Effects of balanced crystalloid vs. 0.9% saline-based vs. balanced 6% tetrastarch infusion on renal function and tubular integrity in ovine endotoxemic shock*

Use of hydroxyethyl starch in sepsis research: A systematic review with meta-analysis

BACKGROUND

After being used for more than a decade the use of hydroxyethyl starch (HES) 130/0.38-0.45 in clinical practice was discouraged because of serious adverse events including bleeding, acute kidney injury and death. But could these adverse effects have been discovered sooner? By comparing the summary effect estimates of the adverse effects of HES 130/0.38-0.45 in different study designs we aimed to disclose any signal of this.

METHODS

We systematically searched MEDLINE, EMBASE and Cochrane Library and hand-searched the reference lists of relevant studies to identify studies for inclusion. Eligible trials were randomised clinical trials (RCTs) and observational studies in patients with sepsis and randomised trials in animals with induced sepsis comparing HES 130/0.38-0.45 to any type of crystalloid. Relevant outcomes were all-cause mortality at longest follow-up, renal replacement therapy (RRT), acute kidney injury (AKI) and bleeding. We extracted data, conducted conventional meta-analyses and assessed the risk of bias and the quality of evidence.

RESULTS

We included 8 RCTs including 3,273 patients, 1 observational study including 379 patients and 5 randomised animal trials including 94 test animals. There was no suggestion of interaction in subgroup analyses comparing the different study designs for any outcomes (all-cause mortality at longest follow-up p = .33; RRT p = .70; AKI p = .63; bleeding p = .20).

CONCLUSIONS

We observed no interaction between the summary effect estimates of RCTs, observational studies in patients and randomised animal trials for any of the outcomes. Accordingly, we found no evidence indicating that the adverse effects of HES 130/0.38-0.45 could have been discovered sooner.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO ID: CRD42018103422.

PROTOCOL

Johansen JR, Perner A, Brodtkorb JH, Møller MH. Use of hydroxyethyl starch in sepsis research: Protocol for a systematic review. Acta Anaesthesiol Scand. 2019;63:814-818. https://doi.org/10.1111/aas.13345.

Differential Effects of Selective and Nonselective Potassium Channel Inhibitors in Ovine Endotoxemic Shock (Macrocirculation) and in a Rat Model of Septic Shock (Microcirculation)

BACKGROUND

Potassium-(K)-channel inhibitors may increase systemic vascular resistance in vasodilatory shock states.

OBJECTIVE

The purpose of the present study was to compare the macro- and microvascular effects of the adenosine triphosphate-sensitive K-channel-(KATP)-inhibitor glipizide and the nonselective K-channel inhibitor tetraethylammonium (TEA) in ovine endotoxemic shock and septic shock in rats.

DESIGN

Two randomized, controlled laboratory studies.

ANIMALS

Thirty female sheep and 40 male Sprague Dawley rats.

SETTING

Animal research facility INTERVENTION:: Systemic hemodynamics were analyzed in ovine endotoxemic shock with guideline-oriented supportive therapy. Sheep were allocated to three treatment groups for 12 h: glipizide 10 mg kg·h, TEA 8 mg kg·h, or 0.9% saline. The microvascular effects of each drug were evaluated in septic rats (cecal ligation and puncture model) receiving a 2-h infusion of each study drug: glipizide 20 mg kg·h; TEA 50 mg kg·h, or 0.9% saline, respectively, followed by intravital microscopy of villi microcirculation.

RESULTS

Compared with the control group, glipizide infusion increased systemic vascular resistance index and decreased cardiac index and heart rate (HR) in sheep (P < 0.05), whereas TEA infusion decreased HR and resulted in a decreased survival time (P = 0.001). In rats, glipizide infusion resulted in an increase in mean arterial pressure and a decrease in HR compared with baseline measurement (P < 0.05) without relevant effects on the villi microcirculation. TEA decreased HR and decreased capillary perfusion of the villi microcirculation compared with the sham group (P = 0.002).

