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

Recurrent Hospitalizations for Fluid Overload in Diabetes with Kidney Failure Treated with Dialysis

INTRODUCTION

Diabetes mellitus is the most common cause of end-stage kidney disease (ESKD) in Singapore. ESKD patients have high disease burden and are at increased risk of recurrent hospitalizations, including fluid overload. This study aimed to characterize the risk factors associated with readmissions for fluid overload that will identify high-risk hospitalizations for interventions to reduce readmissions.

METHODS

Retrospective cohort study of all hospitalizations for fluid overload in adults with diabetes and ESKD on dialysis in SingHealth hospitals between 2018 and 2021. Fluid overload was defined by discharge codes for fluid overload, heart failure, pulmonary edema, and generalized edema. Multivariable Cox regression analysis using the Prentice, Williams and Peterson Total Time model was performed for the outcomes of readmissions for fluid overload within 30 days and 90 days of discharge.

RESULTS

Among 3,234 hospitalizations for fluid overload, readmission for fluid overload within 30 days and 90 days occurred in 585 (18.1%) and 967 (29.9%) hospitalizations, respectively. Ischemic heart disease, peripheral vascular disease, and lower hemoglobin level were independently associated with readmissions for fluid overload within 30 and 90 days. Additionally, heart failure, hemodialysis (compared to peritoneal dialysis), and lack of statin at discharge were associated with increased 90-day readmission risk.

CONCLUSION

Modifiable (hemoglobin level, statin use) and non-modifiable factors (ischemic heart disease, peripheral vascular disease, and heart failure) influenced the risk of readmission for fluid overload. These results may guide risk stratification and inform targeted interventions to reduce avoidable, unplanned readmissions for recurrent fluid overload among individuals with diabetes and ESKD.

Postoperative anaemia and patient-centred outcomes after major abdominal surgery: a retrospective cohort study

BACKGROUND

Compared with anaemia before surgery, the underlying pathogenesis and implications of postoperative anaemia are largely unknown.

METHODS

This retrospective cohort study analysed prospective data obtained from 2983 adult patients across 47 centres enrolled in a clinical trial evaluating restrictive and liberal intravenous fluids. The primary endpoint was persistent disability or death up to 90 days after surgery. Secondary endpoints included major septic complications, hospital stay, and patient quality of recovery using a 15-item quality of recovery (QoR-15) score, hospital re-admissions, and disability-free survival up to 12 months after surgery. Anaemia and disability were defined according to the WHO definitions. Multivariable regression was used to adjust for baseline risk and surgery.

RESULTS

A total of 2983 patients met inclusion criteria for this study, of which 78.5% (95% confidence interval [CI], 76.7-80.1%) had postoperative anaemia. Patients with postoperative anaemia had a higher adjusted risk of death or disability up to 90 days after surgery when compared with those without anaemia: 18.2% vs 9.2% (risk ratio [RR]=1.51; 95% CI, 1.10-2.07, P=0.011); lower QoR-15 scores on Day 3 and Day 30, 105 (95% CI, 87-119) vs 114 (95% CI, 99-128; P<0.001), and 130 (95% CI, 112-140) vs 139 (95% CI, 121-144; P<0.011), respectively; higher adjusted risk of a composite of mortality/septic complications, 2.01 (95% CI, 1.55-42.67; P<0.001); unplanned admission to ICU (RR=2.65; 95% CI, 1.65-4.23; P<0.001); and longer median (inter-quartile range [IQR]) hospital stays, 6.6 (4.4-12.4) vs 3.7 (2.5-6.5) days (P<0.001).

CONCLUSIONS

Postoperative anaemia is common and is independently associated with poor outcomes after surgery. Optimal prevention and treatment strategies need to be investigated.

CLINICAL TRIAL REGISTRATION

NCT04978285 (ClinicalTrials.gov).

Sex and age interaction in fundamental circulatory volumetric variables at peak working capacity

Background

Whether the fundamental hematological and cardiac variables determining cardiorespiratory fitness and their intrinsic relationships are modulated by major constitutional factors, such as sex and age remains unresolved.

