reduces the sensitivity of arterial pulse pressure to perturbations in the left ventricular blood volume. Therefore, arterial pulse pressure must be used with care when used as surrogate of stroke volume in guiding fluid therapy.
Topics: Arteries; Baroreflex; Blood Pressure; Blood Volume; Computer Simulation; Elasticity; Humans; Models, Cardiovascular; Stroke Volume; Systole; Time Factors; Ventricular Function
PubMed: 25006577
DOI: 10.1155/2014/459269 -
PloS One 2009Blood in the splanchnic vasculature can be transferred to the extremities. We quantified such blood shifts in normal subjects by measuring trunk volume by optoelectronic...
Blood in the splanchnic vasculature can be transferred to the extremities. We quantified such blood shifts in normal subjects by measuring trunk volume by optoelectronic plethysmography, simultaneously with changes in body volume by whole body plethysmography during contractions of the diaphragm and abdominal muscles. Trunk volume changes with blood shifts, but body volume does not so that the blood volume shifted between trunk and extremities (Vbs) is the difference between changes in trunk and body volume. This is so because both trunk and body volume change identically with breathing and gas expansion or compression. During tidal breathing Vbs was 50-75 ml with an ejection fraction of 4-6% and an output of 750-1500 ml/min. Step increases in abdominal pressure resulted in rapid emptying presumably from the liver with a time constant of 0.61+/-0.1SE sec. followed by slower flow from non-hepatic viscera. The filling time constant was 0.57+/-0.09SE sec. Splanchnic emptying shifted up to 650 ml blood. With emptying, the increased hepatic vein flow increases the blood pressure at its entry into the inferior vena cava (IVC) and abolishes the pressure gradient producing flow between the femoral vein and the IVC inducing blood pooling in the legs. The findings are important for exercise because the larger the Vbs the greater the perfusion of locomotor muscles. During asystolic cardiac arrest we calculate that appropriate timing of abdominal compression could produce an output of 6 L/min. so that the abdominal circulatory pump might act as an auxiliary heart.
Topics: Adult; Blood Pressure; Blood Volume; Exercise; Female; Humans; Male; Plethysmography; Splanchnic Circulation
PubMed: 19440240
DOI: 10.1371/journal.pone.0005550 -
Critical Care (London, England) 2013Assessment and monitoring of hemodynamics is a cornerstone in critically ill patients as hemodynamic alteration may become life-threatening in a few minutes. Defining... (Review)
Review
Assessment and monitoring of hemodynamics is a cornerstone in critically ill patients as hemodynamic alteration may become life-threatening in a few minutes. Defining normal values in critically ill patients is not easy, because 'normality' is usually referred to healthy subjects at rest. Defining 'adequate' hemodynamics is easier, which embeds whatever pressure and flow set is sufficient to maintain the aerobic metabolism. We will refer to the unifying hypothesis proposed by Schrier several years ago. Accordingly, the alteration of three independent variables - heart (contractility and rate), vascular tone and intravascular volume - may lead to underfilling of the arterial tree, associated with reduced (as during myocardial infarction or hemorrhage) or expanded (sepsis or cirrhosis) plasma volume. The underfilling is sensed by the arterial baroreceptors, which activate primarily the sympathetic nervous system and renin-angiotensin-aldosterone system, as well as vasopressin, to restore the arterial filling by increasing the vascular tone and retaining sodium and water. Under 'normal' conditions, therefore, the homeostatic system is not activated and water/sodium excretion, heart rate and oxygen extraction are in the range found in normal subjects. When arterial underfilling occurs, the mechanisms are activated (sodium and water retention) - associated with low central venous oxygen saturation (ScvO2) if underfilling is caused by low flow/hypovolemia, or with normal/high ScvO2 if associated with high flow/hypervolemia. Although the correction of hemodynamics should be towards the correction of the independent determinants, the usual therapy performed is volume infusion. An accepted target is ScvO2 >70%, although this ignores the arterial underfilling associated with volume expansion/high flow. For large-volume resuscitation the worst solution is normal saline solution (chloride load, strong ion difference = 0, acidosis). To avoid changes in acid-base equilibrium the strong ion difference of the infused solution should be equal to the baseline bicarbonate concentration.
Topics: Blood Volume; Coronary Disease; Critical Care; Critical Illness; Hemodynamics; Humans
PubMed: 23514343
DOI: 10.1186/cc11502 -
ASAIO Journal (American Society For... 2018Long- and short-term adverse outcomes in hemodialysis (HD) have been associated with intradialytic hypotension, a common HD complication and significant cause of...
Long- and short-term adverse outcomes in hemodialysis (HD) have been associated with intradialytic hypotension, a common HD complication and significant cause of morbidity. It has been suggested that knowledge of absolute blood volume (ABV) could be used to significantly improve treatment outcomes. Different dilution-based protocols have been proposed for estimating ABV, all relying on the classic mono-exponential back-extrapolation algorithm (BEXP). In this paper, we introduce a dialysate dilution protocol and an estimation algorithm based on a variable-volume, two-compartment, intravascular blood water content kinetic model (VVKM). We compare ABV estimates derived using the two algorithms in a dialysate dilution study including three arterio-venous (AV) and three central-venous (CV) access patients, and multiple bolus injection tests (3-5) within each of several (2-6) HD treatments. The distribution of differences between ABV estimated from the two methods showed negligible systematic difference between the mean values of ABVs estimated from the BEXP and VVKM algorithms, however, the VVKM estimates were 53% and 42% more precise for the CV and AV patients, respectively. Good agreement was observed between measured and VVKM-estimated blood water concentration with the root-mean-square error (RMSE) less than 0.02 kg/kg (2%) and 0.03 kg/kg (3%) for AV and CV patients, respectively. The dilution protocol and the new VVKM-based estimation algorithm offer a noninvasive, inexpensive, safe, and practical approach for ABV estimation in routine HD settings.
Topics: Aged; Algorithms; Blood Volume; Blood Volume Determination; Dialysis Solutions; Humans; Hypotension; Kinetics; Middle Aged; Renal Dialysis
PubMed: 28742531
DOI: 10.1097/MAT.0000000000000608