Effects of albumin supplementation on microvascular permeability in septic patients

Anesthesia-induced Lymphatic Dysfunction

General anesthetics adversely alters the distribution of infused fluid between the plasma compartment and the extravascular space. This maldistribution occurs largely from the effects of anesthetic agents on lymphatic pumping, which can be demonstrated by macroscopic fluid kinetics studies in awake versus anesthetized patients. The magnitude of this effect can be appreciated as follows: a 30% reduction in lymph flow may result in a fivefold increase of fluid-induced volume expansion of the interstitial space relative to plasma volume. Anesthesia-induced lymphatic dysfunction is a key factor why anesthetized patients require greater than expected fluid administration than can be accounted for by blood loss, urine output, and insensible losses. Anesthesia also blunts the transvascular refill response to bleeding, an important compensatory mechanism during hemorrhagic hypovolemia, in part through lymphatic inhibition. Last, this study addresses how catecholamines and hypertonic and hyperoncotic fluids may mobilize interstitial fluid to mitigate anesthesia-induced lymphatic dysfunction.

Modulation of the capillary leakage by exogenous albumin in a rat model of endothelial glycocalyx damage

BACKGROUND

Endothelial glycocalyx (EG) plays a crucial role in maintaining the plasma proteins within the intravascular space.

OBJECTIVE

We studied whether exogenous albumin protects the EG in an experimental model of EG enzymatic damage in rats.

METHODS

Rats were divided into three groups of 10 animals that received (1) Evans blue (2) Evans blue + hyaluronidase, or (3) Evans blue + hyaluronidase + 20% human albumin via the tail vein. Spectrophotometric analysis was performed 2 h later to quantify the leakage of Evans blue-labeled albumin into the heart, lungs, brain, kidneys, liver, small intestine, spleen, and skeletal muscle.

RESULTS

Administration of hyaluronidase numerically increased the capillary leakage of Evans blue in all examined tissues. Co-administration of albumin decreased the leakage of albumin in all tissues except the heart. In the lungs, the ratio between the absorbance and dry organ weight decreased from 5.3 ± 2.4 to 1.7 ± 0.5 (mean ± SD) (P < 0.002), and in the liver, the absorbance decreased from 2.2 ± 0.7 to 1.5 ± 0.4 (P < 0.011).

CONCLUSION

Exogenous albumin decreased the capillary leakage of albumin which was interpreted as a sign of maintained EG integrity.

The glycocalyx as a permeability barrier: basic science and clinical evidence

Preclinical studies in animals and human clinical trials question whether the endothelial glycocalyx layer is a clinically important permeability barrier. Glycocalyx breakdown products in plasma mostly originate from 99.6–99.8% of the endothelial surface not involved in transendothelial passage of water and proteins. Fragment concentrations correlate poorly with in vivo imaging of glycocalyx thickness, and calculations of expected glycocalyx resistance are incompatible with measured hydraulic conductivity values. Increases in plasma breakdown products in rats did not correlate with vascular permeability. Clinically, three studies in humans show inverse correlations between glycocalyx degradation products and the capillary leakage of albumin and fluid.

Low serum albumin: A neglected predictor in patients with cardiovascular disease

Albumin, the most abundant circulating protein in blood, is an essential protein which binds and transports various drugs and substances, maintains the oncotic pressure of blood and influences the physiological function of the circulatory system. Albumin also has anti-inflammatory, antioxidant, and antithrombotic properties. Evidence supports albumin's role as a strong predictor of cardiovascular (CV) risk in several patient groups. Its protective role extends to those with coronary artery disease, heart failure, hypertension, atrial fibrillation, peripheral artery disease or ischemic stroke, as well as those undergoing revascularization procedures or with aortic stenosis undergoing transcatheter aortic valve replacement, and patients with congenital heart disease and/or endocarditis. Hypoalbuminemia is a strong prognosticator of increased all-cause and CV mortality according to several cohort studies and meta-analyses in hospitalized and non-hospitalized patients with or without comorbidities. Normalization of albumin levels before discharge lowers mortality risk, compared with hypoalbuminemia before discharge. Modified forms of albumin, such as ischemia modified albumin, also has prognostic value in patients with coronary or peripheral artery disease. When albumin is combined with other risk factors, such as uric acid or C-reactive protein, the prognostic value is enhanced. Although albumin supplementation may be a plausible approach, its efficacy has not been established and in patients with hypoalbuminemia, priority is focused on diagnosing and managing the underlying condition. The CV effects of hypoalbuminemia and relevant issues are considered in this review. Large cohort studies and meta-analyses are tabulated and the physiologic effects of albumin and the deleterious effects of low albumin are pictorially illustrated.

Fast versus slow infusion of 20% albumin: a randomized controlled cross-over trial in volunteers

BACKGROUND

We investigated whether plasma volume (PV) expansion of 20% albumin is larger when the fluid is administered rapidly compared with a slow infusion.

METHODS

In this open-labeled randomized interventional controlled trial, 12 volunteers (mean age, 28 years) received 3 mL/kg of 20% albumin (approximately 225 mL) over 30 min (fast) and 120 min (slow) in a cross-over fashion. Blood hemoglobin and plasma albumin were measured on 15 occasions during 6 h to estimate the PV expansion and the capillary leakage of albumin and fluid.

RESULTS

The largest PV expansion was 16.1% ± 6.5% (mean ± SD) for fast infusion and 12.8% ± 4.0% for slow infusion (p = 0.52). The median area under the curve for the PV expansion was 69% larger for the fast infusion during the first 2 h (p = 0.034), but was then similar for both infusions. The half-life of the PV expansion did not differ significantly (median, 5.6 h versus 5.4 h, p = 0.345), whereas the intravascular half-life of the excess albumin was 8.0 h for fast infusion and 6.3 h for slow infusion (p = 0.028). The measured urine output was almost three times larger than the infused volume. The plasma concentration of atrial natriuretic peptide (MR-proANP) accelerated the capillary leakage of albumin and the urine flow.

