Interventions for protecting renal function in the perioperative period

Open partial nephrectomy: current review

Partial nephrectomy (PN) is increasingly considered the gold standard treatment for localized renal cell carcinomas (RCCs) where technically feasible. The advantage of nephron-sparing surgery lies in preservation of parenchyma and hence renal function. However, this advantage is counterbalanced with increased surgical risk. In recent years with the popularization of minimally invasive partial nephrectomy (laparoscopic and robotic), the contemporary role of open PN (OPN) has changed. OPN has several advantages, particularly in complex patients such as those with a solitary kidney, multi-focal tumors, and significant surgical history, as well as providing improved application of renoprotective measures. As such, it is a technique that remains relevant in current urology practice. In this article we discuss the evidence, indications, operative considerations and surgical technique, along with the role of OPN in contemporary nephron-sparing surgery.

Renal Physiology and Robotic Urological Surgery

The use of robotic-assisted laparoscopic techniques has transformed the face of urological surgery in the last decade, with demonstrable benefits over both unassisted laparoscopic and traditional open approaches. For example, robotic-assisted partial nephrectomy is associated with lower morbidity, improved convalescence, reduced postoperative pain, shorter length of hospital stay, and a superior cosmetic result when compared to an open procedure. This review discusses the various perioperative influences on the renal physiology of patients undergoing robotic-assisted urological procedures.

Restrictive versus liberal fluid therapy in major abdominal surgery (RELIEF): rationale and design for a multicentre randomised trial

INTRODUCTION

The optimal intravenous fluid regimen for patients undergoing major abdominal surgery is unclear. However, results from many small studies suggest a restrictive regimen may lead to better outcomes. A large, definitive clinical trial evaluating perioperative fluid replacement in major abdominal surgery, therefore, is required.

METHODS/ANALYSIS

We designed a pragmatic, multicentre, randomised, controlled trial (the RELIEF trial). A total of 3000 patients were enrolled in this study and randomly allocated to a restrictive or liberal fluid regimen in a 1:1 ratio, stratified by centre and planned critical care admission. The expected fluid volumes in the first 24 hour from the start of surgery in restrictive and liberal groups were ≤3.0 L and ≥5.4 L, respectively. Patient enrolment is complete, and follow-up for the primary end point is ongoing. The primary outcome is disability-free survival at 1 year after surgery, with disability defined as a persistent (at least 6 months) reduction in functional status using the 12-item version of the World Health Organisation Disability Assessment Schedule.

ETHICS/DISSEMINATION

The RELIEF trial has been approved by the responsible ethics committees of all participating sites. Participant recruitment began in March 2013 and was completed in August 2016, and 1-year follow-up will conclude in August 2017. Publication of the results of the RELIEF trial is anticipated in early 2018.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier NCT01424150.

Effects of valproic acid and dexamethasone administration on early bio-markers and gene expression profile in acute kidney ischemia-reperfusion injury in the rat

Renal ischemia-reperfusion (IR) causes acute kidney injury (AKI) with high mortality and morbidity. The objective of this investigation was to ameliorate kidney IR injury and identify novel biomarkers for kidney injury and repair. Under general anesthesia, left renal ischemia was induced in Wister rats by occluding renal artery for 45 minutes, followed by reperfusion and right nephrectomy. Thirty minutes prior to ischemia, rats (n = 8/group) received Valproic Acid (150 mg/kg; VPA), Dexamethasone (3 mg/kg; Dex) or Vehicle (saline) intraperitoneally. Animals were sacrificed at 3, 24 or 120 h post-IR. Plasma creatinine (mg/dL) at 24 h was reduced (P<0.05) in VPA (2.7±1.8) and Dex (2.3±1.2) compared to Vehicle (3.8±0.5) group. At 3 h, urine albumin (mg/mL) was higher in Vehicle (1.47±0.10), VPA (0.84±0.62) and Dex (1.04±0.73) compared to naïve (uninjured/untreated control) (0.14±0.26) group. At 24 h post-IR urine lipocalin-2 (μg/mL) was higher (P<0.05) in VPA, Dex and Vehicle groups (9.61–11.36) compared to naïve group (0.67±0.29); also, kidney injury molecule-1 (KIM-1; ng/mL) was higher (P<0.05) in VPA, Dex and Vehicle groups (13.7–18.7) compared to naïve group (1.7±1.9). Histopathology demonstrated reduced (P<0.05) ischemic injury in the renal cortex in VPA (Grade 1.6±1.5) compared to Vehicle (Grade 2.9±1.1). Inflammatory cytokines IL1β and IL6 were downregulated and anti-apoptotic molecule BCL2 was upregulated in VPA group. Furthermore, kidney DNA microarray demonstrated reduced injury, stress, and apoptosis related gene expression in the VPA administered rats. VPA appears to ameliorate kidney IR injury via reduced inflammatory cytokine, apoptosis/stress related gene expression, and improved regeneration. KIM-1, lipocalin-2 and albumin appear to be promising early urine biomarkers for the diagnosis of AKI.

