Peripheral Venous Hemoglobin and Red Blood Cell Mass Mismatch in Volume Overload Systolic Heart Failure: Implications for Patient Management

Understanding the variability in red cell and plasma volume combinations can help guide management in heart failure

AIMS

Quantitative methods have shown clinically significant heterogeneity in blood volume (BV) profiles across heart failure (HF) phenotypes. These profiles extend from hypovolaemia to normal BV and to variable degrees of BV hypervolaemia, frequently with similar clinical presentations. However, a comprehensive survey of BV profiles providing practical clinical guidance for the interpretation and management of quantitative plasma volume (PV) and red blood cell (RBC) mass findings has not been reported. The intent of this study is to advance this concept through a multicentre analysis.

METHODS AND RESULTS

A retrospective analysis of clinical and BV data was undertaken in stable NYHA class II-III HF patients (N = 546). BV was quantitated using established nuclear medicine indicator-dilution methodology. Differing combinations of PV and RBC mass were identified contributing to marked heterogeneity in overall BV profiles. A quantitatively normal BV was identified in 32% of the cohort but of these only ~1/3 demonstrated a true normal BV (i.e., normal PV + normal RBC mass). The remaining portion of normal BV profiles reflected balanced combinations of compensatory PV expansion with RBC mass deficit (anaemia) (14% of cohort) and PV contraction with RBC mass excess (erythrocythemia) (6% of cohort). Main contributors to BV hypervolaemia were PV excess with a normal RBC mass (21% of cohort; 23% female) and PV excess with erythrocythemia (24% of cohort; 26% female). Hypovolaemia was predominately defined by RBC mass deficit with a normal PV (6% of cohort; 57% female) or RBC mass deficit with PV contraction (5% of cohort; 48% female).

CONCLUSIONS

Findings support the clinical relevance of identifying and accurately interpreting the varying combinations of PV and RBC mass in patients with chronic HF. This in turn helps guide appropriate individualized patient management strategies. A practical volume-based guideline is provided in an effort to aid clinician interpretation.

Fluid volume status detection model for patients with heart failure based on machine learning methods

Backgroud

Fluid volume abnormalities are a major cause of exacerbations in heart failure patients. However, there is few efficient, rapid, or cost-effective clinical approach for determining volume status, resulting in inadequate or unsatisfactory treatment. The aim was to develop an early fluid volume detection model for heart failure patients utilizing a machine learning stratification.

Methods

The training set data collected by Tianjin Chest Hospital on heart failure patients from December 2016 to December 2021, included 2056 samples and 97 medical characteristics. The minimum Redundancy Maximum Relevance(mRMR) feature selection method was utilized to filter features that were strongly related to the patient's fluid volume status. Four machine learning classification models were used to predict patients' fluid volume status, and their effectiveness was measured using the receiver operating characteristic (ROC) area under the curve (AUC), calibration curve, accuracy, precision, recall, F1 score, specificity, and sensitivity. Data from 186 heart failure patients collected between January 2022 and July 2022 were employed as an external validation set to investigate the effects of model training. SHapley Additive exPlanations (SHAP) were used to interpret the ML models.

Results

Thirty features were selected for model development, and the area under the ROC curve AUC (95 % CI) for the four machine learning models in the testing set was 0.75 (0.73-0.77), 0.77 (0.74-0.79), 0.70 (0.67-0.73), and 0.76 (0.73-0.78), and the AUC (95 % CI) in the external validation set was 0.74 (0.71-0.76), 0.70 (0.67-0.73), 0.64 (0.59-0.68), and 0.67 (0.63-0.71). Logistic regression models were globally interpreted using SHAP-based summary plots.

Conclusions

Machine learning methods are effective in detecting fluid volume status in heart failure patients and can assist physicians with assisted diagnosis, thus helping clinicians to tailor precise management.

Congestion/decongestion in heart failure: what does it mean, how do we assess it, and what are we missing?-is there utility in measuring volume?

Clinical congestion remains a major cause of hospitalization and re-hospitalizations in patients with chronic heart failure (HF). Despite the high prevalence of this issue and clinical concern in HF practice, there is limited understanding of the complex pathophysiology relating to the "congestion" of congestive HF. There is no unifying definition or clear consensus on what is meant or implied by the term "congestion." Further, the discordance in study findings relating congestion to physical signs and symptoms of HF, cardiac hemodynamics, or metrics of weight change or fluid loss with diuretic therapy has not added clarity. In this review, these factors will be discussed to add perspective to this issue and consider the factors driving "congestion." There remains a need to better understand the roles of fluid retention promoting intravascular and interstitial compartment expansions, blood volume redistribution from venous reservoirs, altered venous structure and capacity, elevated cardiac filling pressure hemodynamics, and heterogeneous intravascular volume profiles (plasma volume and red blood cell mass) with a goal to help demystify "congestion" in HF. Further, this includes highlighting the importance of recognizing that congestion is not the result of a single pathway but a complex of responses some of which produce symptoms while others do not; yet, we confine these varied responses to the single and somewhat vague term "congestion."

