Non-oncotic properties of albumin. A multidisciplinary vision about the implications for critically ill patients

Phases of fluid management and the roles of human albumin solution in perioperative and critically ill patients

OBJECTIVE

Positive fluid balance is common among critically ill patients and leads to worse outcomes, particularly in sepsis, acute respiratory distress syndrome, and acute kidney injury. Restrictive fluid infusion and active removal of accumulated fluid are being studied as approaches to prevent and treat fluid overload. Use of human albumin solutions has been investigated in different phases of restrictive fluid resuscitation, and this narrative literature review was undertaken to evaluate hypoalbuminemia and the roles of human serum albumin with respect to hypovolemia and its management.

METHODS

PubMed/EMBASE search terms were: "resuscitation," "fluids," "fluid therapy," "fluid balance," "plasma volume," "colloids," "crystalloids," "albumin," "hypoalbuminemia," "starch," "saline," "balanced salt solution," "gelatin," "goal-directed therapy" (English-language, pre-January 2020). Additional papers were identified by manual searching of reference lists.

RESULTS

Restrictive fluid administration, plus early vasopressor use, may reduce fluid balance, but in some cases fluid overload cannot be entirely avoided. Deresuscitation, with fluid actively removed through diuretics or ultrafiltration, reduces duration of mechanical ventilation and intensive care unit stay. Combining hyperoncotic human albumin solution with diuretics increases hemodynamic stability and diuresis. Hyperoncotic albumin corrects hypoalbuminemia and raises colloid osmotic pressure, limiting edema formation and potentially improving endothelial function. Serum levels of albumin relative to C-reactive protein and lactate may predict which patients will benefit most from albumin therapy.

CONCLUSIONS

Hyperoncotic human albumin solution facilitates restrictive fluid therapy and the effectiveness of deresuscitative measures. Current evidence is mostly from observational studies, and more randomized trials are needed to better establish a personalized approach to fluid management.

Circulating liver function markers and colorectal cancer risk: A prospective cohort study in the UK Biobank

Evidence links the liver to development of colorectal cancer (CRC). However, it remains unknown how liver function may influence CRC risk in the general population. We conducted a prospective cohort study in the UK Biobank of 375 693 participants who provided blood samples in 2006 to 2010. Circulating levels of liver function markers (alanine transaminase [ALT], aspartate transaminase [AST], total bilirubin [TBIL], gamma glutamyltransferase [GGT], alkaline phosphatase [ALP], total protein [TP] and albumin [ALB]) were measured. Incident cancer cases were identified through linkage to the national cancer registry up to 2019. Repeated biomarker measurements were available from a subset of 11 320 participants who were re-assessed in 2012 to 2013. After a median follow-up of 10.0 years, we documented 2662 cases of CRC. Circulating levels of ALT, AST, TBIL, GGT, TP and ALB at baseline were inversely associated with CRC risk (P < .01), with multivariable hazard ratio (95% confidence interval) comparing decile 10 vs 1 of 0.62 (0.51-0.75), 0.63 (0.53-0.75), 0.85 (0.72-1.02), 0.74 (0.61-0.89), 0.70 (0.59-0.84) and 0.66 (0.55-0.79), respectively. Strengthened associations were found after recalibration for repeated measurements. The associations appeared stronger for proximal colon cancer than distal colon cancer and rectal cancer, but consistent for early-, mid- and late-onset CRC. In a large cohort of general population, the UK Biobank, higher circulating levels of ALT, AST, TBIL, GGT, TP and ALB, largely within the normal range, were associated with a lower risk of CRC. The findings support a link between liver function and CRC, and may spur future research on the gut-microbiota-liver axis.

A patient specific forecasting model for human albumin based on deep neural networks

BACKGROUND AND OBJECTIVES

Hypoalbuminemia can be life threatening among critically ill patients. In this study, we develop a patient-specific monitoring and forecasting model based on deep neural networks to predict concentrations of albumin and a set of selected biochemical markers for critically ill patients in real-time.

