The Effects of Colloid Solutions on Renal Proximal Tubular Cells In Vitro

Investigating influences of intravenous fluids on HUVEC and U937 monocyte cell lines using the magnetic levitation method

Intravenous fluids are being widely used in patients of all ages for preventing or treating dehydration in the intensive care units, surgeries in the operation rooms, or administering chemotherapeutic drugs at hospitals. Dextrose, Ringer, and NaCl solutions are widely received as intravenous fluids by hospitalized patients. Despite their widespread administration for over 100 years, studies on their influences on different cell types have been very limited. Increasing evidence suggests that treatment outcomes might be altered by the choice of the administered intravenous fluids. In this study, we investigated the influences of intravenous fluids on human endothelial (HUVEC) and monocyte (U937) cell lines using the magnetic levitation technique. Our magnetic levitation platform provides label-free manipulation of single cells without altering their phenotypic or genetic properties. It allows for monitoring and quantifying behavior of single cells by measuring their levitation heights, deformation indices, and areas. Our results indicate that HUVEC and U937 cell lines respond differently to different intravenous fluids. Dextrose solution decreased the viability of both cell lines while increasing the heterogeneity of areas, deformation, and levitation heights of HUVEC cells. We strongly believe that improved outcomes can be achieved when the influences of intravenous fluids on different cell types are revealed using robust, label-free, and efficient methods.

Goal-directed fluid therapy using uncalibrated pulse contour analysis and balanced crystalloid solutions during hip revision arthroplasty: a quality implementation project

BACKGROUND

To implement a goal-directed fluid therapy (GDFT) protocol using crystalloids in hip revision arthroplasty surgery within a quality management project at a tertiary hospital using a monocentric, prospective observational study.

METHODS

Adult patients scheduled for elective hip revision arthroplasty surgery were screened for inclusion in this prospective study. Intraoperatively stroke volume (SV) was optimized within a previously published protocol using uncalibrated pulse contour analysis and balanced crystalloids. Quality of perioperative GDFT was assessed by protocol adherence, SV increase as well as the rate of perioperative complications. Findings were then compared to two different historical groups of a former trial: one receiving GDFT with colloids (prospective colloid group) and one standard fluid therapy (retrospective control group) throughout surgery. Statistical analysis constitutes exploratory data analyses and results are expressed as median with 25th and 75th percentiles, absolute and relative frequencies, and complication rates are further given with 95% confidence intervals for proportions using the normal approximation without continuity correction.

RESULTS

Sixty-six patients underwent GDFT using balanced crystalloids and were compared to 130 patients with GDFT using balanced colloids and 130 controls without GDFT fluid resuscitation. There was a comparable increase in SV (crystalloids: 65 (54-74 ml; colloids: 67.5 (60-75.25 ml) and total volume infused (crystalloids: 2575 (2000-4210) ml; colloids: 2435 (1760-3480) ml; and controls: 2210 (1658-3000) ml). Overall perioperative complications rates were similar (42.4% (95%CI 30.3-55.2%) for crystalloids and 49.2% (95%CI 40.4-58.1%) for colloids and lower compared to controls: 66.9% (95%CI 58.1-74.9)). Interestingly, a reduced number of hemorrhagic complications was observed within crystalloids: 30% (95%CI 19.6-42.9); colloids: 43% (95%CI 34.4-52.0); and controls: 62% (95%CI 52.6-69.9). There were no differences in the rate of admission to the post-anesthesia care unit or intensive care unit as well as the length of stay.

CONCLUSIONS

Perioperative fluid management using a GDFT protocol with crystalloids in hip revision arthroplasty surgery was successfully implemented in daily clinical routine. Perioperative complications rates were reduced compared to a previous management without GDFT and comparable when using colloids.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01753050.

Effects of 5% Albumin Plus Saline Versus Saline Alone on Outcomes From Large-Volume Resuscitation in Critically Ill Patients

OBJECTIVES

To compare 5% albumin with 0.9% saline for large-volume resuscitation (> 60 mL/Kg within 24 hr), on mortality and development of acute kidney injury.

DESIGN

Retrospective cohort study.

SETTING

Patients admitted to ICUs in 13 hospitals across Western Pennsylvania. We analyzed two independent cohorts, the High-Density Intensive Care databases: High-Density Intensive Care-08 (July 2000 to October 2008, H08) and High-Density Intensive Care-15 (October 2008 to December 2014, H15).

PATIENTS

Total of 18,629 critically ill patients requiring large-volume resuscitation.

INTERVENTIONS

Five percent of albumin in addition to saline versus 0.9% saline.

