Hetastarch: an overview of the colloid and its metabolism

Effect of hydroxyethyl starch on blood glucose levels

Background

Hydroxyethyl starch (HES), a commonly used resuscitation fluid, has the property to induce hyperglycemia as it contains large ethyl starch, which can be metabolized to produce glucose. We evaluated the effect of 6% HES-130 on the blood glucose levels in non-diabetic patients undergoing surgery under spinal anesthesia.

Methods

Patients scheduled to undergo elective lower limb surgery were enrolled. Fifty-eight patients were divided into two groups according to the type of the main intravascular fluid used before spinal anesthesia (Group LR: lactated Ringer's solution, n = 30 vs. Group HES: 6% hydroxyethyl starch 130/0.4, n = 28). Blood glucose levels were measured at the following time points: 0 (baseline), 20 min (T1), 1 h (T2), 2 h (T3), 4 h (T4), and 6 h (T6).

Results

Mean blood glucose levels at T5 in the LR group and T4, T5 in the HES group, increased significantly compared to baseline. There were no significant changes in the serial differences of mean blood glucose levels from baseline between the two groups.

Conclusions

Administration of 6% HES-130 increased blood glucose levels within the physiologic limits, but the degree of glucose increase was not greater than that caused by administration of lactated Ringer's solution. In conclusion, we did not find evidence that 6% HES-130 induces hyperglycemia in non-diabetic patients.

Crystalloids and colloids for volume replacement

For many years there has been a debate about whether crystalloids or colloids should be used for resuscitation. Some years ago, albumin was the gold standard against which all other solutions were compared. This continues to be the case, despite the fact that other solutions are as effective for volume replacement. This paper stresses the need for a proper understanding of the properties of solutions that may influence the choice for volume replacement. Different classes of solutions are discussed in detail, with special reference to their effects on cardiovascular and oxygen transport parameters. Other important properties such as side-effects and effect on coagulation are also considered.

Hydroxyethyl starch: a review of pharmacokinetics, pharmacodynamics, current products, and potential clinical risks, benefits, and use

OBJECTIVE

To review and summarize the pharmacokinetics and pharmacodynamics of hydroxyethyl starch (HES), as well as reported risks and benefits of HES infusion, and to provide administration and monitoring recommendations for HES use in dogs and cats.

DATA SOURCES

Veterinary and human peer-reviewed medical literature, including scientific reviews, clinical and laboratory research articles, and authors' clinical experience.

SUMMARY

HES solutions are the most frequently used synthetic colloid plasma volume expanders in human and veterinary medicine. The majority of research in human medicine has focused on the adverse effects of HES infusion, with emphasis on acute kidney injury and coagulation derangements. The studies often differ in or fail to report factors, such as the type, amount, interval, and concentration of HES administered; the patient population studied; or concurrent fluids administered. Currently, there is no definitive clinical evidence that the reported adverse effects of HES use in human medicine occur in veterinary species. There is little information available on HES administration techniques or simultaneous administration of additional fluids in human and veterinary medicine. The rationale for HES use in small animals has been largely extrapolated from human medical studies and guidelines. A controlled approach to intravenous fluid resuscitation using crystalloid and HES volumes titrated to reach desired resuscitation end point parameters is outlined for small animal practitioners.

CONCLUSION

The extrapolation of data from human studies directly to small animals should be done with the knowledge that there may be species variations and different pharmacokinetics with different HES solutions. Veterinary reports indicate that bolus and continuous rate infusions of 6% hetastarch solutions at moderate doses are well tolerated in feline and canine subjects. Further research in domesticated species is necessary to better define and expand the knowledge regarding use of HES solutions in small animal medicine.

Ultrasound assessment of ex vivo lung tissue properties using a fluid-filled negative pressure bath

A relationship between tendon stress and strain and ultrasonic echo intensity has previously been defined in tendons, demonstrating a correlation between tissue stiffness and echo intensity. An analogous relationship between volume-dependent pressure changes and echo intensity changes in inflating lungs would indicate a correlation between lung compliance and echo intensity. Lung compliance is an important metric to diagnose pathologies which affect lung tissue mechanics, such as emphysema and cystic fibrosis. The goal of this study is to demonstrate a correlation between ultrasound echo intensity and lung tissue mechanics in an ex vivo model using a fluid-filled negative pressure bath design which provides a controlled environment for ultrasonic and mechanical measurements. Lungs from 4 male Sprague-Dawley rats were removed and mechanically tested via inflation and deflation in a negative pressure chamber filled with hetastarch. Specific volumes (1, 2, 3, and 4 mL) were removed from the chamber using a syringe to create negative pressure, which resulted in lung inflation. A pressure transducer recorded the pressure around the lungs. From these data, lung compliance was calculated. Ultrasound images were captured through the chamber wall to determine echo intensity (grayscale brightness in the ultrasound image), which was then related to mechanical parameters. Ultrasound images of the lung were successfully captured through the chamber wall with sufficient resolution to deduce echo intensity changes in the lung tissue. Echo intensity (0-255 scale) increased with volumetric changes (18.4 ± 5.5, 22.6 ± 5.1, 26.1 ± 7.5, and 42.9 ± 19.5 for volumetric changes of 1, 2, 3, and 4 mL) in a pattern similar to pressure (-6.8 ± 1.7, -6.8 ± 1.4, -9.4 ± 0.7, and -16.9 ± 6.8 cm H2O for 1, 2, 3, and 4 mL), reflecting changes in lung compliance. Measured rat lung tissue compliance was comparable to reported values from ex vivo lungs (0.178 ± 0.067, 0.378 ± 0.051, 0.427 ± 0.062, and 0.350 ± 0.160 mL/cm H20 for 1, 2, 3, and 4 mL), supporting proof of concept for the experimental method. Changes in echo intensity reflected changes in lung compliance in this ex vivo model, thus, supporting our hypothesis that the stiffness-related changes in echo intensity originally seen in tendon can be similarly detected in lung tissue. The presented ultrasound-based methods allowed measurement of local lung tissue compliance in a controlled environment, however, the methods could be expanded to facilitate both ex vivo and in vivo studies.

