[Acute effects of complete blood exchange with ultra-purified hemoglobin solution or hydroxyethyl starch on liver and kidney in the animal model]

Assessment of Hydroxyethyl Starch (6% HES 130/0.4) Kidney Storage in Critically Ill Dogs: A Post-mortem Prospective Study

Objective: Intravenous hydroxyethyl starch (HES) solutions are potentially nephrotoxic due to rapid renal tissue uptake, subsequent osmotic nephrosis, and long-lasting intracellular storage. This study aimed to investigate the severity of intracellular storage of HES in renal tissue samples from critically ill dogs receiving 6% HES 130/0.4.

Materials and Methods: Fresh, post-mortem (<2 h after death) renal tissue samples were analyzed through histology, immunohistochemistry (HES 130/0.4-specific antibodies), and electron microscopy for the severity of renal tubular vacuolization (VAC), intravacuolar HES accumulation (ACC), and ultra-structure impairment. Moreover, we investigated the relationship between VAC or ACC grade and HES dose (mL/kg), duration of HES administration (h), and pre-HES plasma creatinine concentrations.

Results: Histology revealed that 2/20 dogs (10%) had no, 11/20 dogs (55%) had mild, 5/20 dogs (25%) had moderate, and 2/20 dogs (10%) had severe VAC. Immunohistochemistry revealed that 5/20 dogs (25%) had no, 6/20 dogs (30%) had mild, 7/20 dogs (35%) had moderate, and 2/20 dogs (10%) had severe ACC. Both changes were predominantly found in the distal tubular epithelium of mild and moderate cases, and all tubular segments were affected in severe cases. Seven of 20 dogs (35%) had osmotic nephrosis (ON). On electron microscopy, large granules with an electron-dense content were repeatedly detected in individual cells, mainly in the distal tubules. No correlation was found between cumulative HES dose or duration of HES administration and VAC grade, ACC grade, or presence/absence of ON.

Conclusion: A high percentage of dogs had renal tubular HES storage and one-third of dogs showed HES-induced ON. Short-term HES administration caused VAC and ACC, regardless of the dose or duration of administration. In contrast to previous studies, HES 130/0.4 deposits were mainly located in the renal distal tubule.

Hydroxyethyl starches in equine medicine

OBJECTIVE

To review and discuss the use of hydroxyethyl starches (HES) in equine veterinary medicine, and to provide recommendations for its use.

DATA SOURCES

Veterinary and human peer-reviewed medical literature including scientific reviews, meta-analyses, and original research articles.

HUMAN DATA SYNTHESIS

Increasing evidences on adverse effects after HES use and decreasing support for beneficial effects with regards to volume expansion and colloid osmotic pressure (COP) support in critically ill subjects have led to a recent guideline to limit the use of HES in critically ill people.

EQUINE VETERINARY DATA SYNTHESIS

The rationale for HES use in horses is mainly extrapolated from human medicine, and very limited studies in horses are available. There is limited evidence suggesting a superiority of volume expansion effects of HES over crystalloids. The potential for HES to increase and maintain COP is well supported, but there is no evidence that maintaining or increasing plasma COP influences outcome, tissue edema formation, or rates of complications that potentially relate to edema formation. HES induce dose-dependent changes in coagulopathic parameters, but there is no evidence that HES causes clinical coagulopathies. Insufficient data are available on other adverse effects such as acute kidney injury, or mortality in horses. The use of HES should be restricted in septic patients, but may still have some use in cases of hemorrhagic shock resuscitation, hypoalbuminemia, or perioperative fluid replacement.

CONCLUSION

The evidence supporting the use of HES in horses is weak due to lack of species-specific investigations. Acknowledging species differences, the use of HES should be judicious, yet with some recognition of its benefits in particular cases. More research is necessary to improve knowledge on use of HES in horses and to establish better future recommendations.

