Pentastarch 10% (250 kDa/0.45) is an independent risk factor of acute kidney injury following cardiac surgery*:

Development of new colloid osmotic pressure measurement method using ultrafiltration membrane during cardiopulmonary bypass

BACKGROUND

Clinical practice of measuring colloid osmotic pressure (COP) was abandoned after correcting hypoosmolarity did not improve overall patient outcomes. However, the use of albumin and colloidal solutions has contributed to maintaining intraoperative and postoperative fluid balance at lower levels. Reduced perioperative fluid balance is consistently reported to have positive effects on clinical outcomes. Priming solutions for cardiopulmonary bypass typically include colloids; however, the optimal type of priming solution has not yet been determined. Stricter COP management may further improve postoperative courses. To achieve this, the widespread adoption of a measurement method suitable for COP monitoring during cardiopulmonary bypass is required.

METHODS

A test circuit was made which measured COP using an ultrafiltration membrane method based on the changes in hydrostatic pressure that occurs across a semipermeable membrane. We then compared the measurements obtained using this method with colloidal osmometer measurements.

RESULTS

COP measurements were obtained for a total of 100 tests (10 times each for 10 test solutions). The evaluation parameters included simultaneous reproducibility, correlation with the colloid osmometer, and measurement time. The results demonstrated high accuracy of the ultrafiltration membrane method, simultaneous reproducibility within 3%, a high positive correlation with the colloid osmometer (correlation coefficient: R2 = 0.99; p < 0.01), and equal time required for measurement.

CONCLUSION

Measuring COP using ultrafiltration membranes solves problems within existing measurement methods. Although further improvements in the method are necessary, it has implications for future research and clinical applications.

C-reactive Protein/Albumin Ratio and Acute Kidney Injury after Radical Cystectomy among Elderly Patients: A Propensity Score-Matched Analysis

Background

The C-reactive protein (CRP)/albumin ratio is a useful index used to represent patient inflammation and nutritional status. Elderly patients are at the highest risk for acute kidney injury (AKI). We clarified the impact of the preoperative CRP/albumin ratio on AKI and evaluated the impact of postoperative AKI on end-stage renal disease (ESRD) among elderly cystectomy patients.

Methods

We included elderly patients ≥ 65 years of age who underwent radical cystectomy. Multivariate logistic regression analysis and receiver operating characteristic curve analysis were performed to identify risk factors for AKI. Propensity score-matched analysis and conditional logistic regression analysis were performed to elucidate the impact of the CRP/albumin ratio on AKI. The incidence of ESRD was compared between the non-AKI and AKI groups at 12 months after radical cystectomy.

Results

AKI occurred in 110 patients (32.2%). The CRP/albumin ratio and 6% hydroxyethyl starch amount were risk factors for postoperative AKI. The optimal cut-off value for the CRP/albumin ratio predicting AKI was 0.1. After propensity score matching, the AKI incidence in the CRP/albumin ratio ≥ 0.1 group was higher than that in the CRP/albumin ratio < 0.1 group (46.7% vs. 20.6%, P < 0.001), and a CRP/albumin ratio ≥ 0.1 was associated with a higher AKI incidence (odds ratio = 4.111, P < 0.001). The ESRD incidence was higher in the AKI group than in the non-AKI group (7.3% vs. 1.2%, P = 0.017).

Conclusion

A CRP/albumin ratio ≥ 0.1 was associated with an increased incidence of AKI, which was associated with higher ESRD incidence among elderly cystectomy patients.

[Perioperative fluid management]

An appropriate perioperative infusion management is pivotal for the perioperative outcome of the patient. Optimization of the perioperative fluid treatment often results in enhanced postoperative outcome, reduced perioperative complications and shortened hospitalization. Hypovolemia as well as hypervolemia can lead to an increased rate of perioperative complications. The main goal is to maintain perioperative euvolemia by goal-directed therapy (GDT), a combination of fluid management and inotropic medication, to optimize perfusion conditions in the perioperative period; however, perioperative fluid management should also include the preoperative and postoperative periods. This encompasses the preoperative administration of carbohydrate-rich drinks up to 2 h before surgery. In the postoperative period, patients should be encouraged to start per os hydration early and excessive i.v. fluid administration should be avoided. Implementation of a comprehensive multimodal, goal-directed fluid management within an enhanced recovery after surgery (ERAS) protocol is efficient but the exact status of indovodual items remains unclear at present.

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.