Blood Volume Analysis and Cardiorenal Syndrome: From Bench to Bedside

BACKGROUND

This review delves into the intricate landscape of cardiorenal syndrome (CRS) and highlights the pivotal role of blood volume analysis (BVA) in improving patient care and outcomes.

SUMMARY

BVA offers a direct and highly accurate quantification of intravascular volume, red blood cell volume, and plasma volume, complete with patient-specific norms. This diagnostic tool enhances the precision of diuretic and red cell therapies, significantly elevating the effectiveness of conventional care.

KEY MESSAGES

Our objectives encompass a comprehensive understanding of how BVA informs the evaluation and treatment of CRS, including its subtypes, pathophysiology, and clinical significance. We delve into BVA principles, techniques, and measurements, elucidating its diagnostic potential and advantages compared to commonly used surrogate measures. We dissect the clinical relevance of BVA in various CRS scenarios, emphasizing its unique contributions to each subtype. By assessing the tangible impact of BVA on patient outcomes through meticulous analysis of relevant clinical studies, we unveil its potential to enhance health outcomes and optimize resource utilization. Acknowledging the challenges and limitations associated with BVA's clinical implementation, we underscore the importance of multidisciplinary collaboration among cardiologists, nephrologists, and other clinicians. Finally, we identify research gaps and propose future directions for BVA and CRS, contributing to ongoing advancements in this field and patients affected by this complicated clinical syndrome.

Patient Sex Impacts Volume Phenotypes and Hemodynamics in Chronic Heart Failure: A Multicenter Analysis

BACKGROUND

Quantitative methods have shown clinically significant heterogeneity in blood volume (BV) profiles in patients with chronic heart failure (HF). How patients' sex might impact this volume heterogeneity and its relationship to cardiac hemodynamics remains to be defined.

METHODS

Retrospective analysis of clinical and quantitative BV, plasma volume (PV) and red blood cell (RBC) mass data was undertaken across 3 medical centers. BV was quantitated using nuclear medicine I-131-labeled plasma albumin indicator-dilution methodology with cardiac hemodynamics obtained within 24 hours.

RESULTS

In an analysis of 149 males and 106 females, absolute BV was greater, on average, in males (6.9 ± 1.7 vs 5.0 ± 1.2 liters; P < 0.001); however, a wide range in BVs was demonstrated in both sexes (2.9-14.5 liters). Male sex was associated with higher prevalence of large (+ 25% of normal) BV and PV expansions (36% vs 15% and 51% vs 21%, respectively; both P < 0.001). In contrast, female sex was associated with higher prevalence of normal total BV (44% vs 27%; P = 0.005), PV (54% vs 27%; P < 0.001), hypovolemia (23% vs 11%; P = 0.005), and true anemia (42% vs 26%; P < 0.001). Cardiac hemodynamics differed by sex, but only modest associations were demonstrated between volume profiles and cardiac filling pressures.

CONCLUSIONS

Findings support unique intravascular volume profiles reflecting sex-specific differences in the prevalence and distributions of total BV, PV and RBC mass profiles in patients with chronic HF. This underscores the importance of recognizing patients' sex as a significant factor influencing volume homeostasis, which needs to be taken into account to individualize volume-management strategies effectively.

Comparison of Blood Volume Profiles in Heart Failure With Preserved and Reduced Ejection Fractions: Sex Makes a Difference

BACKGROUND

Blood volume (BV) profiles vary markedly in patients with heart failure (HF), but how HF phenotypes and patient sex impact volume profiles remain to be explored. The aim of the study was to differentiate BV, plasma volume, and red blood cell mass profiles by phenotypes of preserved and reduced left ventricular ejection fractions and assess the impact of patient sex on profile heterogeneity.

METHODS

Retrospective analysis of clinical and BV data was undertaken in patients with chronic New York Heart Association II-III heart failure. BV was quantitated using the nuclear medicine indicator-dilution methodology.

RESULTS

A total of 530 BV analyses (360 HF with reduced ejection fraction and 170 HF with preserved ejection fraction) were identified in 395 unique patients. Absolute BV was greater in HF with reduced ejection fraction (6.7±1.8 versus 5.9±1.6 liters: P<0.001); however, large variability in frequency distribution of volume profiles was observed in both phenotypes (-22% deficit to +109% excess relative to normal volumes). HF with reduced ejection fraction was characterized by a higher prevalence of BV expansion ≥+25% of normal (39% versus 26%; P=0.003), and HF with preserved ejection fraction was characterized a by more frequent normal BV (42% versus 24%; P<0.001). Male sex in both phenotypes was associated with a larger absolute BV (7.0±1.6 versus 5.1±1.3 liters; P<0.001) and higher frequency of large BV and plasma volume expansions above normal (both P<0.001), while females in both phenotypes demonstrated a higher prevalence of normal BV and plasma volume (both P<0.001).