THE USE OF HYDROXYETHYL STARCH 200/0,5 AS PLASMA SUBTITUTES IS SAFE IN HYPOVOLEMIC PATIENTS AS INDICATED IN CHANGES OF N-ACETYL--GLUCOSAMINIDASE AND CREATININ SERUM PARAMETERS

Hydroxyethyl Starch (HES) is a compound that improves intravascular volume effectively and rapidly without causing tissue edema. However, HES also has renal safety profile which is still being debated. Based on clinical experience in Dr. Soetomo Hospital, the frequency of acute renal failure following HES 200/0.5 administration at a dose of less than 20 ml/kg (maximum dose) is very rare. The purpose of this study was to evaluate the effect of HES 200/0.5 at a dose of less than 20 ml/kg in patients undergoing surgery. N-acetyl-b-D-Glucosaminidase (NAG) per urine creatinine ratio and creatinine serum were used as main parameter to assess renal injury. This research was observational and prospective design in patients undergoing elective surgery at Gedung Bedah Pusat Terpadu, Dr. Soetomo Hospital, who requiring resuscitation therapy with HES 200/0.5 and met the inclusion and exclusion criteria. NAG was measured prior to surgery and 12 hours after administration of fluid therapy, while creatinine serum was observed before surgery and 48 hours after resuscitation. This study was conducted for three months, and obtained 50 subjects divided into 2 groups, crystalloid group and HES 200/0.5 group. Demographic and baseline characteristics did not differ between groups, except the total bleeding volume. Total bleeding in HES 200/0.5group was higher than crystalloid group (p <0.0001). The mean volume of fluid received in HES 200/0.5 group was 2042.0 ± 673.9 mL, higher when compared with that of crystalloid group (910.0 ± 592.0 ml). Doses of HES 200/0.5 received was 8.31 ± 4.86 ml/kg. Measurement of the of NAG/creatinine ratio and creatinine serum showed significant increase in both groups, but still within the normal range. In addition, the value of these two parameters did not differ between groups. In conclusion, HES 200/0.5 in a dose of less than 20 ml/kg is safe to use in patients who suffered from hypovolemic hemorrhage, without prior history of renal impairment.

Retrospective evaluation of the effects of administration of tetrastarch (hydroxyethyl starch 130/0.4) on plasma creatinine concentration in dogs (2010-2013): 201 dogs

OBJECTIVE

To determine changes in creatinine concentrations following the administration of 6% tetrastarch (hydroxyethyl starch [HES] 130/0.4) compared to crystalloids (CRYSs) in critically ill dogs.

DESIGN

Retrospective case series (2010-2013).

SETTING

University teaching hospital.

ANIMALS

Two hundred and one dogs admitted to the intensive care unit with initial plasma creatinine concentrations not exceeding laboratory reference intervals (52-117 μmol/L [0.6-1.3 mg/dL]) and receiving either CRYSs alone (CRYS group, n = 115) or HES with or without CRYSs (HES group, n = 86) for at least 24 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Creatinine concentrations at admission to the intensive care unit (T0), and 2-13 days (T1) and 2-12 weeks (T2) after initiation of fluid therapy were analyzed. Creatinine concentrations were analyzed as absolute values and as the maximum percentage change from T0 to T1 (T1max%) and from T0 to T2 (T2max%), respectively. Creatinine concentrations were available for 192 dogs during T1 and 37 dogs during T2. The median cumulative dose of HES was 86 mL/kg (range, 12-336 mL/kg). No difference was detected between the groups for age, gender, body weight, and length of hospitalization. Outcome was significantly different between the HES (66% survived) and the CRYS (87% survived) groups (P = 0.014). No significant difference was detected between groups for creatinine concentrations at T0, T1, T2, T1max%, or T2max%. No significant difference was detected between the groups for T1max% creatinine in dogs subclassified as having systemic inflammatory response syndrome or sepsis.

CONCLUSIONS

HES administration in this canine population did not result in increased creatinine concentrations compared to administration of CRYSs. Further studies are needed to establish the safety of HES in critically ill dogs.

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

OBJECTIVES

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

DATA SOURCES

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

HUMAN DATA SYNTHESIS

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

VETERINARY DATA SYNTHESIS

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

CONCLUSIONS

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

Retrospective cohort study on the incidence of acute kidney injury and death following hydroxyethyl starch (HES 10% 250/0.5/5:1) administration in dogs (2007-2010)

OBJECTIVE

To determine the incidence of in-hospital adverse outcomes including acute kidney injury (AKI) and death in a population of dogs admitted to the intensive care unit (ICU) receiving 10% hydroxyethyl starch (HES) [250/0.5/5:1] compared with the general ICU population, while controlling for illness severity.