CONCLUSIONS

The intravascular persistence of albumin was longer, but the fluid kinetics was the same, when 20% albumin was infused over 30 min compared with 120 min. We found no disadvantages of administering the albumin at the higher rate. Trial registration EU Clinical Trials Register, EudraCT2017-003687-12, registered September 22, 2017, https://www.clinicaltrialsregister.eu/ctr-search/trial/2017-003687-12/SE.

Plasma disappearance rate of albumin when infused as a 20% solution

BACKGROUND

The transcapillary leakage of albumin is increased by inflammation and major surgery, but whether exogenous albumin also disappears faster is unclear.

METHODS

An intravenous infusion of 3 mL/kg of 20% albumin was given over 30 min to 70 subjects consisting of 15 healthy volunteers, 15 post-burn patients, 15 patients who underwent surgery with minor bleeding, 10 who underwent surgery with major bleeding (mean, 1.1 L) and 15 postoperative patients. Blood Hb and plasma albumin were measured on 15 occasions over 5 h. The rate of albumin disappearance from the plasma was quantitated with population kinetic methodology and reported as the half-life (T1/2).

RESULTS

No differences were observed for T1/2 between volunteers, post-burn patients, patients who underwent surgery with minor bleeding and postoperative patients. The T1/2 averaged 16.2 h, which corresponds to 3.8% of the amount infused per h. Two groups showed plasma concentrations of C-reactive protein of approximately 60 mg/L and still had a similarly long T1/2 for albumin. By contrast, patients undergoing surgery associated with major hemorrhage had a shorter T1/2, corresponding to 15% of the infused albumin per h. In addition, our analyses show that the T1/2 differ greatly depending on whether the calculations consider plasma volume changes and blood losses.

CONCLUSION

The disappearance rate of the albumin in 20% preparations was low in volunteers, in patients with moderately severe inflammation, and in postoperative patients.

Cardiovascular Responses During Sepsis

Sepsis is the life-threatening organ dysfunction arising from a dysregulated host response to infection. Although the specific mechanisms leading to organ dysfunction are still debated, impaired tissue oxygenation appears to play a major role, and concomitant hemodynamic alterations are invariably present. The hemodynamic phenotype of affected individuals is highly variable for reasons that have been partially elucidated. Indeed, each patient's circulatory condition is shaped by the complex interplay between the medical history, the volemic status, the interval from disease onset, the pathogen, the site of infection, and the attempted resuscitation. Moreover, the same hemodynamic pattern can be generated by different combinations of various pathophysiological processes, so the presence of a given hemodynamic pattern cannot be directly related to a unique cluster of alterations. Research based on endotoxin administration to healthy volunteers and animal models compensate, to an extent, for the scarcity of clinical studies on the evolution of sepsis hemodynamics. Their results, however, cannot be directly extrapolated to the clinical setting, due to fundamental differences between the septic patient, the healthy volunteer, and the experimental model. Numerous microcirculatory derangements might exist in the septic host, even in the presence of a preserved macrocirculation. This dissociation between the macro- and the microcirculation might account for the limited success of therapeutic interventions targeting typical hemodynamic parameters, such as arterial and cardiac filling pressures, and cardiac output. Finally, physiological studies point to an early contribution of cardiac dysfunction to the septic phenotype, however, our defective diagnostic tools preclude its clinical recognition. © 2021 American Physiological Society. Compr Physiol 11:1605-1652, 2021.

Transcapillary escape rate of 125I-albumin in relation to timing of blood sampling: the need for standardization

Background

Increased vascular permeability is an early sign of vascular damage and can be measured with the transcapillary escape rate of albumin (TER_alb). Although TER_alb has a multi-exponential kinetic model, most published TER_alb data are based on mono-exponential kinetic models with variation in blood sampling schemes. Aim of this posthoc study was to evaluate the influence of variation in blood sampling schemes and the impact of mono- or bi-exponential analyses on the calculation of TER_alb. Study participants were part of a cross-over intervention study protocol, investigating effects of sodium loading on blood pressure, endothelial surface layer and microcirculation. Multiple blood samples were drawn between 3 and 60 min after injection of radioactive iodide labeled human serum albumin (rHSA).

Results

In total 27 male participants with 54 measurements were included. For all participants the maximum serum radioactivity was reached within 20 min, while 85% of the participants had their maximum serum activity within 10 min. The TER_alb calculated with the subsequently chosen T_{20–60 min} reference scheme (6.19 ± 0.49%/h) was significantly lower compared to the TER_alb of the T_{3–60 min}, T_{5–60 min}, and T_{max – 60 min} schemes. There was no significant difference between the T_{20–60 min} reference scheme and the T_{10–60 min} and T_{15–60 min} schemes. Bi-exponential kinetic modeling did not result in significant different observations compared to the mono-exponential kinetic analysis.

Conclusions

As there is variation in the timing of the maximum serum radioactivity of rHSA, blood sampling schemes starting before 10 min after administration of rHSA will result in a significant overestimation of TER_alb. In addition, variation in kinetic modeling did not result in significant changes in TER_alb. Therefore, we emphasize the need to standardize TER_alb and for practical and logistical reasons advocate the use of a mono-exponential model with blood sampling starting 20 min after rHSA administration.

Long Intravascular Persistence of 20% Albumin in Postoperative Patients

BACKGROUND

Albumin may persist intravascularly for a shorter time in patients after major surgery than in healthy volunteers due to a surgery-induced breakdown (shedding) of the endothelial glycocalyx layer.

METHODS

In this nonrandomized clinical trial, an IV infusion of 3 mL/kg of 20% albumin was given at a constant rate during 30 minutes to 15 patients on the first day after major open abdominal surgery (mean operating time 5.9 h) and to 15 conscious volunteers. Blood samples and urine were collected during 5 h and mass balance calculations used to estimate the half-lives of the administered albumin molecules and the induced plasma volume expansion, based on measurements of hemodilution and the plasma albumin concentration.