Methods

Transthoracic echocardiography, central hemodynamics and pulmonary oxygen (O₂) uptake were assessed in controlled conditions during submaximal and peak exercise (cycle ergometry) in 85 healthy young (20–44 year) and older (50–77) women and men matched by age-status and moderate-to-vigorous physical activity (MVPA) levels. Main outcomes such as peak left ventricular end-diastolic volume (LVEDV_peak), stroke volume (SV_peak), cardiac output (Q_peak) and O₂ uptake (VO_2peak), as well as blood volume (BV), BV–LVEDV_peak and LVEDV_peak–SV_peak relationships were determined with established methods.

Results

All individuals were non-smokers and non-obese, and MVPA levels were similar between sex and age groups (P ≥ 0.140). BV per kg of body weight did not differ between sexes (P ≥ 0.118), but was reduced with older age in men (P = 0.018). Key cardiac parameters normalized by body size (LVEDV_peak, SV_peak, Q_peak) were decreased in women compared with men irrespective of age (P ≤ 0.046). Older age per se curtailed Q_peak (P ≤ 0.022) due to lower heart rate (P < 0.001). In parallel, VO_2peak was reduced with older age in both sexes (P < 0.001). The analysis of fundamental circulatory relationships revealed that older women require a higher BV for a given LVEDV_peak than older men (P = 0.024).

Conclusions

Sex and age interact on the crucial circulatory relationship between total circulating BV and peak cardiac filling, with older women necessitating more BV to fill the exercising heart than age- and physical activity-matched men.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00409-9.

Risk-Assessment of Hospitalized Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infected Patients Using Laboratory Data and Immune Cell Morphological Assessment

CONTEXT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly infectious agent, with the propensity to cause severe illness. While vaccine uptake has been increasing in recent months, many regions remain at risk of significant coronavirus disease 19 (COVID-19) related healthcare burden. Health systems will continue to benefit from the availability of a variety of clinical and laboratory model when other triaging models are equivocal.

OBJECTIVE

To validate previously reported clinical laboratory abnormalities seen in COVID-19 patients and identify what laboratory parameters might be outcome-predictive.

DESIGN

We undertook an observational study of hospital-admitted COVID-19 patients (n=113), looking at a broad selection of clinical, laboratory, peripheral blood smear, and outcome data over discrete discovery and validation periods from March 2020 to November 2020.

RESULTS

We confirmed the findings of previous studies noting derangement of a variety of laboratory parameters in COVID-19 patients, including peripheral blood morphological changes. We also devised a simple-to-use decision tree by which patients could be risk stratified on the basis of Red Blood Cell count, creatinine, urea, and atypical plasmacytoid lymphocyte ("covidocyte") count. This outcome classifier performed comparably to the World Health Organization clinical classifier and the neutrophil-lymphocyte ratio.

CONCLUSIONS

Our data add to the increasing number of studies cataloguing laboratory changes in COVID-19, and support the clinical utility of incorporating blood morphological assessment in the workup of hospitalized COVID-19 patients.

Blood volume and hemoglobin mass in long-term heart transplant recipients with and without Anemia

BACKGROUND

In systolic chronic heart failure, a heterogeneous blood volume (BV) regulation can be found with plasma volume expansion in many cases, possibly leading to pseudoanemia. Little is known about the volume status after heart transplantation (HTX). So far, anemia of HTX recipients was solely investigated using hemoglobin-concentration that may be misleading in a clinical context. The objective of the study was whether a difference in plasma volume and red cell volume can be observed in clinically stable heart transplant recipients compared to matched control subjects. Secondary, the aim was to describe anemia in the long-term after HTX based on quantitative data.

METHODS

Blood volume and its constituents red cell volume and plasma volume were quantified using an abbreviated carbon monoxide rebreathing method (aCORM) with focus on its primary measure total hemoglobin mass (Hbmass) and coincidental anemia in 36 (7 women) heart transplant recipients. For comparison, a matched control group of 46 (5 women) healthy subjects was selected.

RESULTS

Neither Hbmass nor blood volumes were significantly different in HTX patients compared to matched healthy control group subjects. The prevalence of anemia 6.3 ± 4.3 years after transplantation was 19%. Hbmass and red cell volume were significantly lower in anemic HTX patients compared to non-anemic patients while plasma volume was not expanded. Various immunosuppressant regimens did not have an effect on Hbmass, plasma volume or red cell volume.