DESIGN

Cohort study conducted between January 2007 and March 2010.

SETTING

Veterinary teaching hospital.

ANIMALS

Consecutive sample of dogs receiving HES (n = 180) were compared with a randomly selected sample of dogs (n = 242) admitted to the ICU over the same period.

INTERVENTIONS

None

MEASUREMENTS AND MAIN RESULTS

AKI was defined as an at least 2-fold increase in baseline creatinine concentration or new onset of oliguria/anuria persisting for ≥12 hours. The primary outcome was a composite of in-hospital death or AKI. Unadjusted and adjusted analysis controlling for illness severity using the acute patient physiologic and laboratory evaluation (APPLEfast ) score and other confounders was performed. HES was administered either as incremental boluses (median dose 8.2 mL/kg/day, interquartile range [IQR] 5.0-11.3 mL/kg/day) or as a continuous rate infusion (CRI; median dose 26mL/kg/day, IQR 24.0-48 mL/kg/day). In unadjusted analysis, HES administration was associated with increased risk of mortality (odds ratio [OR] = 2.33, 95% confidence interval [CI] = 1.51-3.58, P < 0.001) or AKI (OR = 3.87, 95% CI = 1.21-12.37, P = 0.02). In an adjusted analysis after controlling for illness severity, admission type, and concurrent administration of blood products, HES administration remained an independent risk factor for the composite adverse outcome (OR = 1.98, 95% CI = 1.22-3.22, P = 0.005), with a number needed to harm (NNH) = 6 (95% CI = 4-23).

CONCLUSIONS

HES therapy is associated with increased risk of an adverse outcome including death or AKI in dogs. A randomized controlled trial investigating the safety of HES therapy in canine patients is warranted.

The effect of 6% hydroxyethyl starch 130/0.4 on renal function, arterial blood pressure, and vasoactive hormones during radical prostatectomy: a randomized controlled trial

BACKGROUND

Although hydroxyethyl starch (HES) is commonly used as an intravascular volume expander in surgical patients, recent studies suggest that it may increase the risk of renal failure in critically ill patients. We hypothesized that patients undergoing radical prostatectomy and receiving HES would be more likely to develop markers of renal failure, such as increasing urinary neutrophil gelatinase-associated lipocalin (u-NGAL), creatinine clearance (C(crea)), and decreasing urine output (UO).

METHODS

In a randomized, double-blinded, placebo-controlled study, 40 patients referred for radical prostatectomy received either 6% HES 130/0.4 or saline 0.9%; 7.5 mL/kg during the first hour of surgery and 5 mL/kg in the following hours; u-NGAL, urine albumin, C(crea), UO, arterial blood pressure, and plasma concentrations of creatinine, renin, angiotensin II, aldosterone, and vasopressin were measured before, during, and after surgery.

RESULTS

Thirty-six patients completed the study. u-NGAL, C(crea), UO, plasma neutrophil gelatinase-associated lipocalin, p-creatinine, urine albumin, and arterial blood pressure were the same in both groups. Blood loss was higher in the HES group (HES 1250 vs saline 750 mL), while p-albumin was reduced to a significantly lower level. P-renin and p-angiotensin-II increased in both groups, whereas p-aldosterone and p-vasopressin increased significantly in the saline group.

CONCLUSIONS

We found no evidence of nephrotoxicity after infusion of 6% HES 130/0.4 in patients undergoing prostatectomy with normal preoperative renal function. Hemodynamic stability and infused fluid volume were the same in both groups. We observed an increased blood loss in the group given 6% HES 130/0.4.

Accumulation of hydroxyethyl starch in human and animal tissues: a systematic review

PURPOSE

To systematically review clinical and preclinical data on hydroxyethyl starch (HES) tissue storage.

METHODS

MEDLINE (PubMed) was searched and abstracts were screened using defined criteria to identify articles containing original data on HES tissue accumulation.