RESULTS

At the end of the infusions, albumin had diluted the plasma volume by 13.3% ± 4.9% (mean ± SD) in the postoperative patients and by 14.2% ± 4.8% in the volunteers (mean difference -0.9, 95% CI, -4.7 to 2.9; 1-way ANOVA P = .61), which amounted to twice the infused volume. The intravascular half-life of the infused albumin molecules was 9.1 (5.7-11.2) h in the surgical patients and 6.0 (5.1-9.0) h in the volunteers (Mann-Whitney U test, P = .26; geometric mean difference 1.2, 95% CI, 0.8-2.0). The half-life of the plasma volume expansion was 10.3 (5.3-17.6; median and interquartile range) h in the surgical patients and 7.6 (3.5-9.0) h in the volunteers (P = .10; geometric mean difference 1.5, 95% CI, 0.8-2.8). All of these parameters correlated positively with the body mass index (correlation coefficients being 0.42-0.47) while age and sex did not affect the results.

CONCLUSIONS

Twenty percent albumin caused a long-lasting plasma volume expansion of similar magnitude in postoperative patients and volunteers.

The Revised Starling Equation: The Debate of Albumin Versus Crystalloids Continues

Objectives: The purpose of this critical narrative review is to discuss the revised Starling equation for microvascular fluid exchange and the associated implications for intravenous fluid administration. Data Sources: PubMed (1946 to December 2019) and EMBASE (1947 to December 2019) were used, and bibliographies of retrieved articles were searched for additional articles. Study Selection and Data Extraction: Articles pertaining to the revised Starling equation and microvascular fluid exchange. Additionally, prospective human studies involving the disposition and oncotic action of radiolabeled albumin and large randomized trials comparing fluid requirements associated with isotonic crystalloid and albumin administration were included. Data Synthesis: In the revised Starling equation, oncotic forces act across the endothelial cell layer, more specifically between the fluid in the vessel lumen and the protein-sparse subglycocalyx space. The revised Starling equation and radiolabeled investigations of albumin necessitate a reconsideration of conventional views of the plasma-expanding properties of exogenous albumin. Large clinical trials demonstrate that the administration of iso-oncotic or hyper-oncotic albumin solutions in patients undergoing resuscitation does not have the reductions in fluid requirements anticipated from a traditional understanding of the oncotic actions of albumin. Relevance to Patient Care and Clinical Practice: When used as a resuscitation fluid, albumin does not have the degree of plasma expansion or intravascular retention commonly used to justify its use. Conclusions: The principles underlying the revised Starling equation in conjunction with data from radiolabeled studies of albumin and large clinical trials demonstrate that albumin does not have the perceived degree of plasma expansion or duration of intravascular retention beyond crystalloid solutions predicted by the classic Starling equation.

The Influence of Albumin Level in Critically Ill Children to Length of Stay and Mortality in Paediatric Intensive Care Unit

BACKGROUND

The use of albumin in the critical care setting is a very controversial issue. Low serum albumin concentration in critical illness is associated with a poor outcome.

AIM

We aimed to evaluate the influence of albumin level in critically ill children to the length of stay and mortality in the Pediatric Intensive Care Unit (PICU) Haji Adam Malik General Hospital, Medan, Indonesia.

METHODS

The study used an observational method with a cross-sectional design. The population of the study was all patients with major postoperative surgery and critically ill that admitted to the PICU at Haji Adam Malik Hospital from the period of June 2008 to September 2008. The albumin level of the subjects was determined on the first day admitted.

RESULTS

The group with hypoalbuminemia (< 3 g/dL) was given albumin supplementation according to a protocol in the PICU. The group with hypoalbuminemia have an average length of stay 7.6 days (9.7%) and mortality of 12 subjects (36.4%). The group with normal albumin level have 4.7 days (5.0%) and mortality 13 subjects (37.1%). There was no significant effect of albumin level to mortality.

CONCLUSION

Albumin level did not affect the length of stay and mortality in PICU.

Albumin mass balance and kinetics in liver transplantation

Background

In major abdominal surgery albumin is shifted from the circulation, presumably leaking into the interstitial space, contributing to a 30–40% decrease in plasma albumin concentration. During and after liver transplantation exogenous albumin is infused for volume substitution and to maintain plasma albumin concentration. Here we used liver transplantation as a model procedure for the study of albumin mass balance and kinetics during major abdominal surgery with albumin substitution.

Methods

Patients were studied during liver transplantation (n = 16), and until postoperative day 3 (POD 3) (n = 11). Cumulative perioperative albumin shift was assessed by mass balance of albumin and hemoglobin. Synthesis rates of albumin and fibrinogen were estimated by the flooding technique using deuterium-labeled phenylalanine. Albumin distribution was assessed by radioiodinated human serum albumin.

Results

At the end of surgery, 37 ± 17 g of albumin (p < 0.0001) had shifted from plasma, and this amount was stable until POD 3 (48 ± 33 g, p = 0.0017 versus baseline). There was 91 ± 37 g exogenous albumin infused peroperatively and another 47 ± 35 g was infused postoperatively until POD 3. Absolute synthesis rates of albumin and fibrinogen on POD 3 were 239 ± 84 mg/kg body weight/day and 33 mg/kg body weight/day (range 5–161), respectively.

Conclusions

Albumin net leakage from plasma progressed until the end of surgery, and was then unaltered until POD 3. This is in contrast with the normalization of the cumulative albumin shift identified at day 3 after non-transplant major abdominal surgery. Liver synthesis of export proteins was high compared to reference values at the third postoperative day, suggesting rapid recovery of synthesis capacity.

Trial registration

Swedish Medical Product Agency, EudraCT 2015-002568-18. Registered on 15 July 2015.

Development of a Physiologically Based Pharmacokinetic Modelling Approach to Predict the Pharmacokinetics of Vancomycin in Critically Ill Septic Patients

BACKGROUND AND OBJECTIVES

Sepsis is characterised by an excessive release of inflammatory mediators substantially affecting body composition and physiology, which can be further affected by intensive care management. Consequently, drug pharmacokinetics can be substantially altered. This study aimed to extend a whole-body physiologically based pharmacokinetic (PBPK) model for healthy adults based on disease-related physiological changes of critically ill septic patients and to evaluate the accuracy of this PBPK model using vancomycin as a clinically relevant drug.

