Albumin resuscitation improves ventricular contractility and myocardial tissue oxygenation in rat endotoxemia

Albumin Versus Balanced Crystalloid for the Early Resuscitation of Sepsis: An Open Parallel-Group Randomized Feasibility Trial. The ABC-Sepsis Trial

OBJECTIVES

International guidelines recommend IV crystalloid as the primary fluid for sepsis resuscitation, with 5% human albumin solution (HAS) as the second line. However, it is unclear which fluid has superior clinical effectiveness. We conducted a trial to assess the feasibility of delivering a randomized controlled trial comparing balanced crystalloid against 5% HAS as sole early resuscitation fluid in patients with sepsis presenting to hospital.

DESIGN

Multicenter, open, parallel-group randomized feasibility trial.

SETTING

Emergency departments (EDs) in 15 U.K. National Health Service (NHS) hospitals.

PATIENTS

Adult patients with sepsis and a National Early Warning Score 2 greater than or equal to five requiring IV fluids withing one hour of randomization.

INTERVENTIONS

IV fluid resuscitation with balanced crystalloid or 5% HAS for the first 6 hours following randomization.

MEASUREMENTS AND MAIN RESULTS

Primary feasibility outcomes were recruitment rate and 30-day mortality. We successfully recruited 301 participants over 12 months. Mean (sd) age was 69 years (± 16 yr), and 151 (50%) were male. From 1303 participants screened; 502 participants were potentially eligible and 300 randomized to receive trial intervention with greater than 95% of participants receiving the intervention. The median number of participants per site was 19 (range, 1-63). Thirty-day mortality was 17.9% (n = 53). Thirty-one participants died (21.1%) within 30 days in the 5% HAS arm, compared with 22 participants (14.8%) in the crystalloid arm (adjusted odds ratio, 1.50; 95% CIs, 0.84-2.83).

CONCLUSIONS

Our results suggest it is feasible to recruit critically ill patients to a fluid resuscitation trial in U.K. EDs using 5% HAS as a primary resuscitation fluid. There was lower mortality in the balanced crystalloid arm. Given these findings, a definitive trial is likely to be deliverable, but the point estimates suggest such a trial would be unlikely to demonstrate a significant benefit from using 5% HAS as a primary resuscitation fluid in sepsis.

Right ventricular myocardial oxygen tension is reduced in monocrotaline-induced pulmonary hypertension in the rat and restored by myo-inositol trispyrophosphate

Pulmonary hypertension (PH) initially results in compensatory right ventricular (RV) hypertrophy, but eventually in RV failure. This transition is poorly understood, but may be triggered by hypoxia. Measurements of RV oxygen tension (pO₂) in PH are lacking. We hypothesized that RV hypoxia occurs in monocrotaline-induced PH in rats and that myo-inositol trispyrophosphate (ITPP), facilitating oxygen dissociation from hemoglobin, can relieve it. Rats received monocrotaline (PH) or saline (control) and 24 days later echocardiograms, pressure–volume loops were obtained and myocardial pO₂ was measured using a fluorescent probe. In PH mean pulmonary artery pressure more than doubled (35 ± 5 vs. 15 ± 2 in control), RV was hypertrophied, though its contractility was augmented. RV and LV pO₂ was 32 ± 5 and 15 ± 8 mmHg, respectively, in control rats. In PH RV pO₂ was reduced to 18 ± 9 mmHg, while LV pO₂ was unchanged. RV pO₂ correlated with RV diastolic wall stress (negatively) and LV systolic pressure (positively). Acute ITPP administration did not affect RV or LV pO₂ in control animals, but increased RV pO₂ to 26 ± 5 mmHg without affecting LV pO₂ in PH. RV oxygen balance is impaired in PH and as such can be an important target for PH therapy. ITPP may be one of such potential therapies.

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

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.

Sepsis-induced myocardial dysfunction

PURPOSE OF REVIEW

Sepsis leads to a complex intramyocardial inflammatory response that results in sepsis-induced myocardial dysfunction. Here, recent findings are reviewed in a physiologic context.

