Effects of hydroxyethyl starch (HES 130/0.42) on endothelial and epithelial permeability in vitro.

Hydroxyethyl starch (HES) is employed to sustain normovolemia in patients. Using a perfused organ model, we recently showed that HES impairs the intestinal barrier which is constituted of endothelial and epithelial cell layers. However, the target cells and molecular actions of HES in the intestine are mainly unknown. Employing a model of human endothelial (HUVEC) and intestinal epithelial cells (Caco-2), we investigated the impact of HES, albumin and HES/albumin on cellular integrity/permeability and evaluated underlying molecular mechanisms. Monolayers of HUVEC and Caco-2 were cultured with HES (3%), albumin (3%) or HES/albumin (1.5%/1.5%). Integrity and permeability of the cell layers were evaluated by FITC-dextran transfer, measurements of cell detachment, vitality, cell volume, LDH release and caspase-3/7 activity. Cellular mechanisms were analyzed by Westernblotting for P-akt, P-erk, claudin-3 and I-FABP. HES application resulted in higher numbers of non-adherent/floating HUVEC cells (P<0.05) but did not change vitality or cell volume. Both, HES and HES/albumin increased the permeability of HUVEC monolayers (P<0.001), while LDH release, caspase-3/7 activity, akt/erk phosphorylation and claudin-3 expression were not affected. HES and HES/albumin did not change any of the parameters in cultures of Caco-2 cells. HES is able to disturb the integrity of the endothelial but not the epithelial barrier in vitro. HES effects are unrelated to cell damage and apoptosis but may involve reduced cell-cell or cell-matrix adhesion.

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.

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.

Physicochemical and Toxic Properties of Novel Genipin Drug Delivery Systems Prepared by Mechanochemistry.

BACKGROUND: Complexes of Genipin and different water-soluble adjuvant polysaccharides, such as arabinogalactane, hydroxyethyl starch, fibergum, and oligosaccharides ß-CD and HP-ß-CD, were synthesized as drug delivery system using mechanochemical technology. METHOD: We have investigated physicochemical properties, stability, and hepatotoxicity of the synthesized complexes in solid state and aqueous solution. The formation of the complexes was evidenced by different physical and spectroscopy assays, and the stability constants of our synthesized Genipin-based complexes were also calculated. RESULTS: The HP-ß-CD inclusion complex showed the highest characteristics. We have found that the molecule of Genipin was completely included in the cyclodextrin cavity of the HP-ß-CD. This complex of Genipin has shown a 6.14-fold increase of solubility compared with the original Genipin, and more stable in solvent and solid states. CONCLUSION: The hepatotoxicity assays showed that our investigated complexes of Genipin are much safer than the original Genipin. These results suggest that new Genipin-based preparations can be synthesized with advantageous of higher stability and safety.

Neurotoxicity of intrathecal 6% hydroxyethyl starch 130/0.4 injection in a rat model.

Epidural blood patch is the gold standard treatment for post-dural puncture headache, although hydroxyethyl starch may be a useful alternative to blood if the latter is contraindicated. The aim of this experimental study was to assess whether hydroxyethyl starch given via an indwelling intrathecal catheter resulted in clinical or histopathological changes suggestive of neurotoxicity. The study was conducted in rats that were randomly allocated to receive three 10-µl injections on consecutive days of either saline or hydroxyethyl starch administered via the intrathecal catheter. Eight rats were given injections of saline 0.9% and 11 were given 6% hydroxyethyl starch 130/0.4 derived from thin boiling waxy corn starch in 0.9% sodium chloride (Voluven). Daily clinical evaluation, activity measured by actimetry and neuropathological analysis of the spinal cord were subsequently performed to assess for signs of neurotoxicity. No clinical or actimetric changes were observed in either group following intrathecal saline or hydroxyethyl starch administration. Histopathological examination showed non-specific changes with no differences between the two groups. This experimental study in the rat suggests that repeated intrathecal injection of hydroxyethyl starch is not associated with neurotoxicity.

Interaction of recombinant octameric hemoglobin with endothelial cells.