METHODS

The literature was searched for relevant information on physiological changes in critically ill patients with sepsis, severe sepsis and septic shock. Consolidated information was incorporated into a validated PBPK vancomycin model for healthy adults. In addition, the model was further individualised based on patient data from a study including ten septic patients treated with intravenous vancomycin. Models were evaluated comparing predicted concentrations with observed patient concentration-time data.

RESULTS

The literature-based PBPK model correctly predicted pharmacokinetic changes and observed plasma concentrations especially for the distribution phase as a result of a consideration of interstitial water accumulation. Incorporation of disease-related changes improved the model prediction from 55 to 88% within a threshold of 30% variability of predicted vs. observed concentrations. In particular, the consideration of individualised creatinine clearance data, which were highly variable in this patient population, had an influence on model performance.

CONCLUSION

PBPK modelling incorporating literature data and individual patient data is able to correctly predict vancomycin pharmacokinetics in septic patients. This study therefore provides essential key parameters for further development of PBPK models and dose optimisation strategies in critically ill patients with sepsis.

Rapid Bolus Administration Does not Increase The Extravasation Rate of Albumin: A Randomized Controlled Trial in The Endotoxemic Pig

Some experimental data suggest that rapid bolus administration of albumin causes less plasma-expanding effects than slow, continuous infusion. To determine whether rapid bolus administration, in comparison with slow infusion, results in greater extravasation of albumin in experimental septic shock we performed a randomized controlled trial with 32 endotoxemic pigs. The animals were monitored and ventilated with standard intensive care equipment and given 10 mL × kg 5% albumin labeled with Technetium-99m, either as a rapid 15-min bolus (Bolus group, n = 16) or as a 2-h infusion (Infusion group, n = 16). Radioactivity was monitored in plasma, extracellular microdialysate, and urine for 6 h. Physiological parameters were monitored hourly. Radioactivity in the liver, spleen, kidney, and lung was analyzed post mortem.The plasma area under the curve activity0-6 h was 4.4 ± 0.9 × 10 in the Bolus group and 4.4 ± 1.1 × 10 counts × min × mL × h in the Infusion group. Blood hemoglobin levels increased in both groups, suggesting severe capillary leakage. Yet, there were no group differences in albumin radioactivity in plasma, muscle tissue, urine, or in the post-mortem analysis of the organs. Following albumin administration, circulatory and respiratory parameters were similar in the two groups.In conclusion, the present results suggest that albumin might be given as a bolus without leading to increased extravasation of albumin, in contrast to previous animal experiments in rodents.

The importance of albumin infusion rate for plasma volume expansion following major abdominal surgery - AIR: study protocol for a randomised controlled trial

BACKGROUND

Administration of fluids to restore normovolaemia is one of the most common therapeutic interventions performed peri-operatively and in the critically ill, but no study has evaluated the importance of infusion rate for the plasma volume-expanding effect of a resuscitation fluid. The present study is designed to test the hypothesis that a slow infusion of resuscitation fluid results in better plasma volume expansion than a rapid infusion.

METHODS/DESIGN

The study is a single-centre, assessor-blinded, parallel-group, randomised prospective study. Patients over 40 years of age admitted to the post-operative care unit after a Whipple procedure or major gynaecological surgery and presenting with signs of hypovolaemia are eligible for inclusion. Patients are randomised in a 1:1 fashion with no stratification to either rapid (30 minutes) or slow (180 minutes) infusion of 5% albumin at a dose of 10 ml/kg ideal body weight. Plasma volume is measured using 125I human serum albumin at baseline (prior to albumin infusion) as well as at 30 minutes and 180 minutes after infusion start. The primary endpoint is change in plasma volume from baseline to 180 minutes after the start of 5% albumin infusion. Secondary endpoints include the integral of plasma volume over time from baseline to 180 minutes after the start of the infusion and transcapillary escape rate of albumin (%/h) from 180 minutes to 240 minutes after the start of albumin infusion. In addition, diuresis, change in central venous oxygen saturation, lactate and blood pressure will be evaluated. A total of 70 patients will be included in the study, and the study has 80% power to detect a difference of 4 ml/kg in plasma volume expansion between the two groups.

DISCUSSION

The present study is the first clinical investigation of the importance of infusion rate for the plasma volume-expanding effect of a resuscitation fluid.

TRIAL REGISTRATION

EudraCT identifier: 2013-004446-42 . Registration date: 20 December 2013. ClinicalTrials.gov identifier: NCT02728921 . Registration date: 31 March 2016.

Oxidative stress biomarkers in pediatric sepsis: a prospective observational pilot study

OBJECTIVES

Oxidative stress is known to participate in the progression of sepsis. Definite data regarding the behavior of oxidative stress biomarkers in pediatric sepsis is still lacking. This study hypothesized that oxidative stress occurs in pediatric sepsis and that the magnitude of the redox derangement is associated with worse clinical progression.

METHODS

Forty-two previously healthy pediatric patients with sepsis and a group of control subjects were included. Oxidative stress and inflammatory activity biomarkers were determined in blood samples. Patients were prospectively followed until their discharge or death.

RESULTS

Patients with non-severe and severe sepsis showed higher levels of plasmatic antioxidant capacity, lower erythrocyte thiol index, lower superoxide dismutase and catalase activities, higher glutathione peroxidase activity, and higher plasmatic F₂-isoprostanes concentration than controls. Patients with severe sepsis had higher NF-kappaB activation than those with non-severe sepsis. Although we observed changes in some biomarkers in patients with worse clinical evolution, the explored biomarkers did not correlate with clinical estimators of outcome.

DISCUSSION

Oxidative stress occurs in pediatric sepsis, resulting in oxidative damage. The explored biomarkers are not useful as outcome predictors in the studied population. The behavior of these biomarkers still needs to be addressed in broader groups of pediatric patients with sepsis.