MEASUREMENTS AND MAIN RESULTS

After excluding patients with acute kidney injury prior to large-volume resuscitation, 673 of 2,428 patients (27.7%) and 1,814 of 16,201 patients (11.2%) received 5% albumin in H08 and H15, respectively. Use of 5% albumin was associated with decreased 30-day mortality by multivariate regression in H08 (odds ratio 0.65; 95% CI 0.49-0.85; p = 0.002) and in H15 (0.52; 95% CI 0.44-0.62; p < 0.0001) but was associated with increased acute kidney injury in H08 (odds ratio 1.98; 95% CI 1.56-2.51; p < 0.001) and in H15 (odds ratio 1.75; 95% CI 1.58-1.95; p < 0.001). However, 5% albumin was not associated with persistent acute kidney injury and resulted in decreased major adverse kidney event at 30, 90, and 365 days. Propensity matched analysis confirmed similar associations with mortality and acute kidney injury.

CONCLUSIONS

During large-volume resuscitation, 5% albumin was associated with reduced mortality and major adverse kidney event at 30, 90, and 365 days. However, a higher rate of acute kidney injury of any stage was observed that did not translate into persistent renal dysfunction.

Fluids in ARDS: more pros than cons

In acute respiratory distress syndrome (ARDS), increased pulmonary vascular permeability makes the lung vulnerable to edema. The use of conservative as compared to liberal fluid strategies may increase the number of ventilator-free days and survival, as well as reduce organ dysfunction. Monitoring the effects of fluid administration is of the utmost importance; dynamic indexes, such as stroke volume and pulse pressure variations, outperform static ones, such as the central venous pressure. The passive leg raise and end-expiratory occlusion tests are recommended for guiding fluid management decisions. The type of intravenous fluids should also be taken into consideration: crystalloids, colloids, and human albumin have all been used for fluid resuscitation. Recent studies have also shown differences in outcome between balanced and non-balanced intravenous solutions. In preclinical studies, infusion of albumin promotes maintenance of the glycocalyx layer, reduces inflammation, and improves alveolar-capillary membrane permeability. Fluids in ARDS must be administered cautiously, considering hemodynamic and perfusion status, oncotic and hydrostatic pressures, ARDS severity, fluid type, volume and infusion rate, and cardiac and renal function. Of note, no guideline to date has recommended a specific fluid composition for use in ARDS; most physicians currently follow recommendations for sepsis.

Iso-Oncotic Albumin Mitigates Brain and Kidney Injury in Experimental Focal Ischemic Stroke

Background: There is widespread debate regarding the use of albumin in ischemic stroke. We tested the hypothesis that an iso-oncotic solution of albumin (5%), administered earlier after acute ischemic stroke (3 h), could provide neuroprotection without causing kidney damage, compared to a hyper-oncotic albumin (20%) and saline.

Objective: To compare the effects of saline, iso-oncotic albumin, and hyper-oncotic albumin, all titrated to similar hemodynamic targets, on the brain and kidney.

Methods: Ischemic stroke was induced in anesthetized male Wistar rats (n = 30; weight 437 ± 68 g) by thermocoagulation of pial blood vessels of the primary somatosensory, motor, and sensorimotor cortices. After 3 h, animals were anesthetized and randomly assigned (n = 8) to receive 0.9% NaCl (Saline), iso-oncotic albumin (5% ALB), and hyper-oncotic albumin (20% ALB), aiming to maintain hemodynamic stability (defined as distensibility index of inferior vena cava <25%, mean arterial pressure >80 mmHg). Rats were then ventilated using protective strategies for 2 h. Of these 30 animals, 6 were used as controls (focal ischemic stroke/no fluid).

Results: The total fluid volume infused was higher in the Saline group than in the 5% ALB and 20% ALB groups (mean ± SD, 4.3 ± 1.6 vs. 2.7 ± 0.6 and 2.6 ± 0.5 mL, p = 0.03 and p = 0.02, respectively). The total albumin volume infused (g/kg) was higher in the 20% ALB group than in the 5% ALB group (1.4 ± 0.6 vs. 0.4 ± 0.2, p < 0.001). Saline increased neurodegeneration (Fluoro-Jade C staining), brain inflammation in the penumbra (higher tumor necrosis factor-alpha expression), and blood-brain barrier damage (lower gene expressions of claudin-1 and zona occludens-1) compared to both iso-oncotic and hyper-oncotic albumins, whereas it reduced the expression of brain-derived neurotrophic factor (a marker of neuroregeneration) compared only to iso-oncotic albumin. In the kidney, hyper-oncotic albumin led to greater damage as well as higher gene expressions of kidney injury molecule-1 and interleukin-6 than 5% ALB (p < 0.001).

Conclusions: In this model of focal ischemic stroke, only iso-oncotic albumin had a protective effect against brain and kidney damage. Fluid therapy thus requires careful analysis of impact not only on the brain but also on the kidney.

