The Pharmacokinetics and Tolerability of an Intravenous Infusion of the New Hydroxyethyl Starch 130/0.4 (6%, 500 mL) in Mild-to-Severe Renal Impairment

Changes in the degree of substitution of HES in vivo and their influence on methods for determining HES concentrations in plasma

OBJECTIVE

The degree of substitution (DS) of HES describes the average proportion of substituted glucose molecules in a starch molecule. Although no quantitative studies of the in vivo behavior of the DS have been conducted so far, most pharmacokinetic studies to date have measured HES concentrations using the enzymatic method. This method assumes that at any point in time after an infusion, the DS in a serum remains constant and is identical to the DS in the infused solution. In the present study, we examined the changes in the DS of HES 130/0.42 in vivo in an animal model and compared two methods of measuring HES concentrations in plasma (the enzymatic and the o-Toluidine method).

METHODOLOGY

We randomized 22 pigs into 2 groups. After induction of anesthesia, the pigs received 500 ml or 1000 ml of HES 130/0.42 (Tetraspan®). The DS was measured directly after the infusion, then after 30, 60, 120 and 240 minutes. In determining the DS, the hydroxyethyl starch was extracted from the plasma and hydrolyzed with hydrochloric acid to form non-substituted glucose and hydroxyethyl glucose. Subsequently, the concentration of free unsubstituted glucose was determined enzymatically and the total concentration of all (i.e., substituted and unsubstituted) glucose molecules was determined using the o-Toluidine method. From this, the concentration of the substituted glucose (hydroxyethyl glucose) and the DS could be calculated. In addition, the HES concentration was measured first in vitro and then in vivo at any point after the infusion by both the enzymatic method and the o-Toluidine method.

RESULTS

The DS increased significantly directly after the infusion from 0.42 to 0.53 (for 500ml) or to 0.50 (for 1000ml); 4 hours later this had further increased to 0.55 and 0.54, respectively (p <0.0001). The HES concentration in vitro showed no significant difference (p = 0.17) when determined with the enzymatic and the o-Toluidine method. In contrast, the serum concentrations in vivo displayed significant differences (p<0.0001) between the two measurement methods. Immediately after the infusion of 500ml HES, the concentration measured with the o-Toluidine method was 31% higher than the one measured with the enzymatic method; 4 hours later, this discrepancy was still at 25%. For 1000 ml HES, the differences amounted to 16% and 25%, respectively.

CONCLUSION

The DS of HES in vivo increases significantly over time. As a result, an HES concentration measured with the enzymatic method in vivo will be significantly lower than the same concentration determined with the o-Toluidine method. In future pharmacokinetic studies, HES concentrations should be measured using a method that takes into account changes in the DS in vivo.

The effects of hydroxyethyl starch 130/0.4 on perioperative renal function in patients undergoing cardiac surgery: A randomised controlled trial

Background

Acute kidney injury (AKI) after cardiac surgery increases the risk of morbidity and mortality. Hydroxyethyl starch (HES) is often used during surgery due to its plasma-volume expanding effect, but the impact of HES 130/0.4 on renal function in patients undergoing cardiac surgery remains unclear. The aim of our study is to investigate the impact of HES 130/0.4 on postoperative renal function in patients undergoing cardiac surgery using cardiopulmonary bypass.

Methods

Our study was a randomised, single-center, single-blind study conducted on 60 adult patients who underwent cardiac surgery using cardiopulmonary bypass: 30 patients were intraoperatively administered with HES 130/0.4; the other 30 with Ringer's bicarbonate. The primary endpoints were occurrence of AKI within 30 days of surgery and the disease stages.

Results

The mean dose of 6% HES 130/0.4 was 28 ml/kg. AKI occurred within 30 days of the operation in 8 cases (28.6%) in the HES group and 6 cases (21.4%) in the crystalloid group (no significance: p = 0.5371). Disease stages were as follows: “no AKI”, “stage 1”, “stage 2″ and “stage 3″, accounting for 20 cases (71.5%), 6 cases (21,4%), 2 cases (7.1%), and 0 cases, respectively, in the HES group, and 22 cases (78.6%), 6 cases (21.4%), 0 cases, and 0 cases, respectively, in the crystalloid group (no significance: p = 0.3508).

Conclusion

There was no significant difference in the occurrences or stages of AKI during the 30 days following cardiac surgery with cardiopulmonary bypass between patients administered with HES 130/0.4 or Ringer's bicarbonate.

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Hydroxyethyl starch 130/0.4 is an effective plasma-volume expander.

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Hydroxyethyl starch has a potential renal toxicity in cardiac surgery.

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Acute kidney injury after cardiac surgery increases the risk of mortality.

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Administration of hydroxyethyl starch 130/0.4 or crystalloid in cardiac surgery.

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No difference in the occurrences or stages of acute kidney injury between groups.

Effects of hydroxyethyl starch and gelatin on the risk of acute kidney injury following orthotopic liver transplantation: A multicenter retrospective comparative clinical study

Objectives

This multicenter retrospective study aimed to compare the effects of HES and gelatin (GEL) on the risk of post-OLT AKI.

Method

A total of 1,672 patients undergoing OLT were enrolled from major transplant centers in China between 2005 and 2013. These patients were divided into three groups: GEL, hydroxyethyl starch (HES), and GEL + HES group.