Hemoglobin-based oxygen carriers (HBOCs) may generate oxidative stress, vasoconstriction and inflammation. To reduce these undesirable vasoactive properties, we increased hemoglobin (Hb) molecular size by genetic engineering with octameric Hb, recombinant (r) HbßG83C. We investigate the potential side effects of rHbßG83C on endothelial cells. The rHbßG83C has no impact on cell viability, and induces a huge repression of endothelial nitric oxide synthase gene transcription, a marker of vasomotion. No induction of Intermolecular-Adhesion Molecule 1 and E-selectin (inflammatory markers) transcription was seen. In the presence of rHbßG83C, the transcription of heme oxygenase-1 (oxidative stress marker) is weakly increased compared to the two other HBOCs (references) or Voluven (control). This genetically engineered octameric Hb, based on a human Hb ßG83C mutant, leads to little impact at the level of endothelial cell inflammatory response and thus appears as an interesting molecule for HBOC development.

A comparative study of neurotoxic potential of synthesized polysaccharide-coated and native ferritin-based magnetic nanoparticles.

AIM: To analyze the neurotoxic potential of synthesized magnetite nanoparticles coated by dextran, hydroxyethyl starch, oxidized hydroxyethyl starch, and chitosan, and magnetic nanoparticles combined with ferritin as a native protein. METHODS: The size of nanoparticles was analyzed using photon correlation spectroscopy, their effects on the conductance of planar lipid membrane by planar lipid bilayer technique, membrane potential and acidification of synaptic vesicles by spectrofluorimetry, and glutamate uptake and ambient level of glutamate in isolated rat brain nerve terminals (synaptosomes) by radiolabeled assay. RESULTS: Uncoated synthesized magnetite nanoparticles and nanoparticles coated by different polysaccharides had no significant effect on synaptic vesicle acidification, the initial velocity of L-[(14)C]glutamate uptake, ambient level of L-[(14)C]glutamate and the potential of the plasma membrane of synaptosomes, and conductance of planar lipid membrane. Native ferritin-based magnetic nanoparticles had no effect on the membrane potential but significantly reduced L-[(14)C]glutamate transport in synaptosomes and acidification of synaptic vesicles. CONCLUSIONS: Our study indicates that synthesized magnetite nanoparticles in contrast to ferritin have no effects on the functional state and glutamate transport of nerve terminals, and so ferritin cannot be used as a prototype, analogue, or model of polysaccharide-coated magnetic nanoparticle in toxicity risk assessment and manipulation of nerve terminals by external magnetic fields. Still, the ability of ferritin to change the functional state of nerve terminals in combination with its magnetic properties suggests its biotechnological potential.

Role of hydroxyethyl starch in ischemia-reperfusion injury in rat intestinal transplantation.

OBJECTIVE: This study was designed to evaluate the role of 0%, 3%, 6% hydroxyethyl starch (HES) and University of Wisconsin (UW) perfusion and preservation solutions on ischemia-reperfusion injury (IRI) of rat intestinal transplantations, solutions, respectively. MATERIALS AND METHODS: Rats underwent orthotopic intestinal transplantation (Lewis to Lewis) after using perfusion and preservation saline (group l), 3% HES (group 2), 6% HES (group 3), or UW (group 4) solutions. The change in weight was recorded from preoperative to postoperative day (POD) 30. At 30 minutes after reperfusion, we harvested intestinal juice preoperatively as well as at 30 minutes after reperfusion and on POD 1 and 3 when recipients underwent open surgery for maltose absorption tests and sampling. The Park' scores of IRI were evaluated by light microscopy after hematoxylin and eosin (H&E) staining. RESULTS: An increased weight was more evident in group 2 than the other groups, particularly the on POD 1 and POD 3 (P < .05). It was significantly greater than groups 1 and 3 on POD 7 (P < .05). Compared with the other groups, the 30-minute post-reperfusion. Park score and intestinal juice content in group 2 was decreased significantly (P < .01), while in group 3 the Park score was increased, and the maltose absorption level decreased significantly (P < .05). CONCLUSION: Three percent HES solution attenuated IRI in rat intestinal transplantation. High-concentration HES solutions were unfit for intestinal preservation. Thus the adverse effects of UW solution may be attribute at least in part to its high HES, concentration.

Acute normovolemic hemodilution can aggravate neurological injury after spinal cord ischemia in rats.