Hydroxyethylstarch (130/0.4) tightens the blood-brain barrier in vitro

In order to prevent cerebral vasospasm after a subarachnoid hemorrhage (SAH), the so-called triple H-therapy (hypertension, hypervolemia, hemodilution) could be applied. In these cases, colloidal solutions containing Hydroxyethylstarch (HES) are used to induce hypervolemia. The administration of HES is very much under debate for the mentioned use, because in general the application of HES for the treatment of critical ill patients has been reduced tremendously in the last years due to its nephrotoxic effects. In this context, there are limited data investigating the influence of HES on the blood-brain barrier. These data might help to assess if a transient administration of HES is possibly justifiable to prevent cerebral ischemia during vasospasm despite the risk of an acute kidney injury. To address this question, a mouse blood-brain barrier in vitro model based on cell line cerebEND was exposed to different HES concentrations and compared to NaCl-containing control solutions. In order to assess the effects of HES on blood-brain barrier properties, cell viability, transendothelial electrical resistance, permeability of carboxyfluorescein, mRNA and protein expression and localization of tight junction proteins were determined. In summary, 1.5-4% HES attenuated cell viability in a mild, concentration dependent manner compared to the NaCl control solution (0% HES). At the mRNA level 1% and 4% HES significantly increased the expression of tight junction associated proteins (ZO-1 and occludin) and the glucose transporter Glut-1 (Slc2a1). In correspondence to this, 4% HES inhibited breakdown of the paracellular barrier in comparison to the control NaCl group (0% HES) shown by transendothelial electrical resistance values and the permeability of the paracellular marker carboxyfluorescein. These effects at the functional level were confirmed by immunofluorescence microscopic images of junctional proteins. The obtained in vitro data showed a potential for HES to counteract blood-brain barrier damage. Future studies are needed to reveal the applicability of HES as a blood-brain barrier stabilizing agent.

Assessment of Neurological Toxicity of Hydroxyethyl Starch 130/0.4 Injected in the Intrathecal Space in Rats

Objective

Epidural blood patch is the procedure of choice to relieve postdural puncture headache. Hydroxyethyl-starch (HES) has been proposed as a patch in some circumstances such as in the case of hematological disease due to the theoretical risk of neoplastic seeding to the central nervous system. Acute neurological HES toxicity has been excluded by a previous animal study, but the long-term neurological toxicity has not been evaluated.

Methods

Rats were randomly assigned to one of three groups: no intrathecal injection, 20 μL of intrathecal saline, or a 20-μL intrathecal HES (6% hydroxyethyl starch 130/0.4) administered via a cervical puncture. Clinical daily rat activity was measured before and after dural puncture by actinometry. The rats were killed at day 28, and the spinal cord was surgically removed and stained with hematoxylin-phloxine-saffron for gross and microscopic examination.

Results

Eleven rats underwent dural puncture without injection, 11 were injected with normal saline, and 12 received intrathecal HES. No clinical or actimetric changes (total distance traveled, number of direction changes, and number of rearings) were observed up to one month after injection. Nonspecific histopathological changes were equally observed in all groups.

Conclusions

The results of the current study indicate that intrathecal injection of HES in rats does not induce any clinical or histopathological evidence of long-term neuronal toxicity. Further safety studies in animals are warranted before HES might be considered a safe alternative to the classic epidural blood patch.

Effects of crystalloid, hyper-oncotic albumin, and iso-oncotic albumin on lung and kidney damage in experimental acute lung injury

BACKGROUND

Conflicting data have reported beneficial effects of crystalloids, hyper-oncotic albumin (20%ALB), and iso-oncotic albumin (5%ALB) in critically ill patients. Although hyper-oncotic albumin may minimize lung injury, recent studies have shown that human albumin may lead to kidney damage proportional to albumin concentration. In this context, we compared the effects of Ringer's lactate (RL), 20%ALB, and 5%ALB, all titrated according to similar hemodynamic goals, on pulmonary function, lung and kidney histology, and molecular biology in experimental acute lung injury (ALI).

METHODS

Male Wistar rats received Escherichia coli lipopolysaccharide intratracheally (n = 24) to induce ALI. After 24 h, animals were anesthetized and randomly assigned to receive RL, 20%ALB, or 5%ALB (n = 6/group) to maintain hemodynamic stability (distensibility index of inferior vena cava < 25%, mean arterial pressure > 65 mmHg). Rats were then mechanically ventilated for 6 h. Six animals, which received neither ventilation nor fluids (NV), were used for molecular biology analyses.