Hydroxyethylstarch in cryopreservation - mechanisms, benefits and problems

As the progress of regenerative medicine places ever greater attention on cryopreservation of (stem) cells, tried and tested cryopreservation solutions deserve a second look. This article discusses the use of hydroxyethyl starch (HES) as a cryoprotectant. Charting carefully the recorded uses of HES as a cryoprotectant, in parallel to its further clinical use, indicates that some HES subtypes are a useful supplement to dimethysulfoxide (DMSO) in cryopreservation. However, we suggest that the most common admixture ratio of HES and DMSO in cryoprotectant solutions has been established by historical happenstance and requires further investigation and optimization.

Hemostatic and electrolyte effects of hydroxyethyl starches in patients undergoing posterior lumbar interbody fusion using pedicle screws and cages

STUDY DESIGN

Prospective, randomized, double blind, clinical study.

OBJECTIVE

To compare the hemostatic and electrolyte effects of 2 commonly administered hydroxyethyl starches (HES) in patients undergoing posterior lumbar interbody fusion (PLIF).

SUMMARY OF BACKGROUND DATA

HES are commonly administered colloid solutions to restore and maintain intravascular volume before transfusion is initiated. However, infusion of HES itself can impair coagulation. HES-induced coagulopathy could be a serious problem in PLIF which involves continuous bone bleeding and oozing. Voluven (Fresenius Kabi, Germany), previously regarded as the least coagulopathic due to its low molecular weight (MW) and degree of substitution (DS), is a saline-based HES. Hextend (Biotime, United States) is a new type of HES with physiologic pH and balanced electrolytes, including calcium, which is beneficial to coagulation. Studies comparing the coagulopathy of Hextend and Voluven are rare. Therefore, coagulation, pH/electrolyte changes, and blood loss using Hextend and Voluven in patients undergoing PLIF were compared. METHODS.: Fifty-four patients scheduled for PLIF involving 3 vertebrae or less were randomly assigned to the Voluven or the Hextend group. Of each solution 15 mL/kg was administered during surgery. Blood loss, coagulation, and electrolyte profiles were checked before infusion and 5 minutes, 3 hours, and 24 hours after the end of infusion.

RESULTS

The Hextend group showed slightly better electrolyte balance, however, more coagulation impairment and postoperative transfusion (37% vs. 11%) compared with the Voluven group. The effect of Hextend on coagulation lasted until 24 hours after infusion.

CONCLUSION

If coagulopathy is a concern during PLIF, then, a HES with low MW/DS in a saline-based medium (Voluven) may be a better alternative than a HES with high MW/DS in a balanced salt medium (Hextend).

Branch retinal vein occlusion: pathogenesis, visual prognosis, and treatment modalities

In branch retinal vein occlusion (BRVO), abnormal arteriovenous crossing with vein compression, degenerative changes of the vessel wall and abnormal hematological factors constitute the primary mechanism of vessel occlusion. In general, BRVO has a good prognosis: 50-60% of eyes are reported to have a final visual acuity (VA) of 20/40 or better even without treatment. One important prognostic factor for final VA appears to be the initial VA. Grid laser photocoagulation is an established treatment for macular edema in a particular group of patients with BRVO, while promising results for this condition are shown by intravitreal application of steroids or new vascular endothelial growth factor inhibitors. Vitrectomy with or without arteriovenous sheathotomy combined with removal of the internal limiting membrane may improve vision in eyes with macular edema which are unresponsive to or ineligible for laser treatment.

Pharmacodynamics and organ storage of hydroxyethyl starch in acute hemodilution in pigs: influence of molecular weight and degree of substitution

OBJECTIVE

To determine the differential influence of molecular weight and the degree of substitution of HES solutions on pharmacodynamics and pharmacokinetics including organ storage in a model of acute hemodilution in pigs.

DESIGN

Prospective controlled randomized animal trial.

INTERVENTIONS

After bleeding, 20 ml/kg, animals were substituted with 6% HES preparations (200/0.62, 200/0.5, and 100/0.5).