CONCLUSIONS

Findings support significant differences in BV, plasma volume, and red blood cell mass profile distributions between heart failure phenotypes, driven in large part by sex-specific factors. This underscores the importance of identifying and distinguishing individual patient volume profiles to help guide volume management strategies.

Clinical importance of distinguishing true anemia from dilutional pseudo-anemia: Consequences of a 3-year follow-up volume assessment in a heart failure patient

In chronic heart failure, dilutional anemia and hypervolemia may occur due to plasma volume expansion, the latter sometimes exacerbated by an increase in red cell volume. Diagnosis and a therapeutic strategy require determination of vascular volumes.

Serial blood volume measurements in patients with compensated chronic heart failure: How do volume profiles change over time?

Among patients with chronic heart failure (HF) intravascular volume profiles vary significantly despite similar clinical compensation. However, little is known regarding changes in blood volume (BV) profiles over time. The objective of this analysis was to identify the extent and character of changes in volume profiles over time. A prospective analysis was undertaken in patients who were hospitalized and treated for fluid overload. Quantitative BV analyses were obtained in a compensated state at hospital discharge (baseline) and follow-up at 1, 3, and 6 mo. Data were available on 10 patients who remained stable without rehospitalization or medication change over a 6-mo period. Baseline BV profiles were highly variable at hospital discharge with an average deviation of +28% above normal in 6 patients and normal BV in 4 patients. Over the follow-up period, the median change in BV was -201 mL [-3% (-6, +3%)] from baseline with profiles remaining in the same volume category in 9 out of 10 patients. Crossover from normal BV to mild contraction (-13% of normal) occurred in one patient. Red blood cell mass demonstrated the largest change over 6 mo [median -275 (-410, +175) mL] with a deviation from normal of -14 (-20, +8) % (reflecting mild anemia). These findings suggest that BV profiles in clinically compensated patients with HF do not change substantially over a 6-mo period regardless of baseline expanded or normal BV. This lack of change in volume profiles particularly from an expanded BV has implications for long-term volume management, clinical outcomes, and also our understanding of volume homeostasis in HF.NEW & NOTEWORTHY The novel findings of this study demonstrate that blood volume profiles while highly variable in clinically compensated patients with HF on stable medical therapy do not change substantially over a 6-mo period regardless of baseline expanded or normal blood volumes. This lack of change in volume profiles particularly from an expanded blood volume has implications for long-term volume management and also for how we understand the pathophysiology of volume homeostasis in chronic HF.

Measurement of Blood Volume in Patients with Heart Failure: Clinical Relevance, Surrogates, Historical Background and Contemporary Methodology

The development of clinical congestion resulting from volume overload, either by renal fluid retention or redistribution of blood volume from venous reservoirs, is a recurrent scenario in patients with chronic heart failure (HF). As a result, the treatment of congestion, most commonly by initiating aggressive diuretic therapy, is a front-line issue in the management of patients with HF. However, the association of clinical congestion and volume overload with physical signs and symptoms, as well as other surrogates of volume assessment, has limitations in accuracy and, therefore, reliability to direct appropriate interventions. The ability to quantitate intravascular volume and identify the variability in volume profiles among patients with HF can uniquely inform individualized volume management and aid in risk stratification. This tool is provided by contemporary nuclear medicine-based BVA-100 methodology, which uses the well-established indicator-dilution principle and is a requested topic for discussion in this review.

A semi-automated device rapidly determine circulating blood volume in healthy males and carbon monoxide uptake kinetics of arterial and venous blood

We examined whether a semi-automated carbon monoxide (CO) rebreathing method accurately detect changes in blood volume (BV) and total hemoglobin mass (tHb). Furthermore, we investigated whether a supine position with legs raised reduced systemic CO dilution time, potentially allowing a shorter rebreathing period. Nineteen young healthy males participated. BV and tHb was quantified by a 10-min CO-rebreathing period in a supine position with legs raised before and immediately after a 900 ml phlebotomy and before and after a 900 ml autologous blood reinfusion on the same day in 16 subjects. During the first CO-rebreathing, arterial and venous blood samples were drawn every 2 min during the procedure to determine systemic CO equilibrium in all subjects. Phlebotomy decreased (P < 0.001) tHb and BV by 166 ± 24 g and 931 ± 247 ml, respectively, while reinfusion increased (P < 0.001) tHb and BV by 143 ± 21 g and 862 ± 250 ml compared to before reinfusion. After reinfusion BV did not differ from baseline levels while tHb was decreased (P < 0.001) by 36 ± 21 g. Complete CO mixing was achieved within 6 min in venous and arterial blood, respectively, when compared to the 10-min sample. On an individual level, the relative accuracy after donation for tHb and BV was 102-169% and 55-165%, respectively. The applied CO-rebreathing procedure precisely detect acute BV changes with a clinically insignificant margin of error. The 10-min CO-procedure may be reduced to 6 min with no clinical effects on BV and tHb calculation. Notwithstanding, individual differences may be of concern and should be investigated further.