A modified Delphi process to identify process of care indicators for the identification, prevention and management of acute kidney injury after major surgery

Background

The outcomes of acute kidney injury (AKI) are well appreciated. However, valid indicators of high quality processes of care for AKI after major surgery are lacking.

Objectives

To identify indicators of high quality processes of care related to AKI prevention, identification, and management after major surgery.

Design

A three stage modified Delphi process.

Setting

The study was conducted in Alberta, Canada using an online format.

Participants

A panel of care providers from surgery, critical care, and nephrology.

Measurements

The degree of validity of candidate indicators were rated by panelists on a 7-point Likert scale that ranged from “strongly disagree” to “strongly agree”.

Methods

A focused literature review was performed to identify candidate indicators. A modified Delphi process, with three rounds, was used to obtain expert consensus on the validity of potential process of care quality indicators.

Results

Thirty-three physicians participated (6 from surgery, 10 from critical care, and 17 from nephrology). A list of 58 potential process of care quality indicators for AKI after surgery was generated including 28 indicators from the initial literature review and 30 indicators suggested by panelists. Following the third round of questioning, 40 process of care indicators were identified with a high level of agreement for face validity; 16 of these reached high consensus among all panelists.

Limitations

The consensus of panelists from Alberta, Canada may not be generalizable to other settings. The modified Delphi process did not focus on the feasibility of measuring these process indicators.

Conclusions

These indicators can be used to measure and improve the quality of care for AKI after major surgery.

Electronic supplementary material

The online version of this article (doi:10.1186/s40697-015-0047-8) contains supplementary material, which is available to authorized users.

Changes in renal medulla gene expression in a pre-clinical model of post cardiopulmonary bypass acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is a common and serious complication of cardiac surgery using cardiopulmonary bypass (CPB). The pathogenesis is poorly understood and the study of AKI in rodent models has not led to improvements in clinical outcomes. We sought to determine the changes in renal medullary gene expression in a novel and clinically relevant porcine model of CPB-induced AKI.

RESULTS

Adult pigs (n = 12 per group) were randomised to undergo sham procedure, or 2.5 hours CPB. AKI was determined using biochemical (Cr51 EDTA clearance, CrCl, urinary IL-18 release) and histological measures. Transcriptomic analyses were performed on renal medulla biopsies obtained 24 hours post intervention or from sham group. Microarray results were validated with real-time polymerase chain reaction and Western Blotting.Of the transcripts examined, 66 were identified as differentially expressed in CPB versus Sham pig's kidney samples, with 19 (29%) upregulated and 47 (71%) down-regulated. Out of the upregulated and downregulated transcripts 4 and 16 respectively were expression sequence tags (EST). The regulated genes clustered into three classes; Immune response, Cell adhesion/extracellular matrix and metabolic process. Upregulated genes included Factor V, SLC16A3 and CKMT2 whereas downregulated genes included GST, CPE, MMP7 and SELL.

CONCLUSION

Post CPB AKI, as defined by clinical criteria, is characterised by molecular changes in renal medulla that are associated with both injury and survival programmes. Our observations highlight the value of large animal models in AKI research and provide insights into the failure of findings in rodent models to translate into clinical progress.