Acute Kidney Injury in the Critically Ill

Acute kidney injury (AKI) occurs frequently in the surgical intensive care unit and results in significant morbidity and mortality. AKI needs to be identified early and underlying causes treated or eliminated. Sepsis, major surgery such as coronary artery bypass, and hypovolemia are the most common causes and patients with underlying comorbidities have increased susceptibility. Treatment should begin by ensuring that patients are adequately resuscitated and all contributing causes are replaced or eliminated. After stabilization of hemodynamic status and elimination of contributing causes, treatment becomes largely supportive and may require the use of a renal replacement therapy.

Postoperative Anemia Is Associated with Acute Kidney Injury in Patients Undergoing Total Hip Replacement Arthroplasty: A Retrospective Study

BACKGROUND

Chronic and acute anemia are both correlated with an increased risk of injury to major organs, such as the brain, heart, and kidney. We evaluated the association between postoperative anemia (hemoglobin [Hb] < 10 g/dL) and acute kidney injury (AKI) in patients undergoing total hip replacement arthroplasty (THRA).

METHODS

Patients who underwent THRA between January 2005 and February 2013 were retrospectively reviewed. We divided patients into 2 groups: Hb < 10 (n = 938) and Hb ≥ 10 (n = 1529). They were then categorized according to changes in plasma creatinine concentration within 48 hours of THRA using Acute Kidney Injury Network criteria. To evaluate the association between postoperative anemia and postoperative AKI, an inverse-probability-of-treatment weighted method was used and both univariate and multivariable analyses were performed.

RESULTS

Postoperative anemia was significantly associated with postoperative AKI (multivariate odds ratio, 2.036; 95% confidence interval, 1.369-3.028; P < 0.001; inverse probability-of-treatment weighted odds ratio, 1.817; 95% confidence interval, 1.169-2.826; P = 0.011). In patients with a normal glomerular filtration rate, postoperative AKI was also related to postoperative anemia (P = 0.010).

CONCLUSIONS

Postoperative anemia was associated with postoperative AKI after THRA. Although our study was limited by its retrospective design, our observation suggests that postoperative anemia may play a role in postoperative AKI.

Postoperative Acute Kidney Injury and Blood Product Transfusion After Synthetic Colloid Use During Cardiac Surgery

OBJECTIVES

This study assessed the effect of 2 types of hydroxyethyl starches (HES) on renal integrity and blood transfusion in cardiac surgery patients.

DESIGN

Retrospective investigation.

SETTING

Patients from a single tertiary medical center.

PARTICIPANTS

Inclusion criteria included coronary artery bypass graft (CABG) and/or valve surgery that included cardiopulmonary bypass with aortic cross-clamping.

INTERVENTIONS

Intraoperative HES and blood product administration.

MEASUREMENTS AND MAIN RESULTS

The study comprised 1,265 patients who met inclusion criteria. Of these patients, 70% received HES, and of these, 47% received<1,000 mL and 53% received≥1,000 mL. There was no difference in the development of acute kidney injury between the 2 groups. A parsimonious propensity model for colloids showed that combined CABG and valve surgery were less likely to be associated with HES administration than was CABG alone (OR 0.68, confidence interval [CI] 0.46-0.97; p = 0.04). Intra-aortic balloon pump use was less likely to be associated with HES administration (OR 0.57, CI 0.38-0.86; p = 0.007). Patients with chronic kidney disease, stages 3 to 5, were less likely to receive HES, with an OR of 0.56 (CI 0.38-0.84; p = 0.004); 0.51 (CI 0.20-1.33; p = 0.170); and 0.23 (CI 0.12-0.44; p<0.0001), respectively, for each stage. No difference was noted in red blood cell transfusion. However, fresh frozen plasma, cryoprecipitate, and platelet transfusions were significantly higher with larger volumes of HES, with an OR of 2.03 (CI 1.64-2.52; p<0.001); 1.60 (CI 1.30-1.97; p<0.000); and 1.62 (CI 1.21-2.15; p = 0.006), respectively. No differences in surgical mortality were found between the colloid and noncolloid groups.

CONCLUSIONS

This study showed no association of postoperative acute kidney injury and red blood cell transfusion between the colloid and noncolloid groups. Although the complication rate was higher with HES administration, there was no difference in surgery mortality between the 2 groups.

Sex and the Risk of AKI Following Cardio-thoracic Surgery: A Meta-Analysis

BACKGROUND AND OBJECTIVES

Being a woman is a well established risk factor for the development of cardiothoracic surgery-associated AKI. In striking contrast, women are less likely to develop AKI associated with noncardiac surgical procedures than men. In an attempt to ascertain why being a woman might be protective for ischemic AKI after general surgery but deleterious in patients undergoing cardiothoracic surgery, we examined cardiothoracic surgery-associated AKI in greater detail.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a systematic review and meta-analysis of cardiothoracic surgery-associated AKI studies published between January of 1978 and December of 2015 to further explore the relationship between sex and cardiothoracic surgery-associated AKI.