CONCLUSIONS

Selective inhibition of KATP-channels in ovine endotoxemic shock with glipizide partially restored vasomotor tone without exerting harmful effects on intestinal microcirculation in septic shock in rats. On the contrary, nonselective K-channel inhibition with TEA showed deleterious effects in both models, including impaired microcirculation and decreased survival time. Future research on glipizide in vasodilatory shock may be warranted.

Effects of Polymyxin B on Clinical Signs, Serum TNF-α, Haptoglobin and Plasma Lactate Concentrations in Experimental Endotoxaemia in Sheep

Introduction

The experiment evaluated the effects of intravenous administration of polymyxin B on experimental endotoxaemia in sheep.

Material and Methods

Twenty clinically healthy fat-tailed sheep were randomly divided into: a group treated with 6,000 U/kg of polymyxin B, a group at 12,000 U/kg, and positive and negative controls. Endotoxaemia was induced by intravenous administration of lipopolysaccharide (LPS) from E. coli serotype O55:B5 at 0.5 μg/kg. polymyxin was infused intravenously along with 2.5 L of isotonic intravenous fluids at 20 mL/kg/h. The positive control group received LPS and 2.5 L of isotonic fluids, the negatives receiving just 2.5 L of isotonic fluids. Clinical signs were evaluated before and at 1.5, 3, 4.5, 6, 24, and 48 h after LPS administration. Blood was also sampled at the denoted hours and serum haptoglobin, tumour necrosis factor-α (TNF-α), and plasma lactate concentrations were assayed.

Results

The serum concentration of TNF-α in the positive control group increased significantly up to 48 h after LPS administration. The concentration of TNF-α was significantly different from those of the polymyxin B and positive control groups from 3 to 48 h; also, the concentrations of haptoglobin at different times in the polymyxin groups were lower than those of the positive control group and were significant at hours 3 to 48 (P < 0.05). Following the LPS administration, haptoglobin and TNF-α concentrations changed without significant difference between the two polymyxin B groups.

Conclusion

Polymyxin B (6,000 U/kg) restrained blood lactate concentrations. Furthermore, it significantly improved the clinical signs in endotoxaemic animals, including rectal temperature and heart and respiratory rates. Polymyxin B may be an antiendotoxic in fat-tailed sheep.

Effects of resuscitation with human albumin 5%, hydroxyethyl starch 130/0.4 6%, or crystalloid on kidney damage in an ovine model of septic shock

BACKGROUND

Colloid solutions have been associated with kidney dysfunction in septic animals and humans. The present study investigated the influence of resuscitation with human albumin (HA) 5%, hydroxyethyl starch (HES) 130/0.4 6%, and balanced crystalloids on ultrastructural kidney damage, kidney function, and survival in a model of ovine septic shock.

METHODS

After induction of peritoneal septic shock, animals were randomised to one of the following groups: (1) HA 5%, (2) HES 130/0.4 6%, (3) balanced crystalloid, and (4) control (each n=10). Causal therapy included re-laparotomy, peritoneal lavage, and antimicrobial therapy. Sequential kidney biopsies were obtained for the assessment of the electron microscopic tubular injury (EMTI) score.

RESULTS

Serum creatinine and urea were highest in the control group, and there were no differences between the intervention groups. Cumulative diuresis was significantly higher in the HA group [1.0 ml kg^-1 h^-1 (0.6; 1.2)] compared with control [0.7 ml kg^-1 h^-1 (0.6; 0.9), P<0.05]. Creatinine clearance was highest in the HA and crystalloid groups. Ultrastructural kidney damage was highest in the control group [EMTI score 7.8 (6.7; 9.0)] without differences between intervention groups. Survival was 100% in the colloid groups vs 90% (crystalloid) and 60% (control, all P<0.05).

CONCLUSION

In an ovine model of septic shock, kidney function and cumulative diuresis were preserved in the 5% albumin and crystalloid resuscitation groups, whereas HES 130/0.4 6% resulted in diminished creatinine clearance. Differences in kidney function between resuscitation fluids could not be explained by differences in ultrastructural kidney damage.

CLINICAL TRIAL REGISTRATION

84-02.04.2011.A300.

