Intravascular persistence of hydroxyethyl starch in man

The Incidence and Risk Factors of Acute Kidney Disease after Total Knee Arthroplasty with Early Postoperative Volume Supplement

Background

Etiology of acute kidney disease (AKD) after total knee arthroplasty (TKA) was considered as multifactorial. However, the role of early postoperative volume supplement in AKD rate has not been investigated. The purpose of this study was to evaluate the incidence and risk factors of AKD in patients with early volume supplement following TKA.

Methods

This was a retrospective study with 458 patients who underwent unilateral TKA. All the patients received 6% tetrastarch, 7.5ml/kg, early in the postoperative period. Postoperative AKD was defined as the postoperative creatinine level ≥ 1.5 times compared with preoperative data. Potential variables associated with AKD were analyzed by multivariate logistic regression model to identify the AKD risk factors in TKA patients after early postoperative volume supplement.

Results

The AKD rate was 3.3% (15 patients) in all patients. Age (OR = 1.09; P = .031) and coronary artery disease (CAD) (OR = 3.63; P = .034) were associated with increased risk of development of postoperative AKD. Other comorbidities as hypertension, diabetes, and CKD were not statistically significant risk factors.

Conclusion

Our study demonstrated that age and CAD were independent risk factors of AKD in TKA patients. However, the common risk factors as hypertension, diabetes, and CKD were not significantly associated with AKD after TKA if early postoperative supplement of tetrastarch is administered.

Contribution of Raman spectroscopy in nephrology: a candidate technique to detect hydroxyethyl starch of third generation in osmotic renal lesions

Raman spectroscopy, a candidate tool for detection of HES, a volume expander administrated after hemodynamic instability, in the kidney.

Pruritus precipitated by hydroxyethyl starch: a review

Hydroxyethyl starch (HES) is widely used for fluid management in broad populations of patients, particularly in the surgery and intensive care settings. Pruritus, often manifested as pruritic crises, is increasingly being recognized as a common major adverse effect of HES administration. This iatrogenic form of pruritus is frequently severe and protracted with a serious negative impact on patient quality of life, including sleep disturbance, disruption of daily routine and mental distress. Such pruritus is generally refractory to available therapies and can persist for up to 12-24 months. All currently clinically available HES solutions entail the risk of pruritus, including those of diverse molecular weights and substitutions. Although dose dependent, HES-induced pruritus nevertheless can often be provoked by relatively low routine doses. The pathophysiological basis for pruritus is the widespread tissue deposition of HES, prominently in macrophages. HES tissue deposits are long lasting and sometimes massive. Usually several weeks elapse between HES exposure and the onset of pruritus. Consequently, it is important to inquire about prior HES exposure in the diagnostic evaluation of pruritus sine materia. Awareness about the scope of the pruritus problem needs to increase among physicians administering HES. Well-designed clinical outcome studies are needed to assess more fully the incidence, dose dependency and mechanisms of pruritus with particular HES solutions.

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.

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.

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%.

Efficacy of pentastarch in granulocyte collection by centrifugal leukapheresis

The efficacy of 6% hydroxyethyl starch (hetastarch, HS) in enhancing granulocyte harvest by centrifugal leukapheresis has been described by a simple equation which predicts the granulocyte collection efficiency (GCE) based on an intrinsic donor variable, the erythrocyte sedimentation rate (ESR): GCE(%) = 1.3 ESR (mm/hr) + 45. Ten percent low molecular weight hydroxyethyl starch (pentastarch, PS) has been reported to be as effective as HS with potentially fewer adverse donor reactions (ADR). The derivation of an analogous equation for PS under conditions previously reported for HS may quantify PS efficacy and allow comparison to HS. We prospectively measured the in vitro and the in vivo effects of PS on the donor ESR in 53 granulocyte collections from 44 donors using the model CS-3000 Plus blood cell separator (CS). We then correlated the findings with the GCE of each procedure and derived an equation which expresses GCE in terms of baseline donor ESR. The in vitro addition of PS increased the donor ESR 2.4-fold, but its administration to a donor during a collection procedure did not appreciably change the ESR. Higher baseline donor ESR was more likely to result in more efficient cell collections: GCE (%) = 0.8 ESR (mm/hr) + 20; (r = 0.37). For granulocyte harvests using the CS and PS as the sedimenting agent 1) baseline donor ESR affects granulocyte harvests, but the poor correlation does not allow an accurate prediction of GCE and cell yield from the baseline donor ESR; 2) in comparison with HS (results from a previous study), PS may be less effective in vitro and not effective in vivo in elevating ESR, and may be less effective in enhancing granulocyte harvest; and 3) the parameters (slope, y-intercept, correlation coefficient) which define the linear relationship between baseline donor ESR and GCE may serve collectively as a quantitative measure of the effectiveness of different hydroxyethyl starch agents in enhancing granulocyte harvests. These parameters may be helpful in rapidly assessing the clinical efficacy of new, potentially useful hydroxyethyl starch agents prior to initiating a randomized, controlled clinical trial.