MEASUREMENTS AND RESULTS

We did not observe any significant differences in the ability to sufficiently achieve plasma volume expansion and restoration of macrocirculation, nor maintenance of indicators of microcirculation between the groups. Urine production was significantly higher in HES-treated animals and highest in animals substituted with HES 100/0.5. Plasma clearance was measured under steady-state conditions with significantly reduced clearance for the HES 200/0.62 group compared with HES 100/0.5 and HES 200/0.5 (6.6 vs. 13.2 and 13.9 ml/min; P < or = 0.001), thus being dependent on the degree of substitution. Even after only 6 h, the amount of infused HES not detectable in either blood or urine was significantly higher in HES 200/0.62-treated animals (50.7% compared with HES 200/0.5 (28.8%), P = 0.020 and HES 100/0.5 (28.4%), P = 0.018), with its proportion rising over time. Finally, we could demonstrate considerable amounts of all HES solutions being stored in liver, kidney, lung, spleen and lymph nodes.

CONCLUSIONS

All preparations analyzed sufficiently restored macro- and microcirculation; however, for all solutions relevant tissue storage of HES was observed after only 6 h.

Hydroxyethyl starch-induced itch: relevance of light microscopic analysis of semi-thin sections and electron microscopy

BACKGROUND

Hydroxyethyl starch (HES) is widely used as a plasma substitute for improving microcirculation. A major side effect of HES is severe pruritus caused by HES deposits in the skin. Since specific changes are difficult to see in paraffin sections, electron microscopy is the golden standard technique in the diagnosis of HES-induced skin disease. Our aim was to compare electron microscopic search for HES deposits with other techniques.

PATIENTS AND METHODS

During the last ten years, we biopsied 21 patients suspected of having HES-induced pruritus. We compared conventional microscopy with hematoxylin & eosin and toluidine blue-stained paraffin sections, toluidine blue-stained glycide ether-embedded, semithin sections and transmission electron microscopy.

RESULTS

In 9 patients specific HES deposits could be found by evaluating toluidine blue stained semithin sections by light microscopy alone. In 6 of these cases electron microscopy was also done and confirmed the findings. In contrast, no specific findings due to HES deposits could be detected by conventional histology.

CONCLUSIONS

If specific HES deposits are found in toluidine blue-stained, glycide ether-embedded semithin sections, electron microscopy is not required.

Pharmacokinetics of Hydroxyethyl Starch

Hydroxyethyl starch has recently become the subject of renewed interest because of the introduction of a new specification, hydroxyethyl starch 130/0.4, as well as the clinical availability of a solution using a previous hydroxyethyl starch type (hydroxyethyl starch 670/0.75) with a carrier other than 0.9% saline. Various types of hydroxyethyl starch show different pharmacokinetic behaviour. Since hydroxyethyl starch is a polydisperse solution acting as a colloid, pharmacodynamic action depends on the number of oncotically active molecules, not on the plasma concentration alone; therefore, solutions with a lower in vivo molecular weight contain more molecules at similar plasma concentrations. On the other hand, high plasma concentrations as well as high in vivo molecular weight can affect blood coagulation, especially factor VIII and von Willebrand factor. Hydroxyethyl starch types with a molar substitution >0.4 accumulate in plasma after repetitive administration, most pronounced with hetastarch (hydroxyethyl starch 670/0.75). Correspondingly, tissue storage as measured by (14)C tracer studies in animals showed significantly higher values for hydroxyethyl starch 200/0.5 compared with hydroxyethyl starch 130/0.4 (about 4-fold at the latest timepoint after the last administration), and considerably higher values for hetastarch compared with both hydroxyethyl starch 130/0.4 and 200/0.5. Hydroxyethyl starch 130/0.4 does not accumulate in plasma after single- and multiple-dose administration in contrast to all other available hydroxyethyl starch specifications. Plasma clearance of hydroxyethyl starch 130/0.4 is at least 20-fold higher than that for hetastarch, and considerably higher than for pentastarch. In patients with renal insufficiency, pharmacokinetic data are only available for hydroxyethyl starch 130/0.4. Cumulative urinary excretion, even in the presence of severe non-anuric renal failure, is higher for hydroxyethyl starch 130/0.4 than values published for older hydroxyethyl starch specifications. Hydroxyethyl starch 130/0.4 may be given to patients with severe renal impairment as long as urine flow is preserved. The pharmacodynamics with respect to the volume effect does not directly mirror pharmacokinetics in the case of hydroxyethyl starch solutions. Equivalent volume efficacy has been proven for hydroxyethyl starch 130/0.4 compared with 200/0.5. Prolonged persistence of hydroxyethyl starch in plasma and tissues can be avoided by using rapidly metabolisable hydroxyethyl starch types with molar substitution <0.5. Influence on coagulation is minimal with hydroxyethyl starch 130/0.4, and no adverse effects on kidney function have been observed even with large repetitive doses when used according to the product information.

Tissue storage of 14C-labelled hydroxyethyl starch (HES) 130/0.4 and HES 200/0.5 after repeated intravenous administration to rats

OBJECTIVE

To investigate the effect of the molar substitution of hydroxyethyl starch (HES) solutions on tissue and organ storage in rats after repeated administration.