RESULTS

The total fluid volume infused was higher in RL compared to 5%ALB and 20%ALB (median [interquartile range], 10.8[8.2-33.2] vs. 4.8[3.6-7.7] and 4.3[3.9-6.6] mL, respectively; p = 0.02 and p = 0.003). B-line counts on lung ultrasound (p < 0.0001 and p = 0.0002) and serum lactate levels (p = 0.01 and p = 0.01) were higher in RL than 5%ALB and 20%ALB. Diffuse alveolar damage score was lower in 5%ALB (10.5[8.5-12]) and 20%ALB (10.5[8.5-14]) than RL (16.5[12.5-20.5]) (p < 0.05 and p = 0.03, respectively), while acute kidney injury score was lower in 5%ALB (9.5[6.5-10]) than 20%ALB (18[15-28.5], p = 0.0006) and RL (16 [15-19], p = 0.04). In lung tissue, mRNA expression of interleukin (IL)-6 was higher in RL (59.1[10.4-129.3]) than in 5%ALB (27.0[7.8-49.7], p = 0.04) or 20%ALB (3.7[7.8-49.7], p = 0.03), and IL-6 protein levels were higher in RL than 5%ALB and 20%ALB (p = 0.026 and p = 0.021, respectively). In kidney tissue, mRNA expression and protein levels of kidney injury molecule (KIM)-1 were lower in 5%ALB than RL and 20%ALB, while nephronectin expression increased (p = 0.01 and p = 0.01), respectively.

CONCLUSIONS

In a rat model of ALI, both iso-oncotic and hyper-oncotic albumin solutions were associated with less lung injury compared to Ringer's lactate. However, hyper-oncotic albumin resulted in greater kidney damage than iso-oncotic albumin. This experimental study is a step towards future clinical designs.

Understanding the Harms of HES: A Review of the Evidence to Date

Intravenous (IV) fluid resuscitation is one of the most common interventions in intensive care medicine. Despite clear guidelines, the choice of IV fluid is largely dependent on physician preference instead of high-quality evidence of efficacy and safety. This is particularly the case for synthetic colloids, such as hydroxyethyl starch (HES). The use of HES in critical care has been associated with increased rates of acute kidney injury (AKI), renal replacement therapy and mortality. In light of this, current guidelines and scientific and regulatory bodies do not recommend the use of HES for fluid therapy in critical illness and caution against its use in many other settings. Despite this, HES products are still debated and used. Awareness of the indications, contraindications, doses, benefits and adverse effects for IV fluids, as well as recommendations from scientific and regulatory bodies, is essential to guarantee patients' safety. Poor awareness of optimal IV fluid therapy has recently been revealed in some countries including Turkey. Therefore, we provide a review of fluids used for resuscitation, discuss safety data and adverse effects of HES, such as increased AKI and mortality, and discuss recent updates from scientific and regulatory bodies in order to raise awareness of fluid therapy. We conclude that given the lack of a clear benefit of HES in any clinical setting and the availability of safer alternatives, such as crystalloids and albumin, HES should be avoided.

Acute kidney injury in postoperative shock: is hyperoncotic albumin administration an unrecognized resuscitation risk factor?

BACKGROUND

The use of hyperoncotic albumin (HA) for shock resuscitation is controversial given concerns about its cost, effectiveness, and potential for nephrotoxicity. We evaluated the association between early exposure to hyperoncotic albumin (within the first 48 h of onset of shock) and acute organ dysfunction in post-surgical patients with shock.

METHODS

This retrospective, cohort study included 11,512 perioperative patients with shock from 2009 to 2012. Shock was defined as requirement for vasopressors to maintain adequate mean arterial pressure and/or elevated lactate (> 2.2 mmol/L). Subsets of 3600 were selected after propensity score and exact matching on demographics, comorbidities, and treatment variables (> 30). There was a preponderance of cardiac surgery patients. Proportional odds logistic regression, multivariable logistic regression or Cox proportional hazard regression models measured association between hyperoncotic albumin and acute kidney injury (AKI), hepatic injury, ICU days, and mortality.

RESULTS

Hyperoncotic albumin-exposed patients showed greater risk of acute kidney injury compared to controls (OR 1.10, 95% CI 1.04, 1.17. P = 0.002), after adjusting for imbalanced co-variables. Within matched patients, 20.3%, 2.9%, and 4.4% of HA patients experienced KDIGO stages 1-3 AKI, versus 19.6%, 2.5%, and 3.0% of controls. There was no difference in hepatic injury (OR 1.16; 98.3% CI 0.85, 1.58); ICU days, (HR 1.05; 98.3% CI 1.00, 1.11); or mortality, (OR 0.88; 98.3% CI 0.64, 1.20).