BACKGROUND: Acute normovolemic hemodilution (ANH) is currently performed during thoracoabdominal aortic surgery. However, the effects of ANH on spinal cord ischemic injury are currently unknown. Because hemodilution below a certain level of hematocrit (Hct) aggravates the neurological damage after cerebral ischemia, we hypothesized that ANH may increase neurological damage after spinal cord ischemia. The aim of these experiments was to determine the effects of ANH on spinal cord ischemic injury. METHODS: Thirty male Sprague-Dawley rats were randomly assigned to 1 of the following 3 groups: no hemodilution (group C), target Hct level of 30% (group HD30), and target Hct level of 25% (group HD25). ANH was performed upon withdrawal of blood and simultaneous replacement with the same volume with hydroxyethyl starch. Spinal cord ischemia and reperfusion were induced by using a balloon-tipped catheter placed in the descending thoracic aorta, and changes in mean arterial blood pressure were recorded. Neurological function of the hindlimbs was evaluated for 7 days and recorded using a motor deficit score (MDS) (0 = normal; 5 = complete paraplegia). The number of motor neurons within the spinal cord was counted after final MDS evaluation. RESULTS: Group HD25 developed hypotension during the latter part of the ANH procedure. Group C and group HD30 experienced 3 minutes of reperfusion hypotension, whereas 6 minutes of hypotension was observed in group HD25. Two rats in group HD25 died during the experimental period. Seven days after reperfusion, the MDS of group C, group HD30, and group HD25 was 1.0 (0.5-2.0), 1.0 (0.5-2.0), and 4.0 (2.8-4.2) (median [95% confidence interval]), respectively. Group HD25 showed significantly higher MDS compared with group C (corrected P = 0.0018; 95% CI for median difference = 1.0-3.5). Motor neuron numbers in the anterior horns of group C, group HD30, and group HD25 were 26.5 (25.0-27.5), 23.5 (22.0-26.5), and 12.5 (8.4-16.6) (median [95% CI]), respectively. Motor neuron numbers of group HD25 were significantly lower than those of group C (corrected P < 0.0001; 95% CI for median difference = 9.0-18.0). CONCLUSION: The results of the present study indicate that intraoperative ANH to an Hct of 25%, combined with coincident hypotension, caused a delayed recovery of baseline mean arterial blood pressure during the reperfusion period and aggravated neurological outcome after spinal cord ischemia.

Impairment of renal function using hyperoncotic colloids in a two hit model of shock: a prospective randomized study.

INTRODUCTION: One of the therapeutic essentials in severe sepsis and septic shock is an adequate fluid replacement to restore and maintain circulating plasma volume, improve organ perfusion and nutritive microcirculatory flow. The type of solution to be used as a fluid replacement remains under discussion. The aim of the study was to evaluate the effects of clinically used fluid replacement solutions on renal function and inflammatory response. METHODS: A total of 23 anesthetized and ventilated female German Landrace pigs were investigated over 19 hours using a two-hit model that combined hemorrhagic and septic shock. The septic shock was induced using an Escherichia coli laden clot placed into the abdominal cavity. Infusions of 6% hydroxyethylstarch 130/0.42 in acetate (6% HES 130), 4% gelatin in acetate (4% gelatin) and 10% hydroxyethylstarch 200/0.5 in saline (10% HES200) compared to Ringer's acetate (RAc) were used for fluid replacement to maintain a central venous pressure of 12 mmHg. Ringer's acetate was also used in the sham-treated group (SHAM). RESULTS: At study end the cardiac output (10% HES200 143±48 ml/kgBW; 6% HES130 171±47 ml/kgBW; RAc 137±32 ml/kgBW; 4% gelatin 160±42 ml/kgBW), as well as mean arterial pressure did not differ between groups. N-acetyl-beta-D-glucosamidase was significantly higher in the hydroxyethylstarch 200 (157±115 U/g creatinine; P<0.05) group compared to hydroxyethylstarch 130 (24±9 U/g creatinine), Ringer's acetate (2±3 U/g creatinine) and SHAM (21±15 U/g creatinine) at the study's end. Creatinine significantly increased by 87±84 percent of baseline in the 10% HES200 group compared to RAc and 6% HES130. We demonstrated in the histology of the kidneys a significant increase in osmotic-nephrosis like lesions for 4% gelatin compared to RAc, 6% HES130 and SHAM. Urine output was lowest in the 10% HES200 and 4% gelatin group, however not significantly.Interleukin(IL)-6 levels were significantly elevated in the 10% HES200 group (3,845±1,472 pg/ml) two hours after sepsis induction compared to all other groups (6% HES130 1,492±604 pg/ml; RAc 874±363 pg/ml; 4% gelatin 1,623±1,242 pg/ml). CONCLUSIONS: Despite similar maintenance of macrocirculation 6% hydroxyethylstarch 130/0.42 and Ringer's acetate significantly preserve renal function and attenuate tubular damage better than 10% hydroxyethylstarch 200/0.5 in saline.