Monitoring perioperative serum albumin can identify anastomotic leakage in colorectal cancer patients with curative intent

BACKGROUND

Preoperative hypoalbuminemia is a well-known risk factor for anastomotic leakage after colorectal surgery, but the association between perioperative albumin level and anastomotic leakage has not been fully investigated in curative colorectal cancer (CRC) patients.

METHODS

In total, 200 CRC patients (Stage I-III) undergoing curative laparoscopic surgery between January 2004 and December 2013 were enrolled in this study. We collected data on surgical factors, perioperative levels of serum albumin and inflammatory markers, and perioperative factors affecting hypoalbuminemia from 196 CRC patients to assess the relation to anastomotic leakage.

RESULTS

Anastomotic leakage occurred in 11 cases (5.6%) and the frequency was higher in rectal cancer patients (p = 0.0044). There was no significant difference of preoperative serum albumin level between the anastomotic leakage group (AL) and the nonanastomotic leakage group (NAL). Postoperative serum albumin levels in AL were significantly lower than in NAL [postoperative day (POD) 0, p = 0.0004; POD1, p = 0.0001; POD3, p = 0.0004; and POD7, p = 0.0021]. On multivariate analysis, lower average level of serum albumin on POD1 and POD3 {odds ratio (OR) [95% confidence interval (CI)] = 7.53 (1.60-55.80), p = 0.0095}, higher average level of serum white blood cells on POD1 and POD3 [OR (95% CI) = 7.24 (1.40-59.25), p = 0.0165], and surgery for rectal cancer [OR (95% CI) = 15.18 (3.26-93.99), p = 0.0004] were independent risk factors for anastomotic leakage.

CONCLUSION

Lower early postoperative serum albumin levels are a potentially valuable indicator of anastomotic leakage in CRC patients undergoing curative surgery.

Fluid management in sepsis: The potential beneficial effects of albumin

Fluid administration is a key intervention in hemodynamic resuscitation. Timely expansion (or restoration) of plasma volume may prevent tissue hypoxia and help to preserve organ function. In septic shock in particular, delaying fluid resuscitation may be associated with mitochondrial dysfunction and may promote inflammation. Ideally, infused fluids should remain in the plasma for a prolonged period. Colloids remain in the intravascular space for longer periods than do crystalloids, although their hemodynamic effect is affected by the usual metabolism of colloid substances; leakage through the endothelium in conditions with increased permeability, such as sepsis; and/or external losses, such as with hemorrhage and burns. Albumin has pleiotropic physiological activities including antioxidant effects and positive effects on vessel wall integrity. Its administration facilitates achievement of a negative fluid balance in hypoalbuminemia and in conditions associated with edema. Fluid resuscitation with human albumin is less likely to cause nephrotoxicity than with artificial colloids, and albumin infusion has the potential to preserve renal function in critically ill patients. These properties may be of clinical relevance in circulatory shock, capillary leak, liver cirrhosis, and de-escalation after volume resuscitation. Sepsis is a candidate condition in which human albumin infusion to preserve renal function should be substantiated.

Effects of circuit albumin coating on coagulation and inflammatory response for patients receiving aortic arch replacement: a randomized controlled trial

OBJECTIVE

To investigate whether human serum albumin coating before cardiopulmonary bypass (CPB) could improve platelet function and hemostasis and mitigate the inflammatory response among patients receiving aortic arch replacement with deep hypothermic circulatory arrest (DHCA).

METHODS

Sixty patients were included and randomized into two groups: the Control Group (CG, receiving 40 g human albumin 5 minutes after the initiation of CPB) and the Study Group (SG, circulating the prime with 40 g albumin for 5 minutes before CPB). Rapid thromboelastography, complete blood count, coagulation tests and cytokines (IL-1, IL-6, IL-10, TNF-α and PAF) were measured at two intervals: after anesthesia induction and before CPB (T1) and 10 minutes after heparin reversal before any blood product transfusion (T2).

RESULTS

Compared with T1, the fibrinogen and MA levels in both groups reduced significantly after heparin reversal and fell within the normal range for most patients. The platelet count reduction (ΔPLT) in the Study Group was significantly less than in the Control Group (p=0.031). Despite the inflammatory factor levels increasing after CPB (p<0.001), no differences were found between the Control Group and the Study Group. Fewer red blood cells were given in the Study Group, but this was not significant (p=0.05).

CONCLUSION

Most patients receiving aortic arch replacement with DHCA have normal platelet function and fibrinogen levels after heparin reversal. Albumin coating before CPB may mitigate the platelet count reduction, but not platelet dysfunction. There is a trend that the patients treated with albumin coating received less red blood cell transfusions.

Albumin Kinetics in Patients Undergoing Major Abdominal Surgery

Background

The drop in plasma albumin concentration following surgical trauma is well known, but the temporal pattern of the detailed mechanisms behind are less well described. The aim of this explorative study was to assess changes in albumin synthesis and transcapillary escape rate (TER) following major surgical trauma, at the time of peak elevations in two well-recognized markers of inflammation.

Methods

This was a clinical trial of radiolabeled human serum albumin for the study of TER and plasma volume. Ten patients were studied immediately preoperatively and on the 2nd postoperative day after major pancreatic surgery. Albumin synthesis rate was measured by the flooding dose technique employing incorporation of isotopically labelled phenylalanine.

Results

Fractional synthesis rate of albumin increased from 11.7 (95% CI: 8.9, 14.5) to 15.0 (11.7, 18.4) %/day (p = 0.027), whereas the corresponding absolute synthesis rate was unchanged, 175 (138, 212) versus 150 (107, 192) mg/kg/day (p = 0.21). TER was unchanged, 4.9 (3.1, 6.8) %/hour versus 5.5 (3.9, 7.2) (p = 0.63). Plasma volume was unchanged but plasma albumin decreased from 33.5 (30.9, 36.2) to 22.1 (19.8, 24.3) g/L. (p<0.001).

Conclusion

Two days after major abdominal surgery, at the time-point when two biomarkers of generalised inflammation were at their peak and the plasma albumin concentration had decreased by 33%, we were unable to show any difference in the absolute synthesis rate of albumin, TER and plasma volume as compared with values obtained immediately pre-operatively. This suggests that capillary leakage, if elevated postoperatively, had ceased at that time-point. The temporal relations between albumin kinetics, capillary leakage and generalised inflammation need to be further explored.