RESULTS

Forty-eight studies were included: 37 human studies with a total of 635 patients and 11 animal studies. The most frequent indication for fluid infusion was surgery accounting for 282 patients (45.9%). HES localization in skin was shown by 17 studies, in kidney by 12, in liver by 8, and in bone marrow by 5. Additional sites of HES deposition were lymph nodes, spleen, lung, pancreas, intestine, muscle, trophoblast, and placental stroma. Among major organs the highest measured tissue concentration of HES was in the kidney. HES uptake into intracellular vacuoles was observed by 30 min after infusion. Storage was cumulative, increasing in proportion to dose, although in 15% of patients storage and associated symptoms were demonstrated at the lowest cumulative doses (0.4 g kg(-1)). Some HES deposits were extremely long-lasting, persisting for 8 years or more in skin and 10 years in kidney. Pruritus associated with HES storage was described in 17 studies and renal dysfunction in ten studies. In one included randomized trial, HES infusion produced osmotic nephrosis-like lesions indicative of HES storage (p = 0.01) and also increased the need for renal replacement therapy (odds ratio, 9.50; 95% confidence interval, 1.09-82.7; p = 0.02). The tissue distribution of HES was generally similar in animals and humans.

CONCLUSIONS

Tissue storage of HES is widespread, rapid, cumulative, frequently long-lasting, and potentially harmful.

Effects of hemodilution with a hemoglobin-based oxygen carrier (HBOC-201) on ischemia/reperfusion injury in a model of partial warm liver ischemia of the rat

BACKGROUND

Ischemia/reperfusion injury is an unavoidable complication in liver surgery and transplantation. Hemodilution with colloids can reduce postischemic injury but limits oxygen transport. Hemoglobin-based oxygen carriers have been evaluated as blood substitute and provide a plasma-derived oxygen transport. It was the aim of our study to evaluate the combined benefits of hemodilution with a better oxygen supply to reperfused liver tissue by the use of HBOC-201 (Hemopure).

MATERIAL AND METHODS

A model of partial warm liver ischemia in the rat was used. One group served as untreated control, the other groups were hemodiluted either with Ringer's lactate, Dextran-70, HBOC-201 or a mixture of Dextran and HBOC-201. After reperfusion, intravital microscopy studies were done and tissue pO(2) levels and transaminases measured. Statistical analysis was done by one- and two-way ANOVA, followed by pairwise comparison.

RESULTS

Hemodilution with Ringer's lactate did not show any improvement compared to the control group. Dextran and HBOC group were superior to the Ringer and control animals in all parameters studied. Leucocyte adherence in postsinusoidal venules improved from 569.03+/-171.87 and 364.52+/-167.32 in control and Ringer group to 131.68+/-58.34 and 68.44+/-20.31/mm(2) endothelium in Dextran and HBOC group (p<0.001). Concerning tissue pO(2) levels, HBOC (23.4+/-5.0 mmHg) proved to be superior to Dextran (7.9+/-4.4 mmHg; p=0.007).

CONCLUSION

HBOC was equivalent to Dextran in reducing I/R injury in the liver, but improved oxygenation of postreperfusion liver tissue.

Osmotic nephrosis: acute kidney injury with accumulation of proximal tubular lysosomes due to administration of exogenous solutes

Osmotic nephrosis describes a morphological pattern with vacuolization and swelling of the renal proximal tubular cells. The term refers to a nonspecific histopathologic finding rather than defining a specific entity. Osmotic nephrosis can be induced by many different compounds, such as sucrose, hydroxyethyl starch, dextrans, and contrast media. It has a broad clinical spectrum that includes acute kidney injury and chronic kidney failure in rare cases. This article discusses the pathological characteristics, pathogenesis, and various clinical entities of osmotic nephrosis.

Comparison of the novel hydroxyethylstarch 130/0.4 and hydroxyethylstarch 200/0.6 in brain-dead donor resuscitation on renal function after transplantation

BACKGROUND

The renal effect of hydroxyethylstarch (HES) solutions remains controversial. We hypothesized that the use of HES with a mean molecular weight of 130 kDa would reduce renal dysfunctions in the recipients. Our study was aimed at comparing the effects of two fluid regimens (HES 130/0.4 or HES 200/0.6) used for the resuscitation of brain-dead donors on the rate of delayed graft function (DGF) and the serum creatinine levels post-transplantation.