The effects of colloid solutions on renal proximal tubular cells in vitro.

Renal failure is a common complication of critically ill patients. Colloids such as hydroxyethyl starch (HES), gelatin, or albumin are regularly used for intravascular volume resuscitation, but there are increasing reports about the nephrotoxic side effects of synthetic colloids in septic patients. Therefore, we investigated the influence of colloids (HES130/0.4 (Voluven®), gelatin (Gelafundin®), human albumin, and the crystalloid Sterofundin® ISO on cell viability of human proximal tubular (HK-2) cells. HK-2 cells were incubated with colloids (0.1%-4%) and with equivalent volumes of the crystalloid solution Sterofundin ISO. After 21 hours, cell viability of HK-2 cells was measured by EZ4U assay (dye XTT). Application of HES130/0.4 decreased cell viability significantly in a concentration-dependent manner (86.80% ± 10.79% by 0.5% HES down to 24.02% ± 4.27% by 4% HES). Human albumin (>1.25%) as well as gelatin (>1%) also showed deleterious effects on HK-2 cells. Interestingly, in lower concentrations, human albumin and the crystalloid solution Sterofundin ISO were cytoprotective in comparison with the NaCl control. In conclusion, synthetic and natural colloids showed a harmful impact on HK-2 cells in higher concentrations without any prior proinflammatory stimulus. HES130/0.4 exhibited the most distinctive harmful impact, whereas the application of crystalloid Sterofundin ISO revealed cytoprotective effects.

[Hydroxyethyl starch]. / Les hydroxyéthylamidons.

OBJECTIVE: The purpose of this review is to draw up a statement on current knowledge available on the more recent hydroxyethyl starch (HES). DATA SOURCES: References were obtained from computerized bibliographic research (Medline), recent review articles, the library of the service and personal files. STUDY SELECTION: All categories of articles on this topic have been selected. DATA EXTRACTION: Articles have been analysed for biophysics, pharmacology, toxicity, side effects, clinical effects and using prospect of HES. DATA SYNTHESIS: The first HES was made available in the United States in 1970. The development of a new generation of HES restarted the discussion on clinical interest and the limits in the use of these macromolecules. This interest is also strengthened today by the recent data attached to plasma substitution in intensive care or perioperative resuscitation. The interest for crystalloids and colloids is still widely debated, and among the latter, the relative interest of the HES last generation compared to older ones. Recent HES development is in line with a decrease molecular weight, change rate molar substitution and to amend the glucose to hydroxyethyl report. The ultimate goal is to reduce the side effects of these molecules preventing their use. Side effects are dominated by haemostasis and renal dysfunction. The latest developments are the so-called HES "balanced" solutions.

Renal effects of saline-based 10% pentastarch versus 6% tetrastarch infusion in ovine endotoxemic shock.

