Renal impact of fluid management with colloids: a comparative review

Low-Fouling Zwitterionic Polymeric Colloids as Resuscitation Fluids for Hemorrhagic Shock

Colloids, known as volume expanders, have been used as resuscitation fluids for hypovolemic shock for decades, as they increase plasma oncotic pressure and expand intravascular volume. However, recent studies show that commonly used synthetic colloids have adverse interactions with human biological systems. In this work, a low-fouling amine(N)-oxide-based zwitterionic polymer as an alternative volume expander with improved biocompatibility and efficacy is designed. It is demonstrated that the polymer possesses antifouling ability, resisting cell interaction and deposition in major organs, and is rapidly cleared via renal filtration and hepatic circulation, reducing the risk of long-term side effects. Furthermore, in vitro and in vivo studies show an absence of adverse effects on hemostasis or any acute safety risks. Finally, it is shown that, in a head-to-head comparison with existing colloids and plasma, the zwitterionic polymer serves as a more potent oncotic agent for restoring intravascular volume in a hemorrhagic shock model. The design of N-oxide-based zwitterionic polymers may lead to the development of alternative fluid therapies to treat hypovolemic shock and to improve fluid management in general.

Effect of Albumin Addition to Cardiopulmonary Bypass Prime on Outcomes in Children Undergoing Open-Heart Surgery (EACPO Study)-A Randomized Controlled Trial

BACKGROUND

There is a paucity of literature regarding the association of high oncotic priming solutions for pediatric cardiopulmonary bypass (CPB) and outcomes, and no consensus exists regarding the composition of optimal CPB priming solution. This study aimed to examine the impact of high oncotic pressure priming by the addition of 20% human albumin on outcomes.

METHODS

Double-blinded, randomized controlled study was done in the pediatric cardiac intensive care unit of a tertiary care hospital. Consecutive children with congenital heart diseases admitted for open-heart surgery were randomized into two groups, where the study group received an additional 20% albumin to conventional blood prime before CPB initiation.

RESULTS

We enrolled 39 children in the high oncotic prime (added albumin) group and 37 children in the conventional prime group. In the first 24-hour postoperative period, children in the albumin group had significantly lower occurrence of hypotension (28.2% vs 54%, P = .02), requirement of fluid boluses (25.6% vs 54%, P = .006), and lactate clearance time (6 vs 9 hours, P < .001). Albumin group also had significantly higher platelet count (×10³/µL) at 24 hours (112 vs 91, P = .02). There was no significant difference in intra-CPB hemodynamic parameters and incidence of acute kidney injury. In subgroup analysis based on risk category, significantly decreased intensive care unit stay (4 vs 5 days, P = .04) and hospital stay (5 vs 7 days, P = .002) were found in the albumin group in low-risk category.

CONCLUSION

High oncotic pressure CPB prime using albumin addition might be beneficial over conventional blood prime, and our study does provide a rationale for further studies.

Starch or Saline After Cardiac Surgery: A Double-Blinded Randomized Controlled Trial

Background:

Despite decades of investigation, the balance of clinical risks and benefits of fluid supplementation with starch remain unresolved. Patient-centered outcomes have not been well explored in a “real-world” trial in cardiac surgery.

Objective:

We sought to compare a starch-based fluid strategy with a saline-based fluid strategy in the cardiac surgery patient.

Design:

A pragmatic blinded randomized controlled trial comparing starch-based with saline-based fluid strategy.

Setting:

A large tertiary academic center in London Ontario between September 2009 and February 2011.

Participants:

Patients undergoing planned, isolated coronary revascularization.

Measurements:

Serum creatinine and patient weight were measured daily postoperatively.

Methods:

Patients were randomized to receive 6% hydroxyethyl starch (Voluven) or saline for perioperative fluid requirements. Fluid administration was not protocolized. Co-primary outcomes were incidence of acute kidney injury (AKI) and maximum postoperative weight gain. Secondary outcomes included bleeding, transfusion, inotropic and ventilator support, and fluid utilization.