[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)

[Pharmacokinetics and changes in the physical properties of blood and urine after administration of dextran 60000]

A study was carried out to assess the changes induced by an infusion of dextran, molecular weight 60,000 daltons, in blood and urine. Plasma and urine dextran and serum protein concentrations, haematocrit, blood and urine viscosities, and blood oncotic pressure were measured in 10 consecutive male patients. Fifteen min after administration of 20 ml dextran 1000 (Promit), they were each given 500 ml (30 g) dextran 60 (Hemodex) over 30 min for plasma volume expansion. The measurements were carried out at the end of the infusion, and then at regular intervals over a 48 h period. The highest dextran blood concentrations were found at the end of the infusion, decreasing thereafter with a distribution half-life of 1.83 +/- 0.64 h, and an elimination half-life of 25.5 +/- 7.6 h. Haematocrit values decreased by 12%, and serum protein concentrations by 9.5%, after the end of the infusion. These changes remained significant for 9 h; they were probably due to the dilution effect of 500 ml of dextran. Colloid osmotic pressure was not significantly altered (20.7 +/- 4.7 mmHg vs. 23.1 +/- 5.1 mmHg 48 h after the end of the infusion). The colloid osmotic pressure due to dextran 60 compensated for the fall in protein concentration. A decrease in blood viscosity was found at different shear rates, despite dextran 60 being highly viscous. This could also be explained by a dilution effect. The highest degree of urinary excretion occurred 30 min after the end of the infusion, and lasted for 3 h. Forty-five percent of the total dextran dose had been excreted by the 48th hour.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of crystalloidal and colloidal solutions for volume replacement in hypovolemic shock

A wide variety of colloidal and crystalloidal fluids, as well as blood and blood products, are available to the clinician for treatment of the hypovolemic patient. These fluids vary with respect to the size, shape, and concentrations of electrolytes, colloidal molecules, and/or cellular components, duration of volume-expanding effects, incidence of allergic reactions, and effect on the coagulation system. When these fluids are administered intravenously, their distribution in the vascular, interstitial, and cellular compartments can be predicted from fundamental physiological principles as well as from the results of laboratory and clinical research. It is thus recognized that colloidal fluids and blood provide more rapid expansion of the intravascular space when compared with crystalloidal fluids. Similar volumes of crystalloidal fluids more rapidly expand the interstitial and intracellular spaces. These principles guide therapy in hypovolemic shock. A logical decision regarding intravenous fluid therapy may be based on the nature of the volume deficit (blood, plasma, or selective protein loss, loss of free water and/or electrolytes) and the predicted changes in cellular and extracellular compartments.

Hydroxyethyl starch: an alternative to plasma for postoperative volume expansion after cardiac surgery

Hydroxyethyl starch (HES) is a recently developed synthetic volume expander. Forty patients undergoing coronary artery surgery were randomized to receive either HES or plasma protein fraction (PPF) as non-blood volume replacement according to standard haemodynamic criteria. The two groups were comparable in all respects. The median colloid use in the first 24 h was 950 ml (range 500-1500) in the HES group and 975 ml (350-2000) in the PPF group (not significant). There was no difference in blood use, urine output or blood loss between the two groups. Tests of coagulation showed the postoperative changes usual in cardiac surgical patients. There was no difference between the two groups in thrombin time, prothrombin time, activated partial thromboplastin time, or fibrinogen concentration. Similarly, tests of platelet function and Factor VIII and von Willebrand Factor activity showed no difference between the two groups. We conclude that HES is a safe and effective volume expander, and its relative lack of expense and ease of availability make its routine use after cardiac surgery an attractive proposition.