METHODS

Under the assumption that metabolism of a patient follows a patient-specific dynamical process that can be determined from sufficient prior data taken from the patient, we apply a machine learning method to develop the patient-specific model for a critically ill, poly-trauma patient. Six representative biochemical markers (albumin (ALB), creatinine (Cr), osmotic pressure (OSM), alanine aminotransferase (ALT), total bilirubin (TB), direct bilirubin (DB)) were collected from the patient while scheduled exogenous albumin injection was administered to the patient for the total of 27 consecutive days. A sliding window of data in 11 consecutive days were used to train and test the neural networks in the model.

RESULTS

The obtained dynamical system model represented by neural networks is used to forecast the biochemical markers of the patient in the next 24 h. The relative error between the predictions and the clinical data remains consistently lower than 2%.

CONCLUSIONS

This study demonstrates that a patient-specific dynamical system model can be established to monitor and forecast dynamical behavior of concentrations of patients' biochemical markers (including albumin) using deep learning methods on neural networks.

Admission C-Reactive Protein-to-Albumin Ratio Predicts the 180-Day Mortality of AIDS-Related Pneumocystis Pneumonia

Assessment tools are necessary for the adequate stratification of patients with AIDS-related pneumocystis pneumonia (PCP). The aim of this study was to evaluate the ability of severity assessment scores and inflammation- and nutrition-based parameters for predicting the 180-day mortality of AIDS-related PCP. This was a retrospective cohort study of patients with AIDS-related PCP admitted at the Beijing Di-Tan Hospital. The CURB-65 score, Pneumonia Severity Index (PSI) score, Acute Physiology And Chronic Health Evaluation II (APACHE II) score, C-reactive protein-to-albumin ratio (CAR), procalcitonin, neutrophil-to-lymphocyte ratio, lymphocyte-to-monocyte ratio, and platelet-to-lymphocyte ratio during the first 24 h of intensive care unit admission were analyzed. The prognostic values of the severity assessment scores and biomarkers for 180-day mortality were evaluated using receiver operating characteristic (ROC) curves and integrated discrimination improvement (IDI) indexes. A total of 123 patients with AIDS-related PCP were included. Fifty-five patients were dead, and 68 were still alive at 180 days after admission. CAR, CURB-65, PSI, and APACHE II were independent predictors of 180-day mortality. The optimal cutoff value of CAR was 2.0 mg/g [area under the ROC curve = 0.844, 95% credential interval (CI) = 0.776-0.913], and CAR >2.0 mg/g increased the prognostic value of all three severity assessment scores, with an IDI index of 5.1% for the CURB-65 score, 8.1% for the PSI score, and 4.1% for the APACHE II score (all p < .05). Combining CAR >2.0 mg/g enhanced the capability of CURB-65, APACHE II, and PSI in predicting the 180-day mortality of patients with AIDS-related PCP.

Effect of albumin administration on outcomes in hypoalbuminemic patients hospitalized with community-acquired pneumonia (ALBUCAP): a prospective, randomized, phase III clinical controlled trial-a trial protocol

Background

Community-acquired pneumonia (CAP) remains a leading cause of death worldwide, and hypoalbuminemia is associated with worse outcomes. However, it remains uncertain whether albumin administration could have any beneficial effects. We aim to assess whether the administration of albumin in hypoalbuminemic patients with CAP increases the proportion of clinically stable patients at day 5 compared with the standard of care alone.

Methods

This is a trial protocol for a superiority, non-blinded, multicenter, randomized, phase 3, interventional controlled clinical trial. The primary endpoint will be the proportion of clinical stable patients at day 5 (intention to treat), defined as those with stable vital signs for at least 24 h. The secondary endpoints will be time to clinical stability, duration of intravenous and total antibiotic treatment, length of hospital stay, intensive care unit admission, duration of mechanical ventilation and vasopressor treatment, adverse events, readmission within 30 days, and all-cause mortality. The trial has been approved by the Spanish Medicines and Healthcare Products Regulatory Agency. The investigators commit to publish the data in peer-reviewed journals within a year of the study completion date. Subjects will be recruited from three Spanish hospitals over a planned enrolment period of 2 years. A follow-up visit will be performed 1 month after discharge. We have estimated the need for a sample size of 360 patients at a two-sided 5% alpha-level with a power of 80% based on intention to treat. Eligible participants must be hospitalized, hypoalbuminemic (≤ 30 g/L), non-immunosuppressed, adults, and diagnosed with CAP. They will be randomly assigned (1:1) to receive standard care plus albumin (20 g in 100 mL) every 12 h for 4 days or standard care alone.