Results:

The study was prematurely terminated due to resource limitations. A total of 69 patients (19% female, mean age = 65) were randomized. Using RIFLE criteria for AKI, “risk” occurred in 12 patients in each group (risk ratio [RR] = 1.0; 95% confidence interval [CI] = 0.5-1.9; P = 1.00), whereas “injury” occurred in 7 of 35 (20%) and 3 of 34 (9%) of patients in the starch and saline groups, respectively (RR = 2.3; 95% CI = 0.6-8.1; P = .31). Maximum weight gain, bleeding and blood product usage, and overall fluid requirement were similar between groups.

Limitations:

The study had to be prematurely terminated due to resource limitations which led to a small sample size which was not sufficiently powered to detect a difference in the primary outcomes.

Conclusions:

This pragmatic double-blinded randomized controlled trial revealed a number of interesting hypothesis-generating trends and confirmed the feasibility of undertaking a logistically complex trial in a pragmatic fashion.

Perioperative-, Recipient-, and Donor-Related Factors Affecting Delayed Graft Function in Kidney Transplantation

OBJECTIVES

Delayed graft function is a frequent complication in deceased-donor kidney transplant, with an incidence ranging from 10% to 50% among different centers; it is also associated with lower graft survival. In this study, we aimed to identify risk factors for delayed graft function, particularly those associated with perioperative management (including cold ischemia time) and nonmodifiable recipient- and donor-related factors. The effects of delayed graft function on graft and patient outcomes were also evaluated.

MATERIALS AND METHODS

Our retrospective analyses included 125 adult patients who underwent deceased-donor kidney transplant. Delayed graft function was diagnosed if at least 1 dialysis treatment was required during the first week posttransplant according to Perico's definition.

RESULTS

Prevalence of delayed graft function was 30.4% (n = 38). Cold ischemia time was significantly prolonged in patients with delayed graft function compared with those without it. Multivariate regression showed that cold ischemia time was the only predictor of delayed graft function. A cutoff of 9 hours and 12 minutes was found as a limit beyond which delayed graft function occurred (sensitivity = 90%; specificity = 29%; area under the curve = 0.68). Greater donor and recipient age and longer pretransplant dialysis time in recipients were associated with occurrence of delayed graft function. In patients with delayed graft function, hospital stay duration was significantly greater and 1-year graft survival was significantly lower.

CONCLUSIONS

Efforts should be focused on limiting cold ischemia time and associated injury to reduce occurrence of delayed graft function and consequently improve long-term graft survival in kidney transplant recipients. Optimization of posttransplant renal function with the help of new technologies, such as pulsatile perfusion, could be crucial for minimization of cold ischemia time.

Is Brain-Dead Donor Fluid Therapy With Colloids Associated With Better Kidney Grafts?

OBJECTIVES

Fluid therapy is required to maintain perfusion to donor organs. Recent reviews on the choices of fluids have emphasized the safety of using crystalloids, as opposed to fluid therapy with colloids, which has been reported to be either unequivocally or potentially harmful in a number of studies on various patient populations. We aimed to analyze whether the type of fluid administered to donors is connected with kidney transplant outcomes.

MATERIALS AND METHODS

A total of 100 consecutive brain-dead multiorgan donors and their respective 181 kidney recipients were studied retrospectively. Data concerning donor fluid therapy, the characteristics of the donors and the recipients, and outcomes after kidney transplant were extracted from organ retrieval and patient records. Cases with early graft function were compared with cases with delayed graft function.

RESULTS

Donors had received both crystalloids and colloids in most cases (84%). Fluid therapy with crystalloids alone was more common among the 40 recipients with delayed (30%) than in the 103 recipients with early graft function (11%) (P = .005). Donor age, time on renal replacement therapy before transplant, and donor fluid therapy with crystalloids alone were independent risk factors for delayed graft function in multivariate analysis.

CONCLUSIONS

Our results suggest that donor fluid therapy including colloids could be beneficial instead of harmful compared with treatment with crystalloids alone. This finding needs to be evaluated in prospective studies.

The Full Spectrum of Clinical Ethical Issues in Kidney Failure. Findings of a Systematic Qualitative Review

BACKGROUND

When treating patients with kidney failure, unavoidable ethical issues often arise. Current clinical practice guidelines some of them, but lack comprehensive information about the full range of relevant ethical issues in kidney failure. A systematic literature review of such ethical issues supports medical professionalism in nephrology, and offers a solid evidential base for efforts that aim to improve ethical conduct in health care.