CONCLUSIONS

There was no difference in blood volumes and Hbmass between HTX patients and control subjects. The pathophysiologic blood volume regulation in chronic heart failure does not seem to be longer active in long-term HTX recipients. However, in the long-term after HTX, anemia occurs in a considerable number of patients as true anemia without a clear association with immunosuppression.

TRIAL REGISTRATION

German registry for clinical studies, DRKS00006078. Registered 09 May 2014, https://www.drks.de/drks_web/navigate.do?navigationId=trial . HTML&TRIAL_ID=DRKS00006078.

Estimated plasma volume status in heart failure: clinical implications and future directions

Congestion is one of the main predictors of poor outcome in patients with heart failure (HF). Assessing and monitoring congestion is essential for optimizing HF therapy. Among the various available methods, serial measurements of estimated plasma volume (ePVS) using routine blood count and/or body weight (e.g., the Strauss, Duarte, Hakim formulas) may be useful in HF management. Further prospective study is warranted to determine whether ePVS can help optimize decongestion therapy (loop diuretics, mineralocorticoid receptor antagonists, SGLT2i) in various HF settings. This narrative review summarizes the recent evidence supporting the association of ePVS with clinical congestion and outcome(s) and discusses future directions for monitoring ePVS in HF.

Reproducibility of the CO rebreathing technique with a lower CO dose and a shorter rebreathing duration at sea level and at 2320 m of altitude

Total hemoglobin mass (Hb_mass) is routinely assessed in studies by the carbon monoxide (CO) rebreathing. Its clinical application is often hindered due to the consequent rise in carboxyhemoglobin (%HbCO) and the concern of CO toxicity. We tested the reproducibility of the CO rebreathing with a CO dose of 0.5 mL/kg body mass (CO_0.5) compared to 1.5 mL/kg (CO_1.5) and when shortening the CO rebreathing protocol. Therefore, CO rebreathing was performed 1×/day in eight healthy individuals on four consecutive days. On each day, either CO_0.5 (CO_0.5-1 and CO_0.5-2) or CO_1.5 (CO_1.5-1 and CO_1.5-2) was administered. Venous blood samples to determine %HbCO and quantify Hb_mass were obtained prior to, and at 6 (T₆), 8 (T₈) and 10 min (T₁₀) of CO rebreathing. This protocol was tested at sea level and at 2320 m to investigate the altitude-related measurement error. At sea level, the mean difference (95% limits of agreement) in Hb_mass between CO_0.5-1 and CO_0.5-2 was 26 g (-26; 79 g) and between CO_1.5-1 and CO_1.5-2, it was 17 g (-18; 52 g)_. The respective typical error (TE) corresponded to 2.4% (CO_0.5) and 1.5% (CO_1.5), while it was 6.5% and 3.0% at 2320 m. With CO_0.5, shortening the CO rebreathing resulted in a TE for Hb_mass of 4.4% (T₈ vs. T₁₀) and 14.1% (T₆ vs T₁₀) and with CO_1.5, TE was 1.6% and 5.8%. In conclusion, the CO dose and rebreathing time for the CO rebreathing procedure can be decreased at the cost of a measurement error ranging from 1.5-14.1%.

Hypovolemia and reduced hemoglobin mass in patients with heart failure and preserved ejection fraction

A fundamental tenet of heart failure (HF) pathophysiology hinges on a propensity for fluid retention leading to blood volume (BV) expansion and hemodilution. Whether this can be applied to heart failure patients with preserved ejection fraction (HFpEF) remains uncertain. The present study sought to determine BV status and key hormones regulating fluid homeostasis and erythropoiesis in HFpEF patients. BV and hemoglobin mass (Hb_mass) were determined with high‐precision, automated carbon monoxide (CO) rebreathing in 20 stable HFpEF patients (71.5 ± 7.3 years, left ventricular ejection fraction = 55.7 ± 4.0%) and 15 healthy age‐ and sex‐matched control individuals. Additional measurements comprised key circulating BV‐regulating hormones such as pro‐atrial natriuretic peptide (proANP), copeptin, aldosterone and erythropoietin (EPO), as well as central hemodynamics and arterial stiffness via carotid–femoral pulse wave velocity (PWV). Carotid–femoral PWV was increased (+20%) in HFpEF patients versus control individuals. With respect to hematological variables, plasma volume (PV) did not differ between groups, whereas BV was decreased (−14%) in HFpEF patients. In consonance with the hypovolemic status, Hb_mass was reduced (−27%) in HFpEF patients, despite they presented more than a twofold elevation of circulating EPO (+119%). Plasma concentrations of BV‐regulating hormones, including proANP (+106%), copeptin (+99%), and aldosterone (+62%), were substantially augmented in HFpEF patients. HFpEF patients may present with hypovolemia and markedly reduced Hb_mass, underpinned by a generalized overactivation of endocrine systems regulating fluid homeostasis and erythropoiesis. These findings provide a novel perspective on the pathophysiological basis of the HFpEF condition.