Blood volume and chronic kidney disease in heart failure - Can volume expansion help balance the Cardio-Renal Axis for better clinical outcomes?

Intravascular volume is largely regulated by the kidneys but how differences in intravascular volume profiles interact with chronic kidney disease (CKD) to influence outcomes in chronic heart failure (HF) has not been explored. Our hypothesis was that a greater degree of volume expansion (VE) would moderate the impact of CKD on HF-related clinical outcomes. Quantitative blood volume (BV) data were available in 137 patients at the time of hospital discharge using a nuclear medicine radiolabeled albumin indicator-dilution technique. The study patients were stratified by the cohort median glomerular filtration rate (GFR, 44 ml/min/1.73 m² ). An a priori cut-point of ≥+25% above normal BV was then used to further stratify the two GFR subgroups and prospectively analyzed for 1-year HF-related mortality or 1st re-hospitalization. Persistent BV expansions ≥+25% were present in 51% of the cohort. In the subgroup with GFR above the median (N = 68) greater or lesser BV expansion from +25% did not differentiate outcomes. However, in the subgroup with GFR below the median (N = 69), BV expansion-stratified risk (log-rank p = 0.022) with <+25% VE associated with poorer outcomes, while VE ≥ + 25% was associated with lower risk and comparable to GFR above the median. In patients with chronic HF, significant intravascular VE and CKD are common co-existing conditions. The presence of larger VE, however, appears to be a factor mitigating the impact of declining renal function on clinical outcomes, and as an element of volume pathophysiology warrants further study.

Fluid Volume Homeostasis in Heart Failure: A Tale of 2 Circulations

Fluid volume homeostasis in health and heart failure (HF) requires a complex interaction of 2 systems, the intravascular and interstitial-lymphatic circulations. With the development of HF both the intravascular and interstitial compartments undergo variable degrees of volume remodeling which can include significant expansion. This reflects the impact of multiple pathophysiologic mechanisms on both fluid compartments which initially play a compensatory role to stabilize intravascular circulatory integrity but with progression in HF can evolve to produce the various manifestations of volume overload and clinical HF congestion. The intent of this review is to help enhance recognition of the pathophysiologic and clinical importance of the interlinked roles of these 2 circulatory systems in volume regulation and chronic HF. It would also be hoped that a better understanding of the interacting functions of the intravascular and interstitial-lymphatic fluid compartments can potentially aid development of novel management strategies particularly addressing the generally undertargeted interstitial-lymphatic system and help bring such approaches forward through a more integrated view of these 2 circulatory systems.

Blood volume expansion, normovolemia, and clinical outcomes in chronic human heart failure: more is better

Expansion in blood volume (BV) is a well-recognized response to arterial underfilling secondary to impaired cardiac output in heart failure (HF). However, the effectiveness of this response in terms of outcomes remains inadequately understood. Prospective analysis was undertaken in 110 patients with HF hospitalized and treated for fluid overload. BVs were measured in a compensated state at the hospital discharge using the indicator-dilution methodology. Data were analyzed for composite 1-year HF-related mortality/first rehospitalization. Despite uniform standard of care, marked heterogeneity in BVs was identified across the cohort. The cohort was stratified by BV expansion greater than or equal to +25% above normal (51% of cohort), mild-moderate expansion (22%), and normal BV (27%). Kaplan-Meier (K-M) survival estimates and regression analyses revealed BV expansion (greater than or equal to +25%) to be associated with better event-free survival relative to normal BV (P = 0.038). Increased red blood cell mass (RBCm; RBC polycythemia) was identified in 43% of the overall cohort and 70% in BV expansion greater than or equal to +25%. K-M analysis demonstrated polycythemia to be associated with better outcomes compared with normal RBCm (P < 0.002). Persistent BV expansion to include RBC polycythemia is common and, importantly, associated with better clinical outcomes compared with normal total BV or normal RBCm in patients with chronic HF. However, compensatory BV expansion is not a uniform physiological response to the insult of HF with marked variability in BV profiles despite uniform standard of care diuretic therapy. Therefore, recognizing the variability in volume regulation pathophysiology has implications not only for impact on clinical outcomes and risk stratification but also potential for informing individualized volume management strategies.NEW & NOTEWORTHY The novel findings of this study demonstrate that intravascular volume profiles among the patients with chronic heart failure (HF) vary substantially even with similar clinical compensation. Importantly, a profile of blood volume (BV) expansion (compared with a normal BV) is associated with lower HF mortality/morbidity. Furthermore, RBC polycythemia is common and independently associated with improved outcomes. These observations support BV expansion with RBC polycythemia as a compensatory mechanism in chronic HF.