Accumulation of hydroxyethyl starch (HES) in the liver of patients with renal failure and portal hypertension

Hydroxyethyl starch (HES) has gained wide clinical acceptance as a colloidal plasma substitute. We were able to study the liver biopsies of two patients with renal failure who developed ascites after repeated infusions of HES. All types of liver cells displayed massive accumulation of HES with the morphologic resemblance to a storage disease. These changes could be distinguished clearly from the lesions of a hereditary disorder by light and electron microscopy. Although it is difficult to establish a causative role for HES in the development of ascites on the bases of morphological changes alone, one should be cautious about giving HES to patients with renal failure until exact data from further experimental studies are available.

Effects of hydroxyethylstarch (Hespan), a plasma expander, on the functional activity of the reticuloendothelial system. Comparison with human serum albumin and pyran copolymer

The purpose of the present investigation was to determine if RES activity was altered after the infusion (bolus i.v. injection over approximately 3-5 min) of hydroxyethylstarch (HES). RES function was determined by vascular clearance of 51Chromium-labeled sheep erythrocytes and the subsequent uptake into the liver, spleen, lungs, and thymus at 1 hr, 3 hr, 6 hr, 1 day, 3 days, and 7 days post infusion. Infusion with the low doses of HES (20 and 40 ml/kg) produced changes in vascular clearance which were comparable to physiological saline. Infusion with 80 ml/kg HES produced a biphasic response with a modest suppression of vascular clearance (i.e., 151% increase in half life) and hepatic phagocytosis (50%) during the first 6 hours after injection, followed by recovery at 24 hours and a stimulation in hepatic uptake (42%) after 3 days. These effects by HES were compared to those produced by infusion with 80 ml/kg HSA, a comparable colloid and with 80 ml/kg pyran copolymer, a positive control.

Peripheral blood lymphocyte numbers, lymphocyte proliferative responses in vitro, and serum immunoglobulins in regular hemapheresis donors

Selected tests of lymphoid function were used to screen a population of volunteer hemapheresis donors. Testing included: 1) absolute lymphocyte numbers, and percentage of T-cell, B-cell, and mononuclear phagocytes, 2) serum immunoglobulins, and, 3) in vitro proliferative responses to lectin mitogens (phytohemagglutinin, concanavalin A, and pokeweed mitogen), soluble antigens (staphylococcal filtrate, candida, and streptococcal varidase), and cell-bound alloantigens (mixed lymphocyte culture). A control population of first-time plateletpheresis donors was examined similarly. Regular donors manifested a small but statistically significant decrease in absolute lymphocyte counts (p less than 0.02), and IgM (p less than 0.02) compared to controls. Leukapheresis donors also manifested significant decreases in percentage of T cells (p less than 0.02). These findings are qualitatively similar to changes reported following intensive lymphocytapheresis and indicate the need for conservative policies regarding donation frequency in hemapheresis programs.

Studies on low-dose hydroxyethyl starch leukapheresis. Rate of elimination of HES in vivo and function of the harvested granulocytes in vitro

We studied the rate of in vivo elimination of hydroxyethyl starch (HES) given during low dose HES leukapheresis in 9 donors and the effect of this procedure on the in vitro function of granulocytes in 3 donors. HES was eliminated more rapidly than has been previously reported for standard leukapheresis. Serum HES declined to one-half of peak concentration between 1 and 2 days and to one-tenth of peak in 23 days. No HES could be detected in serum 90 days after leukapheresis. The function of the harvested granulocytes was compared to that of granulocytes collected just prior to the procedure by measuring superoxide generation, ingestion and cell motility. There was no significant difference in the function of granulocytes harvested by low dose HES leukapheresis compared to those collected by venipuncture before the procedure.

Colloid-induced changes in bleeding following liver resection in the rat

The effect of preoperative infusion of Ringer's solution, Ringer's acetate solution, dextran 70, dextran 40, degraded gelatin and hydroxyethyl starch on haemostasis after standardized liver resection was studied in the rat. Ringer's and Ringer's acetate solutions did not affect haemostasis more than expected from haemodilution. Dextrans, degraded gelatin and hydroxyethyl starch caused a significant increase in bleeding time and blood loss. APT time was significantly increased after infusion of hydroxyethyl starch. Dextran and hydroxyethyl starch impaired ADP- and collagen-induced aggregation. Platelet aggregation was not affected by the infusion of Ringer's solution or Ringer's acetate solution as compared to non-treated controls.