Discussion

If this randomized trial confirms the hypothesis, it should lead to a change in current clinical practice for the management of hypoalbuminemic patients with CAP.

Trial registration

European Clinical Trials Database (EudraCT) 2018-003117-18. Registered on 12 April 2019. ClinicalTrials.gov NCT04071041. Registered on 27 August 2019

The chimeric antigen receptor-intensive care unit (CAR-ICU) initiative: Surveying intensive care unit practices in the management of CAR T-cell associated toxicities

PURPOSE

A task force of experts from 11 United States (US) centers, sought to describe practices for managing chimeric antigen receptor (CAR) T-cell toxicity in the intensive care unit (ICU).

MATERIALS AND METHODS

Between June-July 2019, a survey was electronically distributed to 11 centers. The survey addressed: CAR products, toxicities, targeted treatments, management practices and interventions in the ICU.

RESULTS

Most centers (82%) had experience with commercial and non-FDA approved CAR products. Criteria for ICU admission varied between centers for patients with Cytokine Release Syndrome (CRS) but were similar for Immune Effector Cell Associated Neurotoxicity Syndrome (ICANS). Practices for vasopressor support, neurotoxicity and electroencephalogram monitoring, use of prophylactic anti-epileptic drugs and tocilizumab were comparable. In contrast, fluid resuscitation, respiratory support, methods of surveillance and management of cerebral edema, use of corticosteroid and other anti-cytokine therapies varied between centers.

CONCLUSIONS

This survey identified areas of investigation that could improve outcomes in CAR T-cell recipients such as fluid and vasopressor selection in CRS, management of respiratory failure, and less common complications such as hemophagocytic lymphohistiocytosis, infections and stroke. The variability in specific treatments for CAR T-cell toxicities, needs to be considered when designing future outcome studies of critically ill CAR T-cell patients.

Economic model of albumin infusion in septic shock: The EMAISS study

BACKGROUND

The cost-effectiveness of albumin-based fluid support in patients with septic shock is currently unknown.

METHODS

In a simulation study, we compared standard medical practice and systematic 20% albumin infusion. The study population consisted of patients with septic shock admitted to one of the 28 ICUs belonging to the Cub-Réa regional database between 1 January 2014 and 31 December 2016. Cost estimates were based on French diagnosis-related groups and fixed daily prices. Estimation of mortality reduction relied on ALBIOS trial data documenting a Risk Ratio of 0.87 in a non-preplanned subgroup of patients with septic shock. Life expectancy was estimated with follow up data of 184 patients with septic shock admitted in the year 2000 in the same ICUs. Several sensitivity analyses were performed including a one-way Deterministic Sensitivity Analysis (DSA) and a Probabilistic multivariate Sensitivity Analysis (PSA).

RESULTS

About 6406 patients were included. In the base-case scenario, the mean live years gained with albumin was 0.49. The mean extra cost of using albumin was €480 per year. The cost per year gained was €974. Sensitivity analyses confirmed the robustness of the results. The probability of albumin being cost-effective was 95% and 97% for a threshold fixed at €20 000 and €30 000 per life-year saved, respectively.

CONCLUSION

Based on the risk reduction observed in the septic shock subgroup analysis of the ALBIOS dataset, the application of the ALBIOS trial results to Cub-Réa data may suggest that albumin infusion is likely cost-effective in septic shock.

Role of albumin in the preservation of endothelial glycocalyx integrity and the microcirculation: a review

The endothelial glycocalyx comprises a complex layer of membrane-bound proteoglycans, secreted glycosaminoglycans, glycoproteins, glycolipids and bound plasma proteins such as albumin and antithrombin associated with the endothelial surface. The glycocalyx plays an important role in vascular homeostasis, regulating vascular permeability and cell adhesion, and acts as a mechanosensor for hemodynamic shear stresses; it also has antithrombotic and anti-inflammatory functions. Plasma proteins such as albumin are physiologically bound within the glycocalyx, thus contributing to stability of the layer. Albumin is the major determinant of plasma colloid osmotic pressure. In addition, albumin transports sphingosine-1-phosphate which has protective endothelial effects, acts as a free radical scavenger, and has immunomodulatory and anti-inflammatory effects. This review examines the physiological function of the endothelial glycocalyx and the role of human albumin in preserving glycocalyx integrity and the microcirculation.