Trial Registration

clinicaltrialsregister.eu: EudraCT 2010-08529-21 ClinicalTrials.gov NCT01194492

Colloids in sepsis: evenly distributed molecules surrounded by uneven questions

Colloids are frequently used for fluid expansion in the intensive care unit, although its use on several clinical scenarios remains unproven of any relevant clinical benefit. The purpose of this article was to carry out a narrative review regarding the safety and efficacy of colloids in patients with sepsis and septic shock, with emphasis on the most commonly used colloids, albumin and starches. Colloids are effective fluid expanders and are able to restore the hemodynamic profile with less total volume than crystalloids. These properties appear to be preserved even in patients with sepsis with increased capillary permeability. However, some colloids are associated with renal impairment and coagulation abnormalities. Starch use was associated with increased mortality in two large clinical trials. Also, starches probably have significant renal adverse effects and may be related to more need for renal replacement therapy in severe sepsis. Albumin is the only colloid that has been shown safe in patients with sepsis and that may be associated with improved outcomes on specific subpopulations. No trial so far found any robust clinical end point favoring colloid use in patients with sepsis. Because there is no proven benefit of the use of most colloids in patients with sepsis, its use should not be encouraged outside clinical trials. Albumin is the only colloid solution that has proven to be safe, and its use may be considered on hypoalbuminemic patients with sepsis. Nevertheless, there are no robust data to recommend routine albumin administration in sepsis. Starch use should be avoided in patients with sepsis because of the recent findings of a multicenter randomized study until further evidence is available.

Albumin infusion may deleteriously promote extracellular fluid overload without improving circulating hypovolemia in patients of advanced cirrhosis with diabetes mellitus and sepsis

In patients with liver cirrhosis, albumin is given to improve relative hypovolemia caused by marked splanchnic arteriolar vasodilatation. However, the volume effect of albumin is not predictable and depends also on capillary permeability, hydrostatic pressure and lymphatic ability to re-circulate albumin from interstitium to plasma. In patients with decompensated cirrhosis, the capillary permeability is increased, hydrostatic pressure is higher, and the lymphatics functions are deficient. Hence the albumin molecules are more likely to be extravasated rapidly into the interstitium and are subsequently less likely to be re-circulated back into the plasma. This would not only fail to correct circulating hypovolemia, the purpose for which it is given, but also would favor development of reverse colloid oncotic pressure and fluid movement out of the capillaries leading to development of edema. Thus, anything else which could further increase capillary permeability or hydrostatic pressure in cirrhotic patients might create more problems with albumin infusion. An increased capillary permeability is the hallmark of diabetes mellitus. Furthermore, diabetes mellitus may worsen immunodepression in cirrhotic patients thus increasing the incidence of severe infections which may further have a deleterious effect on hemodynamics and capillary permeability. A diabetic patient with advanced cirrhosis and sepsis usually has markedly increased capillary permeability, high hydrostatic pressure due to hyperdynamic circulation, and compromised lymphatic drainage capacity. Hence, using albumin infusion in them would not only fail to improve relative hypovolemia, but also would deleteriously promote extravascular accumulation of fluid, which might impair the functions of many vital organs. However, the efficacy and safety of albumin infusion in diabetic patients with advanced cirrhosis and sepsis is not known. Such data can have a great clinical implication and would necessitate search of a suitable alternative. Because albumin has relatively smaller molecular weight, synthetic colloids with a higher molecular weight might be effective in conditions of increased capillary permeability.

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.

Albumin limits mesenteric endothelial dysfunction and inflammatory response in cardiopulmonary bypass

The aim of this study was to investigate the potential anti-inflammatory and endothelial protective properties of albumin during cardiopulmonary bypass (CPB) in an experimental porcine model. Two groups underwent CPB for 90 min (n = 7 in each group), and a baseline (BL) control group did not undergo CPB (n = 7). Priming consisted of a gelatin solution (4% gelofusine, CPBG group) or colloid solution (5% albumin, CPBA group). Mesenteric arterial segments were isolated and exposed in vitro to phenylephrine (with or without nitric oxide synthase inhibition) to assess contractility, and exposed to acetylcholine and sodium nitroprusside to assess relaxation. Plasma tumor necrosis factor (TNF)-α levels, intestinal and pulmonary TNF-α and heme oxygenase (HO)-1 mRNA expression, and organ injury were studied. Upon sacrifice, TNF-α levels were significantly higher in the CPBG group than in the CPBA and BL groups. The contractile response was significantly higher in the CPBG group, whereas the response to acetylcholine was significantly lower in the CPBG group than in the other groups. HO-1 mRNA expression was significantly higher in intestine samples in the CPBA group than in the CPBG and BL groups. HO-1 mRNA expression was significantly higher in lung samples in the CPBA group than in the CPBG group. Leukocyte infiltration was significantly higher in intestine and lung samples in the CPBG group than in the CPBA and BL groups. Albumin priming reduced CPB-induced mesenteric vascular dysfunction and prevented the development of a systemic inflammatory response by modeling HO-1 expression in target organs.

Coagulation activation in an experimental pneumonia model in malnourished mice

Malnutrition induces a decrease in immunity that affects the ability of the organism to deal with an infectious challenge. The clotting system is considered a branch of immunity and its activation is important in the pathogenesis of an infectious disease. This work was conducted to determine coagulation modifications in malnourished hosts before and during infection. Weaned mice were malnourished via a protein-free diet. Well-nourished control mice (WNC) consumed a balanced conventional diet. Malnourished mice (MN) and WNC were challenged intranasally with Streptococcus pneumoniae. Blood, bronchoalveolar lavages (BAL), and lung samples were taken at different times post infection. The results were that MN showed altered hemostatic tests and fibrin(ogen) deposits in the lung. Thus, an increase in thrombin-antithrombin complexes (TATc) in plasma and BAL was observed. In the MN group, infection induced a rise in TATc in plasma and BAL and increased plasma fibrinogen and fibrin(ogen) deposits in the lung. A decrease in activated protein C and antithrombin in BAL and an early decrease followed by an increase in plasma Factor VIII were also observed. Thus, malnourishment induced a procoagulant state increased by infection. This is the first work that presents results of an exhaustive study of coagulation in malnourished hosts before and during an infection.