CONCLUSIONS

Early exposure to hyperoncotic albumin in postoperative shock appeared to be associated with acute kidney injury. There did not appear to be any association with hepatic injury, mortality, or ICU days. The clinical and economic implications of this finding warrant further investigation.

Fluid therapy and the hypovolemic microcirculation

PURPOSE OF REVIEW

In shock states, optimizing intravascular volume is crucial to promote an adequate oxygen delivery to the tissues. Our current practice in fluid management pivots on the Frank-Starling law of the heart, and the effects of fluids are measured according to the induced changes on stroke volume. The purpose of this review is to evaluate the boundaries of current macrohemodynamic approach to fluid administration, and to introduce the microcirculatory integration as a fundamental part of tissue perfusion monitoring.

RECENT FINDINGS

Macrocirculatory changes induced by volume expansion are not always coupled to proportional changes in microcirculatory perfusion. Loss of hemodynamic coherence limits the value of guiding fluid therapy according to macrohemodynamics, and highlights the importance of evaluating the ultimate target of volume administration, the microcirculation.

SUMMARY

Current approach to intravascular volume optimization is made from a macrohemodynamic perspective. However, several situations wherein macrocirculatory and microcirculatory coherence is lost have been described. Future clinical trials should explore the usefulness of integrating the microcirculatory evaluation in fluid optimization.

Balanced Hydroxyethylstarch (HES 130/0.4) Impairs Kidney Function In-Vivo without Inflammation

Volume therapy is a standard procedure in daily perioperative care, and there is an ongoing discussion about the benefits of colloid resuscitation with hydroxyethylstarch (HES). In sepsis HES should be avoided due to a higher risk for acute kidney injury (AKI). Results of the usage of HES in patients without sepsis are controversial. Therefore we conducted an animal study to evaluate the impact of 6% HES 130/0.4 on kidney integrity with sepsis or under healthy conditions Sepsis was induced by standardized Colon Ascendens Stent Peritonitis (sCASP). sCASP-group as well as control group (C) remained untreated for 24 h. After 18 h sCASP+HES group (sCASP+VOL) and control+HES (C+VOL) received 50 ml/KG balanced 6% HES (VOL) 130/0.4 over 6 h. After 24 h kidney function was measured via Inulin- and PAH-Clearance in re-anesthetized rats, and serum urea, creatinine (crea), cystatin C and Neutrophil gelatinase-associated lipocalin (NGAL) as well as histopathology were analysed. In vitro human proximal tubule cells (PTC) were cultured +/- lipopolysaccharid (LPS) and with 0.1-4.0% VOL. Cell viability was measured with XTT-, cell toxicity with LDH-test. sCASP induced severe septic AKI demonstrated divergent results regarding renal function by clearance or creatinine measure focusing on VOL. Soleley HES (C+VOL) deteriorated renal function without sCASP. Histopathology revealed significantly derangements in all HES groups compared to control. In vitro LPS did not worsen the HES induced reduction of cell viability in PTC cells. For the first time, we demonstrated, that application of 50 ml/KG 6% HES 130/0.4 over 6 hours induced AKI without inflammation in vivo. Severity of sCASP induced septic AKI might be no longer susceptible to the way of volume expansion.

Phosphodiesterase-4 inhibition with rolipram attenuates hepatocellular injury in hyperinflammation in vivo and in vitro without influencing inflammation and HO-1 expression

Objective:

To investigate the impact of the phophodiesterase-4 inhibition (PD-4-I) with rolipram on hepatic integrity in lipopolysaccharide (LPS) induced hyperinflammation.

Materials and Methods:

Liver microcirculation in rats was obtained using intravital microscopy. Macrohemodynamic parameters, blood assays, and organs were harvested to determine organ function and injury. Hyperinflammation was induced by LPS and PD-4-I rolipram was administered intravenously one hour after LPS application. Cell viability of HepG2 cells was measured by EZ4U-kit based on the dye XTT. Experiments were carried out assessing the influence of different concentrations of tumor necrosis factor alpha (TNF-α) and LPS with or without PD-4-I.

Results:

Untreated LPS-induced rats showed significantly decreased liver microcirculation and increased hepatic cell death, whereas LPS + PD-4-I treatment could improve hepatic volumetric flow and cell death to control level whithout influencing the inflammatory impact. In HepG2 cells TNF-α and LPS significantly reduced cell viability. Coincubation with PD-4-I increased HepG2 viability to control levels. The heme oxygenase 1 (HO-1) pathway did not induce the protective effect of PD-4-I.

Conclusion:

Intravenous PD-4-I treatment was effective in improving hepatic microcirculation and hepatic integrity, while it had a direct protective effect on HepG2 viability during inflammation.