Serum albumin level is associated with the severity of neurological dysfunction of NMOSD patients

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory autoimmune disease of the central nervous system. Serum albumin (SA) has antioxidant, immunomodulatory and anti-inflammatory effects. However, the roles of SA in NMOSD have not been studied. The current study aimed to clarify the association of SA with disease severity and prognosis in NMOSD patients.

METHODS

Serum levels of albumin were measured by Bromcresol Green method. Serum level measurements of interleukins were performed using enzyme-linked immunoassay (ELISA) method.

RESULTS

Of all the 130 NMOSD patients, 96 patients were in the acute phase while 34 patients were in the remission phase of disease at the time of sampling. SA concentration was significantly correlated with EDSS score in patients in the acute phase but not in remission phase (r = - 0.388, p < 0.001 and r = - 0.467, p = 0.809, respectively). Logistic analysis revealed that SA was the only significant factor to predict severe NMOSD (EDSS 8.0-9.5) OR = 0.698, 95%CI 0.563-0.865, p = 0.001) after adjustment of other confounding factors. Furthermore, SA was negatively correlated with the serum level of IL-33 (r = -0.438, p = 0.016) in the acute phase of NMOSD patients.

CONCLUSION

The current study found that low level of SA was an independent indicator of more severe neurological deficit in patients in acute phase of NMOSD. SA concentration was negatively correlated with the serum level of IL-33 in the acute phase of the disease, which implies that SA might participate in the immunopathology of NMOSD partly through its interaction with IL-33.

Albumin: Indications in chronic liver disease

Albumin is currently employed as a plasma expander to prevent and treat specific complications of cirrhosis with ascites, such as the prevention of paracentesis-induced circulatory dysfunction and renal dysfunction induced by spontaneous bacterial peritonitis, as well as the diagnosis and treatment of acute kidney injury and hepatorenal syndrome. Recently, evidence has shown that long-term albumin administration in patients with decompensated cirrhosis reduces mortality and incidence of complications, eases the management of ascites, is cost effective, and has a good safety profile.

Pro-oxidant and pro-inflammatory effects of glycated albumin on cardiomyocytes

Human serum albumin (HSA) is the most abundant circulating protein in the body and presents an extensive range of biological functions. As such, it is prone to undergo post-translational modifications (PTMs). The non-enzymatic early glycation of HSA, one of the several PTMs undergone by HSA, arises from the addition of reducing sugars to amine group residues, thus modifying the structure of HSA. These changes may affect HSA functions impairing its biological activity, finally leading to cell damage. The aim of this study was to quantitate glycated-HSA (GA) levels in the plasma of heart failure (HF) patients and to evaluate the biological effects of GA on HL-1 cardiomyocytes. Plasma GA content from HF patients and healthy subjects was measured by direct infusion electrospray ionization mass spectrometry (ESI-MS). Results pointed out a significant increase of GA in HF patients with respect to the control group (p < 0.05). Additionally, after stimulation with GA, proteomic analysis of HL-1 secreted proteins showed the modulation of several proteins involved, among other processes, in the response to stress. Further, stimulated cells showed a rapid increase in ROS generation, higher mRNA levels of the inflammatory cytokine interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α), and higher levels of the oxidative 4-HNE-protein adducts and carbonylated proteins. Our findings show that plasma GA is increased in HF patients. Further, GA exerts pro-inflammatory and pro-oxidant effects on cardiomyocytes, which suggest a causal role in the etiopathogenesis of HF.