Biliary excretion of hydroxyethyl starch in man

The extent of biliary excretion of hydroxyethyl starch (HES) in man after intravenous administration of 500 ml of a 6% solution to nine healthy male volunteers was determined using a specific gas chromatograph mass spectrometer selected ion monitoring procedure. On the average, less than 1% of the administered dose was recovered in feces over a 14 day period.

Chemical characterization of the persistent fraction of hydroxyethyl starch in rat serum and spleen

Hydroxyethyl starch (HES) found in rat serum and spleen after single and daily administrations of 0.9 g/kg for 1 week was characterized by gas-liquid chromatography. There was very little difference in the degree of substitution (D.S.) and molar substitution (M.S.) of HES in serum samples obtained at 1 hour and 57 days after multiple doses and of HES in spleen samples obtained at 1 hour and 168 days after a single dose of HES. The small increase in D.S. and M.S. was due to a decrease in the glucose content and not due to a change in the ratio of mono- to poly-substituted glucoses.

Hetastarch: an overview of the colloid and its metabolism

Hetastarch, ethoxylated amylopectin, has found clinical utility as a plasma volume expansion agent, a sedimenting agent during pheresis, and a pump priming fluid. Hetastarch is a complex mixture of derivatized amylopectin molecules of various molecular sizes. The derivatization causes resistance to enzymatic hydrolysis, therefore, allowing hetastarch sufficient vascular residence time to be an effective vascular osmotic agent. This has led to its use as a volume expander and to its consequent use as a pump priming fluid. The metabolism of hetastarch proceeds through alpha-amylase hydrolysis of glycosidic bonds, yielding molecules small enough for renal clearance, but does not result in complete hydrolysis. Hence, glucose is not a significant product of hetastarch metabolism. Metabolism proceeds at such a rate that volume expansion is seen for 24-36 hours with a maximum effect (100-172 percent of the infused volume) occurring shortly after infusion. Ninety percent of the dose is eliminated with a half-life of about 17 days.

Pharmacokinetics of hydroxyethyl starch in normal subjects

To determine the elimination of high-molecular-weight hydroxyethyl starch (HES, Mw 450,000) in normal subjects, ten volunteers were given 500 ml 6% HES solution by intravenous infusion, and serial blood and urine samples were collected for nonglucose total carbohydrate determination. On the average, 46 and 64 per cent of the dose was excreted in the urine within two and eight days, respectively. The plasma concentration declined rapidly during the first week after infusion. The average terminal half-life was 17 days during the first 42 days, which accounted for elimination of about 90 per cent of the dose. The remainder was eliminated with a terminal half-life of 48 days determined between days 42 and 83 of the study. As expected, the infusion of HES resulted in plasma volume expansion over a 48-hour period during which time levels of nonglucose carbohydrates were above 3.5 mg/ml. HES is metabolized by alpha-amylase in the body. During the first 48 hours after infusion of HES, plasma alpha-amylase activity was significantly increased over control. Concomitantly, alpha-amylase activity in urine was also elevated but not significantly so.

[The elimination of hydroxyethyl starch 200/0.5, dextran 40 and oxypolygelatine (author's transl)]

After withdrawal of 400 ml whole blood and subsequent infusion of 500 ml of a colloidal plasma substituent, the intravascular and renal colloid elimination was investigated in 40 test subjects. The individual colloidal solutions could no longer be demonstrated in the intravascular space after the following times: 10% hydroxyethyl starch 200/0.5 (anthrone method) after six weeks, 10% dextran 40 (anthrone method) after two weeks, 6% hydroxyethyl starch 200/0.5 (anthrone method) after four weeks and 5.5% oxypolygelatine (hydroxyproline method) after two days. Colloidal plasma substitutes are polydisperse solutions with various molecular weights and degree of hydroxyethylation and therefore, also have a large number of different elimination constants. With repeated application, the intravascular colloid concentration shifts in favour of the molecules with a longer half life which are difficult to eliminate. The elimination of the clinically employed dextran 40 and oxypolygelatine solution could be best described with an open two-compartment model. As a result of its greater heterogeneity, the elimination of the moderately high molecular weight hydroxyethyl starch 200/0.5 could only be characterized approximately even assuming three elimination constants. In the first four days, the hydroxyethyl starch 200/0.5 was more rapidly eliminated compared to dextran 40. However, subsequently a very much lower elimination from the intravascular space was found for about 3% of the administered hydroxyethyl starch 200/0.5. Oxypolygelatine was eliminated especially rapidly. Accordingly, the greatest renal clearance was found for oxypolygelatine, which showed a close relation to the molecular weight. On the other hand, a rapid elimination simultaneously is followed by a correspondingly lower volume effect.