AIM

To identify the full spectrum of clinical ethical issues that can arise for patients with kidney failure in a systematic and transparent manner.

METHOD

A systematic review in Medline (publications in English or German between 2000 and 2014) and Google Books (with no restrictions) was conducted. Ethical issues were identified by qualitative text analysis and normative analysis.

RESULTS

The literature review retrieved 106 references that together mentioned 27 ethical issues in clinical care of kidney failure. This set of ethical issues was structured into a matrix consisting of seven major categories and further first and second-order categories.

CONCLUSIONS

The systematically-derived matrix helps raise awareness and understanding of the complexity of ethical issues in kidney failure. It can be used to identify ethical issues that should be addressed in specific training programs for clinicians, clinical practice guidelines, or other types of policies dealing with kidney failure.

Hydroxyeyhyl starch: Controversies revisited

Hydroxyethyl starch (HES) family has been one of the cornerstones in fluid management for over four decades. Recent evidence from clinical studies and meta-analyses has raised few concerns about the safety of these fluids, especially in certain subpopulations of patients. High-quality clinical trials and meta-analyses have emphasized nephrotoxic effects, increased risk of bleeding, and a trend toward higher mortality in these patients after the use of HES solutions. Scientific evidence was derived from international guidelines, aggregated research literature, and opinion-based evidence was obtained from surveys and other activities (e.g., internet postings). On critical analysis of the current data available, it can be summarized that further large scale trials are still indicated before HES can be discarded.

Perioperative nutritional support and fluid therapy in patients with liver diseases

The prevalence of liver dysfunction and malnutrition is common among patients with obstructive jaundice or cirrhosis, the poor nutrition status in patients with indications for hepatic resection increases the risk of postoperative complications and/or mortality. Hepatic surgery significantly affects body's metabolism and environment. Therefore, it is very important for patients with liver diseases undergoing hepatic surgery to receive essential nutritional support and fluid therapy during perioperative period. There are several principles in nutritional support and fluid therapy that surgeons need to pay attention to, for example, time, nutritional approach, fluid volume, choice of fat emulsions and amino acids. Some issues, such as albumin and plasma application, choice of crystalloid and colloid, liver protective therapy, also need further attention.

Albumin—Beyond Fluid Replacement in Cardiopulmonary Bypass Surgery

Maintaining vascular barrier competence, preventing interstitial edema, and keeping microcirculation intact is crucial to achieve an optimal outcome in cardiopulmonary bypass surgery (CPB). Blood contact with roller pumps and foreign surfaces during CPB induces shear stress and a pressure drop across the pump boot that leads to transient systemic activation of the inflammatory and hemostatic systems. Moreover, patients after CPB often need volume resuscitation using the smallest possible amount of colloid solution because of fluid overload. For this purpose, human-derived albumin may be preferred over synthetic colloids because CPB priming with albumin preserves oncotic pressure, prevents platelet adhesion, and likely induces less consumption of coagulation factors. In patients with increased bleeding or renal failure, albumin is a safe alternative because of its minimal side effects. Large, randomized clinical trials comparing the benefit of albumin versus other fluids are warranted in the future to define albumin’s distinct role in select high-risk surgical populations.

Traumatic coagulopathy--part 2: Resuscitative strategies

OBJECTIVE

To discuss the current resuscitative strategies for trauma-induced hemorrhagic shock and acute traumatic coagulopathy (ATC).

ETIOLOGY

Hemorrhagic shock can be acutely fatal if not immediately and appropriately treated. The primary tenets of hemorrhagic shock resuscitation are to arrest hemorrhage and restore the effective circulating volume. Large volumes of isotonic crystalloids have been the resuscitative strategy of choice; however, data from experimental animal models and retrospective human analyses now recognize that large-volume fluid resuscitation in uncontrolled hemorrhage may be deleterious. The optimal resuscitative strategy has yet to be defined. In human trauma, implementing damage control resuscitation with damage control surgery for controlling ongoing hemorrhage, acidosis, and hypothermia; managing ATC; and restoring effective circulating volume is emerging as a more optimal resuscitative strategy. With hyperfibrinolysis playing an integral role in the manifestation of ATC, the use of antifibrinolytics (eg, tranexamic acid and aminocaproic acid) may also serve a beneficial role in the early posttraumatic period. Considering the sparse information regarding these resuscitative techniques in veterinary medicine, veterinarians are left with extrapolating information from human trials and experimental animal models.