Results

There was no significant difference in the incidence of post-OLT AKI among the GEL, HES, and GEL + HES groups. The GEL + HES group had a lower incidence of stage II post-OLT AKI than the other two groups. Compared with patients receiving GEL, patients receiving HES did not harbor an increased risk of AKI. Our results showed that MELD score (adjusted odds ratio [OR], 1.579; 95% confidence interval [CI], 1.123–2.219; P = 0.009) and preoperative anemia (adjusted OR, 1.533; 95% CI, 1.212–1.939; P < 0.001) were independent risk factors for post-OLT AKI, and normal preoperative Scr level (vs abnormal; adjusted OR, 0.402; 95% CI, 0.222–0.729; P = 0.003) was independent protective factors for post-OLT AKI.

Conclusion

This large-scale multicenter retrospective study found that the intraoperative use of HES did not increase the overall incidence of post-OLT AKI in patients when compared with GEL, and whether to increase the risk of post-OLT AKI needs to be further explored.

Evaluation of the Distribution and Elimination of Balanced Isotonic Crystalloid, 5% Hypertonic Saline, and 6% Tetrastarch 130/0.4 Using Volume Kinetic Modeling and Analysis in Healthy Conscious Cats

This prospective, randomized, blinded, interventional cross-over study investigated the distribution, elimination, plasma volume expansion, half-life, comparative potency, and ideal fluid prescription of three commonly prescribed intravenous (IV) fluids in 10 healthy conscious cats using volume kinetic analysis that is novel to veterinary medicine. Each cat received 20 mL/kg of balanced isotonic crystalloid (PLA), 3.3 mL/kg of 5% hypertonic saline (HS), and 5 mL/kg of 6% tetrastarch 130/0.4 (HES) over 15 min on separate occasions. Hemoglobin concentration, red blood cell count, hematocrit, heart rate, and blood pressure were measured at baseline, 5, 10, 15, 20, 30, 40, 50, 60, and every 15 min until 180 min. Urine output was estimated every 30 min using point-of-care bladder ultrasonography. Plasma dilution derived from serial hemoglobin concentration and red blood cell count served as input variables for group and individual fluid volume kinetic analyses using a non-linear mixed effects model. In general, the distribution of all IV fluids was rapid, while elimination was slow. The half-lives of PLA, HS, and HES were 49, 319, and 104 min, respectively. The prescribed fluid doses for PLA, HS, and HES resulted in similar peak plasma volume expansion of 27–30%. The potency of HS was 6 times higher than PLA and 1.7 times greater than HES, while HES was 3.5 times more potent than PLA. Simulation of ideal fluid prescriptions to achieve and maintain 15 or 30% plasma volume expansion revealed the importance of a substantial reduction in infusion rates following initial IV fluid bolus. In conclusion, volume kinetic analysis is a feasible research tool that can provide data on IV fluid kinetics and body water physiology in cats. The rapid distribution but slow elimination of IV fluids in healthy conscious cats is consistent with anecdotal reports of fluid overload susceptibility in cats and warrants further investigation.

Hydroxyethyl starch 130/0.4 (6%) and succinylated gelatine (4%) interfere with refractometry in dogs with haemorrhagic shock

OBJECTIVE

To determine if low molecular weight synthetic colloid fluids administered to dogs interfere with refractometric estimates of total plasma protein (TPPr) and urine osmolality (UOsm).

STUDY DESIGN

Experimental study.

ANIMALS

Eighteen healthy Greyhound dogs.

METHODS

Anaesthetized Greyhounds subjected to haemorrhage for 60 minutes were given 80 mL kg^-1 of Plasma-Lyte 148 (CRYST), or 20 mL kg^-1 of hydroxyethyl starch 130/0.4 (HES) or succinylated gelatine (GELO) (n = 6 per group) intravenously over 20 minutes. Refractometric (TPPr) and biuret total plasma protein (TPPb) were measured before haemorrhage (Baseline), at end of shock (Shock), immediately (T20), then 40 minutes (T60), 100 minutes (T120) and 160 minutes (T180) after fluid administration. Urine specific gravity (USG) and UOsm were measured at all time points except T20. Estimated UOsm (eUOsm) was calculated from USG. Bias and limits of agreement (LOA) for TPPr versus TPPb, and eUOsm versus UOsm were calculated at each time point.

RESULTS

For dogs given CRYST and GELO, median TPPr and TPPb decreased in parallel, with a small consistent TPP bias (CRYST range of bias, 0.38-0.67 g dL^-1; GELO range of bias, 0.42-0.58 g dL^-1). Dogs given HES showed divergence between median TPPr and TPPb after T20, with a peak bias at T20 of 1.62 g dL^-1 (LOA 1.29-1.95). Dogs given HES and GELO had markedly increased USG [HES peak median USG at T180 of 1.119 (Q1-Q3 1.103-1.122); GELO peak median USG at T120 of 1.114 (Q1-Q3 1.082-1.119)], with large increases in bias between eUOsm and UOsm [HES peak bias at T60 of 2995 mOsm kg^-1 (LOA 2032-3958 mOsm kg^-1); GELO peak bias at T120 of 2465 mOsm kg^-1 (LOA 940-3990 mOsm kg^-1)].

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of HES and GELO to dogs with haemorrhagic shock interferes with refractometric measurements for at least 3 hours after administration.