Greater cardiac response of colloid than saline fluid loading in septic and non-septic critically ill patients with clinical hypovolaemia

BACKGROUND AND OBJECTIVE

The haemodynamics of crystalloid and colloid fluid loading may depend on underlying disease, i.e. sepsis versus non-sepsis.

DESIGN AND SETTING

A single-centre, single-blinded, randomized clinical trial was carried out on 24 critically ill sepsis and 24 non-sepsis patients with clinical hypovolaemia, assigned to loading with normal saline, gelatin 4%, hydroxyethyl starch 6% or albumin 5% in a 90-min (delta) central venous pressure (CVP)-guided fluid loading protocol. Transpulmonary thermodilution was done each 30 min, yielding, among others, global end-diastolic volume and cardiac indices (GEDVI, CI).

RESULTS

Sepsis patients had hyperdynamic hypotension in spite of myocardial depression and dilatation, and greater inotropic/vasopressor requirements than non-sepsis patients. Independent of underlying disease, CVP and GEDVI increased more after colloid than saline loading (P < 0.018), so that CI increased by about 2% after saline and 12% after colloid loading (P = 0.029). The increase in preload-recruitable stroke work was also greater with colloids and did not differ among conditions.

CONCLUSION

Fluid loading with colloids results in a greater linear increase in cardiac filling, output and stroke work than does saline loading, in both septic and non-septic clinical hypovolaemia, in spite of myocardial depression and presumably increased vasopermeability potentially decreasing the effects of colloid fluid loading in the former.

Human serum albumin improves arterial dysfunction during early resuscitation in mouse endotoxic model via reduced oxidative and nitrosative stresses

Human serum albumin (HSA) is used as a resuscitation fluid in sepsis. This study investigated the potential protective properties of HSA on vascular function in a mouse endotoxic model in terms of oxidative and nitrosative stresses. Swiss mice were treated with either lipopolysaccharide (LPS) (50 mg/kg i.p.) or vehicle. One and five hours later, mice were infused with HSA (4%, 10 ml/kg), normal saline (0.9% NaCl, 30 ml/kg), or no fluid. Six hours after treatment, vascular reactivity was assessed on aortae and small mesenteric arteries. Measurements of NO and superoxide anion (O2(-)) by spin trapping and nuclear factor (NF)-kappaB, inducible NO synthase (iNOS), and peroxynitrite by Western blotting and immunohistochemical studies were conducted. HSA partially prevented the reduction of blood pressure induced by LPS and completely prevented both vascular hyporeactivity to phenylephrine and myogenic tone as well as endothelial dysfunction induced by the endotoxin. This was associated with a decreased up-regulation of NF-kappa B, iNOS, and peroxynitrite in the vascular wall. LPS-induced tissue increases in both NO and O2(-) production was decreased by HSA. These data demonstrate the protective effect of HSA treatment in experimental endotoxic shock by reducing the inflammatory process leading to oxidative and nitrosative stresses and vascular hyporeactivity.

Drug insight: the role of albumin in the management of chronic liver disease

Albumin is the most abundant protein in the circulation. Its main physiologic function is to maintain colloid osmotic pressure. Better understanding of albumin's other physiologic functions has expanded its application beyond maintenance of intravascular volume. In patients with cirrhosis, albumin has been used as an adjunct to diuretics to improve the diuretic response. It has also been used to prevent circulatory dysfunction developing after large-volume paracentesis. Newer indications in cirrhotic patients include preventing hepatorenal syndrome in those with spontaneous bacterial peritonitis, and treating established hepatorenal syndrome in conjunction with vasoconstrictor therapies. The use of albumin for many of these indications is controversial, mostly because of the paucity of well-designed, randomized, controlled trials. The cost of albumin infusions, lack of clear-cut benefits for survival, and fear of transmitting unknown viruses add to the controversy. The latest indication for albumin use in cirrhotic patients is extracorporeal albumin dialysis, which has shown promise for the treatment of hepatic encephalopathy; its role in hepatorenal syndrome or acute on chronic liver failure has not been established. Efforts should be made to define the indications for albumin use, dose of albumin required and predictors of response, so that patients gain the maximum benefit from its administration.

The value of an albumin-based intravascular volume replacement strategy in elderly patients undergoing major abdominal surgery

The value of human albumin (HA) for treating hypovolemia is controversial. Less expensive alternatives such as hydroxyethyl starch (HES) are sometimes refused because of unwanted side effects. We prospectively randomized 50 patients older than 70 years old undergoing major abdominal surgery to receive either 5% HA (n = 25) or a third generation HES preparation (6% HES 130/0.4; n = 25) when mean arterial blood pressure was <60 mm Hg and central venous pressure was <10 mm Hg. Hemodynamics, inflammation (interleukin-6), endothelial activation-integrity (adhesion molecules), coagulation (thrombelastography), and renal function (including kidney-specific proteins) were monitored after the induction of anesthesia, after surgery, 5 h in the intensive care unit, and on the first postoperative day. HA patients received 3960 +/- 590 mL of HA and 5070 +/- 1030 mL of Ringer's lactate solution, and HES patients received 3500 +/- 530 mL of HES and 4550 +/- 880 mL of Ringer's lactate solution. Total protein remained normal only in the HA-treated patients. No significant differences (P > 0.1) between the groups were seen with regard to hemodynamics, coagulation, and kidney function. Plasma levels of interleukin-6 and soluble adhesion molecules were significantly (P < 0.05) higher in the HA- than in the HES-treated patients. We conclude that HA in elderly patients undergoing major abdominal surgery can easily be replaced by a modern HES preparation. Because of the decreased inflammatory response and endothelial activation-injury, HES 130/0.4 seems to be the more appropriate fluid strategy for these patients.