RESULTS

Sixty-four studies were identified that provided sex-specific data regarding the incidence of cardiothoracic surgery-associated AKI among 1,057,412 subjects. Using univariate analysis, women were more likely than men to develop AKI postoperatively (odds ratio, 1.21; 95% confidence interval, 1.09 to 1.33; P<0.001). However, when the analysis was restricted to the 120,464 subjects reported in 29 studies that used the Acute Kidney Injury Network criteria, the RIFLE criteria, or the Kidney Disease Improving Global Outcomes criteria to define AKI, there was no significant sex-related difference in risk. Seventeen studies used multivariate analysis to assess risk factors for cardiothoracic surgery-associated AKI and provided sex-specific odd ratios. Among the 1,587,181 individuals included in these studies, the risk of developing cardiothoracic surgery-associated AKI was not significantly associated with sex (odds ratio, 1.04; 95% confidence interval, 0.92 to 1.19; P=0.51). However, when the analysis was restricted to the 5106 subjects reported in four studies that used the Acute Kidney Injury Network criteria to define AKI, the risk of developing AKI was significantly lower in women compared with in men (odds ratio, 0.75; 95% confidence interval, 0.65 to 0.87; P<0.001).

CONCLUSIONS

Our systematic review and meta-analysis contradict the generally held consensus that being a woman is an independent risk factor for the development of cardiothoracic surgery-associated AKI.

Fluid management in abdominal surgery: what, when, and when not to administer

The entire team (including anesthesiologists, surgeons, and intensive care physicians) must work together (before, during, and after abdominal surgery) to determine the optimal amount (quantity) and type (quality) of fluid necessary in the perioperative period. The authors present an overview of the basic principles that underlie fluid management, including evidence-based recommendations (where tenable) and a rational approach for when and what to administer.

Fluid management in living donor hepatectomy: Recent issues and perspectives

The importance of the safety of healthy living liver donors is widely recognized during donor hepatectomy which is associated with blood loss, transfusion, and subsequent post-operative morbidity. Although the low central venous pressure (CVP) technique can still be effective, it may not be advantageous concerning the safety of healthy donors undergoing hepatectomy. Emerging evidence suggests that stroke volume variation (SVV), a simple and useful index for fluid responsiveness and preload status in various clinical situations, can be applied as a guide for fluid management to reduce blood loss during living donor hepatectomy. Synthetic colloid solutions are also associated with serious adverse events such as the use of renal replacement therapy and transfusion in critically ill or septic patients. However, it is uncertain whether the intra-operative use of colloid solution is associated with similarly adverse effects in patients undergoing living donor hepatectomy. In this review article we discuss the recent issues regarding the low CVP technique and the high SVV method, i.e., maintaining 10%-20% of SVV, for fluid management in order to reduce blood loss during living donor hepatectomy. In addition, we briefly discuss the effects of intra-operative colloid or crystalloid administration for surgical rather than septic or critically ill patients.

Association of intraoperative hypotension with acute kidney injury after elective noncardiac surgery

BACKGROUND

Intraoperative hypotension (IOH) may be associated with postoperative acute kidney injury (AKI), but the duration of hypotension for triggering harm is unclear. The authors investigated the association between varying periods of IOH with mean arterial pressure (MAP) less than 55, less than 60, and less than 65 mmHg with AKI.

METHODS

The authors conducted a retrospective cohort study of 5,127 patients undergoing noncardiac surgery (2009 to 2012) with invasive MAP monitoring and length of stay of 1 or more days. Exclusion criteria were preoperative MAP less than 65 mmHg, dialysis dependence, urologic surgery, and surgical duration less than 30 min. The primary exposure was IOH. The primary outcome was AKI (50% or 0.3 mg/dl increase in creatinine) during the first 2 postoperative days. Multivariable logistic regression was used to model the exposure-outcome relationship.

RESULTS

AKI occurred in 324 (6.3%) patients and was associated with MAP less than 60 mmHg for 11 to 20 min and MAP less than 55 mmHg for more than 10 min in a graded fashion. The adjusted odds ratio of AKI for MAP less than 55 mmHg was 2.34 (1.35 to 4.05) for 11- to 20-min exposure and 3.53 (1.51 to 8.25) for more than 20 min. For MAP less than 60 mmHg, the adjusted odds ratio for AKI was 1.84 (1.11 to 3.06) for 11- to 20-min exposure.

CONCLUSIONS

In this analysis, postoperative AKI is associated with sustained intraoperative periods of MAP less than 55 and less than 60 mmHg. This study provides an impetus for clinical trials to determine whether interventions that promptly treat IOH and are tailored to individual patient physiology could help reduce the risk of AKI.