Effect of Hydroxyethyl Starch Priming on the Systemic Inflammatory Response and Lung Edema after Cardiopulmonary Bypass in a Rat Model

Cardiopulmonary bypass (CPB) preserves patients' lives during open heart surgery by providing sufficient oxygen delivery and blood supply to vital organs. However, previous studies have suggested that the interaction of hemodilution and vascular hyperpermeability induces tissue edema and an inflammatory response during CPB. In this study, we hypothesized the suppression of the systemic inflammatory response and tissue edema during CPB by a plasma substitute (hydroxyethyl starch [HES]). Rats (450-500 g) were divided into a SHAM group (n = 5), a Ringer's acetate CPB group (n = 7), and an HES CPB group (n = 7). In the Ringer's acetate group, the CPB circuit was primed with Ringer's acetate solution, and in the HES CPB group, it was primed with HES formulation (6% HES 130/0.4). Blood samples were collected before (baseline) and 30, 60, 90 and 120 min after initiation of CPB. Plasma cytokine levels of tumor necrosis factor-α, interleukin (IL)-6, and IL-10, and biochemical markers (lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, creatinine, liver-type fatty acid-binding protein, and colloid osmotic pressure [COP]) were measured before and 30, 60, 90, and 120 min after the initiation of CPB. In the Ringer's acetate CPB group, the inflammatory cytokines and biochemical markers increased significantly during CPB compared with the SHAM group, but such increases were significantly suppressed in the HES CPB group. In addition, during CPB, it was possible to preserve normal plasma COP in the HES CPB group. The data suggest that 6% HES 130/0.4 is effective for suppressing the inflammatory response during CPB.

The half-life of infusion fluids: An educational review

Supplemental Digital Content is available in the text

An understanding of the half-life (T_1/2) of infused fluids can help prevent iatrogenic problems such as volume overload and postoperative interstitial oedema. Simulations show that a prolongation of the T_1/2 for crystalloid fluid increases the plasma volume and promotes accumulation of fluid in the interstitial fluid space. The T_1/2 for crystalloids is usually 20 to 40 min in conscious humans but might extend to 80 min or longer in the presence of preoperative stress, dehydration, blood loss of <1 l or pregnancy.

The longest T_1/2 measured amounts to between 3 and 8 h and occurs during surgery and general anaesthesia with mechanical ventilation. This situation lasts as long as the anaesthesia. The mechanisms for the long T_1/2 are only partly understood, but involve adrenergic receptors and increased renin and aldosterone release. In contrast, the T_1/2 during the postoperative period is usually short, about 15 to 20 min, at least in response to new fluid.

The commonly used colloid fluids have an intravascular persistence T_1/2 of 2 to 3 h, which is shortened by inflammation. The fact that the elimination T_1/2 of the infused macromolecules is 2 to 6 times longer shows that they also reside outside the bloodstream. With a colloid, fluid volume is eliminated in line with its intravascular persistence, but there is insufficient data to know if this is the same in the clinical setting.

No Differences in Renal Function between Balanced 6% Hydroxyethyl Starch (130/0.4) and 5% Albumin for Volume Replacement Therapy in Patients Undergoing Cystectomy: A Randomized Controlled Trial

BACKGROUND

The use of artificial colloids has declined in critical care, whereas they are still used in perioperative medicine. Little is known about the nephrotoxic potential in noncritically ill patients during routine surgery. The objective of this trial was to evaluate the influences of albumin 5% and balanced hydroxyethyl starch 6% (130/0.4) on renal function and kidney injury.

METHODS

One hundred urologic patients undergoing elective cystectomy were randomly assigned for this prospective, single-blinded, controlled study with two parallel groups to receive either albumin 5% or balanced hydroxyethyl starch 6% (130/0.4) as the only perioperative colloid. The primary endpoint was the ratio of serum cystatin C between the last visit at day 90 and the first preoperative visit. Secondary endpoints were estimated glomerular filtration rate and serum neutrophil gelatinase-associated lipocalin until the third postoperative day and risk, injury, failure, loss, and end-stage renal disease criteria at postoperative days 3 and 90.

RESULTS

The median cystatin C ratio was 1.11 (interquartile range, 1.01 to 1.23) in the albumin and 1.08 (interquartile range, 1.00 to 1.20) in the hydroxyethyl starch group (median difference = 0.03; 95% CI, -0.09 to 0.08; P = 0.165). Also, there were no significant differences concerning serum cystatin C concentrations; estimated glomerular filtration rate; risk, injury, failure, loss, and end-stage renal disease criteria; and neutrophil gelatinase-associated lipocalin. Infusion requirements, transfusion rates, and perioperative hemodynamics were similar in both groups.

CONCLUSIONS

With respect to renal function and kidney injury, this study indicates that albumin 5% and balanced hydroxyethyl starch 6% have comparable safety profiles in noncritically ill patients undergoing major surgery.

Impact of perioperative administration of 6 % hydroxyethyl starch 130/0.4 on serum cystatin C-derived renal function after radical prostatectomy: a single-centre retrospective study

Background

Hydroxyethyl starch (HES) is used for repletion of acute intravasal volume loss in surgical patients. However, in critically ill patients, HES is associated with acute kidney injury. We aimed to evaluate the effect of HES on perioperative cystatin C (cystC)-derived estimated glomerular filtration rates (eGFR_cystC) in patients undergoing open and robot-assisted radical prostatectomy.

Methods

In this retrospective study we included 179 patients who underwent general anaesthesia for radical prostatectomy received HES perioperatively, and had complete cystC and fluid therapy data available. CystC and corresponding eGFR_cystC at postoperative days 1, 3, and 5 were compared with preoperative baseline using Wilcox rank-sum test.