Year in review 2005: Critical Care - resource management

During 2005 Critical Care published several original papers dealing with resource management. Emphasis was placed on sepsis, especially the coagulation cascade, prognosis and resuscitation. The papers highlighted important aspects of the pathophysiology of coagulation and inflammation in sepsis, as well as dealing with the proper use of newly developed compounds. Several aspects of prognosis in critically ill patients were investigated, focusing on biological markers and clinical indexes. Resuscitation received great attention, dealing with the effects of fluid infusion in hemodynamics and the lung. The information obtained can be used to address unknown effects of established therapies, to enlighten current clinical discussion on controversial topics, and to introduce novel medical resources and strategies. Future clinical work will rely heavily on these preclinical and laboratory data.

DO PLASMA SUBSTITUTES HAVE ADDITIONAL PROPERTIES BEYOND CORRECTING VOLUME DEFICITS?

The best strategy for volume therapy has been the focus of debate and there are still no unique accepted guidelines. There is increasing evidence that some plasma substitutes possess additional effects on organ perfusion, microcirculation, tissue oxygenation, inflammation, endothelial activation, capillary leakage, and tissue edema that are beyond their volume replacing properties. Whether the different plasma substitutes differ with regard this additional effects was reviewed. The additional effects of plasma substitutes have mostly been studied experimentally or in animals, much less results are available in humans. The results are not uniform ranging from beneficial to even detrimental effects of a certain volume replacement strategy. Some important results from the literature are not reflected in the actual recommendations for treating volume deficits in the critically ill: although crystalloids have been shown to have considerable negative effects on microcirculation, organ perfusion, tissue oxygenation, and endothelial integrity, they are still often recommended as first choice volume replacement strategy. In several experimental studies hypertonic solutions have been shown to have various beneficial effects, they have not been, however, translated into humans. In future, the choice of the ideal volume replacement regimen should not only be focused on its volume restoring properties, but additional effects (e.g. on organ perfusion on, tissue oxygenation, inflammation, endothelial activation, capillary leakage) should also be taken into account when treating hypovolemia in the critically ill.

Microvascular permeability during experimental human endotoxemia: an open intervention study

INTRODUCTION

Septic shock is associated with increased microvascular permeability. As a model for study of the pathophysiology of sepsis, endotoxin administration to humans has facilitated research into inflammation, coagulation and cardiovascular effects. The present study was undertaken to determine whether endotoxin administration to human volunteers can be used as a model to study the sepsis-associated increase in microvascular permeability.

METHODS

In an open intervention study conducted in a university medical centre, 16 healthy volunteers were evaluated in the research unit of the intensive care unit. Eight were administered endotoxin intravenously (2 ng/kg Escherichia coli O113) and eight served as control individuals. Microvascular permeability was assessed before and 5 hours after the administration of endotoxin (n = 8) or placebo (n = 8) by three different methods: transcapillary escape rate of I(125)-albumin; venous occlusion strain-gauge plethysmography to determine the filtration capacity; and bioelectrical impedance analysis to determine the extracellular and total body water.

RESULTS

Administration of endotoxin resulted in the expected increases in proinflammatory cytokines, temperature, flu-like symptoms and cardiovascular changes. All changes were significantly different from those in the control group. In the endotoxin group all microvascular permeability parameters remained unchanged from baseline: transcapillary escape rate of I(125)-albumin changed from 7.2 +/- 0.6 to 7.7 +/- 0.9%/hour; filtration capacity changed from 5.0 +/- 0.3 to 4.2 +/- 0.4 ml/min per 100 ml mmHg x 10(-3); and extracellular/total body water changed from 0.42 +/- 0.01 to 0.40 +/- 0.01 l/l (all differences not significant).

CONCLUSION

Although experimental human endotoxaemia is frequently used as a model to study sepsis-associated pathophysiology, an endotoxin-induced increase in microvascular permeability in vivo could not be detected using three different methods. Endotoxin administration to human volunteers is not suitable as a model in which to study changes in microvascular permeability.

Changes in serum albumin concentration and volume expanding effects following a bolus of albumin 20% in septic patients

BACKGROUND

Patients with systemic sepsis develop a capillary leak syndrome, and serum -albumin concentration decreases. Hyperoncotic albumin infusion can be used for volume expansion in these patients, but the degree and duration of effect are not well described. We assessed volume expansion by albumin 20% infusion and compared the retention of infused albumin in septic patients and healthy controls.

METHODS

We gave albumin 20%, 200 ml as a rapid infusion to 70 patients with septic shock and 26 controls. Blood samples were taken before and 1, 5, 15, 30, 60, 120 and 240 min after the infusion for measurement of serum albumin concentration and haematocrit. Haemodilution and the percentage of administered albumin remaining intravascularly at each time were calculated.

RESULTS

The mean proportion of the increase in albumin remaining at 4 h was 68.5 (sd 10)% in septic patients and 79 (5)% in controls (P<0.001). The albumin 20%, 200 ml caused a secondary fluid resorption and volume expansion maximal at 30 min, equivalent to a 430 ml infusion in septic patients and 500 ml in controls.

CONCLUSIONS

After giving albumin, serum albumin concentrations decrease significantly faster in septic patients than in healthy controls.

Fluid therapy in sepsis with capillary leakage

Sepsis is associated with a profound intravascular fluid deficit due to vasodilatation, venous pooling and capillary leakage. Fluid therapy is aimed at restoration of intravascular volume status, haemodynamic stability and organ perfusion. Circulatory stability following fluid resuscitation is usually achieved in the septic patient at the expense of tissue oedema formation that may significantly influence vital organ function. The type of fluid therapy, crystalloid or colloid, in sepsis with capillary leakage remains an area of intensive and controversial discussion. The current understanding of the physiology of increased microvascular permeability in health and sepsis is incomplete. Furthermore, there is a lack of appropriate clinical study end-points for fluid resuscitation. This review considers critically the clinical and experimental data analysing the assessment of capillary leakage in sepsis and investigating the effects of different fluid types on increased microvascular permeability in sepsis.