Antimicrobial Effect of Albumin on Bacteria and Yeast Cells

We studied the effect of albumin (human serum, bovine serum, and ovalbumin) on Candida albicans, Cryptococcus neoformans, E. coli, and Staphylococcus aureus cells. Antimicrobial activity was evaluated by microscopy, inoculation, and spectrophotometry. All three albumins showed antimicrobial activity against all studied cultures and their effect was dose-dependent. At concentrations of serum albumins close to physiological (50 mg/ml), the cells of microorganisms were destroyed with the formation of debris vesicles, while at lower concentrations (10 mg/ml), only cell membrane integrity was impaired. According to spectrophotometry, activity of the human serum albumin in a physiological concentration against the studied microorganisms was close to the activity of native human serum.

Comparative pathophysiology and management of protein-losing enteropathy

Protein‐losing enteropathy, or PLE, is not a disease but a syndrome that develops in numerous disease states of differing etiologies and often involving the lymphatic system, such as lymphangiectasia and lymphangitis in dogs. The pathophysiology of lymphatic disease is incompletely understood, and the disease is challenging to manage. Understanding of PLE mechanisms requires knowledge of lymphatic system structure and function, which are reviewed here. The mechanisms of enteric protein loss in PLE are identical in dogs and people, irrespective of the underlying cause. In people, PLE is usually associated with primary intestinal lymphangiectasia, suspected to arise from genetic susceptibility, or “idiopathic” lymphatic vascular obstruction. In dogs, PLE is most often a feature of inflammatory bowel disease (IBD), and less frequently intestinal lymphangiectasia, although it is not proven which process is the true driving defect. In cats, PLE is relatively rare. Review of the veterinary literature (1977‐2018) reveals that PLE was life‐ending in 54.2% of dogs compared to published disease‐associated deaths in IBD of <20%, implying that PLE is not merely a continuum of IBD spectrum pathophysiology. In people, diet is the cornerstone of management, whereas dogs are often treated with immunosuppression for causes of PLE including lymphangiectasia, lymphangitis, and crypt disease. Currently, however, there is no scientific, extrapolated, or evidence‐based support for an autoimmune or immune‐mediated mechanism. Moreover, people with PLE have disease‐associated loss of immune function, including lymphopenia, severe CD4+ T‐cell depletion, and negative vaccinal titers. Comparison of PLE in people and dogs is undertaken here, and theories in treatment of PLE are presented.

Blood, blood components, plasma, and plasma products

This review of 2018 publications identifies side effects of blood, blood components, and plasma products. In addition, albumin, blood transfusion (erythrocytes, granulocytes, and platelets), blood substitutes (hemoglobin-based oxygen carriers), plasma products (alpha1-antitrypsin, C1 esterase inhibitor concentrate, cryoprecipitate, and fresh frozen plasma), plasma substitutes (etherified starches, and gelatin), globulins (intravenous immunoglobulin, subcutaneous immunoglobulin, and anti-D immunoglobulin), coagulation proteins (factor I, factor II, factor VIIa, factor VIII, factor IX, prothrombin complex concentrate, antithrombin III, and von Willebrand factor/factor VIII concentrates), erythropoietin and derivatives, thrombopoietin and receptor agonists, transmission of infectious agents through blood donation, and stem cells are reviewed. This chapter informs the reader about newly recognized and published data in the blood product domain.

JC, Wass MN, Langer K, Michaelis M. Doxorubicin-loaded human serum albumin nanoparticles overcome transporter-mediated drug resistance in drug-adapted cancer cells

