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

Urinary glutathione S-transferases in the pathogenesis and diagnostic evaluation of acute kidney injury following cardiac surgery: a critical review

PURPOSE OF REVIEW

A focused review of the nature, source, physiological role and rapidly expanding evidence for glutathione S-transferase (GST) subtypes π and α as biomarkers of acute kidney injury (AKI) in patients undergoing cardiac surgery. Expanded insights into the site-specific expression of the GSTs in defined parts of the nephron during renal damage are presented, with particular emphasis on the pathogenesis of cardiac surgery and cardiopulmonary bypass (CPB)-associated AKI and the role of GSTs in oxygen radical disposal.

RECENT FINDINGS

Recent developments have highlighted a potential role of urinary α-GST and π-GST in the diagnostic evaluation of cardiac surgery-associated AKI. Both urinary α-GST and π-GST are detected in the postoperative period. π-GST performed best at predicting AKI severity at the time of the initial diagnosis of AKI. α-GST was able to predict the future development of both stage 1 and stage 3 AKI.

SUMMARY

The current data from a small number of patients suggest a potential role of urinary GSTs in the clinical diagnostic evaluation of AKI following cardiac surgery. The performance of the GSTs for the early diagnosis of AKI needs to be validated in larger multicentre studies and in other patient populations at increased risk of AKI (e.g. patients with acute transplant rejection, septic patients). Comparison with other emerging AKI biomarkers is required to continue the development of π-GST and α-GST. Finally, additional studies examining the pathophysiological role of the GSTs in minimizing oxygen free radical exposure in the renal tubules during CPB may shed further light into their role as promising biomarkers of cardiac surgery-associated AKI.

Acute normovolemic hemodilution

Acute normovolemic hemodilution (AHN) is a well known but poorly used "blood saving" method. The authors, based on their own experience and on the "low hematocrit" physiology, present some concepts on AHN and a clinical experience to demonstrate the usefulness and affordability of this method. Consequently we offer several tools concerning both the realization of AHN and the safe use of such dilution, suggesting simple and exciting methods to determine if, when and how to apply this blood saving system.

Are renal adverse effects of hydroxyethyl starches merely a consequence of their incorrect use?

BACKGROUND

Clinical studies such as VISEP-study, which show a negative outcome after the administration of hydroxyethyl starch (HES), are often criticized for an "incorrect" use of HES. It is argued that HES used in these studies differed from usual practice and that recommendations for maximal dosage, duration, and creatinine values were ignored, not enough "free water" was provided and more modern HES solutions should have been used. These comments imply that renal adverse events in clinical studies are the consequence of an inappropriate use of HES. We therefore searched for evidence whether these suggested measures are beneficial.

METHODS

Narrative review; post hoc statistical analysis of epidemiologic data from a representative nationwide survey.

RESULTS

It is evident from published clinical studies that the renal risk of HES increases with cumulative dose and rising serum creatinine values, but no safe upper dose limit or creatinine threshold is known. Suggested safety measures were not able to prevent HES-induced renal failure in clinical studies. Published clinical trials with modern HES solutions are not suited to prove its assumed increased safety because of small sample sizes, low cumulative doses, short observation periods, and inadequate control fluids. Use of HES in a clinical study with negative outcomes conformed to clinical practice, indicating the generalizability of study results.

CONCLUSION

There is no evidence for the assumption that HES-associated renal impairment may be avoided by accompanying measures. Because HES use does not improve clinical outcome, the question arises whether it should be used at all in patients at risk.

[Acute kidney injury: from concept to practice]

Definition and classification of acute renal failure evolved in recent years. The acronym "Acute Kidney Injury" replaces "Acute Renal Failure". The RIFLE classification spreads the AKI in three degrees of severity, and two degrees of disease duration. The group Acute Kidney Injury Network refines this classification into three stages, to improve the sensitivity in detecting moderate forms. The epidemiology of AKI remains imprecise. In the ICU, more than 30% of patients suffered from AKI, often in a context of multiple organs failure. In addition to serum creatinine and urine output, new biomarkers can be assessed. Their early detection should enable a clearer distinction between "acute tubular necrosis" and other causes of AKI, but also to distinguish patients at risk for pejorative evolution of renal function. The management of AKI based on an optimal resuscitation. The administration of loop diuretics or low dose dopamine showed no benefit. Hydration in prevention of the contrast-induced nephropathy is confirmed. The role of acetylcysteine must be determined. The ideal time to initiate a renal replacement therapy and the choice of the technique remain unresolved. The same goes for the dose of dialysis administered. A systematic application of an algorithm, such as proposed by Bagshow would make comparisons easier and the realisation of multicenter studies will help to clarify these points.