Results

In 179 eligible patients, 6 % HES 130/0.4 was administered in a median (25th to 75th percentile) dose of 1000 mL (1000 to 1000 mL). Baseline eGFR_cystC was 109.4 mL/min (100.3 to 118.7 mL/min). eGFR_cystC on postoperative days 1, 3, and 5 was 120.4 mL/min (109.4 to 134.0 mL/min), 120.4 mL/min (109.4 to 132.9 mL/min), and 117.9 mL/min (106.6 to 129.8 mL/min), respectively (p < 0.001 compared with baseline, each). No patient had an eGFR_cystC-decrease of ≥25 % from baseline.

Conclusions

The results indicate that the administration of a median dose of 1000 mL of 6 % HES 130/0.4 is not associated with a postoperative deterioration of renal function in patients with normal to near-normal baseline renal function undergoing radical prostatectomy.

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.

To use or not to use hydroxyethyl starch in intraoperative care: are we ready to answer the 'Gretchen question'?

PURPOSE OF REVIEW

The decision of the European Medicines Agency (EMA) against the use of hydroxyethyl starch (HES)-based volume replacement solutions in critically ill patients has led to a general uncertainty when dealing with HES-based solutions, even though HES-containing solutions can still be used for the treatment of hypovolaemia caused by acute (sudden) blood loss. This review discusses current evidence of the intraoperative use of HES-based solutions.

RECENT FINDINGS

HES solutions are often criticized for possible side-effects on the kidney, the coagulation system or tissue storage. Relevant differences exist between modern 6% HES 130/0.4 and older generation of starches. Because of pathophysiological differences between elective surgery and critical illness, the evidence on renal injury and coagulation impairment with HES administration cannot be generalized. Current data suggest that there is no clinically relevant impact of 6% HES 130/0.4 administration on perioperative renal function and coagulation. Over-resuscitation is a frequent problem associated with adverse outcomes. Due to the higher volume effect, fluid overload with HES is probably more harmful than with crystalloids, whereas goal-directed use of HES may be able to reduce intraoperative fluid accumulation and overload.

SUMMARY

The use of 6% HES 130/0.4 in elective surgery patients is associated with reduced fluid accumulation and no clinically relevant difference in bleeding or the rate of acute kidney injury as compared with crystalloid use alone. Current data do not allow a conclusion on mortality. As they provide no benefit, older starch preparations should not be used.

Conjugates of degraded and oxidized hydroxyethyl starch and sulfonylureas: synthesis, characterization, and in vivo antidiabetic activity

Orally administered drugs usually face the problem of low water solubility, low permeability, and less retention in bloodstream leading to unsatisfactory pharmacokinetic profile of drugs. Polymer conjugation has attracted increasing interest in the pharmaceutical industry for delivering such low molecular weight (Mw) drugs as well as some complex compounds. In the present work, degraded and oxidized hydroxyethyl starch (HES), a highly biocompatible semisynthetic biopolymer, was used as a drug carrier to overcome the solubility and permeability problems. The HES was coupled with synthesized N-arylsulfonylbenzimidazolones, a class of sulfonylurea derivatives, by creating an amide linkage between the two species. The coupled products were characterized using GPC, FT-IR, (1)H NMR, and (13)C NMR spectroscopy. The experiments established the viability of covalent coupling between the biopolymer and N-arylsulfonylbenzimidazolones. The coupled products were screened for their in vivo antidiabetic potential on male albino rats. The coupling of sulfonylurea derivatives with HES resulted in a marked increase of the hypoglycemic activity of all the compounds. 2,3-Dihydro-3-(4-nitrobenzensulfonyl)-2-oxo-1H-benzimidazole coupled to HES10100 was found most potent with a 67% reduction in blood glucose level of the rats as compared to 41% reduction produced by tolbutamide and 38% by metformin.

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.

Activated protein C ameliorates impaired renal microvascular oxygenation and sodium reabsorption in endotoxemic rats

Introduction

We aimed to test whether continuous recombinant human activated protein C (APC) administration would be able to protect renal oxygenation and function during endotoxemia in order to provide more insight into the role of coagulation and inflammation in the development of septic acute kidney injury.

Methods

In anesthetized, mechanically ventilated Wistar rats, endotoxemia was induced by lipopolysaccharide administration (10 mg/kg i.v. over 30 min). One hour later, the rats received fluid resuscitation with 0 (LPS + FR group; n = 8), 10 (APC10 group; n = 8), or 100 (APC100 group; n = 8) μg/kg/h APC for 2 h. Renal microvascular oxygenation in the cortex and medulla were measured using phosphorimetry, and renal creatinine clearance rate and sodium reabsorption were measured as indicators of renal function. Statistical significance of differences between groups was tested using two-way ANOVA with Bonferroni post hoc tests.

Results

APC did not have notable effects on systemic and renal hemodynamic and oxygenation variables or creatinine clearance. The changes in renal microvascular oxygenation in both the cortex (r = 0.66; p < 0.001) and medulla (r = 0.80; p < 0.001) were correlated to renal sodium reabsorption_.

Conclusion

Renal sodium reabsorption is closely correlated to renal microvascular oxygenation during endotoxemia. In this study, fluid resuscitation and APC supplementation were not significantly effective in protecting renal microvascular oxygenation and renal function. The specific mechanisms responsible for these effects of APC warrant further study.

Electronic supplementary material

The online version of this article (doi:10.1186/2197-425X-1-5) contains supplementary material, which is available to authorized users.

Effect of waxy maize-derived hydroxyethyl starch 130/0.4 on renal function in surgical patients

BACKGROUND

The aim of this meta-analysis was to evaluate renal safety with the active substance of the latest generation of waxy maize-derived hydroxyethyl starch in surgical patients. The authors focused on prospective, randomized, controlled studies that documented clinically relevant variables with regard to renal effects of waxy maize-derived hydroxyethyl starch 130/0.40.