Resistance to systemic drug therapy is a major reason for the failure of anticancer therapies. Here, we tested doxorubicin-loaded human serum albumin (HSA) nanoparticles in the neuroblastoma cell line UKF-NB-3 and its ABCB1-expressing sublines adapted to vincristine (UKF-NB-3^rVCR¹) and doxorubicin (UKF-NB-3^rDOX²⁰). Doxorubicin-loaded nanoparticles displayed increased anticancer activity in UKF-NB-3^rVCR¹ and UKF-NB-3^rDOX²⁰ cells relative to doxorubicin solution, but not in UKF-NB-3 cells. UKF-NB-3^rVCR¹ cells were re-sensitised by nanoparticle-encapsulated doxorubicin to the level of UKF-NB-3 cells. UKF-NB-3^rDOX²⁰ cells displayed a more pronounced resistance phenotype than UKF-NB-3^rVCR¹ cells and were not re-sensitised by doxorubicin-loaded nanoparticles to the level of parental cells. ABCB1 inhibition using zosuquidar resulted in similar effects like nanoparticle incorporation, indicating that doxorubicin-loaded nanoparticles successfully circumvent ABCB1-mediated drug efflux. The limited re-sensitisation of UKF-NB-3^rDOX²⁰ cells to doxorubicin by circumvention of ABCB1-mediated efflux is probably due to the presence of multiple doxorubicin resistance mechanisms. So far, ABCB1 inhibitors have failed in clinical trials probably because systemic ABCB1 inhibition results in a modified body distribution of its many substrates including drugs, xenobiotics, and other molecules. HSA nanoparticles may provide an alternative, more specific way to overcome transporter-mediated resistance.

Shared Features of Endothelial Dysfunction between Sepsis and Its Preceding Risk Factors (Aging and Chronic Disease)

Acute vascular endothelial dysfunction is a central event in the pathogenesis of sepsis, increasing vascular permeability, promoting activation of the coagulation cascade, tissue edema and compromising perfusion of vital organs. Aging and chronic diseases (hypertension, dyslipidaemia, diabetes mellitus, chronic kidney disease, cardiovascular disease, cerebrovascular disease, chronic pulmonary disease, liver disease, or cancer) are recognized risk factors for sepsis. In this article we review the features of endothelial dysfunction shared by sepsis, aging and the chronic conditions preceding this disease. Clinical studies and review articles on endothelial dysfunction in sepsis, aging and chronic diseases available in PubMed were considered. The main features of endothelial dysfunction shared by sepsis, aging and chronic diseases were: (1) increased oxidative stress and systemic inflammation, (2) glycocalyx degradation and shedding, (3) disassembly of intercellular junctions, endothelial cell death, blood-tissue barrier disruption, (4) enhanced leukocyte adhesion and extravasation, (5) induction of a pro-coagulant and anti-fibrinolytic state. In addition, chronic diseases impair the mechanisms of endothelial reparation. In conclusion, sepsis, aging and chronic diseases induce similar features of endothelial dysfunction. The potential contribution of pre-existent endothelial dysfunction to sepsis pathogenesis deserves to be further investigated.

Vitamin D status and its influence on outcomes following major burn injury and critical illness

Vitamin D deficiency is common among the general population. It is also observed in up to 76% of critically ill patients. Despite the high prevalence of hypovitaminosis D in critical illness, vitamin D is often overlooked by medical staff as the clinical implications and consequences of vitamin D deficiency in acute contexts remain to be fully understood. Vitamin D has a broad range of pleotropic effects on various processes and systems including the immune-inflammatory response. 1α,25-dihydroxyvitamin D (1,25(OH)₂D), has been shown to promote a tolerogenic immune response limiting deleterious inflammatory effects, modulation of the innate immune system, and enhancement of anti-microbial peptides. Vitamin D deficiency is frequently observed in critically ill patients and has been related to extrinsic causes (i.e., limited sunlight exposure), magnitude of injury/illness, or the treatment started by medical doctors including fluid resuscitation. Low levels of vitamin D in critically ill patients have been associated with sepsis, organ failure, and mortality. Despite this, there are subpopulations of critical illness, such as burn patients, where the literature regarding vitamin D status and its influence on outcomes remain insufficient. Thermal injury results in damage to both burned and non-burned tissues, as well as induces an exaggerated and persistent immune-inflammatory and hypermetabolic response. In this review, we propose potential mechanisms in which burn injury affects the vitamin D status and summarizes current literature investigating the influence of vitamin D status on outcomes. In addition, we reviewed the literature and trials investigating vitamin D supplementation in critically ill patients and discuss the therapeutic potential of vitamin D supplementation in burn and critically ill patients. We also highlight current limitations of studies that have investigated vitamin D status and supplementation in critical illness. Thermal injury influences vitamin D status. More studies investigating vitamin D depletion in burn patients and its influence on prognosis, via standardized methodology, are required to reach definitive conclusions and influence clinical practice.