Pruritus after administration of hetastarch

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Adverse reactions to whole blood donation and plasmapheresis

Whole blood donation is recognized to be extremely safe, yet there have been reports of serious problems stemming from whole blood donation, and so-called "donor reactions" are regularly seen. While the physiologic causes of the common donor reactions are not completely understood, some effects of whole blood donation (such as transient iron deficiency) are understood but probably not significant. In order to avoid accepting any volunteer donor who might be at risk of a serious reaction, we may have been overly cautious in exclusion of potential donors. The pheresis donor is subjected to potential depletion of the protein or cellular elements being removed, problems caused by the device used for automated pheresis, or problems related to the infusion of potentially toxic substances. Documented benefit to the patient must balance these additional risks.

Transfusion of granulocyte rich buffy coats to neutropenic patients

Granulocyte rich buffy coats were transfused to infected neutropenic patients when leukapheresis donors were not available. Efficacy of transfusions was evaluated from data supplied by hospitals administering them. Buffy coats separated from ACD blood contained a mean of 4.9 X 10(8) granulocytes. Fifty-seven patients received a course consisting of a mean of 3.8 transfusions. Of these, 27 received a mean of 17.5 units per transfusion and had a survival rate of 44.4%, which was not significantly different from the 50.0% found in 30 who received a mean of 11.1 units per transfusion. No significant difference in survival rate was found between 31 patients with acute leukemia and 26 with other disorders or 38 patients with positive and 19 with negative cultures. Finally, no significant difference in survival rate was noted between patients who received a course of greater than or equal to four transfusions or less than or equal to three transfusions in any of the above groups. Survival rates were less than those generally reported following similar courses of leukapheresis units. Buffy coat transfusions consisting of a mean of approximately 17.5 units as produced during this study have therefore been shown to be not generally beneficial. The increased survival seen in some studies utilizing leukapheresis products may relate in part to the larger number of granulocytes they contained. Greater benefit from buffy coat transfusions might result if the number of granulocytes infused were increased. Evaluation of possible efficacy associated with transfusions of increased numbers of buffy coat units further enriched with granulocytes may be justified when leukapheresis donors are not available.

Urinary excretion kinetics of hydroxyethyl starch 350/0.60 in normovolaemic man

Rates of urinary excretion concomitant with the molecular size distribution of filtered polymer fragments were determined in five normovolaemic men dosed with 30 g/m2 BSA of a species of HES (HES 350/0.60) possessing a M-W of 350 000 combined with an MS of 0.60. Approximately 13% of the total injected dose of HES 350/0.60 was excreted in urine 1 hr after dosing, and 45% by 72 hours. Gel filtration of Sepharose CL-4B revealed that aliquots of urine collected 1 hour after injection contained polymer fragments of HES 350/0.60 with values of Kav ranging between 0.88 and 0.84, and possessed a Stokes radius (r = 32A) similar to that of Dextran 20 (M-W 22 700). Polymer fragments of HES 350/0.60 excreted 6 to 48 hours after dosing, however, possessed a Kav ranging between 0.78 and 0.73 with a Stokes radius (r = 45A) similar to that of Dextran 40 (M-W 41 000). All filtered polymer fragments were less polydisperse relative to both the injection solution (Kav 0.60) and residual material recovered from blood immediately after injection (Kav 0.72). These data support the hypothesis that the excretion of HES 350/0.60 occurs in two distinct phases: a rapid phase of elimination dependent on the M-n of the injected solution, and a slower phase dependent on the MS (degree of resistance to alpha-amylase attack). This study, in conjunction with our previous investigation of the changes in circulating HES 350/0.60, define the basic differences between clearance and excretion of the dextrans and of the rapidly degraded species of HES. These data are relevant to the utilisation of HES 350/0.60 during centrifugal leucapheresis.

