Update on the Comparative Safety of Colloids: A Systematic Review of Clinical Studies

Intraoperative Use of Albumin in Major Noncardiac Surgery: Incidence, Variability, and Association With Outcomes

BACKGROUND

The impact of albumin use during major surgery is unknown, and a dearth of evidence governing its use in major noncardiac surgery has long precluded its standardization in clinical guidelines.

OBJECTIVE

In this study, we investigate institutional variation in albumin use among medical centers in the United States during major noncardiac surgery and explore the association of intraoperative albumin administration with important postoperative outcomes.

METHODS

The study is an observational retrospective cohort analysis performed among 54 U.S. hospitals in the Multicenter Perioperative Outcomes Group and includes adult patients who underwent major noncardiac surgery under general anesthesia between January 2014 and June 2020. The primary endpoint was the incidence of albumin administration. Secondary endpoints are acute kidney injury (AKI), net-positive fluid balance, pulmonary complications, and 30-day mortality. Albumin-exposed and albumin-unexposed cases were compared within a propensity score-matched cohort to evaluate associations of albumin use with outcomes.

RESULTS

Among 614,215 major surgeries, predominantly iso-oncotic albumin was administered in 15.3% of cases and featured significant inter-institutional variability in use patterns. Cases receiving intraoperative albumin involved patients of higher American Society of Anesthesiologists physical status and featured larger infused crystalloid volumes, greater blood loss, and vasopressor use. Overall, albumin was most often administered at high-volume surgery centers with academic affiliation, and within a propensity score-matched cohort (n=153,218), the use of albumin was associated with AKI (aOR 1.24, 95% CI 1.20-1.28, P <0.001), severe AKI (aOR 1.45, 95% CI 1.34-1.56, P <0.001), net-positive fluid balance (aOR 1.18, 95% CI 1.16-1.20, P <0.001), pulmonary complications (aOR 1.56, 95% CI 1.30-1.86, P <0.001), and 30-day all-cause mortality (aOR 1.37, 95% CI 1.26-1.49, P <0.001).

CONCLUSIONS

Intravenous albumin is commonly administered among noncardiac surgeries with significant inter-institutional variability in use in the United States. Albumin administration was associated with an increased risk of postoperative complications.

Novel Polymerized Human Serum Albumin For Ex Vivo Lung Perfusion

Ex vivo lung perfusion (EVLP) is a method of organ preservation to expand the donor pool by allowing organ assessment and repair. Perfusion solution composition is crucial to maintaining and improving organ function during EVLP. EVLP compared perfusates supplemented with either polymeric human serum albumin (PolyHSA) or standard human serum albumin (HSA). Rat heart-lung blocks underwent normothermic EVLP (37°C) for 120 minutes using perfusate with 4% HSA or 4% PolyHSA synthesized at a 50:1 or 60:1 molar ratio of glutaraldehyde to PolyHSA. Oxygen delivery, lung compliance, pulmonary vascular resistance (PVR), wet-to-dry ratio, and lung weight were measured. Perfusion solution type (HSA or PolyHSA) significantly impacted end-organ metrics. Oxygen delivery, lung compliance, and PVR were comparable among groups ( P > 0.05). Wet-to-dry ratio increased in the HSA group compared to the PolyHSA groups (both P < 0.05) suggesting edema formation. Wet-to-dry ratio was most favorable in the 60:1 PolyHSA-treated lungs compared to HSA ( P < 0.05). Compared to using HSA, PolyHSA significantly lessened lung edema. Our data confirm that the physical properties of perfusate plasma substitutes significantly impact oncotic pressure and the development of tissue injury and edema. Our findings demonstrate the importance of perfusion solutions and PolyHSA is an excellent candidate macromolecule to limit pulmonary edema. http://links.lww.com/ASAIO/A980.

Perioperative Albumin Supplementation is Associated With Decreased Risk of Complications Following Microvascular Head and Neck Reconstruction

PURPOSE

Studies have demonstrated that low serum albumin levels are associated with a high postoperative complication rate after microvascular free flap reconstruction. The aim of this study was to investigate whether perioperative albumin supplementation reduced the postoperative complications of microvascular free flap reconstruction in oral and maxillofacial tumor resections.

PATIENTS AND METHODS

Patients who underwent microvascular free flap reconstruction during oral and maxillofacial tumor resections from January 2012 to December 2017 were enrolled in this retrospective study. The predictor variable was perioperative albumin supplementation. The primary outcome variables were surgery-associated postoperative complications, including local and systemic complications. The secondary outcome variables were the total duration of hospital stay, postoperative ICU admission rate, duration of ICU stay, and mortality during hospitalization.