STUDY DESIGN

A controlled, multiple-dose study was performed in 48 rats. Daily bolus injections of 0.7 g/kg of 10% HES 130/0.4 or 10% HES 200/0.5 were administered on 18 consecutive days. In order to examine quantitatively the distribution and excretion of both preparations on HES tissue storage, radiolabelled HES was measured 3, 10, 24 and 52 days after the last administration. Tissue storage was expressed as percentage radioactivity of total administered HES dose in the total body, carcass, liver, kidney, spleen, lymph nodes, plasma and urine.

RESULTS

52 days after the last administration the remaining radioactivity of labelled HES 200/0.5 was nearly 4-fold higher compared with HES 130/0.4 in the total body (2.45% vs 0.65% of the total administered dose). This difference in tissue storage was statistically significant (p < or = 0.01). A comparable difference was observed for the liver and carcass.

CONCLUSION

Tissue storage after repeated administration of an HES solution with a low molar substitution (0.4) was significantly lower in the total body as well as in the liver and carcass compared with an HES solution with a medium molar substitution (0.5). However, the potential clinical consequences of these present findings have not yet been determined.

Effectiveness of hydroxyethyl starch (HES) on purification of pancreatic islets

BACKGROUND

The isolation of large-scale and high-quality islets from the pancreas is essential for a successful islet transplantation. We developed a hydroxyethyl starch (HES)-Collins solution as the purification medium and evaluated its usefulness on islet isolation from the pancreas of beagle dogs.

MATERIALS AND METHODS

The pancreas of beagle dog was digested using our original 2-step automated technique. Islets were purified by discontinuous purification method on HES-Collins solution (group 1, n = 10) or Euro-Ficoll solution (group 2, n = 16) with a COBE2991 cell processor. Islet yield and purity, changes in islet number during 3-day cultures, static incubation, perifusion study, and insulin content were examined. In addition, the islets were autotransplanted into the liver via the portal vein.

RESULTS

Although no significant differences were detected, yield and purity were higher in group 1. After 3 days of culture, the islet number decreased less in group 1. Both under static incubation and in the perifusion study, stimulation indices were 4.50 +/- 1.82 and 6.02 +/- 1.05, which were significantly higher than the 2.18 +/- 0.67 and 3.32 +/- 1.46 observed in group 2. Also, insulin content of the islets was significantly higher in group 1 than in group 2. Fasting blood glucose levels were maintained at values below 100 mg/dl for 100 days in group 1 and around 200 mg/dl in group 2.

CONCLUSIONS

The use of HES-Collins solution was associated with an improvement of islet yield and purity. Also, islet viability and function were preserved longer during culture. Accordingly, islet purification using HES-Collins solution might be recommended for clinical islet transplantation.

Hydroxyethyl starch in balanced electrolyte solution (Hextend)--pharmacokinetic and pharmacodynamic profiles in healthy volunteers

Hextend is a new plasma volume expander containing 6% hydroxyethyl starch (HES) in a physiologically balanced medium of electrolytes, glucose, and lactate (weight average, molecular weight 670 kDa, molar substitution 0.75). This open-label study was designed to investigate the pharmacokinetic and pharmacodynamic profiles of Hextend in 21 healthy volunteers. We infused Hextend 10 ml/kg IV over 20 min and determined serum concentrations of HES at selected intervals over a 7-day period. Serum concentration-time curves indicated mixed pharmacokinetic behavior reflecting a two-compartment model in most subjects. The median serum half-life over 7 days was 38.2 h. The balanced formulation of the suspension medium did not seem to affect distribution, metabolism, or excretion of Hextend when compared with similar HES. Pharmacodynamic analysis demonstrated decreases in some plasma components compatible with the infusion of that volume of fluid and the duration of plasma volume expansion. Other plasma components remained unchanged, reflecting the benefit of a balanced electrolyte solution. Hemodilution was observed for 24--48 h after short-term infusion of Hextend. Some hemostatic indices showed moderate changes, and serum amylase demonstrated a temporary increase. Our study suggested that Hextend has pharmacokinetic and pharmacodynamic profiles that are similar to those of other HES.

IMPLICATIONS

Hextend is a new plasma volume expander containing 6% hydroxyethyl starch in a physiologically balanced medium. This open-label volunteer study demonstrated that it has pharmacokinetic and pharmacodynamic profiles similar to those of established HES.

Partial colloid starch replacement for therapeutic plasma exchange

Traditionally protein solutions have been used as the replacement solution of choice during therapeutic plasma exchange (TPE). Treatment protocols vary, but neurology patients, who exhibit autonomic instability, are typically replaced entirely with 5% protein solution. Due to sporadic product shortages and the increasing cost of protein solutions, we evaluated the use of 6% and 3% hetastarch (HES) as partial replacement during TPE. All adult neurology patients with normal liver, heart, and kidney function were evaluated for HES replacement. The first seven patients (33 procedures) received 1000 ml of 6% hetastarch as part of their replacement fluid and the next 42 patients (289 procedures) received 1000 ml of 3% HES as part of their replacement fluid. Three patients crossed over into both groups. Patients were evaluated for signs of peripheral edema, evidence of bleeding, skin rash, and any subjective changes. Total protein albumin, osmolality, PT, and aPTT were measured prior to each procedure in the first five patients in each group. In both groups there was a drop in total protein, but all other lab values returned to normal limits within 48 hours of treatment. One patient reported slight peripheral edema after two procedures. In the 3% HES group the BP and P remained stable in 97.3% (280) procedures. Two patients receiving 6% HES and 1 patient receiving 3% HES complained of severe transient back and head pain during HES infusion. There was no evidence of bleeding or subjective changes. Three percent HES is a safe and cost-effective partial replacement for albumin during TPE.