Donor toxicity in granulocyte collections: association of lichen planus with the use of hydroxyethyl starch leukapheresis

A normal male volunteer developed lichen planus in association with leukapheresis, with HES used to increase granulocyte yield. Although there is no direct proof of a causative relationship, the temporal association of the onset of initial symptoms and HES infusion strongly supports such a conclusion.

Intravascular persistence of hydroxyethyl starch (HES) after serial granulocyte collections using HES in man

In 30 granulocyte donors undergoing one or more infusions of 6% hydroxyethyl starch (HES) solution plasma HES concentrations were measured by single radial immunodiffusion. Serial HES applications led to a cumulative increase in plasma HES levels. Up to 3 months after the last HES infusion, plasma concentrations in the range of 3 mg/ml were demonstrable. A possible influence of HES deposits upon reticuloendothelial system function is discussed.

Changes in the molecular size distribution and post-transfusion survival of hydroxyethyl starch 350/0.60 as influenced by a lower degree of hydroxyethylation: a study in normal man

The need to provide a greater rate of colloid clearance from blood than is presently available with the long-acting dosage form of HES 450/0.70 prompted the clinical investigation of a new species of hydroxyethyl starch (HES) possessing a M-w of 350000 concomitant with a molar substitution of 0.60 (HES 350/0.60). The concentration of HES 350/0.60 in serum fell to half its peak value in 10.2 +/- 0.7 (SD) hour (in contrast to an IT50 of approximately 25 hours with HES 450/0.70). Levels of glucose in serum remained elevated in normal fasted subjects after dosing, suggesting that catabolism of the infused HES 350/0.60 was occurring. Hydrolysis of residual HES 350/0.60 was confirmed by Sepharose CL-4B gel filtration analysis of material obtained from serum, showing continual production of smaller molecules relative to the injected solution (in contrast to HES 450/0.70, in which intermediate polymer fragments are recovered). Recovered HES 350/0.60 material displayed a Kav ranging between 0.74 and 0.72 and possessed a Stokes radius (r = 45A) similar to that of dextran 40 (M-w 41000). HES 350/0.69 appears to offer the same advantages as the currently available long-acting HES 450/0.70 but is removed from blood approximately twice as rapidly. This more rapid hydrolysis of HEs 350/0.60 may be useful, for example, in avoiding cumulative build-up of colloid in the blood of normal donors undergoing consecutive leucapheresis procedures.

Post-transfusion survival of hydroxyethyl starch 450/0.70 in man: a long-term study

Intravascular persistence concomitant with changes occurring in the circulating molecular size distribution were determined in five healthy normovolaemic men dosed with 7 ml/kg of a 6% (w/v) solution of a species of hydroxyethyl starch (HES 450/0.70) possessing a M(w)- of 450 000 daltons combined with a molar hydroxyethyl group substitution (MS) of 0.70 (70 hydroxyethyl groups/100 glucose residues). The concentration of HES 450/0.70 in serum fell to 24% of its peak value (measured 2 minutes post injection) one week after the infusion. By 17 weeks after injection, < 1.0% remained in the intravascular space. The HES 450/0.70 material recovered from the bloodstream 2 minutes after injection was shown by gel filtration on a column of Sepharose CL-4B to be less polydisperse than the injected solution. The K(av) calculated for the peak of material eluted after one week showed a definite shift of molecular size toward that of a lower molecular weight composition. However, at four weeks the value of K(av) indicated a shift toward the high molecular weight region of the injected solution, and by seven weeks this movement was quite pronounced. These data clearly indicate the complex nature of the removal of HES 450/0.70 from the intravascular space of man and appear to substantiate previous clinical studies reporting that the MS plays the major role influencing the rate of elimination of this material from the bloodstream.