RESULTS

In total, 315 patients met the criteria. Patients with serum albumin supplementation showed a lower rate of surgery-associated local complications (6.5 vs 21.6%) with an adjusted odds ratio (OR) of 0.24 (95% confidence interval (CI), 0.12 to 0.49, P < .001). The average postoperative hospital stay was significantly shortened for patients with albumin supplementation (12.56 ± 4.23 vs 15.34 ± 5.24 days, P < .001). However, albumin supplementation had no effect on systemic complications.

CONCLUSIONS

The results of this study suggest that perioperative albumin supplementation is associated with a decreased risk of local complications, shortened hospital stay, and decreased need for crystalloid infusion in patients who underwent oral and maxillofacial tumor resections with microvascular free flap reconstruction.

[Solutions for Fluid Treatment and Outcome - an Update]

Fluid therapy is one of the most frequently used medical interventions with the aim of normalizing the fluid balance. A decisive criterion for the efficiency of fluid or volume replacement is the functionality of the glycocalyx, a thin endothelial glycoprotein layer. Its solidity is an essential factor for fluid exchange and transport from the vascular system to the tissue. The recently described revised Starling principle extends the understanding considerably. From a clinical point of view, fluid treatment should aim for timely euvolemia without inducing relevant side effects. Both crystalloid and natural or synthetic colloidal solutions are available. In the case of crystalloid solutions, the so-called balanced solutions seem to be associated with fewer side effects. If the vascular barrier is intact, colloid solutions have a higher volume effect, but may have significant side effects limiting their use. At least in Europe, some synthetic colloids shall therefore no longer be used in critically ill patients. In contrast, treatment with albumin 20% in hypalbuminemic patients with cardiovascular disease leads to a reduced incidence of acute kidney injury and has also been associated with other clinical benefits. To what extent future, individualized therapeutic approaches employing colloids will influence the outcome is currently speculative.

Anaesthesia for Liver Transplantation: An Update

Liver transplantation (LT) is a challenging surgery performed on patients with complex physiology profiles, complicated by multi-system dysfunction. It represents the treatment of choice for end-stage liver disease. The procedure is performed under general anaesthesia, and a successful procedure requires an excellent understanding of the patho-physiology of liver failure and its implications. Despite advances in knowledge and technical skills and innovations in immunosuppression, the anaesthetic management for LT can be complicated and represent a real challenge. Monitoring devices offer crucial information for the successful management of patients. Hemodynamic instability is typical during surgery, requiring sophisticated invasive monitoring. Arterial pulse contour analysis and thermo-dilution techniques (PiCCO), rotational thromboelastometry (RO-TEM), transcranial doppler (TCD), trans-oesophageal echocardiography (TEE) and bispectral index (BIS) have been proven to be reliable monitoring techniques playing a significant role in decision making. Anaesthetic management is specific according to the three critical phases of surgery: pre-anhepatic, anhepatic and neo-hepatic phase. Surgical techniques such as total or partial clamping of the inferior vena cava (IVC), use of venovenous bypass (VVBP) or portocaval shunts have a significant impact on cardiovascular stability. Post reperfusion syndrome (PRS) is a significant event and can lead to arrhythmias and even cardiac arrest.

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.

Albumin mass balance and kinetics in liver transplantation

Background

In major abdominal surgery albumin is shifted from the circulation, presumably leaking into the interstitial space, contributing to a 30–40% decrease in plasma albumin concentration. During and after liver transplantation exogenous albumin is infused for volume substitution and to maintain plasma albumin concentration. Here we used liver transplantation as a model procedure for the study of albumin mass balance and kinetics during major abdominal surgery with albumin substitution.

Methods

Patients were studied during liver transplantation (n = 16), and until postoperative day 3 (POD 3) (n = 11). Cumulative perioperative albumin shift was assessed by mass balance of albumin and hemoglobin. Synthesis rates of albumin and fibrinogen were estimated by the flooding technique using deuterium-labeled phenylalanine. Albumin distribution was assessed by radioiodinated human serum albumin.