The various types of parenteral fluids and their indications

Assessment of hydration and perfusion is essential in patient evaluation. The acid-base and electrolyte disturbances that accompany many illnesses should also be considered. The duration of illness and body systems involved are also of major importance in patient evaluation. Fluid therapy is an important and potentially life-saving treatment of many and varied problems. The clinician must be able to assess the patient and determine whether the intravascular or extravascular compartments, or both, are deficient. Of primary concern is the status of the intravascular volume, then restoration of total body water and electrolytes. Fluid therapy is divided into three phases; the emergency phase, the rehydration phase, and the maintenance phase; not all patients require the three-phase therapy. The clinician must also be able to select (1) the appropriate solution to treat the volume deficit and correct the acid-base and electrolyte abnormalities and (2) the rate of administration to optimize outcome. Therefore, knowledge of electrolyte composition in plasma and of the various types of commercially available fluids is essential in order to select the appropriate therapy for the individual animal. In addition to the therapeutic aspects of fluid therapy, a knowledge of the side effects and complications of inappropriate fluid selection and rate of delivery is also important. With the individual requirements of each patient seen in a practice, the prescription approach to parenteral fluid therapy will optimize patient response to this extremely important aspect of overall patient management as well as make the practice of fluid therapy intellectually stimulating. This article has introduced the clinician to the parenteral fluids available and their indications in veterinary patients; it also contains a discussion of how to utilize preferred solutions for treatment of specific diseased states. Although there are definite "right" and "wrong" fluids to select for specific problems, there also remains individual preference in fluid choice, which is based on appropriate laboratory data and the practitioner's clinical judgment of the status of the individual patient vis-à-vis the spectrum of its disease. Recommendations for selection of different fluid types to treat similar conditions are usually based on these variables.

Decreased activity of acid alpha-glucosidase in a patient with persistent periocular swelling after infusions of hydroxyethyl starch

After infusion therapy with hydroxyethyl starch (HES) on account of sudden hearing loss, a 68-year-old woman developed a marked and persistent periocular swelling. This extraordinary adverse effect caused us to search for an explanation by means of histopathology, immunohistochemistry, immunoelectron microscopy and biochemistry. In lesional periocular skin and in normal-appearing skin, lysosomal storage of HES could be detected with a specific HES antibody in histiocytes, endothelial cells, basal keratinocytes and small nerves. In the periocular skin, a stronger deposition of HES was found in addition to distinct xanthomatous changes as well as features of lymphoedema. In view of lysosomal HES storage we measured the pH-dependent activity of the lysosomal alpha-glucosidase (GAA) in cultured fibroblasts. We found a 50% decreased activity of the acid GAA, which is consistent with a heterozygous state of glycogenosis type II (Pompe's disease) and potentially of pathogenetic relevance for the intralysosomal accumulation of HES. Xanthomatous changes and lymphoedema are likely to be secondary effects, but contribute considerably to the clinical manifestation of persistent visible swelling. This observation could point to a role for GAA in the elimination of tissue-stored HES. Patients with decreased activities of GAA may be at risk of unusual adverse effects following extraordinary and prolonged tissue storage of HES, especially if it is infused in large quantities.

Effect of isovolaemic haemodilution on visual outcome in branch retinal vein occlusion

AIMS

To assess the efficacy of isovolaemic haemodilution therapy (IHT) in the treatment of patients with branch retinal vein occlusion (BRVO).

METHODS

Patients presenting with BRVO between 1 July 1991 and 31 August 1993 were eligible for inclusion and randomised into treatment and control groups. Patients randomised to receive IHT were treated for 6 weeks with venesection and volume replacement using hydroxyethylstarch, a plasma expander. The target haematocrit was 35%. Follow up was for 1 year.

RESULTS

The baseline visual acuity of the two groups was similar at 0.74 and 0.75 logMAR units (Snellen 6/36), for the IHT and control groups, respectively. At 6 weeks, visual acuity in the IHT group had improved by 0.20 logMAR units (2 lines on the Bailey-Lovie chart) (p = 0.0001). Vision was unchanged in the control group. At 1 year, the IHT group exhibited an improvement of 0.43 logMAR units. By comparison, the improvement in the control group at 1 year was significantly less at 0.17 logMAR units (p = 0.03). The final visual acuity in the IHT and control groups was 0.30 (Snellen 6/12) and 0.60 (Snellen 6/24) logMAR units, respectively.

CONCLUSIONS

The results support the theory that IHT has a positive effect on the visual outcome in patients with BRVO.