MATERIALS AND METHODS

The authors carefully searched for all available prospective, randomized studies and evaluated the greatest delta from baseline values in renal safety variables (serum creatinine values, calculated creatinine clearance, incidence of renal replacement therapy, and acute renal failure). The authors included 17 studies that analyzed patients (n = 1,230) undergoing a variety of surgical procedures.

RESULTS

For maximum serum creatinine values, the effect size estimate was 0.068 (95% CI = -0.227 to 0.362), P = 0.65. For calculated creatinine clearance values, pooled risk difference was 0.302 (95% CI = -0.098 to 0.703), P = 0.14. For incidence of acute renal failure, pooled risk difference was 0.0003 (95% CI = -0.018 to 0.019), P = 0.98. For incidence of renal replacement therapy, pooled risk difference was -0.003 (95% CI = -0.028 to 0.022), P = 0.85.

CONCLUSIONS

The authors found no evidence for renal dysfunction caused by modern waxy maize-derived hydroxyethyl starch 130/0.40 in surgical patients.

In vitro evaluation of canine hemostasis following dilution with hydroxyethyl starch (130/0.4) via thromboelastometry

OBJECTIVE

To assess the effects of in vitro hemodilution of canine blood with a low molecular weight hy-droxyethyl starch (HES 130/0.4) by means of thromboelastometry (TEM).

DESIGN

In vitro experimental study.

SETTING

University Teaching Hospital.

ANIMALS

Ten healthy adult staff-owned dogs were sampled for the purposes of the study. Samples were also collected from 45 clinically normal dogs to establish thromboelastometric reference intervals.

INTERVENTIONS

For each dog whole blood was collected by jugular venipuncture and placed into tubes containing 3.8% trisodium citrate and stored at 37°C. Two standard dilutions (1:4 and 1:10) from canine blood specimens were prepared with HES 130/0.4 and saline 0.9%.

MEASUREMENTS AND MAIN RESULTS

The effects of dilution were studied by TEM. No statistically significant differences were observed between the TEM values of the control samples and the samples diluted with saline solution (ratio 1:10 and 1:4). In contrast, hypocoagulability was observed in the samples treated with HES 130/0.4, with more severe effects at 1:4 dilution than at 1:10 dilution. The 1:4 dilution with HES 130/0.4 produced marked alterations: CT (P = 0.035) and CFT (P = 0.0007) on the ex-TEM profile, CT (P = 0.0005) and ML (P = 0.0017) on the fib-TEM profile and CFT (P = 0.0043) on the in-TEM, were all significantly increased (P < 0.05), whereas MCF (P = 0.0042) and alpha angle (P = 0.002) on the in-TEM and MCF (P = 0.011) and alpha angle (P = 0.001) ex-TEM profiles and MCF (P = 0.0001) on the fib-TEM profile were significantly decreased (P < 0.05).

CONCLUSIONS

Dilution of canine blood with HES 130/0.4 results in a thromboelastometric pattern consistent with hypocoagulation and this effect appears to result from a dose-dependent alteration in fibrinogen concentration and inhibition of platelet function. As this is an in vitro study, further in vivo investigations are necessary to confirm the results.

Anesthesia considerations during cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

This article outlines the anesthetic management of patients undergoing cytoreductive surgery with hyperthermic intraperitoneal chemotherapy. This includes a discussion of preoperative evaluation, hemodynamic monitoring, fluid and electrolyte therapy, and temperature management. An understanding of the unique physiologic consequences of this procedure is essential to ensure good outcomes and avoid patient injuries.

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.

Effect of molecular weight and substitution on tissue uptake of hydroxyethyl starch: a meta-analysis of clinical studies

BACKGROUND

Intravenously infused hydroxyethyl starch (HES) can be found in urine, plasma and tissues. HES remaining in plasma and tissues is thought to increase the risk of clinical complications. HES solutions of lower molecular weight and substitution have been developed to increase urinary excretion and reduce plasma persistence. However, their effect on tissue uptake of HES has not been investigated in human subjects.

OBJECTIVE

Our objective was to test the hypothesis that lower molecular weight and substitution decrease tissue uptake of HES.

DATA SOURCES

Computer searches were performed of MEDLINE; EMBASE; the Cochrane Library; meeting abstract databases in surgery, anaesthesiology and intensive care; ClinicalTrials.gov; and Google. Supplementary sources were reference lists and electronic tables of journal contents. No time period or language restrictions were imposed.

STUDY SELECTION

Clinical studies were eligible for inclusion in the meta-analysis, if data were reported both for cumulative urinary excretion of HES over 24 hours after infusion and for plasma HES concentration at 24 hours.

DATA EXTRACTION

Data were extracted on 24-hour urinary excretion of HES, 24-hour HES plasma concentration, plasma volume, HES molecular weight and substitution, study design, type and demographics of subjects, indication for fluid infusion, and HES infusion regimen. Tissue uptake of HES was computed as the difference between the infused dose and the sum of urinary excretion and residual plasma HES at 24 hours.