DIAGNOSIS

Viscoelastic tests integrated with predictive scoring systems may prove to be the most reliable methods for early detection of ATC as well as for guiding transfusion requirements.

SUMMARY

Hemorrhage accounts for up to 40% of human trauma-related deaths and remains the leading cause of preventable death in human trauma. The exact proportion of trauma-related deaths due to exsanguinations in veterinary patients remains uncertain. Survivability depends upon achieving rapid definitive hemostasis, early attenuation of posttraumatic coagulopathy, and timely restoration of effective circulating volume. Early institution of damage control resuscitation in severely injured patients with uncontrolled hemorrhage has the ability to curtail posttraumatic coagulopathy and the exacerbation of metabolic acidosis and hypothermia and improve survival until definitive hemostasis is achieved.

Should hydroxyethyl starch solutions be totally banned?

The choice of which intravenous solution to prescribe remains a matter of considerable debate in intensive care units around the world. Trends have been moving away from using hydroxyethyl starch solutions following concerns about safety. But are the available data sufficient to clearly assess the risk-benefit balance for all patients, and is there enough evidence of harm to justify removing these drugs completely from our hospitals?

[Fluid therapy in acute pancreatitis]

Severe acute pancreatitis (AP) is associated with an increased need for fluids due to fluid sequestration and, in the most severe cases, with decreased peripheral vascular tone. For several decades, clinical practice guidelines have recommended aggressive fluid therapy to improve the prognosis of AP. This recommendation is based on theoretical models, animal studies, and retrospective studies in humans. Recent studies suggest that aggressive fluid administration in all patients with AP could have a neutral or harmful effect. Fluid therapy based on Ringer's lactate could improve the course of the disease, although further studies are needed to confirm this possibility. Most patients with AP do not require invasive monitoring of hemodynamic parameters to guide fluid therapy administration. Moreover, the ability of these parameters to improve prognosis has not been demonstrated.

Albumin utilization in cardiac surgery after transition to hydroxyethyl starch 130/0.4

OBJECTIVE

Evaluate the impact of replacing hydroxyethyl starch (HES) 670/0.75 with lower molecular weight HES 130/0.4 on albumin utilization in cardiac surgery, as well as any impact on renal function and bleeding.

DESIGN

A pre- and postimplementation, retrospective analysis.

SETTING

Community, not-for-profit, tertiary medical center.

PARTICIPANTS

One hundred forty-six patients undergoing nonemergent cardiac bypass graft and cardiac valve surgeries after exclusion for documented anemia, malignancy, coagulation disorder, end-stage renal disease, or personal objection to receiving blood products.

INTERVENTION

HES 130/0.4 utilization instead of HES 670/0.75 for volume expansion.

MEASUREMENTS AND MAIN RESULTS

Patients were less likely to be administered albumin intraoperatively (odds ratio [OR] 0.16, confidence interval [CI] 0.08-0.35, P < .001). When albumin was utilized, intraoperative amounts were similar (mean ± standard deviation [SD]: 36.1 ± 17.1 g vs 43.8 ± 15.5 g, P = .16). Patients were more likely to receive an intraoperative HES product after the formulary change (OR 11.1, CI 4.4-27.6, P < .001) as well as larger volumes (mean ± SD: 743 ± 544 mL vs 500 ± 0 mL, P = .01). No differences were detected in mean baseline-to-discharge changes in serum creatinine or in postoperative urine output, nor were there differences in clinically significant bleeding.

CONCLUSIONS

Change to a lower molecular weight HES decreased intraoperative albumin utilization and increased HES utilization with no detected difference in renal function or bleeding complications.