Albumin administration is associated with acute kidney injury in cardiac surgery: a propensity score analysis

Introduction

The risk of acute kidney injury (AKI) with the use of albumin-containing fluids compared to starches in the surgical intensive care setting remains uncertain. We evaluated the adjusted risk of AKI associated with colloids following cardiac surgery.

Methods

We performed a retrospective cohort study of patients undergoing on-pump cardiac surgery in a tertiary care center from 2008 to 2010. We assessed crystalloid and colloid administration until 36 hours after surgery. AKI was defined by the RIFLE (risk, injury, failure, loss and end-stage kidney disease) risk and Acute Kidney Injury Network (AKIN) stage 1 serum creatinine criterion within 96 hours after surgery.

Results

Our cohort included 984 patients with a baseline glomerular filtration rate of 72 ± 19 ml/min/1.73 m². Twenty-three percent had a reduced left ventricular ejection fraction (LVEF), thirty-one percent were diabetics and twenty-three percent underwent heart valve surgery. The incidence of AKI was 5.3% based on RIFLE risk and 12.0% based on the AKIN criterion. AKI was associated with a reduced LVEF, diuretic use, anemia, heart valve surgery, duration of extracorporeal circulation, hemodynamic instability and the use of albumin, pentastarch 10% and transfusions. There was an important dose-dependent AKI risk associated with the administration of albumin, which also paralleled a higher prevalence of concomitant risk factors for AKI. To address any indication bias, we derived a propensity score predicting the likelihood to receive albumin and matched 141 cases to 141 controls with a similar risk profile. In this analysis, albumin was associated with an increased AKI risk (RIFLE risk: 12% versus 5%, P = 0.03; AKIN stage 1: 28% versus 13%, P = 0.002). We repeated this methodology in patients without postoperative hemodynamic instability and still identified an association between the use of albumin and AKI.

Conclusions

Albumin administration was associated with a dose-dependent risk of AKI and remained significant using a propensity score methodology. Future studies should address the safety of albumin-containing fluids on kidney function in patients undergoing cardiac surgery.

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.

Duration of hemodynamic effects of crystalloids in patients with circulatory shock after initial resuscitation

Background

In the later stages of circulatory shock, monitoring should help to avoid fluid overload. In this setting, volume expansion is ideally indicated only for patients in whom the cardiac index (CI) is expected to increase. Crystalloids are usually the choice for fluid replacement. As previous studies evaluating the hemodynamic effect of crystalloids have not distinguished responders from non-responders, the present study was designed to evaluate the duration of the hemodynamic effects of crystalloids according to the fluid responsiveness status.

Methods

This is a prospective observational study conducted after the initial resuscitation phase of circulatory shock (>6 h vasopressor use). Critically ill, sedated adult patients monitored with a pulmonary artery catheter who received a fluid challenge with crystalloids (500 mL infused over 30 min) were included. Hemodynamic variables were measured at baseline (T0) and at 30 min (T1), 60 min (T2), and 90 min (T3) after a fluid bolus, totaling 90 min of observation. The patients were analyzed according to their fluid responsiveness status (responders with CI increase >15% and non-responders ≤15% at T1). The data were analyzed by repeated measures of analysis of variance.

Results

Twenty patients were included, 14 of whom had septic shock. Overall, volume expansion significantly increased the CI: 3.03 ± 0.64 L/min/m² to 3.58 ± 0.66 L/min/m² (p < 0.05). From this period, there was a progressive decrease: 3.23 ± 0.65 L/min/m² (p < 0.05, T2 versus T1) and 3.12 ± 0.64 L/min/m² (p < 0.05, period T3 versus T1). Similar behavior was observed in responders (13 patients), 2.84 ± 0.61 L/min/m² to 3.57 ± 0.65 L/min/m² (p < 0.05) with volume expansion, followed by a decrease, 3.19 ± 0.69 L/min/m² (p < 0.05, T2 versus T1) and 3.06 ± 0.70 L/min/m² (p < 0.05, T3 versus T1). Blood pressure and cardiac filling pressures also decreased significantly after T1 with similar findings in both responders and non-responders.

Conclusions

The results suggest that volume expansion with crystalloids in patients with circulatory shock after the initial resuscitation has limited success, even in responders.

Risk factors of postoperative acute kidney injury in patients undergoing esophageal cancer surgery

OBJECTIVE

The purpose of this study was to identify perioperative risk factors for postoperative acute kidney injury (AKI) in patients undergoing esophageal cancer surgery.