Results

At the end of surgery, 37 ± 17 g of albumin (p < 0.0001) had shifted from plasma, and this amount was stable until POD 3 (48 ± 33 g, p = 0.0017 versus baseline). There was 91 ± 37 g exogenous albumin infused peroperatively and another 47 ± 35 g was infused postoperatively until POD 3. Absolute synthesis rates of albumin and fibrinogen on POD 3 were 239 ± 84 mg/kg body weight/day and 33 mg/kg body weight/day (range 5–161), respectively.

Conclusions

Albumin net leakage from plasma progressed until the end of surgery, and was then unaltered until POD 3. This is in contrast with the normalization of the cumulative albumin shift identified at day 3 after non-transplant major abdominal surgery. Liver synthesis of export proteins was high compared to reference values at the third postoperative day, suggesting rapid recovery of synthesis capacity.

Trial registration

Swedish Medical Product Agency, EudraCT 2015-002568-18. Registered on 15 July 2015.

No Differences in Renal Function between Balanced 6% Hydroxyethyl Starch (130/0.4) and 5% Albumin for Volume Replacement Therapy in Patients Undergoing Cystectomy: A Randomized Controlled Trial

BACKGROUND

The use of artificial colloids has declined in critical care, whereas they are still used in perioperative medicine. Little is known about the nephrotoxic potential in noncritically ill patients during routine surgery. The objective of this trial was to evaluate the influences of albumin 5% and balanced hydroxyethyl starch 6% (130/0.4) on renal function and kidney injury.

METHODS

One hundred urologic patients undergoing elective cystectomy were randomly assigned for this prospective, single-blinded, controlled study with two parallel groups to receive either albumin 5% or balanced hydroxyethyl starch 6% (130/0.4) as the only perioperative colloid. The primary endpoint was the ratio of serum cystatin C between the last visit at day 90 and the first preoperative visit. Secondary endpoints were estimated glomerular filtration rate and serum neutrophil gelatinase-associated lipocalin until the third postoperative day and risk, injury, failure, loss, and end-stage renal disease criteria at postoperative days 3 and 90.

RESULTS

The median cystatin C ratio was 1.11 (interquartile range, 1.01 to 1.23) in the albumin and 1.08 (interquartile range, 1.00 to 1.20) in the hydroxyethyl starch group (median difference = 0.03; 95% CI, -0.09 to 0.08; P = 0.165). Also, there were no significant differences concerning serum cystatin C concentrations; estimated glomerular filtration rate; risk, injury, failure, loss, and end-stage renal disease criteria; and neutrophil gelatinase-associated lipocalin. Infusion requirements, transfusion rates, and perioperative hemodynamics were similar in both groups.

CONCLUSIONS

With respect to renal function and kidney injury, this study indicates that albumin 5% and balanced hydroxyethyl starch 6% have comparable safety profiles in noncritically ill patients undergoing major surgery.

The Evolving Science of Trauma Resuscitation

This review summarizes the evolution of trauma resuscitation from a one-size-fits-all approach to one tailored to patient physiology. The most dramatic change is in the management of actively bleeding patients, with a balanced blood product-based resuscitation approach (avoiding crystalloids) and surgery focused on hemorrhage control, not definitive care. When hemostasis has been achieved, definitive resuscitation to restore organ perfusion is initiated. This approach is associated with decreased mortality, reduced duration of stay, improved coagulation profile, and reduced crystalloid/vasopressor use. This article focuses on the tools and methods used for trauma resuscitation in the acute phase of trauma care.

Future Therapies in Burn Resuscitation

Since the 1940s, the resuscitation of burn patients has evolved with dramatic improvements in mortality. The most significant achievement remains the creation and adoption of formulae to calculate estimated fluid requirements to guide resuscitation. Modalities to attenuate the hypermetabolic phase of injury include pharmacologic agents, early enteral nutrition, and the aggressive approach of early excision of large injuries. Recent investigations into the genomic response to severe burns and the application of computer-based decision support tools will likely guide future resuscitation, with the goal of further reducing mortality and morbidity, and improving functional and quality of life outcomes.

Different effects of fluid loading with saline, gelatine, hydroxyethyl starch or albumin solutions on acid-base status in the critically ill

Introduction

Fluid administration in critically ill patients may affect acid-base balance. However, the effect of the fluid type used for resuscitation on acid-base balance remains controversial.

Methods

We studied the effect of fluid resuscitation of normal saline and the colloids gelatine 4%, hydroxyethyl starch (HES) 6%, and albumin 5% on acid-base balance in 115 clinically hypovolemic critically ill patients during a 90 minute filling pressure-guided fluid challenge by a post-hoc analysis of a prospective randomized clinical trial.