RECENT FINDINGS

Decreased systolic contractility during sepsis limits ventricular ejection and stroke volume. Initially, this effect is compensated for by increased diastolic filling during volume resuscitation. Reduced afterload due to arterial vasodilation also compensates so that cardiac output can be maintained or increased. Recent results recognize the importance of diastolic dysfunction, reduced ventricular diastolic compliance that impedes ventricular filling. Diastolic dysfunction becomes increasingly important as severity of septic shock increases. When impaired ventricular ejection is coupled with limited diastolic filling, stroke volume must decrease. Accordingly, diastolic dysfunction is more closely related to mortality than systolic dysfunction. Recent trials of beta-adrenergic agonists and levosimendan have been disappointing, while approaches to modulating the intramyocardial inflammatory response show promise.

SUMMARY

Sepsis-induced myocardial dysfunction is increasingly recognized as a major contributor to outcome of septic shock. Significant strides have been made in understanding the intramyocardial inflammatory response that causes myocardial dysfunction. A number of novel approaches show promise by modulating the intramyocardial inflammatory response.

How to transform a fixed stroke alternating syringe ventricle into an adjustable elastance ventricle

Most devices used for bench simulation of the cardiovascular system are based either on a syringe-like alternating pump or an elastic chamber inside a fluid-filled rigid box. In these devices, it is very difficult to control the ventricular elastance and simulate pathologies related to the mechanical mismatch between the ventricle and arterial load (i.e., heart failure). This work presents a possible solution to transforming a syringe-like pump with a fixed ventricle into a ventricle with variable elastance. Our proposal was tested in two steps: (1) fixing the ventricle and the aorta and changing the peripheral resistance (PHR); (2) fixing the aorta and changing the ventricular elastance and the PHR. The signals of interest were acquired to build the ventricular pressure-volume (P-V) loops describing the different physiological conditions, and the end-systolic pressure-volume relationships (ESPVRs) were calculated with linear interpolation. The results obtained show a good physiological behavior of our mock for both steps. (1) Since the ventricle is the same, the systolic pressures increase and the stroke volumes decrease with the PHR: the ESPVR, obtained by interpolating the pressure and volume values at end-systolic phases, is linear. (2) Each ventricle presents ESPVR with different slopes depending on the ventricle elastance with a very good linear behavior. In conclusion, this paper demonstrates that a fixed stroke alternating syringe ventricle can be transformed into an adjustable elastance ventricle.

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

INTRODUCTION

Effective resuscitation with human albumin solutions is achieved with less fluid than with crystalloid solutions. However, the role of albumin in today's critical care unit is also linked to its multiple pharmacological effects. Areas covered: The potential clinical benefits of albumin in select populations of critically ill patients like sepsis seem related to immunomodulatory and anti-inflammatory effects, antibiotic transportation and endothelial stabilization. Albumin transports many drugs used in critically ill patients. Such binding to albumin is frequently lessened in critically ill patients with hypoalbuminemia. These changes could result in sub-optimal treatment. Albumin has immunomodulatory capacity by binding several bacterial products. Albumin also influences vascular integrity, contributing to the maintenance of the normal capillary permeability. Moreover, the albumin molecule encompasses several antioxidant properties, thereby significantly reducing re-oxygenation injury, which is especially important in sepsis. In fact, most studies of albumin administration are a combination of a degree of resuscitation with a degree of maintenance or supplementation of albumin. Expert commentary: The potential clinical benefits of the use of albumin in selected critically ill patients such as sepsis seem related to its immunomodulatory and anti-inflammatory effects, antioxidant properties, antibiotic transportation and endothelial stabilization. Additional studies are warranted to further elucidate the underlying physiologic and molecular rationale.

Effects of the Infusion of 4% or 20% Human Serum Albumin on the Skeletal Muscle Microcirculation in Endotoxemic Rats

Background

Sepsis-induced microcirculatory alterations contribute to tissue hypoxia and organ dysfunction. In addition to its plasma volume expanding activity, human serum albumin (HSA) has anti-oxidant and anti-inflammatory properties and may have a protective role in the microcirculation during sepsis. The concentration of HSA infused may influence these effects. We compared the microcirculatory effects of the infusion of 4% and 20% HSA in an experimental model of sepsis.