Year in review 2009: Critical Care--shock

The research papers on shock that have been published in Critical Care throughout 2009 are related to four major subjects: first, alterations of heart function and, second, the role of the sympathetic central nervous system during sepsis; third, the impact of hemodynamic support using vasopressin or its synthetic analog terlipressin, and different types of fluid resuscitation; as well as, fourth, experimental studies on the treatment of acute respiratory distress syndrome. The present review summarizes the key results of these studies together with a brief discussion in the context of the relevant scientific and clinical background published both in this and other journals.

Hemodynamic support of the trauma patient

PURPOSE OF REVIEW

The aim of this review is to address and summarize some key issues and recent insights into the hemodynamic support of the trauma patient related to fluid administration.

RECENT FINDINGS

Colloids are not superior to crystalloids in treating hypovolemia in the trauma patient and show no survival benefit. Furthermore, several adverse effects (renal failure, bleeding complications and anaphylaxis) have been reported with the use of artificial colloids. Hypertonic saline is effective and well tolerated in the treatment of hypovolemic shock and traumatic brain injury. Potential benefits are reduced fluid requirements and immune modulation. Resuscitation strategies should depend on the type of injury (penetrating vs. blunt; concomitant brain injury). Excessive fluid resuscitation, which can cause acute respiratory distress syndrome, abdominal compartment syndrome and brain edema, should be avoided. Dynamic parameters to guide volume therapy are probably more reliable than static parameters and minimally invasive techniques to monitor the microcirculation are becoming more important to determine the endpoints of resuscitation.

SUMMARY

Hemodynamic support is an early goal in the treatment of the trauma patient. The use of crystalloids is currently recommended in trauma resuscitation. The amount of fluid we give should be tailored to the individual trauma patient in which clear endpoints of resuscitation are of vital importance to maximize the chances of survival.

Hydroxyethylstarch supplementation in burn resuscitation--a prospective randomised controlled trial

INTRODUCTION

Hydroxyethylstarches (HES) are thought to be beneficial in trauma and major surgery management, due to their volume expansion and anti-inflammatory properties. This study examined the use of 6% (HES) in burn resuscitation.

METHODS

26 adult patients with burns exceeding 15% total body surface area (TBSA) were randomised to either crystalloid (Hartmann's solution) or a colloid-supplemented resuscitation regime, where 1/3 of the crystalloid-predicted requirement was replaced by 6% HES.

RESULTS

There was no difference in age, gender or TBSA between the two groups. The median (95% CI) fluid volume/%TBSA received in the first 24 h was 307 ml and 263 ml for the crystalloid only and HES-supplemented group respectively (p=0.0234, Mann-Whitney). Body weight gain within the first 24 h after injury was significantly lower in the HES-supplemented group 2.5 kg versus 1.4 kg respectively (p=0.0039). The median (95% CI) serum C-reactive protein at 48 h after injury was 210 (167-257) and 128 (74-145) mg/L for the crystalloid only and HES-supplemented group respectively (p=0.0001). Albumin-creatinine ratio per % burn (ACR, a marker of capillary leak) was lower in the HES-supplemented group at 12h after burn (p=0.0310).

CONCLUSIONS

Patients treated with HES-supplemented resuscitation required less fluid, showed less interstitial oedema and a dampened inflammatory response compared to patients receiving isotonic crystalloid alone.

Fluids in septic shock: too much of a good thing?

In a recent issue of Critical Care, Brandt and colleagues report the effects of a 'liberal' fluid loading protocol compared to a more 'restrictive' protocol on hemodynamics and mortality in pigs in which septic shock had been induced. It appears that the former protocol was associated with higher mortality in spite of improved hemodynamics compared to the latter. The results of the paper are discussed here in view of the scope and mechanisms of these findings. With regard to fluid resuscitation, they indicate that too much of an otherwise good thing is harmful, even if overhydration and edema formation seem to have been prevented. They also do not exclude a specific toxic effect of the larger volumes of hydroxyethyl starch in the 'liberal' strategy. The precise nature of a toxic effect remains obscure, however, but may involve the kidneys.

[Acute perioperative disturbances of renal function. Strategies for prevention and therapy]

The increasing life expectancy in industrial nations leads to an increase in the number of elderly and aged persons treated in hospital. Increasingly more complex operations are being carried out on this group of patients. Renal dysfunction in the preoperative situation increases morbidity and mortality. Acute kidney injury (AKI) is nearly always part of a multi-organ dysfunction syndrome in critically ill patients. The treatment strategy of the AKI should be oriented to the degree of organ dysfunction. However, the stage of organ dysfunction is mostly unknown so that the therapeutically exploitable interval is often missed. The same therapy is practically always used for all patients: administration of fluids and diuretics often under the premise of "the kidneys must be rinsed". A unified classification of the continuation of kidney function disorders using the RIFLE criteria (risk, injury, failure, loss, endstage kidney disease) can assist recognition of early stages of kidney failure in order to react correspondingly with therapeutic measures and to critically question or optimize the use of conservative treatment strategies.