Results

About 1700 mL was infused per patient in the saline and 1500 mL in each of the colloid groups (P<0.001). Overall, fluid loading slightly decreased pH (P<0.001) and there was no intergroup difference. This mildly metabolic acidifying effect was caused by a small increase in chloride concentration and decrease in strong ion difference in the saline- and HES-, and an increase in (uncorrected) anion gap in gelatine- and albumin-loaded patients, independent of lactate concentrations.

Conclusion

In clinically hypovolemic, critically ill patients, fluid resuscitation by only 1500–1700 mL of normal saline, gelatine, HES or albumin, resulted in a small decrease in pH, irrespective of the type of fluid used. Therefore, a progressive metabolic acidosis, even with increased anion gap, should not be erroneously attributed to insufficient fluid resuscitation.

Trial registration

ISRCTN Registry ISRCTN19023197

Cardiac surgery-associated acute kidney injury

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a well-recognized complication resulting with the higher morbid-mortality after cardiac surgery. In its most severe form, it increases the odds ratio of operative mortality 3-8-fold, length of stay in the Intensive Care Unit and hospital, and costs of care. Early diagnosis is critical for an optimal treatment of this complication. Just as the identification and correction of preoperative risk factors, the use of prophylactic measures during and after surgery to optimize renal function is essential to improve postoperative morbidity and mortality of these patients. Cardiopulmonary bypass produces an increased in tubular damage markers. Their measurement may be the most sensitive means of early detection of AKI because serum creatinine changes occur 48 h to 7 days after the original insult. Tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 are most promising as an early diagnostic tool. However, the ideal noninvasive, specific, sensitive, reproducible biomarker for the detection of AKI within 24 h is still not found. This article provides a review of the different perspectives of the CSA-AKI, including pathogenesis, risk factors, diagnosis, biomarkers, classification, postoperative management, and treatment. We searched the electronic databases, MEDLINE, PubMed, EMBASE using search terms relevant including pathogenesis, risk factors, diagnosis, biomarkers, classification, postoperative management, and treatment, in order to provide an exhaustive review of the different perspectives of the CSA-AKI.

Simultaneous assessment of the synthesis rate and transcapillary escape rate of albumin in inflammation and surgery

Background

Better knowledge of albumin kinetics is needed to define the indications for albumin use in clinical practice. This study involved two approaches: the synthesis rate and transcapillary escape rate of albumin were measured simultaneously at different levels of plasma albumin concentration in relation to acute inflammation and surgery; and two different tracers were compared to determine plasma volume and the transcapillary escape rate.

Methods

Healthy volunteers (n = 10), patients with acute inflammatory abdominal disease (n = 10), and patients undergoing elective pancreatic resection (n = 10) were studied. The albumin synthesis rate was measured by the incorporation of deuterium-labeled phenylalanine. Plasma volume and the transcapillary escape rate were assessed using ¹²³I-labeled and ¹²⁵I-labeled albumin.

Results

A 50 % elevated de-novo albumin synthesis rate was seen in patients with acute inflammation and marked hypoalbuminemia, while patients with marginal hypoalbuminemia before the start of surgery had a normal albumin synthesis rate. The transcapillary escape rate was elevated intraoperatively during the reconstructive phase of pancreatic surgery, when plasma albumin was decreased but stable. In acute inflammation with marked hypoalbuminemia, the transcapillary escape rate was no different from normal. ¹²³I-labeled and ¹²⁵I-labeled albumin were found exchangeable for plasma volume determinations, but could be used only in groups of patients for the transcapillary escape rate.

Conclusions

This observational study illustrates the limited information contained in albumin plasma concentrations to reflect albumin kinetics. On the contrary, single measurements of the synthesis rate and/or transcapillary escape rate of albumin obviously cannot explain the plasma level of albumin or the changes seen in plasma albumin concentration.

Trial registration

www.clinicaltrials.gov, study number NCT01686776. Registered 13 September 2012.