DESIGN

A retrospective analysis of the prospectively collected medical data.

SETTING

A tertiary care university hospital.

PARTICIPANTS

All consecutive adult patients (n=595) who underwent elective esophageal surgery for cancer between January 2005 and April 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

AKI was defined by the AKI Network criteria based on serum creatinine changes within the first 48 hours after esophageal cancer surgery. The relationship between perioperative variables and AKI was evaluated using multivariate logistic regression. Postoperative AKI developed in 210 (35.3%) patients. Risk factors for AKI were body mass index (odds ratio [OR] 1.07; 95% confidence interval [CI] 1.01-1.14), preoperative serum albumin level (OR 0.52; 95% CI 0.33-0.84), use of angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers (OR 1.35; 95% CI 1.05-1.75), colloid infusion during surgery (OR 1.11; 95% CI 1.06-1.18), and postoperative 2-day C-reactive protein (OR 1.05; 95% CI 1.01-1.09). Postoperative AKI was associated with prolonged length of hospital stay.

CONCLUSIONS

Postoperative AKI is common in patients undergoing esophageal surgery for cancer. Closer evaluation and monitoring in patients with risk factors for AKI may be warranted.

Hydroxyethyl starch for fluid resuscitation in critically ill patients

BACKGROUND

Intravenous fluid therapy is one of the most frequent interventions provided to patients in the intensive care unit; however, the type of fluid (i.e., crystalloid or colloid) used for resuscitation remains controversial. The most common type of colloid administered to resuscitate critically ill patients is hydroxyethyl starch (HES); however, its safety and efficacy have not been rigorously evaluated in large pragmatic randomized trials, and emerging data have accumulated to question its potential for toxic adverse effects.

OBJECTIVE

To evaluate the efficacy and safety of HES for fluid resuscitation in critically ill patients with a focus on survival and kidney function.

DESIGN

Multicentre (32 sites in Australia and New Zealand) blinded randomized controlled parallel-group trial.

METHODS

Seven thousand eligible adult patients (age - ≥ 18 yr) admitted to an intensive care unit and judged by their treating clinician to require fluid resuscitation were included in the study. Study treatment allocation used encrypted Web-based randomization stratified by site and an admission diagnosis of trauma.

INTERVENTION

Randomized patients were assigned to receive either 6% HES with a molecular weight of 130 kD and molar substitution ratio of 0.4 (130/0.4; Voluven(®), Fresenius Kabi) in 0.9% sodium chloride or 0.9% sodium chloride (saline) in indistinguishable Free flex 500 mL bags until intensive care unit (ICU) discharge, death, or 90 days after randomization. According to registration guidelines, the study fluid was administered to a maximum dose of 50 mL kg(-1) body weight per day and followed, if necessary, by open-label saline during the remaining 24-hr period.

MEASUREMENTS

The primary efficacy outcome was death within 90 days after randomization. The key secondary outcomes were incidence of acute kidney injury (AKI), defined by the RIFLE (Risk, Injury, Failure, Loss, Endstage) criteria; treatment with renal replacement therapy(RRT); development of new organ dysfunction, defined by the sequential organ failure assessment score; duration of mechanical ventilation; duration of RRT; cause-specific mortality; and adverse events. Tertiary outcomes were ICU and hospital lengths of stay and ICU and hospital mortality. The primary outcome was evaluated across six a prior idefined subgroups: urine output criteria for AKI; presence of sepsis; presence of trauma, with or without traumatic brain injury; acute physiology and chronic health evaluation (APACHE) score C ≥ 25; and receipt of HES prior to randomization.