High-Intensity Interval Training for Heart Failure Patients With Preserved Ejection Fraction (HIT-HF)-Rational and Design of a Prospective, Randomized, Controlled Trial

Background: The pathophysiology of HF with preserved ejection fraction (HFpEF) has not yet been fully understood and HFpEF is often misdiagnosed. Remodeling and fibrosis stimulated by inflammation appear to be main factors for the progression of HFpEF. In contrast to patients with HF with reduced ejection fraction, medical treatment in HFpEF is limited to relieving HF symptoms. Since mortality in HFpEF patients remains unacceptably high with a 5-year survival rate of only 30%, new treatment strategies are urgently needed. Exercise seems to be a valid option. However, the optimal training regime still has to be elucidated. Therefore, the aim of the study is to investigate the effects of a high-intensity interval (HIT) training vs. a moderate continuous training (MCT) on exercise capacity and disease-specific mechanisms in a cohort of patients with HFpEF. Methods: The proposed study will be a prospective, randomized controlled trial in a primary care setting including 86 patients with stable HFpEF. Patients will undergo measurements of exercise capacity, disease-specific blood biomarkers, cardiac and arterial vessel structure and function, total hemoglobin mass, metabolic requirements, habitual physical activity, and quality of life (QoL) at baseline and follow-up. After the baseline visit, patients will be randomized to the intervention or control group. The intervention group (n = 43) will attend a supervised 12-week HIT on a bicycle ergometer combined with strength training. The control group (n = 43) will receive an isocaloric supervised MCT combined with strength training. After 12 weeks, study measurements will be repeated in all patients to quantify the effects of the intervention. In addition, telephone interviews will be performed at 6 months, 1, 2, and 3 years after the last visit to assess clinical outcomes and QoL. Discussion: We anticipate clinically significant changes in exercise capacity, expressed as VO_2peak, as well as in disease-specific mechanisms following HIT compared to MCT. Moreover, the study is expected to add important knowledge on the pathophysiology of HFpEF and the clinical benefits of a training intervention as a novel treatment strategy in HFpEF patients, which may help to improve both QoL and functional status in affected patients. Trial registration: ClinicalTrials.gov, identifier: NCT03184311, Registered 9 June 2017.

[The use of diuretics in chronic heart failure. Position paper of the Russian Heart Failure Society]

The document focuses on key issues of diuretic therapy in CHF from the standpoint of current views on the pathogenesis of edema syndrome, its diagnosis, and characteristics of using diuretics in various clinical situations.

Time course of red cell volume and plasma volume over six months in compensated chronic heart failure

Background

In patients with chronic heart failure (CHF), volume overload is usually described as an expansion of plasma volume (PV). Additional red cell volume (RCV) expansion also occurs in a relevant fraction of compensated CHF patients. So far, little is known about the stability of these vascular volumes and possible volume excess in compensated CHF patients over time.

Methods and results

This study aims at quantification of blood volume and its components, RCV and PV (raw values and adjusted for sex and anthropometric characteristics, expressed as per cent of the expected normal value), using an abbreviated carbon monoxide (CO) rebreathing method (aCORM) in 14 patients (two women) with systolic CHF at baseline and at a follow‐up visit after approximately 6 months. While a vast heterogeneity was observed concerning RCV (82% to 134% of normalized alues) and PV (72% to 131% of normalized values), the vascular volumes showed a mean change of 1.2% and −1.3% after a mean follow‐up of 183 days.

Conclusions

The vascular volumes including individual volume excess appear to be stable in compensated CHF patients. The reason for this individual volume response concerning both RCV and PV in CHF remains unclear and deserves further clarification.

A carbon monoxide 'single breath' method to measure total haemoglobin mass: a feasibility study

NEW FINDINGS

What is the central question of this study? Is it possible to modify the CO-rebreathing method to acquire reliable measurements of haemoglobin mass in ventilated patients? What is the main finding and its importance? A 'single breath' of CO with a subsequent 30 s breath hold provides almost as exact a measure of haemoglobin mass as the established optimized CO-rebreathing method when applied to healthy subjects. The modified method has now to be checked in ventilated patients before it can be used to quantify the contributions of blood loss and of dilution to the severity of anaemia.