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

BACKGROUND

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

OBJECTIVE

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

DATA SOURCES

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

STUDY SELECTION

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

DATA EXTRACTION

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

DATA SYNTHESIS

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

CONCLUSIONS

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

Consensus statement of the ESICM task force on colloid volume therapy in critically ill patients

PURPOSE

Colloids are administered to more patients than crystalloids, although recent evidence suggests that colloids may possibly be harmful in some patients. The European Society of Intensive Care Medicine therefore assembled a task force to compile consensus recommendations based on the current best evidence for the safety and efficacy of the currently most frequently used colloids--hydroxyethyl starches (HES), gelatins and human albumin.

METHODS

Meta-analyses, systematic reviews and clinical studies of colloid use were evaluated for the treatment of volume depletion in mixed intensive care unit (ICU), cardiac surgery, head injury, sepsis and organ donor patients. Clinical endpoints included mortality, kidney function and bleeding. The relevance of concentration and dosage was also assessed. Publications from 1960 until May 2011 were included. The quality of available evidence and strength of recommendations were based on the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RECOMMENDATIONS AND CONCLUSIONS

We recommend not to use HES with molecular weight ≥ 200 kDa and/or degree of substitution >0.4 in patients with severe sepsis or risk of acute kidney injury and suggest not to use 6% HES 130/0.4 or gelatin in these populations. We recommend not to use colloids in patients with head injury and not to administer gelatins and HES in organ donors. We suggest not to use hyperoncotic solutions for fluid resuscitation. We conclude and recommend that any new colloid should be introduced into clinical practice only after its patient-important safety parameters are established.

Fluid and electrolyte management for the surgical patient

For surgical patients, appropriate selection and administration of fluids can mitigate against organ failure, whereas improper dosing can exacerbate already injured systems. Fluid and electrolyte goals and deficiencies must be defined for individual patients to provide the appropriate combination of resuscitation and maintenance fluids. Specific electrolyte abnormalities should be anticipated, identified, and corrected to optimize organ functions. Using the strong-ion approach to acid-base assessment, delivered fluids that contain calculated amounts of electrolytes will interact with the patient's plasma charge and influence the patient's pH, allowing the clinician to achieve a more precise end point.

[Volume replacement in intensive care medicine]

Volume substitution represents an essential component of intensive care medicine. The amount of fluid administered, the composition and the timing of volume replacement seem to affect the morbidity and mortality of critically ill patients. Although restrictive volume strategies bear the risk of tissue hypoperfusion and tissue hypoxia in hemodynamically unstable patients liberal strategies favour the development of avoidable hypervolemia with edema and resultant organ dysfunction. However, neither strategy has shown a consistent benefit. In order to account for the heavily varying oxygen demand of critically ill patients, a goal-directed, demand-adapted volume strategy is proposed. Using this strategy, volume replacement should be aligned to the need to restore tissue perfusion and the evidence of volume responsiveness. As the efficiency of volume resuscitation for correction of tissue hypoxia is time-dependent, preload optimization should be completed in the very first hours. Whether colloids or crystalloids are more suitable for this purpose is still controversially discussed. Nevertheless, a temporally limited use of colloids during the initial stage of tissue hypoperfusion appears to represent a strategy which uses the greater volume effect during hypovolemia while minimizing the risks for adverse reactions.

The efficacy and safety of colloid resuscitation in the critically ill

Despite evidence from clinical studies and meta-analyses that resuscitation with colloids or crystalloids is equally effective in critically ill patients, and despite reports from high-quality clinical trials and meta-analyses regarding nephrotoxic effects, increased risk of bleeding, and a trend toward higher mortality in these patients after the use of hydroxyethyl starch (HES) solutions, colloids remain popular and the use of HES solutions is increasing worldwide. We investigated the major rationales for colloid use, namely that colloids are more effective plasma expanders than crystalloids, that synthetic colloids are as safe as albumin, that HES solutions have the best risk/benefit profile among the synthetic colloids, and that the third-generation HES 130/0.4 has fewer adverse effects than older starches. Evidence from clinical studies shows that comparable resuscitation is achieved with considerably less crystalloid volumes than frequently suggested, namely, <2-fold the volume of colloids. Albumin is safe in intensive care unit patients except in patients with closed head injury. All synthetic colloids, namely, dextran, gelatin, and HES have dose-related side effects, which are coagulopathy, renal failure, and tissue storage. In patients with severe sepsis, higher doses of HES may be associated with excess mortality. The assumption that third-generation HES 130/0.4 has fewer adverse effects is yet unproven. Clinical trials on HES 130/0.4 have notable shortcomings. Mostly, they were not performed in intensive care unit or emergency department patients, had short observation periods of 24 to 48 hours, used cumulative doses below 1 daily dose limit (50 mL/kg), and used unsuitable control fluids such as other HES solutions or gelatins. In conclusion, the preferred use of colloidal solutions for resuscitation of patients with acute hypovolemia is based on rationales that are not supported by clinical evidence. Synthetic colloids are not superior in critically ill adults and children but must be considered harmful depending on the cumulative dose administered. Safe threshold doses need to be determined in studies in high-risk patients and observation periods of 90 days. Such studies on HES 130/0.4 are still lacking despite its widespread and increasing use. Because there are safer and equally effective alternatives in the form of crystalloids, use of synthetic colloids should be avoided except in the context of clinical studies.