The effect of hetastarch on serum colloid oncotic pressure in hypoalbuminemic dogs

The purpose of this study was to determine the duration of action of a single dose of hetastarch, a synthetic colloid, in hypoalbuminemic dogs. Thirty hypoalbuminemic dogs (albumin concentration, < or = 2.0 g/dL) received 1 dose of hetastarch each, with an average dose of 18.1 mL/kg. Doses ranged from 7.7 to 43.9 mL/kg, with the majority of doses (n = 26) in the range of 10 to 25 mL/kg. Dogs were allotted to one of several groups: all dogs, dogs with acute gastrointestinal protein loss, dogs with chronic gastrointestinal protein loss, all dogs with gastrointestinal protein loss, and dogs with nongastrointestinal protein loss. Colloid oncotic pressure was measured immediately before and immediately after hetastarch administration, and 12 hours after hetastarch administration. There was a significant (P < .001) increase in the mean colloid oncotic pressure after hetastarch treatment in all groups, except in the group with acute gastrointestinal protein loss. Twelve hours after hetastarch treatment, the mean colloid oncotic pressure had decreased significantly (P < .001) from the immediate post-treatment value in all groups, except in dogs in the groups with acute and chronic gastrointestinal protein loss. Twelve hours after hetastarch treatment the mean colloid oncotic pressure was not significantly (P < .001) different from the baseline mean colloid oncotic pressure in any of the groups. Twenty-three dogs (77%) survived their illness and were sent home, whereas, 7 (23%) died or were euthanized. The effect of a single dose of hetastarch on raising colloid oncotic pressure in dogs with hypoalbuminemia decreases significantly within 12 hours of administration, and is no longer significantly above baseline values. We conclude that multiple dosing is necessary to prolong the beneficial effects of hetastarch.

Mechanisms of postoperative prolonged plasma volume expansion with low molecular weight hydroxethy starch (HES 200/0.62, 6%)

OBJECTIVE

To define the mechanisms of the stable and prolonged post-operative plasma volume expansion observed with Hydroxyethyl Starches (HES) and to determine whether a partial intravascular hydrolysis of large molecules contribute to reinforce the colloid-osmotic effect.

DESIGN

Prospective, pharmacologic study using single dose of drug.

SETTING

University-based, post-anesthesia care unit.

PATIENTS

The protocol was performed during the post-operative period, in 10 patients after stable recovery from general anesthesia for carotid endarterectomy.

INTERVENTIONS

HES 200/0.62 (500 ml) was infused over 30 min. Standard hemodynamic and biological variables, HES concentration and colloid osmotic pressure were obtained at each measurement. Plasma volume was calculated using 51Cr-labelled RBCs. Patterns of changes in number average molecular weight (MWn) and weight average MW (MWw) were measured using gel permeation chromatography. Measurements were obtained at control, end of infusion, 1 h, 3 h, 6 h and 24 h after infusion.

MEASUREMENTS AND MAIN RESULTS

Plasma volume increased by 693 ml (+21%) after the infusion of HES and remained constant over 24 h. HES concentration progressively decreased to reach a value of 35% of the peak at 24 h. MWn and MWw, initially decreased when compared with the dose solution and changed little in the 24 h study period. Diuresis significantly decreased at 3 h up to 24 h. Plasma albumin decreased after infusion and then progressively increased to reach a significantly higher value at 24 h than after infusion.

CONCLUSION

Initial plasma volume expansion and decrease in HES concentration agree with previously-published data. Maintenance of plasma volume expansion over 24 h was not related to a partial intravascular hydrolysis. Low elimination rate of HES, extravascular mobilization of albumin and post-operative renal adaptations were possibly the 3 main mechanisms to explain a prolonged plasma volume expansion with HES 200/0.62, 6%.

The use of hetastarch as adjunct therapy in 26 dogs with hypoalbuminemia: a phase two clinical trial

The purpose of this study was to evaluate the safety and efficacy of the synthetic colloid hetastarch in dogs with hypoalbuminemia. Individual doses of hetastarch ranged from 9 to 27 mL/kg, and multiple doses were used frequently. Total doses ranged from 9 to 59 mL/kg. Colloid oncotic pressure was measured in 13 dogs before and after treatment. Mean colloid oncotic pressure +/- SD was 9.32 +/- 2.35 mm Hg before treatment and 16.41 +/- 1.61 mm Hg in 8 healthy pet dogs used as controls. The difference in these values was significant (P < .001). There was a significant increase in mean colloid oncotic pressure after the first dose of hetastarch, but there was no relationship between the dose of hetastarch and the magnitude of increase in colloid oncotic pressure. Peripheral edema or body cavity transudates resolved or decreased in 83% of the dogs despite concurrent use of crystalloid fluid therapy. There was also no relationship between the dose of hetastarch and resolution of edema. Worsening of the results from coagulograms occurred in 5 of 18 dogs, and included increased prothrombin time (n = 1), increased partial thromboplastin time (n = 5), and decreased platelet count (n = 3). Bleeding that occurred in 3 dogs could not be directly attributed to the hetastarch. There was no relationship between the dose of hetastarch and worsening of the values in the coagulograms.

Hydroxyethylstarch deposits in human skin--a model for pruritus?