Liberal or restrictive fluid management during elective surgery: a systematic review and meta-analysis

This article reviews if a restrictive fluid management policy reduces the complication rate if compared to liberal fluid management policy during elective surgery. The PubMed database was explored by 2 independent researchers. We used the following search terms: "Blood transfusion (MESH); transfusion need; fluid therapy (MESH); permissive hypotension; fluid management; resuscitation; restrictive fluid management; liberal fluid management; elective surgery; damage control resuscitation; surgical procedures, operative (MESH); wounds (MESH); injuries (MESH); surgery; trauma patients." A secondary search in the Medline, EMBASE, Web of Science, and Cochrane library revealed no additional results. We selected randomized controlled trials performed during elective surgeries. Patients were randomly assigned to a restrictive fluid management policy or to a liberal fluid management policy during elective surgery. The patient characteristics and the type of surgery varied. All but 3 studies reported American Society of Anaesthesiologists groups 1 to 3 as the inclusion criterion. The primary outcome of interest is total number of patients with a complication and the complication rate. Secondary outcome measures are infection rate, transfusion need, postoperative rebleeding, hospital stay, and renal function. In total, 1397 patients were analyzed (693 restrictive protocol, 704 liberal protocol). Meta-analysis showed that in the restrictive group as compared with the liberal group, fewer patients experienced a complication (relative risk [RR], 0.65; 95% confidence interval [CI], 0.55-0.78). The total complication rate (RR, 0.57; 95% CI, 0.52-0.64), risk of infection (RR, 0.62; 95% CI, 0.48-0.79), and transfusion rate (RR, 0.81; 95% CI, 0.66-0.99) were also lower. The postoperative rebleeding did not differ in both groups: RR, 0.76 (95% CI, 0.28-2.06). We conclude that compared with a liberal fluid policy, a restrictive fluid policy in elective surgery results in a 35% reduction in patients with a complication and should be advised as the preferred fluid management policy.

Cross-Sectional Guidelines for Therapy with Blood Components and Plasma Derivatives: Chapter 5 Human Albumin - Revised

Chapter 5 'Human Albumin' that was suspended on January 10, 2011 has been completed and updated in the present version.

Clinical practice guide for the choice of perioperative volume-restoring fluid in adult patients undergoing non-cardiac surgery

The present Clinical practice guide responds to the clinical questions about security in the choice of fluid (crystalloid, colloid or hydroxyethyl starch 130) in patients who require volume replacement during perioperative period of non-cardiac surgeries. From the evidence summary, recommendations were made following the GRADE methodology. In this population fluid therapy based on crystalloids is suggested (weak recommendation, low quality evidence). In the events where volume replacement is not reached with crystalloids, the use of synthetic colloids (hydroxyethyl starch 130 or modified fluid gelatin) is suggested instead of 5% albumin (weak recommendation, low quality evidence). The choice and dosage of the colloid should be based in the product characteristics, patient comorbidity and anesthesiologist's experience.

[Prehospital resuscitation of patients with multiple injuries]

INTRODUCTION

Polytrauma is the leading cause of morbidity and mortality in young adults (aged 35-45 years). At 30-40%, traumatic hemorrhage is the most frequent preventable cause of death. Approximately every fourth patient with multiple injuries suffers from trauma-induced coagulopathy.

METHODS

The current knowledge of prehospital resuscitation of patients with multiple injuries based on a selective literature research and experience in a level I trauma center are presented.

RESULTS

Hemorrhagic shock is a clinical diagnosis and the recognition by the first responding emergency physician requires rapid evaluation of the accident situation, injury pattern and patient's hemodynamic status. In the future, tools will help to reliably estimate shock. Development of trauma-induced coagulopathy is multifactorial and is characterized by interaction of tissue damage, shock, hypothermia, acidosis and dilution. Preclinical therapy follows the concept of damage control resuscitation and involves bleeding hemostasis, permissive hypotension with a target systolic blood pressure between 80 and 90 mmHg (≥80 mmHg in presence of traumatic brain injury) by modest infusion of primarily crystalloid solutions, avoiding hypothermia and acidosis.

CONCLUSION

The current knowledge and therapy recommendations are presented.

Perioperative clinical and economic outcomes associated with replacing first-generation high molecular weight hydroxyethyl starch (Hextend®) with low molecular weight hydroxyethyl starch (Voluven®) at a large medical center

Background

Several plasma volume expander alternatives exist to enhance intravascular volume status in patients undergoing surgery. The optimal intravascular volume expander in the perioperative setting is currently unknown. Low molecular weight hetastarch, Voluven® (130/0.4), may have a better safety profile than high molecular weight hetastarch, Hextend® (450/0.7). We examined the clinical and cost outcomes of converting from Hextend® to Voluven® in a large tertiary medical center.