Hyperoncotic colloids and acute kidney injury: a meta-analysis of randomized trials

Introduction

It has been hypothesized that hyperoncotic colloids might contribute to acute kidney injury (AKI). However, the validity of this hypothesis remains unclear.

Methods

A meta-analysis was conducted of randomized controlled trials evaluating AKI after infusion of hyperoncotic albumin and hydroxyethyl starch (HES) solutions. Mortality was a secondary endpoint. Eligible trials were sought by multiple methods, and the pooled odds ratios (OR) for AKI and death and 95% confidence intervals (CI) were computed under a random effects model.

Results

Eleven randomized trials with a total of 1220 patients were included: 7 evaluating hyperoncotic albumin and 4 hyperoncotic HES. Clinical indications were ascites, surgery, sepsis and spontaneous bacterial peritonitis. Hyperoncotic albumin decreased the odds of AKI by 76% (OR, 0.24; CI, 0.12-0.48; P < 0.0001), while hyperoncotic HES increased those odds by 92% (OR, 1.92; CI, 1.31-2.81; P = 0.0008). Parallel effects on mortality were observed, with hyperoncotic albumin reducing the odds of death by 48% (OR, 0.52; CI, 0.28-0.95; P = 0.035) and hyperoncotic HES raising those odds by 41% (OR, 1.41; CI, 1.01-1.96; P = 0.043).

Conclusions

This meta-analysis does not support the hypothesis that hyperoncotic colloid solutions per se injure the kidney. Renal effects appear instead to be colloid-specific, with albumin displaying renoprotection and HES showing nephrotoxicity.

Analysis of gelatin plasma substitutes in blood based on detection of hydroxyproline derivatives

The gelatin plasma substitute is often polydisperse and heterogenous, making it difficult to determine the elimination rate and half-life in the body. In this study, one method was developed based on quantitative determination of hydroxyproline derivatives. Two plasma substitutes were prepared by succinylation and genipin-crosslinking, respectively. After transfusion, the blood samples were hydrolyzed and derivatized, and then analyzed by HPLC. A two-phase exponential association equation was used for fitting the time-concentration curves. The results indicated that this method could be used for quantitative determination of gelatin in blood, and the pharmacokinetic parameters such as elimination rate and half-life.

Emerging therapies in traumatic hemorrhage control

PURPOSE OF REVIEW

Care of the injured patient is a dynamic process. Hemorrhage remains the primary cause of preventable death after trauma. Rapid and effective early care can improve survival and outcomes. Emerging therapies to address traumatic hemorrhage will be discussed.

RECENT FINDINGS

Current concepts in trauma care include damage control resuscitation with rapid surgical correction of bleeding; prevention of the development of the lethal triad; limitation of crystalloid administration and application of high ratios of plasma and platelets to packed red blood cells. Prehospital resuscitation strategies can effect care of the hemorrhaging trauma patient, as well. The goal should be to preserve vital functions without increasing the risk for further bleeding. The concept of hypotensive resuscitation has been formulated to address this issue. The type of resuscitation fluid also plays an important role, with novel fluids currently being studied for routine use. Compressible hemorrhage constitutes an important component of potentially survivable injury. Hemostatic dressings and tourniquets can prove essential to the management of combat and civilian wounds.