METHODS

This retrospective matched-paired study was conducted in an intensive care unit of a university hospital. Case-controls were matched at the donor patient level as follows: gender, BMI, duration of ICU stay, serum creatinine levels, vasopressor, and volume of colloids. The organ donation from 64 brain-dead donors resulted in 115 transplants.

RESULTS

The renal function was similar among all donors. The characteristics of the recipients, including the cold ischaemia time, were similar. The rate of DGF was 22% in the donors treated with HES 130/0.4, compared with 33% in those treated with HES 200/0.6 (P=0.27). The serum creatinine levels at 1 month were 133 (38) micromol litre(-1) when the donors had been treated with HES 130/0.4 and 172 (83) micromol litre(-1) when they were treated with HES 200/0.6 (P=0.005). A difference was found 1 yr after transplantation [128 (36) vs147 (43) micromol litre(-1), P=0.05].

CONCLUSIONS

Using a modern, third-generation, rapidly degradable HES preparation with a low degree of substitution seems to be associated with a better effect on the renal function of recipients.

Effects of hydroxyethyl starch administration on renal function in critically ill patients

BACKGROUND

The influence of hydroxyethyl starch (HES) solutions on renal function is controversial. We investigated the effect of HES administration on renal function in critically ill patients enrolled in a large multicentre observational European study.

METHODS

All adult patients admitted to the 198 participating intensive care units (ICUs) during a 15-day period were enrolled. Prospectively collected data included daily fluid administration, urine output, sequential organ failure assessment (SOFA) score, serum creatinine levels, and the need for renal replacement therapy (RRT) during the ICU stay.

RESULTS

Of 3147 patients, 1075 (34%) received HES. Patients who received HES were older [mean (SD): 62 (SD 17) vs 60 (18) years, P = 0.022], more likely to be surgical admissions, had a higher incidence of haematological malignancy and heart failure, higher SAPS II [40.0 (17.0) vs 34.7 (16.9), P < 0.001] and SOFA [6.2 (3.7) vs 5.0 (3.9), P < 0.001] scores, and less likely to be receiving RRT (2 vs 4%, P < 0.001) than those who did not receive HES. The renal SOFA score increased significantly over the ICU stay independent of the type of fluid administered. Although more patients who received HES needed RRT than non-HES patients (11 vs 9%, P = 0.006), HES administration was not associated with an increased risk for subsequent RRT in a multivariable analysis [odds ratio (OR): 0.417, 95% confidence interval (CI): 0.05-3.27, P = 0.406]. Sepsis (OR: 2.03, 95% CI: 1.37-3.02, P < 0.001), cardiovascular failure (OR: 6.88, 95% CI: 4.49-10.56, P < 0.001), haematological cancer (OR: 2.83, 95% CI: 1.28-6.25, P = 0.01), and baseline renal SOFA scores > 1 (P < 0.01 for renal SOFA 2, 3, and 4 with renal SOFA = 0 as a reference) were all associated with a higher need for RRT.

CONCLUSIONS

In this observational study, haematological cancer, the presence of sepsis, cardiovascular failure, and baseline renal function as assessed by the SOFA score were independent risk factors for the subsequent need for RRT in the ICU. The administration of HES had no influence on renal function or the need for RRT in the ICU.

BOVINE POLYMERIZED HEMOGLOBIN VERSUS HEXTEND RESUSCITATION IN A SWINE MODEL OF SEVERE CONTROLLED HEMORRHAGIC SHOCK WITH DELAY TO DEFINITIVE CARE