ABSTRACT

Anaemia is defined by the concentration of haemoglobin (Hb). However, this value is dependent upon both the total circulating haemoglobin mass (tHb-mass) and the plasma volume (PV) - neither of which is routinely measured. Carbon monoxide (CO)-rebreathing methods have been successfully used to determine both PV and tHb-mass in various populations. However, these methods are not yet suitable for ventilated patients. This study aimed to modify the CO-rebreathing procedure such that a single inhalation of a CO bolus would enable its use in ventilated patients. Eleven healthy volunteers performed four CO-rebreathing tests in a randomized order, inhaling an identical CO volume. In two tests, CO was rebreathed for 2 min (optimized CO rebreathing; oCOR), and in the other two tests, a single inhalation of a CO bolus was conducted with a subsequent breath hold of 15 s (Proc_new 15s) or 30 s (Proc_new 30s). Subsequently, the CO volume in the exhaled air was continuously determined for 20 min. The amount of CO exhaled after 7 and 20 min was respectively 3.1 ± 0.3 and 5.9 ± 1.1 ml for oCOR, 8.7 ± 3.6 and 12.0 ± 4.4 ml for Proc_new 15s and 5.1 ± 2.0 and 8.4 ±2.6 ml for Proc_new 30s. tHb-mass was 843 ± 293 g determined by oCOR, 821 ± 288 g determined by Proc_new 15s (difference: P < 0.05) and 849 ± 311 g determined by Proc_new 30s. Bland-Altman plots demonstrated slightly lower tHb-mass values for Proc_new 15s compared with oCOR (-21.8 ± 15.3 g) and similar values for Proc_new 30s. In healthy volunteers, a single inhalation of a CO bolus, preferably followed by a 30 s breath hold, can be used to determine tHb-mass. These results must now be validated for ventilated patients.

Plasma Volume Status and Its Association With In-Hospital and Postdischarge Outcomes in Decompensated Heart Failure

BACKGROUND

Prior analyses suggest an association between formula-based plasma volume (PV) estimates and outcomes in heart failure (HF). We assessed the association between estimated PV status by the Duarte-ePV and Kaplan Hakim (KH-ePVS) formulas, and in-hospital and postdischarge clinical outcomes, in the ASCEND-HF trial.

METHODS AND RESULTS

The KH-ePVS and Duarte-ePV were calculated on admission. We assessed associations with in-hospital worsening HF, 30-day composite cardiovascular mortality or HF rehospitalization and 180-day all-cause mortality. There were 6373 (89.2%), and 6354 (89.0%) patients who had necessary characteristics to calculate KH-ePVS and Duarte-ePV, respectively. There was no association between PV by either formula with in-hospital worsening HF. KH-ePVS showed a weak correlation with N-terminal prohormone BNP, and with measures of decongestion such as body weight change and urine output (r < 0.3 for all). Duarte-ePV was trending toward an association with worse 30-day (adjusted odds ratio 1.07, 95% confidence interval [CI] 1.00-1.15, P = .058), but not 180-day outcomes (adjusted hazard ratio 1.03, 95% CI 0.97-1.09, P = .289). A continuous KH-ePVS of >0 (per 10-unit increase) was associated with improved 30-day outcomes (adjusted odds ratio 0.75, 95% CI 0.62-0.91, P = .004). The continuous KH-ePVS was not associated with 180-day outcomes (adjusted hazard ratio 1.05, 95% CI 0.98-1.12, P = .139).

CONCLUSIONS

Baseline PV estimates had a weak association with in-hospital measures of decongestion. The Duarte-ePV trended toward an association with early clinical outcomes in decompensated HF, and may improve risk stratification in HF.

Intravascular Volume Modulates the Outcome Predictive Capacity of Clinical Renal Function Biomarkers in Clinically "Euvolemic" Chronic Heart Failure Patients

BACKGROUND

Cardiorenal interconnections are complex and may in part be mediated by the extent of intravascular volume expansion. The impact of subclinical volume excess on outcomes in heart failure (HF) patients with chronic kidney disease (CKD) has not been examined previously.

OBJECTIVES

To assess the impact of volume-kidney interactions on outcomes in clinically "euvolemic" chronic HF patients (NYHA class II) with coexisting CKD.

METHODS

Plasma volume (PV) was prospectively measured in 110 stable HF patients with different degrees of renal function using a standardized radiolabeled albumin indicator-dilution technique. To examine the interactive roles of volume expansion and biomarkers of CKD, the cohort was dichotomized by median PV and then further stratified by cohort median serum creatinine, eGFR, and BUN, and analyzed for outcomes of HF-related mortality and 1st hospitalization.