Molecular size and origin do not influence the harmful side effects of hydroxyethyl starch on human proximal tubule cells (HK-2) in vitro

BACKGROUND

Recently, clinical trials revealed renal impairment induced by hydroxyethyl starch (HES) in septic patients. In prior studies, we managed to demonstrate that HES accumulated in renal proximal tubule cells (PTCs). The related pathomechanism has not yet been discovered. To validate our hypothesis that the HES molecule itself is harmful, regardless of its molecule size or origin, we conducted a comprehensive study to elucidate the influences of different HES preparations on PTC viability in vitro.

METHODS

Cell viability of human PTC was measured with a cytotoxicity assay, quantifying the reduction of tetrazolium salt to colored formazan. Experiments were performed by assessing the influence of different carrier solutions of HES (balanced, nonbalanced, culture medium), different average molecular weights (70, 130, 200 kDa), different origins (potato or corn derived), and various durations of incubation (2-21 hours). Furthermore, HES 130/0.4 was fractionated by ultrafiltration, and the impact on cell viability of average single-size fractions with <3, 3 to 10, 10 to 30, 30 to 50, 50 to 100, and >100 kDa was investigated. We also tested the possible synergistic effects of inflammation induced by tumor necrosis factor-α.

RESULTS

All tested HES solutions, regardless of origin or carrier matrix, decreased cell viability in an equivalent, dose-dependent manner. Coincubation with tumor necrosis factor-α did not reduce HES-induced reduction of cell viability. Minor differences were detected comparing 70, 130, and 200 kDa preparations. Analysis of fractionated HES revealed that each fraction decreased cell viability. Even small HES molecules (10-30 kDa) were significantly deleterious.

CONCLUSIONS

For the first time, we were able to show that only the total mass of HES molecules applied is responsible for the harmful impact on renal PTC in vitro. Neither molecular size nor their origin showed any relevance.

Pros and cons of tetrastarch solution for critically ill patients

Proper fluid management is crucial for the management of critically ill patients. However, there is a continuing debate about the choice of the fluid, i.e., crystalloid vs. colloid. Colloid solution is theoretically advantageous to the crystalloid because of larger volume effect and less interstitial fluid accumulation, and hydroxyethyl starch (HES) is most frequently used for perioperative setting. Nevertheless, application of HES solution is relatively limited due to its side effects including renal toxicity and coagulopathy. Since prolonged presence of large HES molecule is responsible for these side effects, rapidly degradable HES solution with low degree of substitution (tetrastarch) supposedly has less potential for negative effects. Thus, tetrastarch may be more frequently used in the ICU setting. However, several large-scale randomized trials reported that administration of tetrastarch solution to the patients with severe sepsis has negative effects on mortality and renal function. These results triggered further debate and regulatory responses around the world. This narrative review intended to describe the currently available evidence about the advantages and disadvantages of tetrastarch in the ICU setting.

Perioperative intravascular volume replacement and kidney insufficiency

Perioperative acute kidney injury (AKI) occurrence is probably increased in recent years due to the increased level of complexity of surgical procedures and severity of illness of surgical patients. Perioperative AKI has a multifactorial aetiology (preoperative co-morbidities such as diabetes, heart failure and chronic kidney disease, emergent surgery, exposure to nephrotoxic drugs, haemodynamic instability, hypothermia, inflammatory response to surgery, hospital-acquired infections and abdominal compartment syndrome). However, fluid choice for perioperative volume replacement might have a major role in perioperative AKI, as administration of crystalloid solutions, colloids or haemoderivates has the potential for kidney injury. This review focusses on the issue of fluid replacement quality and quantity and their association with renal dysfunction.

Kidney function after the intraoperative use of 6% tetrastarches (HES 130/0.4 and 0.42)

Concerns about the nephrotoxicity of tetrastarches have recently increased with the accumulation of new evidence, particularly in relationship to septic patients. Two meta-analyses in 2011 and early 2012 also raised concerns about nephrotoxicity in surgical patients and prompted the present review of the nephrotoxicity of tetrastarches solely in the surgical setting. Seven reports consisting of two review articles and five single-trial papers published between 2012 and August 2013 were examined. Six of the seven studies did not show any adverse renal outcomes following the intraoperative use of tetrastarch, although their data are not robust enough to confirm definitive safety. Moreover, balanced electrolyte solutions are strongly recommended as a carrier solution for tetrastarches to reduce adverse outcomes.

Low molecular weight pentastarch is more effective than crystalloid solution in goal-directed fluid management in patients undergoing major gastrointestinal surgery

BACKGROUND

This prospective observational study compared the volume effect between hydroxyethyl starch (HES) and crystalloid solution and its context dependency in intraoperative goal-directed fluid management.