Severe itching for unknown reasons has been reported after administration of hydroxyethylstarch (HES) in haemodilution therapy of humans. After HES treatment, vacuoles in cells of various organs in humans have been shown, predominantly affecting the mononuclear phagocyte system. These vacuoles present indirect evidence for phagocytosis of HES particles. Since phagocytosis is also known to occur in the skin, this organ might represent a target for HES deposition, resulting in subsequent release of mediators responsible for the observed itching. The aim of the present investigation was to study skin biopsies of patients, who had received HES and suffered subsequently from itch. Skin sections were investigated for morphological impairment by means of light and electron microscopy, immunohistochemistry and immunoelectron microscopy using a polyclonal anti-HES antiserum. Storage of HES was demonstrated in the skin of all patients, mainly in dermal macrophages, endothelial cells of blood and lymph vessels, some perineural cells and endoneural macrophages of larger nerve fascicles, some keratinocytes and Langerhans cells. Treatment with antihistaminic agents proved ineffective in these patients; this fits with the observation that morphological signs of histamine release from mast cells were absent. These findings indicate that other mediators from HES-affected cells must be responsible for the development of the itching. Thus, investigation of HES storage may be a useful contribution to the elucidation of release of itch mediators and induction of pruritus.

Human monocytes and keratinocytes in culture ingest hydroxyethylstarch

Severe itching for unknown reasons has been reported after administration of hydroxyethylstarch (HES) in haemodilution therapy of humans. In skin sections from patients who had received HES for otological reasons HES deposition was found by immunohistochemical methods in keratinocytes, epidermal dendritic cells, endothelial cells and macrophages. The aim of the present investigation was to study the interaction of cultured human monocytes and keratinocytes, normal (HNK) and malignant (KB, A431), with FITC-conjugated HES (200/0.5). Peripheral blood monocytes from healthy donors were isolated by Ficoll-Hypaque gradient centrifugation and adherence to plastic surfaces. Cells were incubated with HES-FITC (1 mg/ml) for 10, 20, 30, 60 and 120 min at 37 degrees C, washed several times to minimize cell-associated HES-FITC. The uptake of HES-FITC (200/0.5) was detected by fluorescence microscopy and flow cytometry. Monocytes and keratinocytes (HNK, KB, A431) acquired significant amounts of HES-FITC after 120 min. Endocytosis was blunted by the addition of unconjugated HES in ten-fold concentration. At 4 degrees C, a further inhibition was achieved, indicating an uptake of HES-FITC by monocytes and keratinocytes in vitro. These results indicate that a connection between the storage of HES by keratinocytes and monocytes and the observed itching in patients might be possible.

[Pharmacology of low molecular weight hydroxyethyl starch]

In the last ten years, the practice of plasma volume expansion has changed significantly. Most clinicians have put a stop to the use of fresh frozen plasma because of growing concerns about hepatitis and AIDS transmission. Today, natural and synthetic colloids and crystalloids are used to a great extent. Although clinical practice varies from one institution to another, the most widely observed change was a major increase in the administration of human serum albumin (HSA). As a result, the cost of plasma volume expansion became so high that it justified finding safe and cheaper alternatives to HSA. Low molecular weight, hydroxyethylstarch (HES) are the synthetic colloids which are closest to HSA. HES are modified natural polymers whose physico-chemical properties are defined by their molecular weight and molar substitution ratio. Average molecular weights of these poly-dispersed solutions are approximately 200 to 250 kd (in weight) and 60 kd (in number). Hydroxyethylation, which slows down hydrolysis by alpha-amylase, is best quantified by the molar substitution ratio between the proportions of hydroxyethyl-ether and glucose. HES have pharmacokinetic properties which are independent of molecular weight and directly related to the molar substitution ratio. The two HES available in France are Elohes and Lomol, Elohes, at a concentration of 6%, has a colloid-osmotic effect close to that of plasma. It induces an initial plasma volume expansion greater than that of the infused volume, and has a long lasting effect (24 h) related to its molar substitution ratio (0.62). Lomol, at a concentration of 10%, is hyperoncotic.(ABSTRACT TRUNCATED AT 250 WORDS)

Severe anaphylactoid reaction to hydroxyethyl starch

A case is presented of a severe anaphylactoid reaction to hydroxyethyl starch solution that occurred peri-operatively and required extended intensive management of the resultant bronchospasm and hypotension. Subsequent intradermal injection of hetastarch produced a delayed positive response, suggestive of a complement-mediated mechanism.

Albumin/hetastarch drug utilization review in an operating room pharmacy

A prospective drug utilization review (DUR) was performed on the colloids albumin 5% and hetastarch 6% at the University of Illinois Hospital Operating Room Pharmacy. This DUR's purpose was to evaluate the usage patterns of the two colloids. With the addition of hetastarch 6% to the formulary, an alternative colloid was available that could be therapeutically substituted for albumin 5% at a cost savings. Its usage, however, was not what would have been expected. Usage information was obtained by placing utilization forms inside the individual boxes of albumin 5% and hetastarch 6%. These forms were completed by the anesthesiologists and returned to the pharmacy, where the remainder of each form was completed. It was concluded that 93 percent of the patients administered albumin 5% could have received hetastarch 6%. Hence, potential yearly savings of approximately $12,346.00 could be realized by the Department of Pharmacy.