Prognostic impact of plasma volume estimated from hemoglobin and hematocrit in heart failure with preserved ejection fraction

BACKGROUND

Plasma volume (PV) estimated from Duarte's formula (based on hemoglobin/hematocrit) has been associated with poor prognosis in patients with heart failure (HF). There are, however, limited data regarding the association of estimated PV status (ePVS) derived from hemoglobin/hematocrit with clinical profiles and study outcomes in patients with HF and preserved ejection fraction (HFpEF).

METHODS AND RESULTS

Patients from North and South America enrolled in the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist trial (TOPCAT) with available hemoglobin/hematocrit data were studied. The association between ePVS (Duarte formula and Hakim formula) and the composite of cardiovascular mortality, HF hospitalization, or aborted cardiac arrest was assessed. Among 1747 patients (age 71.6 years; males 50.1%), mean ePVS derived from Duarte formula was 4.9 ± 1.0 mL/g. Higher Duarte-derived ePVS was associated with prior HF admission, diabetes, more severe congestion, poor renal function, higher natriuretic peptide level, and E/e'. After adjustment for potential covariates including natriuretic peptide, higher Duarte-derived ePVS was associated with an increased rate of the primary outcome [highest vs. lowest ePVS quartile: adjusted-HR (95%CI) = 1.79 (1.28-2.50), p < 0.001]. Duarte-derived ePVS improved prognostic performance on top of clinical and routine variables (including natriuretic peptides) (NRI = 11, p < 0.001), whereas Hakim-derived ePVS did not (p = 0.59). The prognostic value of Duarte-derived ePVS was not modified by renal function (P interaction > 0.10 for all outcomes).

CONCLUSION

ePVS from Duarte's formula was associated with congestion status and improved risk stratification regardless of renal function. Our findings suggest that Duarte-derived ePVS is a useful congestion variable in patients with HFpEF.

Relationship between plasma volume and essential blood constituents in patients with heart failure and preserved ejection fraction

INTRODUCTION

Notwithstanding recent progress on molecular mechanisms underlying heart failure with preserved ejection fraction (HFpEF), multiple pathophysiological aspects of this condition including the basis of anaemia and other haematological disorders remain unresolved. In this study, we sought to determine the relationship of plasma volume (PV), a plausible confounding factor for the concentration of solutes in blood, with key haematological markers in HFpEF patients.

METHODS

Total circulating PV was determined with high precision, automated carbon monoxide rebreathing in 24 stable HFpEF patients (70 ± 8 years, left ventricular ejection fraction = 55±5%) and 18 healthy age- and sex-matched control (HC) individuals. Linear regression analyses were performed to determine the association of PV with a comprehensive set of haematological variables.

RESULTS

Haematocrit (40·1 ± 4·9 versus 43·6 ± 2·7%, P = 0·004) and haemoglobin concentration (131 ± 16 versus 142 ± 7 g l^-1 , P = 0·003) were reduced in HFpEF patients compared with HC individuals. In regression analyses, PV was negatively associated with haematocrit (r = -0·45, P = 0·029) and haemoglobin concentration (r = -0·44, P = 0·030) in HFpEF patients, whereas these variables were not associated with PV in HC individuals (P≥0·198). Regarding blood electrolytes, PV was negatively associated with K⁺ (r = -0·43, P = 0·036) and Ca²⁺ (r = -0·44, P = 0·032) in HFpEF patients but not in HC individuals (P≥0·734). None of the above associations were detected in HFpEF patients when using ideal instead of measured PV.