METHODS

With institutional review board (IRB) approval, 35 patients undergoing major gastrointestinal surgery were enrolled. Fluid challenge consisting of 250 ml of either bicarbonate Ringer solution (BRS) or low molecular weight pentastarch (HES 70/0.5) was given to maintain stroke volume index >35 ml/m2. The context of fluid challenge was classified as related to either epidural block (EB) or blood loss (BL) or as nonspecific. The primary end point was the interval between index fluid challenge and the next fluid challenge, and the secondary end point was the hemodynamic parameter at the end of fluid challenge. Differences in these parameters in each clinical context were compared between BRS and HES 70/0.5. A p value <0.05 was considered statistically significant.

RESULTS

Eighty-eight, 77, and 127 fluid challenges were classified as related to EB and BL and as nonspecific, respectively. In the nonspecific condition, the median (range) interval after fluid challenge with HES 70/0.5 and BRS was 45 (11-162) min and 18 (8-44) min, respectively, and the difference was statistically significant. Also, mean arterial pressure and stroke volume index significantly increased, whereas stroke volume variation significantly decreased after fluid challenge with HES 70/0.5 compared with BRS. Such differences were not observed in the other situations.

CONCLUSIONS

HES 70/0.5 exerted larger volume effects than did crystalloid under nonspecific conditions. However, similar volume effects were observed during volume loss and extensive sympathetic blockade.

Dose and type of crystalloid fluid therapy in adult hospitalized patients

OBJECTIVE

In this narrative review, an overview is given of the pros and cons of various crystalloid fluids used for infusion during initial resuscitation or maintenance phases in adult hospitalized patients. Special emphasis is given on dose, composition of fluids, presence of buffers (in balanced solutions) and electrolytes, according to recent literature. We also review the use of hypertonic solutions.

METHODS

We extracted relevant clinical literature in English specifically examining patient-oriented outcomes related to fluid volume and type.

RESULTS

A restrictive fluid therapy prevents complications seen with liberal, large-volume therapy, even though restrictive fluid loading with crystalloids may not demonstrate large hemodynamic effects in surgical or septic patients. Hypertonic solutions may serve the purpose of small volume resuscitation but carry the disadvantage of hypernatremia. Hypotonic solutions are contraindicated in (impending) cerebral edema, whereas hypertonic solutions are probably more helpful in ameliorating than in preventing this condition and improving outcome. Balanced solutions offer a better approach for plasma composition than unbalanced ones, and the evidence for benefits in patient morbidity and mortality is increasing, particularly by helping to prevent acute kidney injury.

CONCLUSIONS

Isotonic and hypertonic crystalloid fluids are the fluids of choice for resuscitation from hypovolemia and shock. The evidence that balanced solutions are superior to unbalanced ones is increasing. Hypertonic saline is effective in mannitol-refractory intracranial hypertension, whereas hypotonic solutions are contraindicated in this condition.

Anemia increases the risk of renal cortical and medullary hypoxia during cardiopulmonary bypass

Introduction:

Anemia is an independent predictor of acute kidney injury (AKI) following cardiopulmonary bypass (CPB), possibly due to inadequate renal oxygen delivery. The objective of this study was to investigate the effects of CPB and anemia on tissue oxygen tension (pO2) and blood flow in the renal cortex and medulla.

Methods:

Rats (n=6/group) underwent 1hr of normothermic cardiopulmonary bypass (CPB), with target hemoglobin concentrations (Hb) of 10g/dL (CPB) or 6.5g/dL (anemia-CPB). Renal blood flow (RBF) and tissue PO2 were measured before, during and after 1hr of CPB. To confirm the observed differences in renal cortical and medullary PO2, HIF-1α (ODD) luciferase mice were exposed to 8% O2 (hypoxia) and HIF-1α dependent luminescence was measured in the renal cortex and medulla (n=5).

Results:

Renal tissue PO2 values decreased initially and returned towards baseline, however, values at the end of CPB. Anemia-CPB resulted in a significant increase in both renal cortical and medullary blood flow, PO2 remained significantly reduced throughout anemia-CPB. Renal medullary HIF-1α-dependent luminescence confirmed a greater degree of hypoxia in the renal medulla.

Discussion:

During CPB, renal O2 delivery was transiently jeopardized, but recovered after 1hr. Anemia-CPB resulted in a dramatic and sustained reduction in renal cortical and medullary PO2, which suggests an increased risk of renal hypoxic injury with anemia.

Conclusion:

The clear difference in the degree of hypoxia in the renal cortex and medulla may be useful in understanding the progress of medullary hypoxia during CPB with anemia and the potential development of AKI. Further studies should aim at identifying early markers of medullary hypoxia and potential agents that may decrease the work and O2 consumption in the renal medulla to reduce the risk of hypoxic damage during CPB and anemia.