BACKGROUND: Conflicting data exist on the renal effects of hydroxyethyl starch (HES) preparations. The current study evaluates the effects of saline-based 6% HES 130/0.4, 10% HES 200/0.5, and a balanced isotonic crystalloid on renal function and microscopic changes in ovine endotoxemic shock. METHODS: Thirty sheep were subjected to endotoxin infusion (Salmonella typhosa) at incremental doses until mean arterial pressure was less than 65 mmHg. Animals were randomized to receive fluid resuscitation with saline-based 6% HES 130/0.4, 10% HES 200/0.5, or a balanced isotonic crystalloid (n = 10 each). Animals surviving the 12-h intervention period were anesthetized and killed. Kidney samples were taken for microscopic analyses. RESULTS: Endotoxemia was associated with hemoconcentration, protein extravasation, and arterial hypotension. Fluid resuscitation established a hypotensive-hyperdynamic circulation with increased cardiac index and oxygen delivery and decreased afterload. Diuresis was lowest in animals treated with 10% HES 200/0.5. In addition, plasma creatinine and urea concentrations increased in sheep treated with 10% HES 200/0.5 (1.2 +/- 0.1 and 19 +/- 2 mg/dl) when compared with the other two groups (0.9 +/- 0.1 and 15 +/- 1 mg/dl, 6% HES 130/0.4; 0.9 +/- 0.1 and 15 +/- 1 mg/dl, crystalloids; each P < 0.05). Electron microscopic tubular injury score was highest in sheep treated with 10% HES 200/0.5 (P < 0.001 vs. 6% HES 130/0.4). CONCLUSIONS: In ovine endotoxemic shock, saline-based 10% HES 200/0.5 was linked to impaired renal function and more pronounced tubular epithelial injury when compared with 6% HES 130/0.4 and balanced crystalloids.

rFVIIa and NN1731 reduce bleeding in hydroxyethyl starch hemodiluted rabbits.

BACKGROUND: Colloid plasma expanders are used to maintain blood pressure and ensure tissue perfusion during hypovolemia, e.g., caused by traumatic bleeding. Although colloids stabilize the cardiovascular system, they can also potentially cause coagulopathy. Consequently, bleeding tendency may increase, as well as the associated risk of morbidity and mortality. Thus, there is a need for hemostatic treatment options for these patients. rFVIIa (NovoSeven, Novo Nordisk A/S, Bagsvaerd, Denmark) is a hemostatic agent that effectively controls bleedings in patients with inhibitor-complicated hemophilia. rFVIIa works by enhancing thrombin generation on the activated platelet surface at the site of injury, leading to the formation of a stable fibrin clot. NN1731 is an rFVIIa analog with increased hemostatic potential and is currently under clinical development. METHODS: In this study, the effect of rFVIIa and NN1731 on cuticle bleeding in rabbits 50% hemodiluted with hydroxyethyl starch (molecular weight ∼ 200,000) was tested. Cuticle bleeding was induced after a two-stage hemodilution procedure. After 5 minutes, the animals were treated with rFVIIa (2, 5, or 10 mg/kg), NN1731 (1 or 2 mg/kg), or vehicle, followed by 30 minutes of observation. RESULTS: Hemodilution caused a significant increase in bleeding time and blood loss. rFVIIa dose-dependently reduced bleeding time and blood loss, reaching statistical significance at 10 mg/kg. However, 2 mg/kg NN1731 reduced bleeding time and blood loss significantly and to a similar extent as 10 mg/kg rFVIIa. This increased hemostatic potential of NN1731 compared with rFVIIa and was confirmed by findings using thromboelastography on ex vivo hemodiluted whole blood. CONCLUSION: In summary, rFVIIa and NN1731 significantly and dose-dependently reduced bleeding in extensively hemodiluted rabbits.

Equivalent metabolic acidosis with four colloids and saline on ex vivo haemodilution.

Colloid infusions can cause metabolic acidosis. Mechanisms and relative severity with different colloids are incompletely understood. We compared haemodilution acid-base effects of 4% albumin, 3.5% polygeline, 4% succinylated gelatin (all weak acid colloids, strong ion difference 12 mEq/l, 17.6 mEq/l and 34 mEq/l respectively), 6% hetastarch (non-weak acid colloid, strong ion difference zero) and 0.9% saline (crystalloid, strong ion difference zero). Gelatin weak acid properties were tracked via the strong ion gap. Four-step ex vivo dilutions of pre-oxygenated human venous blood were performed to a final [Hb] near 50% baseline. With each fluid, base excess fell to approximately -13 mEq/l. Base excess/[Hb] relationships across dilution were linear and direct (R2 > or = 0.96), slopes and intercepts closely resembling saline. Baseline strong ion gap was -0.3 (2.1) mEq/l. Post-dilution increases occurred in three groups: small with saline, hetastarch and albumin (to 3.5 (02) mEq/l, 4.3 (0.3) mEq/l, 3.3 (1.4) mEq/l respectively), intermediate with polygeline (to 12.2 (0.9) mEq/l) and greatest with succinylated gelatin (to 20.8 (1.4) mEq/l). We conclude that, despite colloid weak acid activity ranging from zero (hydroxyethyl starch) to greater than that of albumin with both gelatin preparations, ex vivo dilution causes a metabolic acidosis of identical severity to saline in each case. This uniformity reflects modifications to the albumin and gelatin saline vehicles, in part aimed at pH correction. By proportionally increasing the strong ion difference, these modifications counter deviations from pure saline effects caused by colloid weak acid activity. Extrapolation in vivo requires further investigation.