MAIN RESULTS

The HES and saline groups had similar characteristics at baseline. The average age was 63 yr, 60.4% of patients were male, and 42.7% were admitted to the ICU after surgery (54.7% after elective surgery). The median [interquartile range] APACHE II score was 17[12.0-23.0] with a score C ≥ 25 in 18.2%. Sepsis and trauma were primary diagnoses in 28.8% and 7.9% of patients, respectively. Mechanical ventilation was received by 64.5% of patients, vasopressor therapy by 45.8%, and HES fluid prior to randomization by 15.1%. Enrolment occurred approximately 11 hr after ICU admission. During the first four days after randomization, the mean (standard deviation) study fluid received by the HES group was less when compared with the saline group [526 (425) mL day(-1) vs 616 (488) mL day(-1), respectively; P < 0.001]. Mortality at 90 days was 18.0% in patients receiving HES (597/3,315) and 17.0% in those receiving saline (566/3,336) (relative risk [RR] for HES, 1.06; 95% confidence interval (CI), 0.96 to 1.18; P = 0.26). There was no significant difference in 90-day mortality across the six a priori defined subgroups. Renal replacement therapy was received in 7.0% of patients in the HES group (235/3,352) and 5.8% of patients in the saline group (196/3,376) (RR for HES, 1.21; 95% CI, 1.00 to 1.45; P = 0.04). In the HES and saline groups, RIFLE - Injury occurred in 34.6% and 38.0% of patients,respectively (P = 0.005), and RIFLE - Failure occurred in 10.4% and 9.2% of patients, respectively (P = 0.12). There were no differences in mortality in ICU, in hospital, or at 28 days. Hydroxyethyl starch was associated with a decrease in new cardiovascular organ failure compared with saline (36.5% vs 39.9%, respectively; RR 0.91; 95% CI, 0.84 to 0.99; P = 0.03) and an increase in new hepatic organ failure compared with saline (1.9% vs 1.2%, respectively; RR 15.6; 95% CI, 1.03 to 2.36; P = 0.03). There were no differences between HES and saline for days in ICU or hospital or for duration of mechanical ventilation or RRT. Hydroxyethyl starch was associated with more adverse events compared with saline (5.3% vs 2.8%, respectively; RR 1.86; 95% CI, 1.46 to 2.38; P < 0.001). Adverse events were predominantly accounted for by pruritis and skin rash.

CONCLUSION

In critically ill patients receiving fluid resuscitation, there was no significant difference in 90-day mortality between 6% HES (130/0.4) or saline. Even so, more patients who received resuscitation with HES were treated with RRT and experienced adverse events.

Rational fluid management in today's ICU practice

Intravenous fluid therapy has evolved significantly over time. From the initial report of the first intravenous administration of sodium-chloride-based solution to the development of goal-directed fluid therapy using novel dynamic indices, efforts have focused on improving patient outcomes. The goal of this review is to provide a brief overview of current concepts for intravenous fluid administration in the ICU. Results of recently published clinical trials suggesting harmful effects of starch-based solutions on critically ill patients are discussed. Concepts for goal-directed fluid therapy and new modalities for the assessment of fluid status as well as for the prediction of responsiveness to different interventions will continue to emerge. Advances in technology will have to be critically evaluated for their ability to improve outcomes in different clinical scenarios.

Colloids in the intensive care unit

PURPOSE

The most recent published evidence on the use of colloids versus crystalloids in critical care is reviewed, with a focus on population-dependent differences in safety and efficacy.

SUMMARY

Colloids offer a number of theoretical advantages over crystalloids for fluid resuscitation, but some colloids (e.g., hydroxyethyl starch solutions, dextrans) can have serious adverse effects, and albumin products entail higher costs. The results of the influential Saline Versus Albumin Fluid Evaluation (SAFE) trial and a subsequent SAFE subgroup analysis indicated that colloid therapy should not be used in patients with traumatic brain injury and other forms of trauma due to an increased mortality risk relative to crystalloid therapy. With regard to patients with severe sepsis, two meta-analyses published in 2011, which collectively evaluated 82 trials involving nearly 10,000 patients, indicated comparable outcomes with the use of either crystalloids or albumins. For patients requiring extracorporeal cardiopulmonary bypass (CPB) during heart surgery, the available evidence supports the use of a colloid, particularly albumin, for CPB circuit priming and postoperative volume expansion. In select patients with burn injury, the published evidence supports the use of supplemental colloids if adequate urine output cannot be maintained with a crystalloid-only rescue strategy.

CONCLUSION

The results of the SAFE trial and a subgroup analysis of SAFE data suggest that colloids should be avoided in patients with trauma and traumatic brain injury. There are minimal differences in outcome between crystalloids and hypo-oncotic or iso-oncotic albumin for fluid resuscitation in severe sepsis; in select populations, such as patients undergoing cardiac surgery, the use of iso-oncotic albumin may confer a survival advantage and should be considered a first-line alternative.

Effects of Intravascular Volume Replacement on Lung and Kidney Function and Damage in Nonseptic Experimental Lung Injury

Background:

Intravascular volume replacement is often required in the presence of increased pulmonary capillary leakage, for example in patients with volutrauma with major hemorrhage. In the present study, the effects of Ringer’s acetate (RA), gelatin-polysuccinate (GEL), and a modern hydroxyethyl starch (HES, 6% 130/0.42) on lung and kidney function and damage were compared in a two-hit model of acute lung injury. The authors hypothesized that GEL and HES, compared to RA: (1) reduced lung histological damage, (2) impaired kidney morphology and function.