Comparison of first-line and second-line terlipressin versus sole norepinephrine in fulminant ovine septic shock

The Surviving Sepsis Guidelines suggest the use of vasopressin in case of catecholamine-refractory septic shock. Terlipressin (TP) as a V₁-selective AVP analogue is a potential alternative, though data regarding the first-line administration in septic shock are scarce. The present study explored and compared the effects of first-line vs. second-line infusion of TP or sole norepinephrine regarding organ function, fluid and norepinephrine requirements and survival in fulminant ovine septic shock. Peritoneal sepsis was induced in 23 ewes after laparotomy and faecal withdrawal from the caecum. After onset of shock, causal and supportive sepsis therapy (antibiotics, peritoneal lavage, fluids and open-label norepinephrine) was performed in all animals. Concurrently, animals were randomized to receive 0.9% sodium chloride (control group) or TP (2 µg∙kg^-1∙h^-1, first-line group) after shock onset. In the second-line TP group, TP (2 µg∙kg^-1∙h^-1) was started once norepinephrine requirements exceeded 0.5 µg∙kg^-1∙min^-1. No significant differences were found between groups regarding survival, haemodynamics as well as fluid- and catecholamine-requirements. Kidney function and electron microscopic kidney injury were comparable between groups. In the present model of fulminant ovine septic shock, first-line TP infusion had no significant effect on fluid and norepinephrine requirements or organ dysfunction as compared to second-line TP infusion or placebo.

Effects of polymyxin B on clinical signs, serum TNF-α, haptoglobin and plasma lactate concentrations in experimental endotoxaemia in sheep

Introduction

The experiment evaluated the effects of intravenous administration of polymyxin B on experimental endotoxaemia in sheep.

Material and Methods

Twenty clinically healthy fat-tailed sheep were randomly divided into: a group treated with 6,000 U/kg of polymyxin B, a group at 12,000 U/kg, and positive and negative controls. Endotoxaemia was induced by intravenous administration of lipopolysaccharide (LPS) from E. coli serotype O55:B5 at 0.5 μg/kg. polymyxin was infused intravenously along with 2.5 L of isotonic intravenous fluids at 20 mL/kg/h. The positive control group received LPS and 2.5 L of isotonic fluids, the negatives receiving just 2.5 L of isotonic fluids. Clinical signs were evaluated before and at 1.5, 3, 4.5, 6, 24, and 48 h after LPS administration. Blood was also sampled at the denoted hours and serum haptoglobin, tumour necrosis factor-α (TNF-α), and plasma lactate concentrations were assayed.

Results

The serum concentration of TNF-α in the positive control group increased significantly up to 48 h after LPS administration. The concentration of TNF-α was significantly different from those of the polymyxin B and positive control groups from 3 to 48 h; also, the concentrations of haptoglobin at different times in the polymyxin groups were lower than those of the positive control group and were significant at hours 3 to 48 (P < 0.05). Following the LPS administration, haptoglobin and TNF-α concentrations changed without significant difference between the two polymyxin B groups.

Conclusion

Polymyxin B (6,000 U/kg) restrained blood lactate concentrations. Furthermore, it significantly improved the clinical signs in endotoxaemic animals, including rectal temperature and heart and respiratory rates. Polymyxin B may be an antiendotoxic in fat-tailed sheep.

Histopathology of Septic Acute Kidney Injury: A Systematic Review of Experimental Data

OBJECTIVE

The histopathologic changes associated with septic acute kidney injury are poorly understood, in part, because of the lack of biopsy data in humans. Animal models of septic acute kidney injury may help define such changes. Therefore, we performed a systematic review of the histopathologic changes found in modern experimental septic acute kidney injury models.

DATA SOURCES

MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature, and PubMed (from January 2007 to February 2015).

STUDY SELECTION

We reviewed experimental studies reporting findings on the histopathology of contemporary experimental septic acute kidney injury.

DATA EXTRACTION

We focused on the presence or the absence of acute tubular necrosis, tubular cell apoptosis, and other nonspecific findings.