DATA SYNTHESIS

Twenty-five clinical studies totalling 287 subjects were included. Tissue uptake of low-molecular-weight HES (≤200 kD) was 42.3% (95% confidence interval [CI] 39.6, 45.0) compared with 24.6% (CI 17.8, 31.4) for high-molecular-weight HES (p < 0.001). Similarly, tissue uptake of lower-substitution HES (≤0.5) was 42.4% (CI 39.5, 45.3) versus 26.6% (CI 19.6, 33.6) for higher-substitution HES (p < 0.001). Among the three most often investigated single HES solutions, tissue uptake of 130/0.4 (42.6%; CI 35.0, 50.2) and HES 200/0.5 (43.3%; CI 39.4, 47.2) closely coincided, whereas uptake of HES 450/0.7 (22.2%; CI 14.8, 29.6) was lower (p = 0.001 and p < 0.001, respectively).

CONCLUSIONS

This meta-analysis did not support the hypothesis that lower molecular weight and substitution decrease tissue uptake of HES. Further clinical studies of HES tissue uptake are needed.

Pharmacokinetics and safety of 6 % hydroxyethyl starch 130/0.4 in healthy male volunteers of Japanese ethnicity after single infusion of 500 ml solution

PURPOSE

This phase I study was performed in volunteers of Japanese ethnicity to compare pharmacokinetic data after infusion of 6 % hydroxyethyl starch (HES) 130/0.4 with historical data of Caucasians.

METHODS

In an open-label, uncontrolled, single-center study, 12 healthy male Japanese volunteers received single intravenous infusions of 500 ml 6 % HES 130/0.4 (Voluven 6 %; Fresenius Kabi Deutschland, Bad Homburg, Germany) over 30 min.

RESULTS

Plasma concentration of 6 % HES 130/0.4 was highest at end of infusion (5.53 ± 0.55 mg/ml) and decreased following a biphasic manner. Total plasma clearance and rapid and slow elimination half-lives obtained by a two-compartment model were 1.14 ± 0.16 l/h, 1.12 ± 0.26 h, and 9.98 ± 2.38 h, respectively, and the volume of distribution was 4.76 ± 0.64 l. Mean area under the concentration-time curve was 26.7 ± 3.75 mg/ml h. The total amount of HES excreted into urine was 59.4 % of the applied dose. Hemodilution was observed in all 12 subjects as indicated by a decrease of hemoglobin from 15.5 ± 0.4 g/dl at baseline to 13.8 ± 0.4 g/dl after the end of infusion. Adverse events in this study refer to changes of laboratory parameters and were assessed as not clinically relevant.

CONCLUSION

Single administration of a 500 ml solution of 6 % HES 130/0.4 was confirmed to be safe and tolerable in healthy male Japanese subjects. A rapid renal excretion was observed within 24 h after drug administration, accounting for 96 % of the total amount excreted. A comparison with pharmacokinetic data derived from Caucasians did not reveal significant differences to Japanese and confirmed the good tolerability in both ethnic groups.

Hydroxyethyl starch 130/0.42/6:1 for perioperative plasma volume replacement in 1130 children: results of an European prospective multicenter observational postauthorization safety study (PASS)

INTRODUCTION

Third-generation hydroxyethyl starch (HES) is now approved also for the use in children, but safety studies including large numbers of pediatric patients are still missing. Therefore, we performed an European multicentric prospective observational postauthorization safety study (PASS) to evaluate the use of HES 130/0.42/6:1 in normal saline (ns-HES) or a balanced electrolyte solution (bal-HES) in children undergoing surgery.

METHODS

Children aged up to 12 years with ASA risk scores of I-III receiving ns-HES (Venofundin 6%; Braun) or bal-HES (Tetraspan 6%; Braun) were followed perioperatively. Demographic data, surgical procedures performed, anesthesia, hemodynamic and laboratory data, adverse events (AE), and adverse drug reactions (ADR) were documented using a standardized case report form.

RESULTS

Of 1130 children studied at 11 European pediatric centers from 2006 to 2009 (ns-HES, 629 children; bal-HES, 475 children; mean age, 3.6 ± 3.8 [range, day of birth-12 years]; and body weight, 15.4 ± 13 [0.9-90 kg]), 1104 were included for analysis. The mean infused HES volume was 10.6 ± 5.8 (0.83-50) ml·kg(-1). In the 399 (36.1%) cases with blood gas analysis before and after HES infusion, hemoglobin and strong ion difference decreased significantly in both groups, whereas bicarbonate and base excess (BE before infusion: ns-HES -1.8 ± 3.1, bal-HES -1.2 ± 3.3 mm; after infusion: ns-HES -2.5 ± 2.8; bal-HES -1.1 ± 3.2 mm, P < 0.05) decreased only with ns-HES but remained stable with bal-HES. Chloride concentrations increased in both groups and were significantly higher with ns-HES (Cl before infusion: ns-HES 105.5 ± 3.6, bal-HES 104.9 ± 2.9 mm; Cl after infusion: ns-HES 107.6 ± 3.4, bal-HES 106.3 ± 2.9 mm, P < 0.05). For the AE/ADR rates, dose-response but no age relationships could be demonstrated. No serious and no severe ADR directly related to HES (i.e. anaphylactoid reaction, clotting disorders, renal failure) were observed.

CONCLUSION

Moderate doses of HES 130/0.42/6:1 for perioperative plasma volume replacement seem to be safe even in neonates and small infants. The probability of serious ADR is lower than 0.3%. Changes in acid-base balance may be decreased when HES is used in an acetate-containing balanced electrolyte solution instead of normal saline. Caution should be exercised in patients with renal function disturbances and those with an increased bleeding risk.

Are renal adverse effects of hydroxyethyl starches merely a consequence of their incorrect use?