Rational fluid management in today's ICU practice

Intravenous fluid therapy has evolved significantly over time. From the initial report of the first intravenous administration of sodium-chloride-based solution to the development of goal-directed fluid therapy using novel dynamic indices, efforts have focused on improving patient outcomes. The goal of this review is to provide a brief overview of current concepts for intravenous fluid administration in the ICU. Results of recently published clinical trials suggesting harmful effects of starch-based solutions on critically ill patients are discussed. Concepts for goal-directed fluid therapy and new modalities for the assessment of fluid status as well as for the prediction of responsiveness to different interventions will continue to emerge. Advances in technology will have to be critically evaluated for their ability to improve outcomes in different clinical scenarios.

Effects of Intravascular Volume Replacement on Lung and Kidney Function and Damage in Nonseptic Experimental Lung Injury

Background:

Intravascular volume replacement is often required in the presence of increased pulmonary capillary leakage, for example in patients with volutrauma with major hemorrhage. In the present study, the effects of Ringer’s acetate (RA), gelatin-polysuccinate (GEL), and a modern hydroxyethyl starch (HES, 6% 130/0.42) on lung and kidney function and damage were compared in a two-hit model of acute lung injury. The authors hypothesized that GEL and HES, compared to RA: (1) reduced lung histological damage, (2) impaired kidney morphology and function.

Methods:

Acute lung injury was induced in 30 anesthetized pigs by tidal volumes approximately 40 ml/kg, after saline lung lavage. Protective ventilation was initiated and approximately≈25% of estimated blood volume was drawn. Animals were randomly assigned to receive RA, GEL, or HES (n = 10/group) aimed at approximately 90% of intrathoracic blood volume before blood drainage.

Results:

Fluid volumes were higher with RA (2,250 ± 764 ml) than GEL (704 ± 159 ml) and HES (837 ± 82 ml) (P &lt; 0.05). Compared to RA, HES reduced diffuse alveolar damage overall, and GEL in nondependent zones only. GEL and HES yielded lower wet-to-dry ratios compared to RA (6.5 ± 0.5 and 6.5 ± 0.6 vs. 7.9 ± 0.9, respectively, P &lt; 0.05). HES and RA resulted in less kidney damage than GEL, but kidney function did not differ significantly among groups. Compared to GEL, HES yielded lower lung elastance (55 ± 12 vs. 45 ± 13 cm H2O/l, P &lt; 0.05) and intra-abdominal pressure (15 ± 5 vs. 11 ± 4 cm 14;H2O, P &lt; 0.05).

Conclusions:

In this model of acute lung injury, intravascular volume expansion after major hemorrhage with HES yielded less lung damage than RA and less kidney damage than GEL.

Effects of crystalloids and colloids on liver and intestine microcirculation and function in cecal ligation and puncture induced septic rodents

Background

Septic acute liver and intestinal failure is associated with a high mortality. We therefore investigated the influence of volume resuscitation with different crystalloid or colloid solutions on liver and intestine injury and microcirculation in septic rodents.

Methods

Sepsis was induced by cecal ligation and puncture (CLP) in 77 male rats. Animals were treated with different crystalloids (NaCl 0.9% (NaCl), Ringer’s acetate (RA)) or colloids (Gelafundin 4% (Gel), 6% HES 130/0.4 (HES)). After 24 h animals were re-anesthetized and intestinal (n = 6/group) and liver microcirculation (n = 6/group) were obtained using intravital microscopy, as well as macrohemodynamic parameters were measured. Blood assays and organs were harvested to determine organ function and injury.

Results

HES improved liver microcirculation, cardiac index and DO₂-I, but significantly increased IL-1β, IL-6 and TNF-α levels and resulted in a mortality rate of 33%. Gel infused animals revealed significant reduction of liver and intestine microcirculation with severe side effects on coagulation (significantly increased PTT and INR, decreased haemoglobin and platelet count). Furthermore Gel showed severe hypoglycemia, acidosis and significantly increased ALT and IL-6 with a lethality of 29%. RA exhibited no derangements in liver microcirculation when compared to sham and HES. RA showed no intestinal microcirculation disturbance compared to sham, but significantly improved the number of intestinal capillaries with flow compared to HES. All RA treated animals survided and showed no severe side effects on coagulation, liver, macrohemodynamic or metabolic state.

Conclusions

Gelatine 4% revealed devastated hepatic and intestinal microcirculation and severe side effects in CLP induced septic rats, whereas the balanced crystalloid solution showed stabilization of macro- and microhemodynamics with improved survival. HES improved liver microcirculation, but exhibited significantly increased pro-inflammatory cytokine levels. Crystalloid infusion revealed best results in mortality and microcirculation, when compared with colloid infusion.