SUMMARY

Given the potential to preserve life with appropriate attention applied to the bleeding trauma victim, it is vitally important to explore the options currently available and continue to make improvements in care.

Hydroxyethyl starch (HES) versus other fluid therapies: effects on kidney function

BACKGROUND

Hydroxyethyl starches (HES) are synthetic colloids commonly used for fluid resuscitation, yet controversy exists about their impact on kidney function.

OBJECTIVES

To examine the effects of HES on kidney function compared to other fluid resuscitation therapies in different patient populations.

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register, the Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library), MEDLINE, EMBASE, MetaRegister and reference lists of articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs in which HES was compared to an alternate fluid therapy for the prevention or treatment of effective intravascular volume depletion. Primary outcomes were renal replacement therapy (RRT), author-defined kidney failure and acute kidney injury (AKI) as defined by the RIFLE criteria. Secondary outcomes included serum creatinine and creatinine clearance.

DATA COLLECTION AND ANALYSIS

Screening, selection, data extraction and quality assessments for each retrieved article were carried out by two authors using standardised forms. Authors were contacted when published data were incomplete. Preplanned sensitivity and subgroup analyses were performed after data were analysed with a random effects model.

MAIN RESULTS

The review included 34 studies (2607 patients). Overall, the RR of author-defined kidney failure was 1.50 (95% CI 1.20 to 1.87; n = 1199) and 1.38 for requiring RRT (95% CI 0.89 to 2.16; n = 1236) in HES treated individuals compared with other fluid therapies. Subgroup analyses suggested increased risk in septic patients compared to non-septic (surgical/trauma) patients. Non-septic patient studies were smaller and had lower event rates, so subgroup differences may have been due to lack of statistical power in these studies. Only limited data was obtained for analysis of kidney outcomes by the RIFLE criteria. Overall, methodological quality of studies was good but subjective outcomes were potentially biased because most studies were unblinded.

AUTHORS' CONCLUSIONS

Potential for increased risk of AKI should be considered when weighing the risks and benefits of HES for volume resuscitation, particularly in septic patients. Large studies with adequate follow-up are required to evaluate the renal safety of HES products in non-septic patient populations. RIFLE criteria should be applied to evaluate kidney function in future studies of HES and, where data is available, to re-analyse those studies already published. There is inadequate clinical data to address the claim that safety differences exist between different HES products.

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

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

Renal outcomes and mortality following hydroxyethyl starch resuscitation of critically ill patients: systematic review and meta-analysis of randomized trials: ATTENTION: The analysis and conclusions of this article are being revised by the authors. This is due to the journal Anesthesia and Analgesia's retraction of a paper by Dr. Joachim Boldt, an author in seven of the studies analyzed in this review. As such, the editors of Open Medicine recommend interpreting this review with extreme caution until Zarychanski et al. publish a new analysis and interpretation in Open Medicine. For more information, see Anesthesia and Analgesia's press release

BACKGROUND

Hydroxyethyl starch (HES) is a type of colloid fluid that is commonly used for volume resuscitation of patients admitted to the intensive care unit. Data regarding the renal consequences of HES are conflicting.

PURPOSE

To evaluate the effect of HES solutions on renal outcomes and mortality among critically ill patients requiring acute volume resuscitation.

DATA SOURCES

We searched electronic databases (MEDLINE, EMBASE, the Cochrane Central Registry of Controlled Trials and the SCOPUS database) from 1950 to 2008. Conference proceedings and grey literature sources were searched from 2002 to 2007.

STUDY SELECTION

We included only randomized controlled trials of acute volume resuscitation of critically ill patients comparing HES fluid with an alternative resuscitation fluid.

DATA SYNTHESIS

Two reviewers independently assessed trial eligibility, extracted data and evaluated trial quality. Random-effects models were used for all summary measures of effect.

RESULTS

Twenty-two trials (n = 1865 patients) were included. Patients who received HES were more likely to have received renal replacement therapy (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.22-2.96, I(2) 9.5%, n = 749). There was no difference in overall mortality (OR 1.07, 95% CI 0.85-1.34, n = 1657). However, in trials that included patients with severe sepsis and septic shock, in high-quality and multicentre trials, and in trials with adequate allocation concealment, there was a trend toward increased risk of death in association with HES.