CONCLUSION

The blood concentration of routine markers of anaemia and electrolyte balance is specifically and linearly associated with PV in HFpEF patients. Excess or deficit of circulating PV may confound clinical diagnosis in this population.

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.

Evaluation of kidney function and urinary analytes in Nigerian trade cattle

This cross-sectional study evaluated kidney function and urinary analytes in cattle presented for slaughter at Nsukka abattoir, Enugu State, Nigeria. A total of 133 cattle were evaluated; they were physically examined at the lairage before slaughter and after slaughter, blood for hematology and serum biochemistry were collected from the jugular vein, and urine samples for urinalysis was also collected from the urinary bladder. Standard procedures were followed in all the laboratory determinations. Results showed that, out of 133 sample population of cattle evaluated, 74 (55.6%) were apparently healthy, while 59 (44.4%) were unhealthy with observable clinical signs of diseases or disorders. Serum creatinine evaluation of the 133 cattle showed that 7.5% (10 cattle out of 133) had renal impairment (serum creatinine above 2 mg/dl). There was no significant association (p > 0.05) between renal impairment and age or sex. Out of the sampled cattle, 11 (8.3%) had positive urine bilirubin levels, while none (0%) had urobilinogen in urine, and 5 (3.8%) were positive for ketonuria. Only 6 (4.5%) were positive for urine glucose, but 113 (92.5%) were positive for urine proteins. The cattle sampled had urine pH ranging from 6 to 9, and specific gravity ranging from 1.000 to 1.030 and of all the sampled cattle, 6 (4.5%) were positive for nitrite. Based on the results, it is suggestive that based on the serum creatinine level which is a known marker of kidney function, 7.5% of cattle sampled had renal impairment.

Age-dependent impairment of the erythropoietin response to reduced central venous pressure in HFpEF patients

Despite growing research interest in the pathophysiology of heart failure with preserved ejection fraction (HFpEF), it remains unknown whether central hemodynamic alterations inherently present in this condition do affect blood pressure and blood volume (BV) regulation. The present study sought to determine hemodynamic and endocrine responses to prolonged orthostatic stress in HFpEF patients. Central venous pressure (CVP) assessed via the internal jugular vein (IJV) aspect ratio with ultrasonography, arterial pressure and heart rate were determined at supine rest and during 2 hours of moderate (25-30°) head-up tilt (HUT) in 18 stable HFpEF patients (71.2 ± 7.3 years), 14 elderly (EC), and 10 young (YC) healthy controls. Parallel endocrine measurements comprised main BV-regulating hormones: pro-atrial natriuretic peptide, copeptin, aldosterone, and erythropoietin (EPO). At supine rest, the IJV aspect ratio was higher (>30%) in HFpEF patients compared with EC and YC, while mean arterial pressure was elevated in HFpEF patients (98.0 ± 13.1 mm Hg) and EC (95.6 ± 8.3 mm Hg) versus YC (87.3 ± 5.0 mm Hg) (P < 0.05). HUT increased heart rate (+10%) and reduced the IJV aspect ratio (-52%), with similar hemodynamic effects in all groups (P for interaction ≥ 0.322). The analysis of endocrine responses to HUT revealed a group×time interaction for circulating EPO, which was increased in YC (+10%) but remained unaltered in HFpEF patients and EC. The EPO response to a given reduction in CVP is similarly impaired in HFpEF patients and elderly controls, suggesting an age-dependent dissociation of EPO production from hemodynamic regulation in the HFpEF condition.

Erythropoietin response to anaemia in heart failure

Background

Despite multiple factors correlating with the high prevalence of anaemia in heart failure, the prevailing mechanisms have yet to be established. The purpose of this study is to systematically review the literature and determine whether low circulating haemoglobin is primarily underlain by erythropoietin resistance or defective production in heart failure.

Design and methods

We conducted a systematic search of MEDLINE since its inception until May 2017 for articles reporting erythropoietin and haemoglobin concentrations in heart failure patients not treated with erythropoietin-stimulating agents. The primary outcome was the mean difference in observed/predicted (O/P) erythropoietin ratio between heart failure patients and normal reference values. Meta-regression analyses assessed the influence of potential moderating factors.