The plasma kinetics of hydroxyethyl starch 350/0.60: a potential new adjunct for centrifugal leucapheresis

A modified species of hydroxyethyl starch (HES 350/0.60) possessing a Mw- of 350,000 daltons combined with a molar hydroxyethyl group substitution (MS) of 0.60 (60 hydroxyethyl groups.100 glucose residues) was clinically assessed in seven normal subjects to determine the influence of these chemical modifications on intravascular clearance kinetics concomitantly with effects on the suspension stability (ESR) of blood. Following a standardised intravenous dose (30 gm.m2 BSA), the concentration of HES 350/0.60 in serum fell to half its peak value in 11.8 +/- 1.3 (SD) hours, while the ESR remained elevated for up to 12 hours post-injection. By adopting a Mw- of 350,000 daltons, the critical molecular weight (Cmw) of this colloid was surpassed, while the critical concentration (Cc), below which the suspension stability of blood is not affected, was shown to range between 0.3 and 0.5 gm.dl-1. In comparison to the present species of HES (Mw- 450,000 daltons, MS: 0.70) utilised as a sedimenting agent duirng centrifugal leucapheresis, HES 350,000/0.60 appears to affect the ESR in a similar manner, but is removed from the intravascular space approximately twice as rapidly. This more rapid clearance should be useful in avoiding cumulative build-up of HES in blood concomitant with reducing the total amount of intravascular H2O bound to this colloid, in normal and CML donors undergoing multiple cell collection procedures.

In vitro comparison of the erythrocyte sedimenting properties of dextran, hydroxyethyl starch and a new low-molecular-weight hydroxyethyl starch

A low-molecular-weight preparation of hydroxyethyl starch (LMW-HES) may serve as a desirable substitute for the erythrocyte sedimenting agents presently employed to improve neutrophil yields in centrifugation and gravity leukapheresis. The cell-separating and erythrocyte-sedimenting properties of LMW-HES, assessed in vitro by the recovery of various blood cells in plasma supernatant fluids, were similar to those of the higher-molecular-weight hydroxyethyl starch in current use and to dextran under a variety of conditions. These data predict success for LMW-HES as a sedimenting agent in leukapheresis and recommend that it be evaluated in clinical trials.

Leukapheresis and granulocyte transfusion

Granulocyte transfusion is becoming widely used in the treatment of infections in granulocytopenic patients. Several techniques are available for granulocyte collection. Some involve centrifugation of the whole blood and one removes granulocytes from whole blood by reversible adhesion to nylon fibers. The risks to the donor from leukapheresis do not appear to be greater than from whole blood donation. Granulocytes collected by centrifuge techniques function normally in vitro and have normal intravascular recovery and disappearance following transfusion. Granulocytes collected by filtration leukapheresis function almost normally in vitro but have a reduced intravascular recovery and abnormal kinetics as they leave the circulation. The role of leukocyte typing and compatibility testing for granulocyte transfusion is controversial. When the recipient has circulating antibody against donor leukocytes, transfused leukocytes do not circulate or migrate to sites of infection but are sequestered in the liver and spleen. Clinical studies have not defined whether patients benefit equally well clinically from transfusion of compatible or incompatible granulocytes. Initial reports of clinical trials of granulocyte transfusion were promising. However, similar patients who did not receive granulocytes were not studied. Most subsequent controlled trials showed a clear benefit from granulocyte transfusion while others did not. Differences in antibiotic therapy, chemotherapy, use of laminar flow rooms, and grouping of patients make it difficult to compare these clinical trials. Some, but not all, infected granulocytopenic patients benefit from transfusion. Granulocyte transfusions improve survival of granulocytopenic patients with gram negative sepsis and prolonged bone marrow aplasia. Studies are now attempting to identify other patients who should receive granulocytes, the optimum dose and schedule of transfusions, the optimum time to begin transfusion, and the value, if any, of prophylactic transfusions.

Therapeutic neutrophil transfusions: are controlled studies no longer appropriate?

The aim of this review is to determine whether sufficient data have been reported to completely define the role and/or efficacy of neutrophil transfusions in the treatment of specific types of infections in neutropenic patients. Data were collected from the literature pertaining to the use of therapeutic neutrophil transfusions. When only the controlled studies are analyzed, a significant therapeutic advantage for neutrophil transfusions plus antibiotics can be demonstrated when this treatment is compared to treatment with antibiotics alone. However, the controlled studies are vulnerable to critical analysis, and several points argue against applying data from these studies indiscriminately to all infected, neutropenic patients encountered in practice. Moreover, it is apparent when all of the data (controlled and uncontrolled studies) are tabulated, that information is insufficient to establish the efficacy of neutrophil transfusions as treatment for most types of specific bacterial infections. Several problems exist in the wholesale acceptance of liberal transfusion policies, and the benefits that justify continued controlled studies deserve emphasis.