DATA SYNTHESIS

We identified 102 studies in 1,059 animals. Among the 1,059 animals, 53 (5.0%) did not have any renal histopathologic changes, but acute tubular necrosis was found in 184 (17.4%). The prevalence of acute tubular necrosis was not related to animal size or model of sepsis and was only found in models with low cardiac output and decreased renal blood flow (p < 0.0001). Only 21 studies (170 animals) assessed the prevalence of tubular cell apoptosis, which was reported in 158 animals (92.9%). The prevalence of tubular cell apoptosis was significantly higher in studies using small animals (p < 0.0001) and in peritonitis models (p < 0.0001). Simultaneous acute tubular necrosis and tubular cell apoptosis was rare (55 animals [32.4%]) and only seen with decreased cardiac output and renal blood flow. Nonspecific changes (vacuolization of tubular cells, loss of brush border, and tubular cell swelling) were each observed in 423 (39.9%), 250 (23.6%) and 243 (22.9%) animals, respectively.

CONCLUSIONS

In models of experimental septic acute kidney injury in contemporary articles, acute tubular necrosis was relatively uncommon and, when present, reflected the presence of an associated low cardiac output or low renal blood flow syndrome. Tubular cell apoptosis seemed frequent in the few studies in which it was investigated. Nonspecific morphologic changes, however, were the most common histopathologic findings.

Provision of physiological data and reference values in awake and anaesthetized female sheep aged 6-12 months

OBJECTIVE

To provide physiological data and reference values in awake and anaesthetized sheep aged 6-12 months.

STUDY DESIGN

Descriptive study.

ANIMALS

Data from 260 female sheep of the species Ovis orientalis aries aged 6-12 months were extracted from 10 experimental trials.

METHODS

Data from pulmonary arterial thermodilution in awake (cohort 1; n = 109) and anaesthetized animals (cohort 2; n = 81), and transpulmonary thermodilution in anaesthetized animals (cohort 3; n = 70) were analysed. General anaesthesia was induced by intramuscular injection of S-ketamine and midazolam and maintained by inhaled isoflurane. Standard laboratory variables (blood gas and clinical chemistry) were assessed.

RESULTS

A total of 7553 single data entries from 260 healthy sheep were included. Measurement errors or invalid data documentation meant that 313 data entries (4.1%) were excluded. A small confidence interval for median values was calculated for nearly all variables. The median body weight was 39.8 kg (2.5-97.5th percentile 30.6-48.1 kg). A set of reference values (2.5-97.5th percentiles) is provided for common cardiopulmonary and laboratory variables. Compared to awake animals, haemodynamic variables were markedly influenced by anaesthesia, as reflected by a considerably lower stroke volume index in anaesthetized sheep. There were also differences in stroke volume index between the cohorts of pulmonary artery and transpulmonary thermodilution.

CONCLUSIONS AND CLINICAL RELEVANCE

The present work presents a large and consistent database of a variety of physiological variables measured in healthy juvenile female sheep. The data appear to be robust and allow the establishment of standardized inclusion criteria for experimental studies and may help to better evaluate past, present and future research. Differences between pulmonary artery and transpulmonary thermodilution should be assessed in future studies.

Controversies in the use of hydroxyethyl starch solutions in small animal emergency and critical care

OBJECTIVES

To (1) review the development and medical applications of hydroxyethyl starch (HES) solutions with particular emphasis on its physiochemical properties; (2) critically appraise the available evidence in human and veterinary medicine, and (3) evaluate the potential risks and benefits associated with their use in critically ill small animals.

DATA SOURCES

Human and veterinary original research articles, scientific reviews, and textbook sources from 1950 to the present.

HUMAN DATA SYNTHESIS

HES solutions have been used extensively in people for over 30 years and ever since its introduction there has been a great deal of debate over its safety and efficacy. Recently, results of seminal trials and meta-analyses showing increased risks related to kidney dysfunction and mortality in septic and critically ill patients, have led to the restriction of HES use in these patient populations by European regulatory authorities. Although the initial ban on the use of HES in Europe has been eased, proof regarding the benefits and safety profile of HES in trauma and surgical patient populations has been requested by these same European regulatory authorities.