RESULTS

PV was expanded above normal in 76% of the cohort. Over 1.5 years of follow-up, sCr and BUN above and eGFR below cohort median stratified higher risks for the composite endpoint only in ambulatory HF patients with a severe degree of PV expansion (median PV expansion ≥+26%; p = 0.02). With less expansion (<+26% expansion), these biomarkers reflecting worse renal function did not discriminate risk (p = 0.578). The percentage of subjects experiencing composite outcome events was, however, comparable for both greater and lesser degrees of PV expansion in HF patients with stable clinical status.

CONCLUSIONS

In clinically stable chronic HF patients with coexisting CKD, substantial subclinical PV expansion is common even when patients are considered clinically to be euvolemic, and, importantly, the extent of PV expansion impacts outcomes including early HF mortality. Better kidney function appears to mitigate the effects of excess PV expansion, while less volume expansion appears to limit the risk of worse renal function as reflected by clinical biomarkers of renal function. Thus, the extent of volume expansion impacts the capacity of standard clinical biomarkers of CKD to differentiate outcome risk in ambulatory chronic (NYHA class II) HF patients.

Increased Red Cell Volume Is a Relevant Contributing Factor to an Expanded Blood Volume in Compensated Systolic Chronic Heart Failure

BACKGROUND

In patients with chronic heart failure (CHF), volume overload is usually described as an expansion of plasma volume. Additional red cell volume (RCV) expansion is less commonly recognized. So far, little is known about quantitative differences in blood volume status and its different components in patients with stable CHF compared to healthy controls.

METHODS

This study aimed to quantify blood volume and its constituents, RCV and plasma volume, by using an abbreviated carbon monoxide rebreathing method with particular focus on its primary measure total hemoglobin mass in 47 patients (10 women) with systolic CHF and a left ventricular ejection fraction of 29.0 ± 9.4%. These were compared to an age-matched control group of 84 healthy subjects (44 women) using the same method.

RESULTS

In both absolute and body-surface-area-corrected analysis, hemoglobin mass (446 ± 81 vs 353 ± 64 g/m²) as well as RCV (1293 ± 231 vs 1033 ± 176 mL/m²) were significantly increased in CHF. In addition, significant plasma volume expansion was observed in CHF (2069 ± 400 vs 1750 ± 231 mL/m²) and, in conjunction with RCV, constituted a significantly increased blood volume (3361 ± 574 vs 2783 ± 369 mL/m²). In 66% of patients with compensated CHF, RCV was excessive compared to 14% in the control group.

CONCLUSIONS

An increased RCV is a relevant contributing factor to hypervolemia in stable CHF. This is associated with an increased oxygen-carrying capacity, so it may be regarded as a possible compensatory mechanism for a reduced ejection fraction.

Impact of Obesity on Volume Status in Patients With Ambulatory Chronic Heart Failure

BACKGROUND

Fluid overload is common in heart failure (HF) and obesity; however, the relationship between the extent of intravascular volume expansion and indices such as body mass index (BMI) in obese and non-obese patients with HF has not been defined to address the issue of a HF obesity phenotype.

METHODS

Total blood volume (TBV) was measured clinically using a radiolabeled albumin indicator-dilution technique in patients with predominately class III ambulatory chronic HF (N=66). Obesity was defined by BMI ≥30 kg/m².

RESULTS

Markedly increased intravascular volume expansion (defined by TBV expansion >+25% above normal) was highly prevalent in the obese (53%) compared to non-obese patients with HF (29%, P = .04) driven by plasma volume expansion. TBV was correlated with excess body weight and BMI (both P < .01). Also, cardiac index was higher, systemic vascular resistance lower, and left ventricular filling pressures comparable in obese compared with non-obese patients.

CONCLUSIONS

Quantitative assessment of intravascular volume demonstrates for the first time that severe (not mild or moderate) volume expansion is highly common in obese patients with ambulatory chronic HF. This supports an evolving concept of an obesity-specific HF phenotype. Further study is needed to understand the mechanisms controlling volume regulation and the potential compensatory or detrimental impact on outcomes in obesity and HF.

Heart Failure Outcomes With Volume-Guided Management

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.