Methods

Adult male Wistar rats were equipped with arterial and venous catheters and received an intravenous infusion of lipopolysaccharide (LPS, serotype O127:B8, 10 mg/kg over 30 minutes) or vehicle (SHAM, n = 6). Two hours later, endotoxemic animals were randomized to receive 10 mL/kg of either 4% HSA (LPS+4%HSA, n = 6), 20% HSA (LPS+20%HSA, n = 6) or 0.9% NaCl (LPS+0.9%NaCl, n = 6). No fluids were given to an additional 6 animals (LPS). Vessel density and perfusion were assessed in the skeletal muscle microcirculation with sidestream dark field videomicroscopy at baseline (t0), 2 hours after LPS injection (t1), after HSA infusion (t2) and 1 hour later (t3). The mean arterial pressure (MAP) and heart rate were recorded. Serum endothelin-1 was measured at t2.

Results

MAP was stable over time in all groups. The microcirculatory parameters were significantly altered in endotoxemic animals at t1. The infusion of both 4% and 20% HSA similarly increased the perfused vessel density and blood flow velocity and decreased the flow heterogeneity to control values. Microvascular perfusion was preserved in the LPS+20%HSA group at t3, whereas alterations reappeared in the LPS+4%HSA group.

Conclusions

In a rat model of normotensive endotoxemia, the infusion of 4% or 20% HSA produced a similar acute improvement in the microvascular perfusion in otherwise unresuscitated animals.

Low tidal volume ventilation ameliorates left ventricular dysfunction in mechanically ventilated rats following LPS-induced lung injury

Background

High tidal volume ventilation has shown to cause ventilator-induced lung injury (VILI), possibly contributing to concomitant extrapulmonary organ dysfunction. The present study examined whether left ventricular (LV) function is dependent on tidal volume size and whether this effect is augmented during lipopolysaccharide(LPS)-induced lung injury.

Methods

Twenty male Wistar rats were sedated, paralyzed and then randomized in four groups receiving mechanical ventilation with tidal volumes of 6 ml/kg or 19 ml/kg with or without intrapulmonary administration of LPS. A conductance catheter was placed in the left ventricle to generate pressure-volume loops, which were also obtained within a few seconds of vena cava occlusion to obtain relatively load-independent LV systolic and diastolic function parameters. The end-systolic elastance / effective arterial elastance (Ees/Ea) ratio was used as the primary parameter of LV systolic function with the end-diastolic elastance (Eed) as primary LV diastolic function.

Results

Ees/Ea decreased over time in rats receiving LPS (p = 0.045) and high tidal volume ventilation (p = 0.007), with a lower Ees/Ea in the rats with high tidal volume ventilation plus LPS compared to the other groups (p < 0.001). Eed increased over time in all groups except for the rats receiving low tidal volume ventilation without LPS (p = 0.223). A significant interaction (p < 0.001) was found between tidal ventilation and LPS for Ees/Ea and Eed, and all rats receiving high tidal volume ventilation plus LPS died before the end of the experiment.

Conclusions

Low tidal volume ventilation ameliorated LV systolic and diastolic dysfunction while preventing death following LPS-induced lung injury in mechanically ventilated rats. Our data advocates the use of low tidal volumes, not only to avoid VILI, but to avert ventilator-induced myocardial dysfunction as well.

Human Albumin Solution Resuscitation in Severe Sepsis and Septic Shock

There has been a recent resurgence of interest in the use of human albumin solution (HAS) for the resuscitation of critically ill patients. In particular, it may be beneficial for patients with severe sepsis and septic shock. We outline the evidence for the biological plausibility of this effect, perform a meta-analysis of randomised controlled trials comparing the effect of HAS with other fluid resuscitation on mortality in this group of patients and discuss the likely contribution of recently completed trials in this area. We included nine trials of 1,435 patients in the meta-analysis. Although HAS resuscitation was associated with a trend to lower mortality (relative risk 0.90, 95% confidence interval 0.79–1.02), we found that most trials reported to date are small and of variable methodological quality. The questions of a potential differential effect of dose on outcome and the pharmacological variability of HAS products have not been adequately addressed to date. We conclude that the routine administration of HAS to patients with severe sepsis and septic shock is difficult to justify on the basis of current knowledge.