Hydroxyethylstarch impairs renal function and induces interstitial proliferation, macrophage infiltration and tubular damage in an isolated renal perfusion model.

INTRODUCTION: The aim of the study was to evaluate some of the underlying pathomechanisms of hydroxyethylstarch (HES) induced adverse effects on renal function using 24 porcine kidneys in an isolated perfusion model over six hours. METHODS: Infusion of either 10% HES 200/0.5, 6% HES 130/0.42 or Ringer's lactate (RL) was performed to achieve an haematocrit of 20% in eight kidneys from four animals per group. Physiological and pathophysiological parameters were determined (including N-acetyl-beta-aminoglucosidase as a marker for lysosomal tubular damage). Histological investigations and immunohistological stainings of the kidneys were performed. RESULTS: Initially after haemodilution, HES 130/0.42 and HES 200/0.5 reduced urine output compared with RL (P < 0.01). After six hours, N-acetyl-beta-aminoglucosidase was significantly higher in HES 200/0.5 (81 +/- 23 U/L) compared with HES 130/0.42 (38 +/- 12 U/L) and RL (21 +/- 13 U/L; P < 0.001). Osmotic nephrosis-like lesions (OL) of the tubuli were present in all groups showing a significantly lower number of OL in RL (1.1 +/- 0.4; P = 0.002) compared with both HES groups (HES 200/0.5 = 2.1 +/- 0.6; HES 130/0.42 = 2.0 +/- 0.5). Macrophage infiltration was significantly higher in HES 200/0.5 compared with HES 130/0.42 (1.3 +/- 1.0 vs. 0.2 +/- 0.04; P = 0.044). There was a significant increase in interstitial cell proliferation in the HES 200/0.5 group vs. HES 130/0.42 (18.0 +/- 6.9 vs. 6.5 +/- 1.6; P = 0.006) with no significant difference in RL (13.5 +/- 4.0). CONCLUSIONS: We observed impaired diuresis and sodium excretion by HES and identified renal interstitial proliferation, macrophage infiltration and tubular damage as potential pathological mechanisms of HES-induced adverse effects on renal function using an isolated porcine renal perfusion model. Furthermore, we demonstrated that 10% HES 200/0.5 had more of a pro-inflammatory effect compared with 6% HES 130/0.42 and caused more pronounced tubular damage than 6% HES 130/0.42 and RL. OL were present in all groups, but to a lesser degree after RL administration.

Influence of a long-term, high-dose volume therapy with 6% hydroxyethyl starch 130/0.4 or crystalloid solution on hemodynamics, rheology and hemostasis in patients with acute ischemic stroke. Results of a randomized, placebo-controlled, double-blind study.

BACKGROUND: This study was performed to investigate the clinical effects of a 4-day volume therapy with a newly developed, 6% hydroxyethyl starch (HES) 130/0.4 versus crystalloid solution, with particular regard to systemic and cerebral hemodynamics, rheology and safety. METHODS: In a randomized, double-blind study, 40 patients suffering from an acute ischemic stroke received either 6% HES 130/0.4 or crystalloid solution as continuous infusion over 4 days with a total dose of 6.5 liters. Efficacy parameters studied included hemodynamics (cardiac output, blood pressure, flow velocity with transcranial Doppler) and rheology (hematocrit and plasma viscosity). Safety parameters examined included laboratory, hemostaseology (including factor VIII) and an adverse event questionnaire (including pruritus). RESULTS: In both groups, a small, but not significant increase in cardiac output was observed. There were no significant changes regarding the remaining efficacy or safety parameters, except for the well-known increase in serum alpha-amylase through the infusion of HES. CONCLUSION: In our study with patients suffering from acute ischemic stroke, continuous infusion (1 ml/min) of HES 130/0.4 or crystalloid solution did not differ regarding safety or hemodynamic efficacy.