Methods

Using a large electronic database, we retrospectively compared two different time periods (2009 and 2010) where the availability of semisynthetic colloids changed. Perioperative and postoperative outcomes including the use of red blood cells (RBC), platelets and coagulation factors, length of stay in the postoperative acute care unit (PACU), intensive care unit and hospital, as well as 30-day and 1-year mortality were compared. In addition, direct acquisition costs of all intraoperative and PACU colloids and crystalloid use were determined.

Results

A total of 4,888 adult subjects were compared of which 1,878 received Hextend® (pre-conversion) and 2,759 received Voluven® (post-conversion) during two separate 7-month periods within 1 year apart, with the remainder receiving Plasmanate. The patients were similar in terms of patient demographics, preoperative comorbidities, ASA status, emergency surgery, types of surgery, intraoperative, and PACU times. In unadjusted outcomes, patients in the Hextend® group received more lactated Ringer’s than in the Voluven® group (2,220 + 1,312 vs. 1,946 ± 1,097 ml; P < 0.0001). The use of albumin (Plasmanate) was reduced from 10.5% of patients to 1.1% when Voluven® was substituted for Hextend®. Unadjusted outcomes were similar in each group including hospital LOS, percent change from baseline creatinine and receipt of intraoperative and PACU blood product administration. However, overall unadjusted total fluid costs were greater in the Voluven® compared to Hextend® group ($116.7 compared to $59.3; P < 0.001).

Conclusions

Conversion from Hextend® to Voluven® in the perioperative period resulted in decreased albumin use and was not associated with changes in clinical outcomes and short- and long-term mortality. The conversion was associated with decreases in crystalloid use and an increase in colloid use and hence IV fluid acquisition costs in the Voluven® group.

Choices in fluid type and volume during resuscitation: impact on patient outcomes

We summarize the emerging new literature regarding the pathophysiological principles underlying the beneficial and deleterious effects of fluid administration during resuscitation, as well as current recommendations and recent clinical evidence regarding specific colloids and crystalloids. This systematic review allows us to conclude that there is no clear benefit associated with the use of colloids compared to crystalloids and no evidence to support the unique benefit of albumin as a resuscitation fluid. Hydroxyethyl starch use has been associated with increased acute kidney injury (AKI) and use of renal replacement therapy. Other synthetic colloids (dextran and gelatins) though not well studied do not appear superior to crystalloids. Normal saline (NS) use is associated with hyperchloremic metabolic acidosis and increased risk of AKI. This risk is decreased when balanced salt solutions are used. Balanced crystalloid solutions have shown no harmful effects, and there is evidence for benefit over NS. Finally, fluid resuscitation should be applied in a goal-directed manner and targeted to physiologic needs of individual patients. The evidence supports use of fluids in volume-responsive patients whose end-organ perfusion parameters have not been met.

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

OBJECTIVE

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

DATA SOURCES

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

SUMMARY

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

CONCLUSION

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

Albumin administration in the acutely ill: what is new and where next?

Albumin solutions have been used worldwide for the treatment of critically ill patients since they became commercially available in the 1940s. However, their use has become the subject of criticism and debate in more recent years. Importantly, all fluid solutions have potential benefits and drawbacks. Large multicenter randomized studies have provided valuable data regarding the safety of albumin solutions, and have begun to clarify which groups of patients are most likely to benefit from their use. However, many questions remain related to where exactly albumin fits within our fluid choices. Here, we briefly summarize some of the physiology and history of albumin use in intensive care before offering some evidence-based guidance for albumin use in critically ill patients.

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.

[Current role of albumin in critical care]

The use of colloids in fluid therapy has been, and still continues to be a controversial topic, particularly when referring to the critical patient. The choice of the fluid that needs to be administered depends on several factors, many of which are theoretical, and continue being an object of debate. The interest in the clinical use of the albumin has emerged again, immediately after recent publications in the search of the most suitable colloid. It is the most abundant protein in the plasma, being responsible for 80% of the oncotic pressure. It regulates the balance between the intra- and extra-vascular volumes. Recent multicenter studies question the supposed lack of safety that was previously assigned to it. Furthermore, in vitro studies demonstrate other important actions besides oncotic, for example neutralization of free radicals, and exogenous (drugs) and endogenous substances (bile pigments, cholesterol). Being aware of these secondary properties of albumin, and evaluating the pathophysiology of the critical patient (in particular, sepsis), to maintain plasma albumin levels within the normal range, could be of great importance. Based on the most recent publications, the aim of this review is to briefly analyze the pathophysiology of albumin, as well as to discuss its possible indications in the critical patient.