Resuscitation fluids and endotoxin-induced myocardial dysfunction: is selection a load-independent differential issue?

Along with redistributive shock, myocardial dysfunction is now recognized as highly prevalent in early severe sepsis. Indeed, aside from their distinct loading potency, resuscitation fluids have been poorly investigated as to their specific molecular impact on myocardial dysfunction. The objective of this study was to evaluate the load-independent biological impact of different resuscitation fluids on endotoxin-induced myocardial dysfunction. Adult rats implanted with a central venous catheter were given an intraperitoneal injection of endotoxin (lipopolysaccharides [LPSs], Escherichia coli, 10 mg/kg) or normal saline (sham) and subsequently infused or not with similar "fluid potency" loading resuscitation fluid (normal saline, albumin [Alb], or hypertonic saline solution) for 6 to 24 h, followed by echocardiographic and hemodynamic monitoring together with biochemical and histopathologic evaluation. Intervention was to assess the selective influence of load-independent fluid infusion on the aforementioned parameters in groups of animals challenged or not with LPS. At comparative plasma volumes, Alb improved myocardial homeostasis after LPS challenge by (i) reducing left ventricular relative wall diastolic thickness, interstitial space enlargement, and endogenous Alb content; (ii) limiting cardiac apoptosis and sustaining extracellular signal-regulated mitogen-activated protein kinase activation; and (iii) enhancing the expression pattern of heme-oxygenase 1/inducible nitric oxide synthase. Hypertonic saline solution was also cardioprotective by early prevention of myocardial dysfunction and by reducing cardiac apoptosis. Fluid infusions have distinct load-independent structural/biological impacts on endotoxin-induced myocardial dysfunction. Albumin and hypertonic saline solution are the most pleiotropic fluids in protecting the heart after a "sepsis" hit.

Beneficial effects of hyperoncotic albumin on liver injury and survival in peritonitis-induced sepsis rats

Liver injury/dysfunction developing in patients with sepsis may lead to an increased risk of death. Small-volume resuscitation with hyperoncotic albumin (HA) has been proposed to restore physiologic hemodynamics in hemorrhagic and septic shock. We evaluated whether HA resuscitation could alleviate the development of liver injury/dysfunction in rats with polymicrobial sepsis induced by cecal ligation and puncture (CLP). The male Wistar rats received 0.9% saline or HA (25%, 3 mL/kg intravenously) at 3 h after CLP or sham operation. All hemodynamic and biochemical variables were measured during the 18-h observation. After 18 h of CLP, the septic rats developed circulatory failure (i.e., hypotension, tachycardia, and poor tissue perfusion), liver injury (examined by biochemical variables and histologic studies), and a higher mortality. Hyperoncotic albumin not only ameliorated the deterioration of hemodynamic changes but also attenuated neutrophil infiltration and cell death in the liver of septic animals. The septic rats treated with HA had a higher survival when compared with those with 0.9% saline treatment. Moreover, the increased plasma IL-1β, plasma IL-6, plasma nitrite/nitrate concentrations, liver iNOS expression, and liver superoxide levels in CLP rats were attenuated after administration of HA. Thus, HA may be regarded as a potential therapeutic agent in the early treatment of septic shock to prevent or reduce subsequent liver failure.

Endotoxin impairs cardiac hemodynamics by affecting loading conditions but not by reducing cardiac inotropism