Action of hydroxyethyl starch (HES) on the activity of plasmatic clotting factors.

Studies were carried out on the effects of different doses of hydroxyethyl starch 200/0.5 (HES) on plasma clotting factors in dogs, as an animal model for the human clotting system. In 8 German shepherd dogs 15% of the total blood was isovolemically substituted either by Ringer's solution with lactate alone (controls) or with 0.6, 1.3, 1.9, 2.5 g HES/kg b.w. Immediately after the infusion, the HES concentration in the recipients' plasma amounted to 8 mg/ml up to 38 mg/ml. In the following 6 h, the HES decreased to 25% in each case. It was found that the higher the plasma HES content was, the lower the haematocrit. Neither the thrombin-nor the batroxobin-time showed any significant change, irrespective of the plasma HES concentration. The prothrombin-time was decreased directly after the infusion in parallel to the haematocrit. The single clotting factors FI, FII, FV, FVII, FVIII, FX, and FXII behaved approximately in the same way: their activities directly after infusion, but also 6 h later, were lowered in proportion to the amount of HES infused. The loss of factor activity correlated with the volume-expanding effect of HES shortly after the infusion, but not 6 h later. It is concluded that there are two different modes of HES action on clotting factors: the dilution by plasma volume expansion and a non-dilutional action. Cautious handling might be required in patients with clotting disturbances as well as in long-term treatment.

[Hydroxyethyl starch--an interim report]. / Hydroxyethylstärke--ein Zwischenbericht.

Since the beginning of this century, a few biopolymers have been used as basic materials for volume substitution. Aside from gelatin and dextran, modified starch (hydroxyethyl starch, HES) is currently the first-choice means. Due to special manufacturing processes, different hydroxyethyl starches are now available. They have several different characteristics and produce different clinical effects. These clinical properties depend on the average molecular weight and the distribution of molecular weight as well as on the degree and pattern of substitution. The duration of volume effect, one of the most important parameters for the effectiveness of a volume substitute, depends to a large degree on the substitution. Elimination of HES from serum is delayed by a high degree of substitution and a high C2/C6 ratio of the substitution pattern. The molecular parameters of HES also influence other effects, such as cumulation in various organs and hemostasis. Critical reading of current HES literature shows that many questions still have to be answered. At the same time ways and means of optimizing differential volume substitution therapy and hemodilution therapy are emerging.

Increased haemorrhagic risk after repeated infusion of highly substituted medium molecular weight hydroxyethyl starch.

Infusion of the large volumes of high molecular weight hydroxyethyl starch (HES) has been know to lead to coagulation disorders. Medium molecular starch is considered a safe alternative, even after repeated administration. In 10 patients with cerebrovascular diseases, a 10-day hemodilution was carried out using 10% HES 200/0.62. Initially, a loading dose of 500 ml was administered once over 45-60 min, followed by 500 ml maintenance dose per day for 10 days. Its high intravascular molecular weight (120,000 D) showed that cleavage of the starch is slowed due to the higher degree of substitution. The continuous increase of HES-serum concentration to 27.7 mg/ml gave evidence of a cumulation of poorly degradable molecules. Although this caused a prolonged volume effect, plasma viscosity and erythrocyte aggregation were influenced in an unfavourable way. The negative effects were not evident in their influence on the coagulation system. Under therapy, a significant 42.8% increase (p < 0.01) in activated partial thromboplastin time occurred. Factor VIII:C, von Willebrand ristocetin co-factor and von Willebrand factor antigen dropped during the therapy below the hemostasiological limit of 30% (p < 0.01), and in some patients below 10%. A high degree of substitution, particularly after repeated infusion, leads to a cumulation of large molecules that are difficult to break down and which unfavourably affect rheological and hemostasiological parameters.