VETERINARY DATA SYNTHESIS

The veterinary literature is limited mostly to experimental studies and clinical investigations with small populations of patients with short-term end points and there is insufficient evidence to generate recommendations.

CONCLUSIONS

Currently, there are no consensus recommendations regarding the use of HES in veterinary medicine. Veterinarians and institutions affected by the HES restrictions have had to critically reassess the risks and benefits related to HES usage based on the available information and sometimes adapt their procedures and policies based on their reassessment. Meanwhile, large, prospective, randomized veterinary studies evaluating HES use are needed to achieve relevant levels of evidence to enable formulation of specific veterinary guidelines.

IL-1 receptor blockade alleviates endotoxin-mediated impairment of renal drug excretory functions in rats

The aim of our study was to investigate whether two potent anti-inflammatory agents, dexamethasone and anakinra, an IL-1 receptor antagonist, may influence acute kidney injury (AKI) and associated drug excretory functions during endotoxemia (LPS) in rats. Ten hours after LPS administration, untreated endotoxemic rats developed typical symptoms of AKI, with reduced GFR, impaired tubular excretion of urea and sodium, and decreased urinary excretion of azithromycin, an anionic substrate for multidrug resistance-transporting proteins. Administration of both immunosuppressants attenuated the inflammatory response, liver damage, AKI, and increased renal clearance of azithromycin mainly by restoration of GFR, without significant influence on its tubular secretion. The lack of such an effect was related to the differential effect of both agents on the renal expression of individual drug transporters. Only dexamethasone increased the urinary clearance of bile acids, in accordance with the reduction of the apical transporter (Asbt) for their tubular reabsorption. In summary, our data demonstrated the potency of both agents used for the prevention of AKI, imposed by endotoxins, and for the restoration of renal drug elimination, mainly by the improvement of GFR. The influence of both drugs on altered tubular functions and the expression of drug transporters was differential, emphasizing the necessity of knowledge of transporting pathways for individual drugs applied during sepsis. The effect of anakinra suggests a significant contribution of IL-1 signaling to the pathogenesis of LPS-induced AKI.

The case for 0.9% NaCl: is the undefendable, defensible?

Although 0.9% NaCl solution is by far the most-used fluid for fluid therapy in resuscitation, it is difficult to find a paper advocating its use over other types of crystalloid solutions. Literature on the deleterious effects of 0.9% NaCl has accumulated over the last decade, but critical appraisal of alternative crystalloid solutions is lacking. As such, the literature seems to suggest that 0.9% NaCl should be avoided at all costs, whereas alternative crystalloid solutions can be used without scrutiny. The basis of this negative evaluation of 0.9% NaCl is almost exclusively its effect on acid-base homeostasis, whereas the potentially deleterious effects present in other types of crystalloids are neglected. We have the challenging task of defending the use of 0.9% NaCl and reviewing its positive attributes, while an accompanying paper will argue against the use of 0.9% NaCl. It is challenging because of the large amount of literature, including our own, showing adverse effects of 0.9% NaCl. We will discuss why 0.9% NaCl solution is the most frequently used resuscitation fluid. Although it has some deleterious effects, all fluids share common features of concern. As such the emphasis on fluid resuscitation should be on volume rather than on composition and should be accompanied by a physiological assessment of the impact of fluids. In this paper, we hope to discuss the context within which fluids, specifically 0.9% NaCl, can be given in a safe and effective manner.