Perioperative intravascular volume replacement and kidney insufficiency

Perioperative acute kidney injury (AKI) occurrence is probably increased in recent years due to the increased level of complexity of surgical procedures and severity of illness of surgical patients. Perioperative AKI has a multifactorial aetiology (preoperative co-morbidities such as diabetes, heart failure and chronic kidney disease, emergent surgery, exposure to nephrotoxic drugs, haemodynamic instability, hypothermia, inflammatory response to surgery, hospital-acquired infections and abdominal compartment syndrome). However, fluid choice for perioperative volume replacement might have a major role in perioperative AKI, as administration of crystalloid solutions, colloids or haemoderivates has the potential for kidney injury. This review focusses on the issue of fluid replacement quality and quantity and their association with renal dysfunction.

Colloids in sepsis: evenly distributed molecules surrounded by uneven questions

Colloids are frequently used for fluid expansion in the intensive care unit, although its use on several clinical scenarios remains unproven of any relevant clinical benefit. The purpose of this article was to carry out a narrative review regarding the safety and efficacy of colloids in patients with sepsis and septic shock, with emphasis on the most commonly used colloids, albumin and starches. Colloids are effective fluid expanders and are able to restore the hemodynamic profile with less total volume than crystalloids. These properties appear to be preserved even in patients with sepsis with increased capillary permeability. However, some colloids are associated with renal impairment and coagulation abnormalities. Starch use was associated with increased mortality in two large clinical trials. Also, starches probably have significant renal adverse effects and may be related to more need for renal replacement therapy in severe sepsis. Albumin is the only colloid that has been shown safe in patients with sepsis and that may be associated with improved outcomes on specific subpopulations. No trial so far found any robust clinical end point favoring colloid use in patients with sepsis. Because there is no proven benefit of the use of most colloids in patients with sepsis, its use should not be encouraged outside clinical trials. Albumin is the only colloid solution that has proven to be safe, and its use may be considered on hypoalbuminemic patients with sepsis. Nevertheless, there are no robust data to recommend routine albumin administration in sepsis. Starch use should be avoided in patients with sepsis because of the recent findings of a multicenter randomized study until further evidence is available.

Effect of waxy maize-derived hydroxyethyl starch 130/0.4 on renal function in surgical patients

BACKGROUND

The aim of this meta-analysis was to evaluate renal safety with the active substance of the latest generation of waxy maize-derived hydroxyethyl starch in surgical patients. The authors focused on prospective, randomized, controlled studies that documented clinically relevant variables with regard to renal effects of waxy maize-derived hydroxyethyl starch 130/0.40.

MATERIALS AND METHODS

The authors carefully searched for all available prospective, randomized studies and evaluated the greatest delta from baseline values in renal safety variables (serum creatinine values, calculated creatinine clearance, incidence of renal replacement therapy, and acute renal failure). The authors included 17 studies that analyzed patients (n = 1,230) undergoing a variety of surgical procedures.

RESULTS

For maximum serum creatinine values, the effect size estimate was 0.068 (95% CI = -0.227 to 0.362), P = 0.65. For calculated creatinine clearance values, pooled risk difference was 0.302 (95% CI = -0.098 to 0.703), P = 0.14. For incidence of acute renal failure, pooled risk difference was 0.0003 (95% CI = -0.018 to 0.019), P = 0.98. For incidence of renal replacement therapy, pooled risk difference was -0.003 (95% CI = -0.028 to 0.022), P = 0.85.

CONCLUSIONS

The authors found no evidence for renal dysfunction caused by modern waxy maize-derived hydroxyethyl starch 130/0.40 in surgical patients.

Effect of the colloids gelatin and HES 130/0.4 on blood coagulation in cardiac surgery patients: a randomized controlled trial

Objective:

The choice of the prime solution for cardiopulmonary bypass can play an important role in limiting the effect on blood coagulation, but it is still unclear what the effect of colloids on blood coagulation is. The aim of this study was to investigate the effect of synthetic colloids on blood loss and blood coagulation in patients after on-pump coronary artery bypass graft (CABG) procedures.

Methods:

Sixty elective, on-pump CABG patients were randomly assigned to receive the prime solutions lactated Ringer’s solution combined with hydroxyethyl starch 130/0.4 (HES, 6% Volulyte, Fresenius Kabi Nederland BV, Zeist, the Netherlands) (HES group) or gelatin (Gelofusin®, B Braun Melsung AG, Melsungen, Germany) (Gelo group). Blood loss was assessed using post-operative chest tube output; secondary endpoints were number of blood component transfusions, routine coagulation test values and rotation thromboelastometry values (Rotem® delta, Pentapharm GmbH, Munich, Germany).