LIMITATIONS

Data regarding adverse events, including renal outcomes, were not reported in the majority of published randomized trials. Considerable clinical and methodologic heterogeneity existed among trials.

CONCLUSIONS

The use of HES for acute volume resuscitation of critically ill patients, and in particular those with severe sepsis and septic shock, appeared to be associated with increased use of renal replacement therapy. Further randomized controlled trials evaluating clinically important end points are required to examine the efficacy and safety of HES fluids for critically ill patients.

Hydroxyethyl starch interferes with human blood ex vivo coagulation, platelet function and sedimentation

BACKGROUND

Hydroxyethyl starch (HES) solutions are widely used for intravascular volume expansion. In Taiwan, the medium molecular weight of HES 200/0.5 and HES 130/0.4 solutions are most commonly used. It has been demonstrated that HES may affect coagulation and platelet function significantly. However, the differential effects of each medium molecular weight HES on platelets remain poorly reported. Therefore, we studied the influence of the two HES solutions on platelet function in vitro by mixing whole blood with different proportions of HES 130 kD, HES 200 kD, and saline to determine the differences.

METHODS

Human blood samples for platelet function analyzer (PFA), aggregometry and blood/HES mixed test were drawn from the antecubital vein and put into test tubes containing 3.2% trisodium citrate (blood:citrate, 9:1). The specimens were divided into four groups, designated as whole blood, 10%, 20%, and 30% dilution with normal saline (N/S), HES130 or HES200 solution. The platelet function of each sample was measured by both PFA and platelet aggregometry.

RESULTS

The results showed that the PFA-100 closure times CEPI-CT and CADP-CT were significantly prolonged in the samples diluted with normal saline, HES130 and HES200 than in the controls. The ADP triggered whole blood aggregometry showed that attenuated impedance was observed in samples of 20% diluted with HES130 and HES200 groups. The blood/HES mixed sedimentation test showed significantly increased proportion of the upper liquid layer in the HES200 group than in other groups.

CONCLUSION

Our data demonstrated that HES200 and HES130 possess noticeably inhibitory effects on platelet function, especially when the HES replaced proportion was more than 20%. HES200 has a greater effect on blood cells and plasma separation than does HES130.

PRO: hydroxyethylstarch can be safely used in the intensive care patient--the renal debate

INTRODUCTION

Correcting hypovolemia is fundamental when treating the critically ill. Different hydroxyethylstarch (HES) preparations with different physicochemical characteristics (mean molecular weight (Mw), molar substitution (MS), C2/C6 ratio, balanced/unbalanced) are available. The possible detrimental effect of HES on kidney function has become a major objection to using HES.

METHODS

This review focuses on the effect of HES on kidney function.

RESULTS

First and second-generation HES with high Mw (>200 kD) and high MS (>0.5) have been shown to impair kidney function in some studies of septic patients, especially when using hyperoncotic HES. More rapidly degradable HES preparations (Mw 130 kD; MS < 0.5) did not cause deterioration of kidney function in a variety of clinical conditions. Even when kidney function was impaired (serum creatinine >1.5 mg/dL) this HES preparation was without negative effect. Dissolving HES in a balanced solution instead of saline may further improve the safety of HES with regard to kidney function. Dose limitations of the specific HES preparation should be carefully considered.

CONCLUSIONS

Hyperoncotic HES should not be used in patients who are at risk of developing kidney dysfunction. In patients without preexisting kidney dysfunction there seems to be no negative effects of modern HES preparations. In septic patients with reduced kidney function (serum creatinine >2.5 mg/dL) HES should be used cautiously, because studies of these patients are not available. Dissolving HES in a balanced solution further improves the safety of HES with regard to kidney function. At present, there seems to be no good reason to generally ban use of HES in our patients.

Pro/con debate: should synthetic colloids be used in patients with septic shock?

You have recently heard reports that synthetic colloids may be associated with renal failure and other morbidities in certain populations of critically ill patients. You have been asked by the hospital chief of staff whether there should be a suspension of the use of synthetic colloids until further information is available. You need to make a decision.