Modulation of early inflammatory response by different balanced and non-balanced colloids and crystalloids in a rodent model of endotoxemia

The use of hydroxyethyl starch (HES) in sepsis has been shown to increase mortality and acute kidney injury. However, the knowledge of the exact mechanism by which several fluids, especially starch preparations may impair end-organ function particularly in the kidney, is still missing. The aim of this study was to measure the influence of different crystalloid and colloid fluid compositions on the inflammatory response in the kidney, the liver and the lung using a rodent model of acute endotoxemia. Rats were anesthetized and mechanically ventilated. Lipopolysaccharide (5 mg/kg) was administered intravenously. After one hour crystalloids [lactate-buffered (RLac) or acetate-buffered (RAc)] were infused i.v. (30 ml/kg) in all groups. At 2 hours rats either received different crystalloids (75 ml/kg of RLac or RAc) or colloids (25 ml/kg of HES in saline or HES in RAc or gelatin in saline). Expression of messenger RNA for cytokine-induced neutrophil chemoattractant-1 (CINC-1), monocyte chemotactic protein-1 (MCP-1), necrosis factor α (TNFα) and intercellular adhesion molecule 1 (ICAM-1) was assessed in kidney, liver and lung tissue by real-time PCR after 4 hours. The use of acetate-buffered solutions was associated with a significantly higher expression of CINC-1 and TNFα mRNA in the liver, in the kidney and in the lung. Only marginal effects of gelatin and hydroxyethyl starch on mRNA expression of inflammatory mediators were observed. The study provides evidence that the type of buffering agent of different colloidal and crystalloid solutions might be a crucial factor determining the extent of early end-organ inflammatory response in sepsis.

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.

Fluids are drugs: type, dose and toxicity

PURPOSE OF REVIEW

We discuss the formulation of a prescription for intravenous (i.v.) fluid therapy (a 'volume prescription') for critically ill patients: pros/cons of different fluid types; accurate dosing; and qualitative and quantitative toxicities. Updated physiologic concepts are invoked and results of recent major clinical trials on i.v. fluid therapy in the acutely ill are interpreted.

RECENT FINDINGS

Context is vital and any fluid can be harmful if dosed incorrectly. When contrasting 'crystalloid versus colloid', differences in efficacy are modest, but differences in safety are significant. Differences in chloride load and strong ion difference appear to be clinically important. Quantitative toxicity is mitigated when dosing is based on dynamic parameters that predict volume responsiveness. Qualitative toxicity for colloids (even with newer hydroxyethyl starch 130/0.4 solutions) and isotonic saline remain a concern.

SUMMARY

Similar to any drug used in acutely ill patients, clinicians ordering a volume prescription must recognize that context is crucial. Physiologically balanced crystalloids may be the 'default' fluid for acutely ill patients, and the role for colloids is unclear. Optimal dosing involves assessment of volume responsiveness.

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.

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.

Systematic analysis of hydroxyethyl starch (HES) reviews: proliferation of low-quality reviews overwhelms the results of well-performed meta-analyses

PURPOSE

Hydroxyethyl starch (HES) is a synthetic colloid used widely for resuscitation despite the availability of safer, less costly fluids. Numerous HES reviews have been published that may have influenced clinicians' practice. We have therefore examined the relationship between the methodological quality of published HES reviews, authors' potential conflicts of interest (pCOI) and the recommendations made.

METHODS

Systematic analysis of reviews on HES use.

RESULTS

Between 1975 and 2010, 165 reviews were published containing recommendations for or against HES use. From the 1990s onwards, favorable reviews increased from two to eight per year and HES's share of the artificial colloid market tripled from 20 to 60 %. Only 7 % (12/165) of these reviews of HES use contained meta-analyses; these 7 % had higher Overview Quality Assessment Questionnaire (OQAQ) scores [median (range) 6.5 (3-7)] than reviews without meta-analysis [2 (1-4); p < 0.001]. The rates of recommending against HES use are 83 % (10/12) in meta-analyses and 20 % (31/153) in reviews without meta-analysis (p < 0.0001). Fourteen authors published the majority (70/124) of positive reviews, and ten of these 14 had or have since developed a pCOI with various manufacturers of HES.

CONCLUSIONS

Low-quality HES reviews reached different conclusions than high-quality meta-analyses from independent entities, such as Cochrane Reviews. The majority of these low-quality positive HES reviews were written by a small group of authors, most of whom had or have since established ties to industry. The proliferation of positive HES reviews has been associated with increased utilization of an expensive therapy despite the lack of evidence for meaningful clinical benefit and increased risks. Clinicians need to be more informed that marketing efforts are potentially influencing scientific literature.