Results:

Total post-operative chest tube output was 500 ± 420 ml in the HES group versus 465 ± 390 ml in the Gelo group ( p = 0.48). No significant differences were observed in any of the routine coagulation tests values, thromboelastometry parameters or number of blood component transfusions between the groups.

Conclusions:

In this randomized, controlled trial of adults after on-pump CABG procedures, there was no significant difference in blood loss or blood coagulation between the HES group and the Gelo group.

Fluid replacement with hydroxyethyl starch in critical care--a reassessment

BACKGROUND

Hydroxyethyl starch (HES) is used for fluid replacement in millions of patients around the world every year, yet it has been found to have adverse effects that have a negative impact on patient survival. Recent clinical trials with a modern HES solution (HES 130) and meta-analyses now enable a reassessment of its risks and benefits.

METHODS

On the basis of a selective literature search focusing on reports of the use of HES 130/0.4 and HES 130/0.42 in sepsis, trauma, and intensive care medicine, data from randomized controlled trials (RCTs) are presented, and up-to-date meta-analyses and reviews are discussed. Moreover, the authors conducted an independent meta-analysis of HES 130 in comparison to crystalloids or albumin in intensive care medicine, sepsis, and trauma.

RESULTS

Seven RCTs were evaluated, involving a total of 7838 patients treated for sepsis or trauma, or in intensive care. HES 130 was associated with a higher cumulative risk of death (relative risk [RR] 1.10, 95% confidence interval [CI] 1.01-1.20), more frequent need for a renal replacement procedure (RR 1.26, 95% CI 1.08-1.46), and more frequent need for blood transfusion (RR 1.22, 95% CI 1.08-1.37). There was no patient-relevant benefit. Four recent meta-analyses of data from a total of more than 10 000 patients confirmed these concerns about the safety of HES in general and, in particular, of low-molecular-weight HES 130 for patients in intensive care. The safety of 6% HES 130 in the immediate perioperative period has not been adequately demonstrated.

DISCUSSION

Because of safety concerns, fluid replacement with HES in critically ill patients cannot be recommended. Evidence for its superior efficacy, safety and cost effectiveness in preoperative use is also lacking.

Protocoled resuscitation and the prevention of acute kidney injury

PURPOSE OF REVIEW

Acute kidney injury (AKI) occurrence in critically ill patients is common and is associated with a substantial increase in morbidity and mortality. The scope of this review is to summarize the most recent evidence-based knowledge for prevention of AKI.

RECENT FINDINGS

Recent recommendations for prevention of AKI in ICU patients are all 'negative' and, similarly, the most recent and updated guidelines about major topic areas of interest for AKI, including definition and classification, prevention, and pharmacologic treatment, have failed to identify single evidence-based recommendations for prevention and treatment of AKI. Therefore, the evaluation and management of AKI should be guided by clinical algorithms aiming to protocolized hemodynamic optimization, metabolic control, monitoring of intra-abdominal hypertension, use of diuretics to control fluid overload, and careful management of nephrotoxic factors.

SUMMARY

Key components of optimal AKI prevention include maintenance of renal perfusion and avoidance of precipitating factors. Adequate renal blood flow maintenance is the first strategy to employ not only to assure renal oxygenation, but also to prevent nephrotoxic drugs-associated AKI. Many potential therapies and interventions are on the horizon, but most of the future research will need to focus more on a step-wise, protocoled, kidney-oriented approach, than on single treatments.

Update on clinical trials for the prevention of acute kidney injury in patients undergoing cardiac surgery

BACKGROUND

Effective therapeutic agents for the prevention and treatment of acute kidney injury (AKI) after cardiac surgery remain elusive despite the tremendous advances in surgical techniques, technology, and understanding of disease processes. Recent developments and their effect on the incidence of AKI after cardiac surgery are discussed.

DATA SOURCES

Published clinical trials in PubMed, strength of evidence assessed by the guidelines of the American Family Physicians.

CONCLUSIONS

The definition of AKI has changed, and the focus of interventions has shifted from treatment to prevention to recovery from AKI. Antioxidants and biological agents have been added to classic armaments of hydration and diuretics in addition to tighter metabolic control to prevent AKI. Although the treatment options remain unsatisfactory, a lot of progress nevertheless continues to be made in the prevention and treatment of AKI.