Methods:

Acute lung injury was induced in 30 anesthetized pigs by tidal volumes approximately 40 ml/kg, after saline lung lavage. Protective ventilation was initiated and approximately≈25% of estimated blood volume was drawn. Animals were randomly assigned to receive RA, GEL, or HES (n = 10/group) aimed at approximately 90% of intrathoracic blood volume before blood drainage.

Results:

Fluid volumes were higher with RA (2,250 ± 764 ml) than GEL (704 ± 159 ml) and HES (837 ± 82 ml) (P &lt; 0.05). Compared to RA, HES reduced diffuse alveolar damage overall, and GEL in nondependent zones only. GEL and HES yielded lower wet-to-dry ratios compared to RA (6.5 ± 0.5 and 6.5 ± 0.6 vs. 7.9 ± 0.9, respectively, P &lt; 0.05). HES and RA resulted in less kidney damage than GEL, but kidney function did not differ significantly among groups. Compared to GEL, HES yielded lower lung elastance (55 ± 12 vs. 45 ± 13 cm H2O/l, P &lt; 0.05) and intra-abdominal pressure (15 ± 5 vs. 11 ± 4 cm 14;H2O, P &lt; 0.05).

Conclusions:

In this model of acute lung injury, intravascular volume expansion after major hemorrhage with HES yielded less lung damage than RA and less kidney damage than GEL.

Fluid management and use of diuretics in acute kidney injury

Critically ill adult patients at risk for or with acute kidney injury (AKI) require careful attention to their hemodynamic status because hypotension and hypovolemia may contribute to or worsen kidney injury. Increasing evidence suggests that isotonic crystalloids should be used instead of colloids for initial expansion of intravascular volume in patients at risk for AKI or with AKI, such as those with sepsis, septic shock, or trauma. The timing and amount of volume to be administered to prevent AKI and other organ damage is still debated, but an aggressive fluid repletion in the early setting is probably beneficial. However, fluid overload has also been associated with increased mortality and reduced rate of kidney recovery in observational studies in critically ill patients with AKI. Diuretics may prevent or treat fluid overload and may also affect kidney function. The efficacy of these procedures in critically ill AKI patients need to be confirmed with randomized controlled trials. This review focuses on early volume resuscitation, overall fluid management, and use of diuretics in critically ill adult patients at risk for or with AKI and their effect on mortality and kidney function in this setting.

Place of the colloids in fluid resuscitation of the traumatized patient

PURPOSE OF REVIEW

The examination of the recent literature aimed at analysing the most recent data that could affect decisions regarding the use of colloids in trauma resuscitation.

RECENT FINDINGS

Animal data have generally shown a beneficial effect of colloids in trauma resuscitation, with improvements in capillary leak demonstrated in lung, intestine and brain. In most studies, hydroxyethyl starch resuscitation was more effective than crystalloid and decreased markers of inflammatory processes were observed. Brain injury in animals was attenuated with colloids. In uncontrolled haemorrhage, resuscitation with colloid increased bleeding and mortality.Human studies have also failed to confirm the suggestion that albumin resuscitation may be associated with a worse outcome in head injury. However, there is a strong suggestion that aggressive prehospital resuscitation, particularly with colloid, may be harmful. Studies in burns have consistently shown an improvement in the tendency to fluid overload with the inclusion of colloid in the resuscitation strategy, but so far no outcome benefit has been shown.Two studies of general trauma resuscitation have shown apparent benefit from the use of HES in early resuscitation with reductions in mortality and in renal injury.

SUMMARY

Recent trauma studies provide ongoing, but not conclusive, evidence of a benefit from colloid resuscitation in trauma.

Preoperative hypoalbuminemia is a major risk factor for acute kidney injury following off-pump coronary artery bypass surgery

PURPOSE

To investigate the association between preoperative low serum albumin level and acute kidney injury (AKI) after off-pump coronary artery bypass surgery (OPCAB) METHOD: We assessed preoperative and perioperative risk factors, and preoperative serum albumin concentration in 1,182 consecutive adult patients with preoperative normal renal function who underwent OPCAB surgery. Each patient was categorized by maximal Acute Kidney Injury Network (AKIN) criteria based on creatinine changes within the first 48 h after OPCAB. Logistic regression and propensity analyses were performed to evaluate the association between preoperative low serum albumin level and postoperative AKI.

RESULTS

Of the 1,182 patients, 334 (28.3%) developed AKI. Risk factors for AKI were old age, diabetes mellitus, maximal cardiovascular component of the sequential organ failure assessment score, perioperative transfusion, and postoperative C-reactive protein concentration. The risk of AKI was negatively correlated with the volume of crystalloid infused during surgery. A preoperative serum albumin level of <4.0 g/dl was independently associated Ith postoperative AKI [multivariable logistic analysis: odds ratio (OR) 1.83, 95 % confidence interval (CI) 1.27-2.64; P = 0.001; propensity analysis: OR 1.62, 95 % CI 1.12-2.35; P = 0.011). AKI was associated with prolonged stay in the intensive care unit and hospital and a high mortality rate.