BACKGROUND

Clinical studies such as VISEP-study, which show a negative outcome after the administration of hydroxyethyl starch (HES), are often criticized for an "incorrect" use of HES. It is argued that HES used in these studies differed from usual practice and that recommendations for maximal dosage, duration, and creatinine values were ignored, not enough "free water" was provided and more modern HES solutions should have been used. These comments imply that renal adverse events in clinical studies are the consequence of an inappropriate use of HES. We therefore searched for evidence whether these suggested measures are beneficial.

METHODS

Narrative review; post hoc statistical analysis of epidemiologic data from a representative nationwide survey.

RESULTS

It is evident from published clinical studies that the renal risk of HES increases with cumulative dose and rising serum creatinine values, but no safe upper dose limit or creatinine threshold is known. Suggested safety measures were not able to prevent HES-induced renal failure in clinical studies. Published clinical trials with modern HES solutions are not suited to prove its assumed increased safety because of small sample sizes, low cumulative doses, short observation periods, and inadequate control fluids. Use of HES in a clinical study with negative outcomes conformed to clinical practice, indicating the generalizability of study results.

CONCLUSION

There is no evidence for the assumption that HES-associated renal impairment may be avoided by accompanying measures. Because HES use does not improve clinical outcome, the question arises whether it should be used at all in patients at risk.

Adult laryngotracheal surgery

The human larynx plays a pivotal role in airway protection, respiration, and phonation. Laryngeal disorders can be divided into two categories, benign lesions and malignant lesions. Most benign lesions are treatable with surgery and speech therapy, whereas the malignant lesions require more invasive surgery as well as radiation and chemotherapy. Preoperative assessment and anesthesia management for adult laryngotracheal surgery are reviewed.

Masking and manipulation

The list of prohibited substances in sports includes a group of masking agents that are forbidden in both in- and out-of-competition doping tests. This group consists of a series of compounds that are misused in sports to mask the administration of other doping agents, and includes: diuretics, used to reduce the concentration in urine of other doping agents either by increasing the urine volume or by reducing the excretion of basic doping agents by increasing the urinary pH; probenecid, used to reduce the concentration in urine of acidic compounds, such as glucuronoconjugates of some doping agents; 5alpha-reductase inhibitors, used to reduce the formation of 5alpha-reduced metabolites of anabolic androgenic steroids; plasma expanders, used to maintain the plasma volume after misuse of erythropoietin or red blood cells concentrates; and epitestosterone, used to mask the detection of the administration of testosterone. Diuretics may be also misused to achieve acute weight loss before competition in sports with weight categories. In this chapter, pharmacological modes of action, intended pharmacological effects for doping purposes, main routes of biotransformation and analytical procedures used for anti-doping controls to screen and confirm these substances will be reviewed and discussed.

Hydroxyethyl starch 130/0.4 attenuates early hepatic damage in ischemia/reperfusion injury

PURPOSE

Ischemia/reperfusion injury (IRI) remains a clinical challenge. We tested the hypothesis that fluid therapy using hydroxyethyl starch (HES) 130/0.4 during the early phase of IRI in rat liver decreases markers of hepatic injury.

METHODS

We induced liver IRI in three groups of rats anesthetized with ketamine and chlorpromazine by means of 60 min of segmental hepatic ischemia followed by 120 min of reperfusion. At the onset of reperfusion, Group 1 (IRI + HES; n = 12) was given 13 mL.kg(-1) of HES; Group 2 (IRI + HS; n = 12) received the same volume of 7.5% saline (HS), and Group 3 (IRI-only; n = 12) received no fluid. Three other groups of 12 animals each were sham-operated and received the same fluid as the test groups. We euthanized the animals after three hours, drew blood for alanine aminotransferase (ALT) quantification, and took ischemic liver samples for histomorphological study.

RESULTS

Serum ALT activity was greater in all of the IRI groups than in the sham-operated animals. The ALT activity was 1,081 +/- 575 IU.L(-1) in IRI + HES Group 1; 2,363 +/- 1,839 IU.L(-1) in IRI + HS Group 2; and 2,866 +/- 2,491 IU.L(-1) in IRI-only Group 3. There was a statistically significant difference between the IRI + HES and the IRI-only groups (P = 0.001), but not between the IRI + HS and the IRI-only groups (P > 0.05). Likewise, histological scores were greater in all IRI groups compared with the sham-operated animals. Scores were higher in the IRI-only group (median 3.5) than in the groups receiving fluid (IRI + HES median 2; IRI + HS median 3). The difference between IRI + HES and IRI-only was statistically significant (P = 0.008) but not so between IRI + HS and IRI-only (P > 0.05).

CONCLUSIONS

Giving HES 130/0.4 attenuates rat liver IRI compared with no fluid, while giving HS does not. This suggests a role for HES in hepatoprotection associated with liver IRI.

Recent developments in liposomes, microparticles and nanoparticles for protein and peptide drug delivery

Proteins and peptides are increasingly recognized as potential leads for the development of new therapeutics for a variety of human ailments. Due to their relatively specific mode of action, proteins and peptides can be administered at relatively low doses for therapeutic effects. As natural biological products, these low doses reduce the risk otherwise caused by other small molecular drugs or larger charged molecules. Unfortunately, their therapeutic potential and clinical application is frequently hampered by various obstacles to their successful delivery. This review discusses the recent developments in the fields of liposome, microparticle and nanoparticle pertinent to protein and peptide delivery covering those systems tested and/or validated in vivo.