To compare the efficacy of low-volume resuscitation with bovine polymerized hemoglobin (HBOC-201) versus hetastarch (HEX) in an intermediate severity combat-relevant hemorrhagic shock swine model with a simulated delay to hospital care. Twenty-four anesthetized pigs were hemorrhaged 55% estimated blood volume in conjunction with a 5-min rectus abdominus crush. At 20 min, pigs were resuscitated with 10 mL/kg of HBOC-201 or HEX or nothing (NON); resuscitated pigs received additional infusions (5 mL/kg) at 30, 60, 120, or 180 min if hypotension or tachycardia persisted. Pigs were monitored for a 4-h "prehospital" period. At 4-h, hospital arrival was simulated: surgical sites were repaired, blood, or saline provided, and pigs were recovered from anesthesia. Pigs were monitored for 72 h and then killed for histological evaluation. One hundred percent (8/8) of HBOC-201-, 75% (6/8) of HEX-, and 25% (2/8) of NON-resuscitated pigs survived to 72 h (P = 0.007 overall, HBOC vs. HEX P > 0.05). Mean arterial pressure and mean pulmonary arterial pressure were highest in the HBOC-201 group (P < 0.001), and HR was lowest (P < 0.001). HBOC-201- and HEX-resuscitated pigs had comparable cardiac index and prehospital fluid requirements. HBOC-201 pigs had higher transcutaneous tissue oxygen tension, P < 0.001) and lower urine output (P < 0.001). At simulated hospital arrival, no HBOC-201 pigs required additional fluids or blood transfusion. In contrast, 100% of HEX pigs required blood transfusions (P < 0.01). In this swine model of controlled hemorrhage with low-volume resuscitation and delayed definitive care, HBOC-201 pigs had improved hemodynamics, transcutaneous tissue oxygen tension, and transfusion avoidance compared with HEX.

Enhanced central organ oxygenation after application of bovine cell-free hemoglobin HBOC-201

PURPOSE

While the effects of dilutional anemia or isovolemic hemodilution (IHD) on the oxygen extraction and tissue oxygenation in peripheral organs after application of hemoglobin-based oxygen carriers like HBOC-201 have been studied intensively, little is known about tissue oxygenation properties of hemoglobin solutions in central organs like the liver.

METHODS

Twelve Foxhounds were anesthetized and then randomized to either a control group without hemodilution (Group 1) or underwent first step isovolemic hemodilution (pulmonary artery occlusion pressure constant) with Ringer's solution (Group 2) to a hematocrit of 25% with second step infusion of HBOC-201 until a hemoglobin concentration of +0.6 g.dL(-1) was reached. Tissue oxygen tensions (tpO2) were measured in the gastrocnemius muscle using a polarographic needle probe, and in the liver using a flexible polarographic electrode.

RESULTS

While arterial oxygen content and oxygen delivery decreased with hemodilution in Group 2, global liver and muscle oxygen extraction ratio increased after hemodilution and additional application of HBOC-201. Hemodilution and application of HBOC-201 provided augmentation of the mean liver tpO2 (baseline: 48 +/- 9, 20 min: 53 +/- 10, 60 min: 67 +/- 11*, 100 min: 68 +/- 7*; *P < 0.05 vs baseline and Group 1), while oxygen tensions in Group 1 remained unchanged. Oxygen tension in the skeletal muscle increased after hemodilution and additionally after application of HBOC-201 in comparison to baseline and to the control group (P < 0.05).

CONCLUSION

In the present animal model, IHD with Ringer's solution and additional application of HBOC-201 increased oxygen extraction and tpO(2) in the liver and skeletal muscle, in parallel and in comparison with baseline values and a control group.

Hydroxyethyl starch and change in renal function in patients undergoing coronary artery bypass graft surgery

BACKGROUND

Several case reports and clinical lore have suggested that exposure to the colloid hydroxyethyl starch may impair renal function, but few studies have systematically addressed this issue, and several have produced conflicting results. We sought to study the question in a formal analysis of postoperative change in renal function in patients undergoing coronary artery bypass graft (CABG) surgery.

METHODS

We identified 238 consecutive patients who underwent CABG surgery at a large academic medical center. Glomerular filtration rate (GFR) was estimated using the Cockroft-Gault formula at baseline as well as on postoperative days 3 and 5. Linear regression analysis was used to study the relation between changes in GFR and intraoperative hydroxyethyl starch administration. Multivariate models controlled for potential demographic, clinical, and surgery-related confounders.