CONCLUSIONS

Preoperative low serum albumin level is an independent risk factor for AKI, and postoperative AKI is associated with poor outcomes after OPCAB in patients with preoperative normal renal function.

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.

Preventing acute kidney injury after cardiac surgery

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a serious complication that significantly increases morbidity, mortality and cost of care after cardiac surgery. In this review we identify the current literature that addresses strategies for renal protection and the prevention of AKI after cardiac surgery.

RECENT FINDINGS

Even with aggressive medical care and renal replacement therapy (RRT) the morbidity, mortality and cost of postoperative AKI after cardiac surgery is substantial. An emphasis on preventive strategies would therefore appear to be the most cost-effective approach. Recent literature offers hope that as our understanding of the pathogenesis of AKI after cardiac surgery continues to improve, new directions for the prevention and amelioration of AKI will emerge. Approaches to the prevention of postoperative AKI include careful risk stratification of patients, allowing adequate recovery following a prior AKI, consideration of less extensive surgical procedures, avoidance of cardiopulmonary bypass, minimizing injury from radiocontrast dyes or other nephrotoxic agents, and optimizing cardiovascular function and oxygen delivery. Early identification of AKI and prompt, judicious application of RRT may also improve outcomes. Interest in pharmacologic renoprotection is currently directed toward statins and sodium bicarbonate.

SUMMARY

Postoperative AKI is a serious complication after cardiac surgery. Therapeutic interventions and RRT have limited influence on the outcome of AKI, and a preventive strategy remains the mainstay to attenuate its impact.

Have we changed the outcome in membranous nephropathy? A propensity study on the role of immunosuppressive therapy

BACKGROUND AND OBJECTIVES

The long-term effect of immunosuppressive therapy (IS) on kidney survival in idiopathic membranous nephropathy (MGN) is debated. The introduction of renin angiotensin blockade, rigorous BP control, and the increasing age at presentation of patients with MGN adds further uncertainty. Given these important changes, we sought to determine whether implementation of IS has altered outcome.

DESIGN, SETTING, PARTICIPANTS, & METHODS

We prospectively evaluated 280 incident MGN patients from three distinct 10-year periods starting from 1975.

RESULTS

We found expected changes in treatment regimens but also variations in age, renal function, severity of proteinuria, and BP at presentation over this time. Outcomes did not differ over time if these significant variations in clinical characteristics were not accounted for across the eras. The effect of IS in the 57 patients treated with currently recommended regimens was assessed using propensity adjustment to address selection bias and the effect of newer, conservative therapies. A propensity score estimating the probability of receiving IS permitted the pairing of 39 treated patients with controls with similar high risk of progression of clinical features. Using this approach, IS was associated not only with remissions in proteinuria but also with substantially improved renal survival.

CONCLUSIONS

The study confirms that patient presenting characteristics and management regimens have changed significantly over time and the natural history of MGN has been altered. A study of propensity-matched patients confirms that current recommendations for IS have improved outcomes in MGN patients at high risk of progression.

Association of 6% hetastarch resuscitation with adverse outcomes in critically ill trauma patients

BACKGROUND

Six percent hetastarch is used as a volume expander but has been associated with poor outcomes. The aim of this study was to evaluate trauma patients resuscitated with hetastarch.

METHODS

A retrospective review was performed of adult trauma patients. Demographics, injury severity, laboratory values, outcomes, and hetastarch use were recorded.

RESULTS

A total of 2,225 patients were identified, of whom 497 (22%) received hetastarch. There were no differences in age, gender, injury mechanism, lactate, hematocrit, or creatinine. The mean injury severity score was different: 29.7 ± 12.6 with hetastarch versus 27.5 ± 12.6 without hetastarch. Acute kidney injury developed in 65 hetastarch patients (13%) and in 131 (8%) without hetastarch (relative risk, 1.73; 95% confidence interval [CI], 1.30-2.28). Hetastarch mortality was 21%, compared with 11% without hetastarch (relative risk, 1.84; 95% CI, 1.48-2.29). Multivariate logistic regression demonstrated hetastarch use (odds ratio, 1.96; 95% CI, 1.49-2.58) as independently significant for death. Hetastarch use was independently significant for renal dysfunction as well (odds ratio, 1.70; 95% CI, 1.22-2.36).

CONCLUSIONS

Because of the detrimental association with renal function and mortality, hetastarch should be avoided in the resuscitation of trauma patients.