Fluid balance and acute kidney injury

Intravenous fluids are widely administered to patients who have, or are at risk of, acute kidney injury (AKI). However, deleterious consequences of overzealous fluid therapy are increasingly being recognized. Salt and water overload can predispose to organ dysfunction, impaired wound healing and nosocomial infection, particularly in patients with AKI, in whom fluid challenges are frequent and excretion is impaired. In this Review article, we discuss how interstitial edema can further delay renal recovery and why conservative fluid strategies are now being advocated. Applying these strategies in critical illness is challenging. Although volume resuscitation is needed to restore cardiac output, it often leads to tissue edema, thereby contributing to ongoing organ dysfunction. Conservative strategies of fluid management mandate a switch towards neutral balance and then negative balance once hemodynamic stabilization is achieved. In patients with AKI, this strategy might require renal replacement therapy to be given earlier than when more-liberal fluid management is used. However, hypovolemia and renal hypoperfusion can occur in patients with AKI if excessive fluid removal is pursued with diuretics or extracorporeal therapy. Thus, accurate assessment of fluid status and careful definition of targets are needed at all stages to improve clinical outcomes. A conservative strategy of fluid management was recently tested and found to be effective in a large, randomized, controlled trial in patients with acute lung injury. Similar randomized, controlled studies in patients with AKI now seem justified.

Perioperative crystalloid and colloid fluid management in children: where are we and how did we get here?

It has been more than 50 yr since the landmark article in which Holliday and Segar (Pediatrics 1957;19:823-32) proposed the rate and composition of parenteral maintenance fluids for hospitalized children. Much of our practice of fluid administration in the perioperative period is based on this article. The glucose, electrolyte, and intravascular volume requirements of the pediatric surgical patient may be quite different than the original population described, and consequently, use of traditional hypotonic fluids proposed by Holliday and Segar may cause complications, such as hyperglycemia and hyponatremia, in the postoperative surgical patient. There is significant controversy regarding the choice of isotonic versus hypotonic fluids in the postoperative period. We discuss the origins of perioperative fluid management in children, review the current options for crystalloid fluid management, and present information on colloid use in pediatric patients.

Effects of a predominantly hydroxyethyl starch (HES)-based and a predominantly non HES-based fluid therapy on renal function in surgical ICU patients

PURPOSE

To compare the effects of predominantly hydroxyethyl starch (HES 6% 130/0.4)-based with predominantly gelatin 4%-based fluid therapy on renal function in surgical intensive care unit (ICU) patients.

METHODS

Before-after, retrospective, study of surgical ICU patients. All patients admitted from January to June 2005 formed the HES group, with HES 130/0.4 as the standard colloid of choice. All patients admitted from January to June 2006 formed the GEL group, with gelatin 4% as the primary colloid. Acute renal failure (ARF) was defined as new need for renal replacement therapy (RRT) or at least a two-fold increase in baseline creatinine.

RESULTS

There were 1383 patients in the HES group and 1528 in the GEL group; 118 and 87, in each group respectively, had severe sepsis. The incidence of ARF and ICU and hospital mortality rates were similar in the two groups. In a post-hoc multivariable analysis, cumulative doses >33 ml/kg of either HES (OR = 1.85, 95% CI: 1.01-3.41, p < 0.001) or gelatin (OR = 1.99, 95% CI: 1.05-3.79, p = 0.035) were associated with a higher risk of ARF.

CONCLUSIONS

The incidence of ARF was similar in patients who received predominantly HES (6% 130/.04) fluid therapy and in those who received predominantly gelatin 4%. Moderate cumulative doses of modern HES or gelatin solutions may be associated with a higher risk of ARF.

The early effect of Voluven, a novel hydroxyethyl starch (130/0.4), on cerebral oxygen supply and consumption in resuscitation of rabbit with acute hemorrhagic shock

BACKGROUND

Voluven (hydroxyethyl starch [HES] 130/0.4), a new generation of HES product with low molecular weight, has been widely used for the treatment of traumatic and hemorrhagic shock in clinics. However, no data are available whether it affects the balance of cerebral oxygen supply and consumption when applied to resuscitate hemorrhagic shock. The purpose of this study was to address this question in rabbits subjected to a severe hemorrhagic shock.

METHODS

In New Zealand rabbits, an acute hemorrhagic shock was induced by withdrawing 45% to 50% of total blood volume from the femoral vein in 10 minutes when the mean arterial pressure was reduced to 60% of the baseline level. Thirty minutes after the hemorrhage, animals were infused with either an equal amount of Voluven (group V) or a tripled amount of lactated Ringer's solution (group R). The saturation of oxygen was obtained in arterial (Sao2) and venous (SjvO2) blood samples from the femoral artery and jugular bulb, respectively. Arterial oxygen content (Cao2), jugular oxygen content (CjvO2), arteriovenous oxygen difference (AVDO2), and cerebral oxygen extraction rate (CERO2) were calculated accordingly to evaluate the oxygenation state in the brain.

RESULTS

Levels of SjvO2 and CjvO2 were decreased after hemorrhagic shock, and there were increases in AVDO2 and CERO2 values. After resuscitation, the SjvO2, AVDO2, and CERO2 levels in group V were quickly recovered to the basal levels, whereas the values in group R remained in the abnormal levels (p < 0.05). There were significant differences between the groups in their SjvO2 and CERO2 levels at 30 minutes after resuscitation. In addition, the mean arterial pressure was restored to the basal levels in group V but not in group R after resuscitation (p < 0.05).

CONCLUSION

We conclude that early infusion of Voluven is beneficial for maintenance of the hemodynamic stability and for the balance of cerebral oxygen supply and consumption during the resuscitation of acute hemorrhagic shock.