Acute myocardial dysfunction is a typical manifestation of septic shock. Experimentally, the administration of endotoxin [lipopolysacharride (LPS)] to laboratory animals is frequently used to study such dysfunction. However, a majority of studies used load-dependent indexes of cardiac function [including ejection fraction (EF) and maximal systolic pressure increment (dP/dt(max))], which do not directly explore cardiac inotropism. Therefore, we evaluated the direct effects of LPS on myocardial contractility, using left ventricular (LV) pressure-volume catheters in mice. Male BALB/c mice received an intraperitoneal injection of E. coli LPS (1, 5, 10, or 20 mg/kg). After 2, 6, or 20 h, cardiac function was analyzed in anesthetized, mechanically ventilated mice. All doses of LPS induced a significant drop in LV stroke volume and a trend toward reduced cardiac output after 6 h. Concomitantly, there was a significant decrease of LV preload (LV end-diastolic volume), with no apparent change in LV afterload (evaluated by effective arterial elastance and systemic vascular resistance). Load-dependent indexes of LV function were markedly reduced at 6 h, including EF, stroke work, and dP/dt(max). In contrast, there was no reduction of load-independent indexes of LV contractility, including end-systolic elastance (ejection phase measure of contractility) and the ratio dP/dt(max)/end-diastolic volume (isovolumic phase measure of contractility), the latter showing instead a significant increase after 6 h. All changes were transient, returning to baseline values after 20 h. Therefore, the alterations of cardiac function induced by LPS are entirely due to altered loading conditions, but not to reduced contractility, which may instead be slightly increased.

[Albumin in sepsis]

Human serum albumin is a small (66kD) globular protein representing over 60 % of the total plasma protein content. It is made up of 585 amino 6 acids and contains 35 cysteine residues forming disulfide bridges that contribute to its overall tertiary structure. It has a free cysteine-derived thiol group at Cys-34, which accounts for 80 % of its redox activity. Physiologically, serum albumin exists in a reduced form with a free thiol contributing to its antioxidant properties. It is synthesized primarily in the liver and is an acute-phase protein. It is a multifunctional plasma protein ascribed ligand-binding and transport properties as well as antioxidants and enzymatic functions. It maintains colloid osmotic pressure, modulates inflammatory response and may influence oxidative damage. Hypoalbuminemia is common in the intensive care unit and may be due to decreased synthesis by the liver and/or to increased losses or increased proteolysis and clearance. Although albumin was long used to control vascular collapse in critically ill patients, the evidence suggests that it does not offer a benefit over crystalloid solutions in vascular collapse. However, human serum albumin is an important circulating antioxidant and it may be beneficial in critically ill patients to limit oxidative damage. A number of studies suggest that in specific groups of hypoalbuminemic critically ill patients, albumin administration may have beneficial effects on organ function, although the exact mechanisms remain undefined. Further trials are needed to confirm theses observations and to clearly demonstrate whether albumin should be administered in critically ill patients with hypoalbuminemia.

Is albumin administration in hypoalbuminemic elderly cardiac surgery patients of benefit with regard to inflammation, endothelial activation, and long-term kidney function?

BACKGROUND

Because patients with low albumin levels may benefit from human albumin (HA) administration, we studied correction of hypovolemia with HA in hypoalbuminic elderly cardiac surgery patients.

METHODS

In a prospective, randomized study, 50 patients aged >80 yr undergoing cardiac surgery using cardiopulmonary bypass with a preoperative serum albumin concentration of <3.5 mg/dL, received either 5% HA (n = 25) or hydroxyethyl starch (6% HES 130/0.4) (n = 25). Volume was added to the priming (500 mL) and given until the morning of the second postoperative day to keep pulmonary capillary wedge pressure or central venous pressure between 12 and 14 mm Hg.

RESULTS

Inflammatory response (interleukins-6, -10), endothelial activation (intercellular adhesion molecule-1), and kidney function (including glutathione transferase-alpha and neutrophil gelatinase-associated lipocalin) were measured after induction of anesthesia, 5 h after surgery, and the first and second postoperative day. A follow-up, approximately 60 days after discharge from the hospital, was done. Two thousand nine hundred eighty +/- 430 mL of HA and 3060 +/- 680 mL of HES 130/0.4 were given. Serum albumin concentration was significantly increased by HA (to 4.5 +/- 0.3 mg/dL). Serum creatinine, glomerular filtration rate, and urinary levels of alpha-glutathione transferase and neutrophil gelatinase-associated lipocalin were not different in the HA-compared to the HES-treated patients. The inflammatory response was similar in both groups, whereas endothelial activation was less in the HES group. None of the patients developed renal failure requiring renal replacement therapy.

CONCLUSION

Use of HA in hypoalbuminemic cardiac surgery patients aged >80 yr was without benefit with regard to inflammatory response, endothelial activation, and renal function compared to 6% HES 130/0.4.