Results

Forty-one studies were included after systematic review, comprising a total of 3137 stable heart failure patients with mean age and left ventricular ejection fraction ranging from 52 years to 80 years and 21% to 59%. The O/P erythropoietin ratio was below reference values in 24 of 25 studies in anaemic heart failure patients ( n = 1094, range = 0.49–1.05), whereas only one out of 16 studies in non-anaemic heart failure patients presented a low O/P erythropoietin ratio ( n = 2043, range = 0.91–1.97). In studies comparing anaemic versus non-anaemic heart failure patients ( n = 1531), the mean O/P erythropoietin ratio was consistently reduced in anaemic heart failure patients (mean difference = –0.68, 95% confidence interval = −0.78, −0.57; p < 0.001). In meta-regression, the O/P erythropoietin ratio was negatively associated with age, female sex, left ventricular ejection fraction, inflammation and disease severity.

Conclusion

Anaemia in heart failure is overwhelmingly characterized by impaired erythropoietin production, which is exacerbated with age, female sex, left ventricular ejection fraction, inflammation and disease severity.

Hyponatremia in Acute Heart Failure in Relation to Hematocrit Levels: Clinical Relevance and Prognostic Implication

BACKGROUND

Hyponatremia is the most common electrolyte abnormality found in hospitalized patients with acute heart failure (AHF) and is related to poor prognosis. This study sought to evaluate: (1) the different prognostic impact of dilutional versus depletional hyponatremia, evaluating short- and long-term outcome; (2) the relationship between both types of hyponatremia and intravenous furosemide dose, renal function changes, and persistent congestion at discharge.

METHODS

This retrospective single-center study included 233 consecutive patients with a primary diagnosis of AHF. Hyponatremia was defined as serum sodium < 135 mEq/L, which could be either dilutional (hematocrit < 35%) or depletional (hematocrit ≥35%). Persistent congestion was defined as a congestion score ≥2 at discharge. Patients were followed 180 days for occurrence of death or rehospitalization for AHF.

RESULTS

Hyponatremia was present in 68/233 patients with 27 cases classified as dilutional hyponatremia versus 41 as depletional. The proportion of patients with persistent congestion was higher in the dilutional hyponatremia group, but similar in the depletional hyponatremia group (52 vs. 81 vs. 58%; p = 0.02). After adjustment for important baseline characteristics, dilutional hyponatremia was significantly associated with the risk of death or rehospitalization for AHF at 60 days (HR 2.17 [1.08-4.37]; p = 0.03) and 180 days (HR 1.88 [1.10-3.21]; p = 0.02). In contrast, depletional hyponatremia was only significantly associated with the same endpoint at 180 days (HR 1.64 [1.05-2.57]; p = 0.03).

CONCLUSIONS

Low hematocrit levels in AHF patients with hyponatremia characterize a population that is more difficult to decongest and has poor clinical outcome. In contrast, patients with hyponatremia but normal hematocrit are better decongested and have better short-term outcome.

Development, validation, and potential applications of biotinylated red blood cells for posttransfusion kinetics and other physiological studies: evidenced-based analysis and recommendations

The current reference method in the United States for measuring in vivo population red blood cell (RBC) kinetics utilizes chromium-51 (⁵¹ Cr) RBC labeling for determining RBC volume, 24-hour posttransfusion RBC recovery, and long-term RBC survival. Here we provide evidence supporting adoption of a method for kinetics that uses the biotin-labeled RBCs (BioRBCs) as a superior, versatile method for both regulatory and investigational purposes. RBC kinetic analysis using BioRBCs has important methodologic, analytical, and safety advantages over ⁵¹ Cr-labeled RBCs. We critically review recent advances in labeling human RBCs at multiple and progressively lower biotin label densities for concurrent, accurate, and sensitive determination of both autologous and allogeneic RBC population kinetics. BioRBC methods valid for RBC kinetic studies, including successful variations used by the authors, are presented along with pharmacokinetic modeling approaches for the accurate determination of RBC pharmacokinetic variables in health and disease. The advantages and limitations of the BioRBC method-including its capability of determining multiple BioRBC densities simultaneously in the same individual throughout the entire RBC life span-are presented and compared with the ⁵¹ Cr method. Finally, potential applications and limitations of kinetic BioRBC determinations are discussed.