RESULTS

Hydroxyethyl starch use was independently associated with a reduction in GFR on both postoperative days 3 and 5, with GFR declining by 7.2 mL/min/1.73 m2 on day 3 per unit of hydroxyethyl starch administered (95% CI, 1.7 to 12.7; P = 0.012), and by 6.6 mL/min/1.73 m2 on day 5 (95% CI, 1.2 to 11.9; P = 0.018).

CONCLUSION

Intraoperative use of hydroxyethyl starch may be associated with modest impairment in renal function in patients undergoing CABG surgery. Randomized clinical trials will be necessary to confirm these findings and to further investigate their clinical implications.

Current status of artificial oxygen carriers

Artificial oxygen carriers may be grouped into modified hemoglobin solutions and fluorocarbon emulsions. In animal experiments, both have been shown to be efficacious in improving tissue oxygenation and as substitutes for blood transfusions. Advantages and disadvantages are being discussed in this article as well as the latest steps in the clinical development.

Blood substitutes. Haemoglobin therapeutics in clinical practice

Early approaches to the development of oxygen carriers involved the use of stroma-free hemoglobin solutions. These solutions did not require blood typing or crossmatching and could be stored for long periods. In addition, a variety of methods have been developed in chemically modifying and stabilizing the hemoglobin molecule. Several hemoglobin therapeutics are now in clinical trials as temporary alternatives to blood or as therapeutic agents for ischemia. The various hemoglobin products under development are derived from three principal sources: human, bovine and genetically engineered hemoglobin. Diaspirin cross-linked hemoglobin (DCLHb), administered at doses ranging from approximately 20-1000 ml, has been investigated in a number of clinical trials in patients undergoing orthopedic, abdominal aortic repair, major abdominal surgery, cardiac surgery and in critically ill patients with septic shock. In several studies, DCLHb was effective in avoiding the transfusion. However, Baxter Healthcare Corporation (Chicago, Illinois, USA) stopped the development of DCLHb after two unsuccessful trials in trauma patients. Bovine polymerized hemoglobin has also been extensively studied. Several phase II and phase III trials have been performed with this product in hemorrhagic surgery, cardiac surgery and vascular surgery, but data have not yet been published. Hemoglobin therapeutics could provide an important new option as an alternative to blood transfusion. Furthermore, they may be able to provide an immediate on-site replacement for traumatic blood loss, prevent global ischemia and organ failure, treat focal ischemia, and provide effective hemodynamic support for septic shock-induced hypotension.

The pharmacokinetics of acetyl starch as a plasma volume expander in patients undergoing elective surgery

Acetyl starch (ACS) is a new synthetic colloid solution for plasma volume expansion and is now undergoing phase 2 clinical trials. We compared the pharmacokinetics of ACS with those of hydroxyethyl starch (HES) in 32 patients (ASA physical status I and II) undergoing elective surgery. In this randomized, double-blind trial, patients received either 15 mL/kg ACS 6% (average molecular weight [Mw] 200,000/molar substitution [MS] 0.5) or HES 6% (Mw 200,000/MS 0.5) i.v. up to a maximal dose of 1000 mL. Plasma colloid concentrations were measured by repetitive arterial blood sampling over 24.5 h. Plasma colloid concentrations were detected using a high-pressure liquid chromatography controlled enzymatic test. Standard pharmacokinetics were calculated, including initial half-life (t(1/2init)), i.e., the time required for a 50% decline of the maximal plasma colloid concentration at the end of drug infusion. Whereas HES was eliminated by second-order kinetics, ACS followed first-order characteristics. In the first hours after i.v. administration, t(1/2init) and clearances were similar in both groups. However, the terminal half-life of HES was significantly longer than that of ACS (9.29 +/- 1.43 h vs 4.37 +/- 1.06 h). After 16.5 and 24.5 h, ACS showed significantly lower plasma concentrations than HES, which indicates that the final degradation of ACS by esterases and amylase was significantly more rapid. ACS might be an alternative plasma volume expander, which avoids the accumulation of persisting macromolecules.

IMPLICATIONS

We studied the pharmacokinetics of acetyl starch, a newly developed colloid solution for plasma volume substitution, compared with hydroxyethyl starch in 32 surgical patients undergoing elective major general surgical procedures. In contrast to hydroxyethyl starch, this new agent undergoes rapid and nearly complete enzymatic degradation.