Haemodilution therapy in ischaemic stroke: plasma concentrations and plasma viscosity during long-term infusion of dextran 40 or hydroxyethyl starch 200/0.5

In 21 patients with ischaemic strokes we have monitored plasma viscosity, total plasma concentration, numeric average molecular weight (Mn), and weight average molecular weight (Mw) of Dextran 40 (dextran) and hydroxyethylstarch 200/0.5 (HES) during 10 days of treatment (days 1-4, 2 X 500 ml; days 5-10, 1 X 500 ml). Plasma concentrations of dextran increased during the first 4 days (8.3 mg X ml-1 on the first day to 18.0 mg X ml-1 on the fifth day), reached an apparent steady state of 17.2 mg X ml-1 during the next 6 days, and declined subsequently with a half-time (t1/2) of 4.03 days. After ten days treatment Mn and Mw were shifted towards higher values. Plasma viscosity increased from 1.26 mPas to 1.69 mPas on Day 10 (p less than 0.01) and was linearly correlated with the total plasma concentration of dextran (p less than 0.001; r = 0.88). Total plasma concentrations of HES averaged 11.7 mg X ml-1 on Day 1 and 12.4 mg X ml-1 on Day 5. The molecular weight distribution did not change during the infusions but decreased in comparison with the administered solution. Plasma viscosity fell from 1.40 mPas to 1.30 mPas at Day 10 (p less than 0.05) and was not related to the concentration of HES. The haemodiluting effect, as indicated by a decrease of the haematocrit, was 22% and 16.8% for dextran and HES respectively. These data suggest several advantages of HES compared with dextran in haemodilution therapy of ischaemic stroke.

[Ascites as a complication of hepatic storage of hydroxyethyl starch in long-term dialysis]

Three adult dialysis patients developed ascites after having received repeatedly the plasma substitute hydroxyethyl starch (HES 40/0.5). In two cases (total dose 180, and 330 g HES, respectively) the ascites was reversible after discontinuation of the HES administration. In the third case (total dose 915 g HES) the ascites could be controlled only by implantation of a Denver shunt. In this latter case it was shown by histological, electron microscopical, and biochemical findings that the ascites was caused by hepatic sinusoidal obstruction due to an extreme storage of HES in the sinusoidal lining cells. Additional storage was detected in hepatocytes, bile duct epithelia, endothelial cells, and fibroblasts in the portal tracts. Biochemically HES was found in liver tissue at a concentration of 4% (w/w). Although in renal impairment plasma clearance of HES is not significantly different from normal individuals, long-term administration of HES must be regarded inadvisable because of tissue storage which apparently is especially significant in this condition.

Effect of hydroxyethyl starch and dextran on plasma volume and blood hemostasis and coagulation

Six healthy male subjects were given in a crossover fashion medium molecular weight (HES 125) and low molecular weight (HES 40) hydroxyethyl starch, dextran, and balanced salt solution by intravenous infusion. The plasma volumes were determined using labeled albumin and plasma protein measurements. Three properties of factor VIII protein complex and indices of blood coagulation and hemostasis were measured before and after the infusions. Both the salt solution and HES 40 increased plasma volume, but their effect wore off within 3 hours. Dextran and HES 125 increased plasma volume significantly (P less than 0.001) more than the salt solution did, and the expansion was maintained for 24 hours. Plasma volume increases (dextran and HES 125) were associated with high nonglucose carbohydrate levels in plasma and low levels in urine. No or slight increases in plasma volumes (HES 40), on the other hand, were associated with low and high carbohydrate levels in plasma and urine, respectively. Serum alpha-amylase activity increased significantly after both HES preparations as compared to salt solution. Dextran and HES 125 decreased all the three values of factor VIII, these decreases being maximal 3 to 6 hours after administration and highest (about 25 per cent) for F VIII R:Ag and F VIII R:cof. It is concluded that HES 125 and dextran are equally effective plasma expanders.

Colloids vs. crystalloids--a continuing controversy

The crystalloid vs. colloid controversy is based on a disagreement as to the most effective, safest, and most economical method of maintaining an effective plasma volume in shock patients. This review discusses Starling's law of fluid movement, with a definition of each term in the normal physiological state, and presents examples of how each component of Starling's law differs in the two major types of pulmonary edema: (1) cardiogenic and (2) noncardiogenic. The colloid-crystalloid literature is reviewed briefly with an emphasis on the major studies that support each side, and the deficiencies in each study. The arguments supporting each side of the crystalloid-colloid debate are then listed, with a summary that demonstrates the areas of agreement between the two schools of thought on fluid resuscitation. Each major colloid (albumin, dextran, hetastarch) and a representative crystalloid (lactated Ringer's) are discussed in terms of their chemistry; pharmacology and indications; and precautions, adverse reactions, and side effects. A table is included that summarizes the available products' data regarding composition, volume expansion, duration of expansion, half-life, metabolism, elimination, precautions, adverse reactions, and dose.