Hemoglobin concentration, total hemoglobin mass and plasma volume in patients: implications for anemia

In practice, clinicians generally consider anemia (circulating hemoglobin concentration < 120 g.l^-1 in non-pregnant females and < 130 g.l^-1 in males) as due to impaired hemoglobin synthesis or increased erythrocyte loss or destruction. Rarely is a rise in plasma volume relative to circulating total hemoglobin mass considered as a cause. But does this matter? We explored this issue in patients, measuring hemoglobin concentration, total hemoglobin mass (optimized carbon monoxide rebreathing method) and thereby calculating plasma volume in healthy volunteers, surgical patients, and those with inflammatory bowel disease, chronic liver disease or heart failure. We studied 109 participants. Hemoglobin mass correlated well with its concentration in the healthy, surgical and inflammatory bowel disease groups (r=0.687-0.871, P<0.001). However, they were poorly related in liver disease (r=0.410, P=0.11) and heart failure patients (r=0.312, P=0.16). Here, hemoglobin mass explained little of the variance in its concentration (adjusted R²=0.109 and 0.052; P=0.11 and 0.16), whilst plasma volume did (R² change 0.724 and 0.805 in heart and liver disease respectively, P<0.0001). Exemplar patients with identical (normal or raised) total hemoglobin masses were diagnosed as profoundly anemic (or not) depending on differences in plasma volume that had not been measured or even considered as a cause. The traditional inference that anemia generally reflects hemoglobin deficiency may be misleading, potentially resulting in inappropriate tests and therapeutic interventions to address 'hemoglobin deficiency' not 'plasma volume excess'. Measurement of total hemoglobin mass and plasma volume is now simple, cheap and safe, and its more routine use is advocated.

True Anemia―Red Blood Cell Volume Deficit―in Heart Failure

Background—

Anemia in heart failure (HF) is commonly diagnosed according to hemoglobin concentration [Hb], hence may be the result of hemodilution or true red blood cell volume (RBCV) deficit. Whether true (nonhemodilutional) anemia in HF can or cannot be generally inferred by [Hb] measurements and clinical correlates remains unclear. The purpose of this study was to systematically review the literature and investigate the status and correlates of RBCV in patients with HF.

Methods and Results—

MEDLINE, Scopus, and Web of Science were searched since their inceptions until April 2016 for articles directly reporting or allowing the calculation of intravascular volumes (RBCV, plasma volume) in patients with HF according to the International Council for Standardization in Hematology. Eighteen studies were included after systematic review, comprising a total of 368 patients with HF (limits for mean age=49–80 years, sex=0%–92% females, left ventricular ejection fraction=26%–61%). Mean RBCV was reduced (limits=67%–88% of normal) in all studies including HF patients with anemia (low [Hb]) (7 studies, n=127), whereas only 2 of 10 studies in nonanemic patients with HF presented lower than normal mean RBCV (90% and 96%). In metaregression analyses, RBCV was positively associated with [Hb] ( B =6.10, SE=1.44) and negatively associated with age ( B =−1.14, SE=0.23), % females ( B =−0.38, SE=0.04), left ventricular ejection fraction ( B =−0.81, SE=0.20), and body mass index ( B =−3.55, SE=0.46; P <0.001).

Conclusions—

Presence or absence of true anemia in patients with HF as determined by RBCV status mainly concurs with diagnosis based on [Hb] and presents negative relationships with age, female sex, left ventricular ejection fraction, and body mass index.

Assessment and Management of Volume Overload and Congestion in Chronic Heart Failure: Can Measuring Blood Volume Provide New Insights?

BACKGROUND

Volume overload and fluid congestion remain primary clinical challenges in the assessment and management of patients with chronic heart failure (HF).

SUMMARY

The pathophysiology of volume regulation is complex, and the simple concept of passive intravascular fluid accumulation is not adequate. The dynamics of interstitial and intravascular fluid compartment interactions and fluid redistribution from venous splanchnic beds to the central pulmonary circulation need to be taken into account in strategies of volume management. Clinical bedside evaluations and right heart hemodynamic assessments can alert of changes in volume status, but only the quantitative measurement of total blood volume can help identify the heterogeneity in plasma volume and red blood cell mass that are features of volume overload in chronic HF. The quantitative assessment of intravascular volume is an effective tool to help guide individualized, appropriate therapy.

KEY MESSAGE

Not all volume overload is the same, and the measurement of intravascular volume identifies heterogeneity to guide tailored therapy.

Fluid Volume Overload and Congestion in Heart Failure

Volume regulation, assessment, and management remain basic issues in patients with heart failure. The discussion presented here is directed at opening a reassessment of the pathophysiology of congestion in congestive heart failure and the methods by which we determine volume overload status. Peer-reviewed historical and contemporary literatures are reviewed. Volume overload and fluid congestion remain primary issues for patients with chronic heart failure. The pathophysiology is complex, and the simple concept of intravascular fluid accumulation is not adequate. The dynamics of interstitial and intravascular fluid compartment interactions and fluid redistribution from venous splanchnic beds to central pulmonary circulation need to be taken into account in strategies of volume management. Clinical bedside evaluations and right heart hemodynamic assessments can alert clinicians of changes in volume status, but only the quantitative measurement of total blood volume can help identify the heterogeneity in plasma volume and red blood cell mass that are features of volume overload in patients with chronic heart failure and help guide individualized, appropriate therapy—not all volume overload is the same.