Anaesthesia in patients undergoing cytoreductive surgery with hyperthermic intraperitoneal chemotherapy: retrospective analysis of a single centre three-year experience

Background

Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is a treatment option for selected patients with peritoneal carcinomatosis. There are limited data available on anaesthesia management and its impact on patients’ outcome. Our aim was to retrospectively analyze and evaluate perioperative management and the clinical course of patients undergoing CRS/HIPEC within a three-year period.

Methods

After ethic committee approval, patient charts were retrospectively reviewed for patient characteristics, interventions, perioperative management, postoperative course, and complications. Analysis was intervention based. Data are presented as median (range).

Results

Between 2009 and 2011, 54 consecutive patients underwent 57 interventions; median anaesthesia time was 715 (range 370 to 1135) minutes. HIPEC induced hyperthermia with an overall median peak temperature of 38.1 (35.7-40.2)°C with active cooling. Bleeding, expressed as median blood loss was 0.8 (0 to 6) litre and large fluid shifts occurred, requiring a total fluid input of 8.4 (4.2 to 29.4) litres per patient. Postoperative renal function was dependent on preoperative function and the type of fluids used. Administration of hydroxyethyl starch colloid solution had a significant negative impact on renal function, especially in younger patients. Major complications occurred after 12 procedures leading to death in 2 patients. Procedure time and need for blood transfusion were associated with a significantly higher risk for major complications.

Conclusions

Cytoreductive surgery with HIPEC is a high-risk surgical procedure associated with major hemodynamic and metabolic changes. As well as primary disease and complexity of surgery, we have shown that anaesthesia management, the type and amount of fluids used, and blood transfusions may also have a significant effect on patients’ outcome.

Patients with chronic kidney disease

Chronic kidney disease (CKD) is a major public health problem worldwide. Roughly 1 in 10 adult Americans has CKD. These patients are at significant risk for excessive morbidity and mortality during the perioperative period. Given the health and cost burden of end-stage renal disease (ESRD), preventing or avoiding progression of CKD to ESRD is critical. Therefore, identifying risk factors and implementing risk mitigation strategies to prevent further deterioration of renal function during the perioperative period is of paramount importance. This article reviews patient risk stratification, preoperative evaluation and management, and perioperative interventions for renal protection.

Interventions for protecting renal function in the perioperative period

BACKGROUND

Various methods have been used to try to protect kidney function in patients undergoing surgery. These most often include pharmacological interventions such as dopamine and its analogues, diuretics, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, N-acetyl cysteine (NAC), atrial natriuretic peptide (ANP), sodium bicarbonate, antioxidants and erythropoietin (EPO).

OBJECTIVES

This review is aimed at determining the effectiveness of various measures advocated to protect patients' kidneys during the perioperative period.We considered the following questions: (1) Are any specific measures known to protect kidney function during the perioperative period? (2) Of measures used to protect the kidneys during the perioperative period, does any one method appear to be more effective than the others? (3) Of measures used to protect the kidneys during the perioperative period,does any one method appear to be safer than the others?

SEARCH METHODS

In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2012), MEDLINE (Ovid SP) (1966 to August 2012) and EMBASE (Ovid SP) (1988 to August 2012). We originally handsearched six journals (Anesthesia and Analgesia, Anesthesiology, Annals of Surgery, British Journal of Anaesthesia, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery) (1985 to 2004). However, because these journals are properly indexed in MEDLINE, we decided to rely on electronic searches only without handsearching the journals from 2004 onwards.

SELECTION CRITERIA

We selected all randomized controlled trials in adults undergoing surgery for which a treatment measure was used for the purpose of providing renal protection during the perioperative period.

DATA COLLECTION AND ANALYSIS

We selected 72 studies for inclusion in this review. Two review authors extracted data from all selected studies and entered them into RevMan 5.1; then the data were appropriately analysed. We performed subgroup analyses for type of intervention, type of surgical procedure and pre-existing renal dysfunction. We undertook sensitivity analyses for studies with high and moderately good methodological quality.

MAIN RESULTS

The updated review included data from 72 studies, comprising a total of 4378 participants. Of these, 2291 received some form of treatment and 2087 acted as controls. The interventions consisted most often of different pharmaceutical agents, such as dopamine and its analogues, diuretics, calcium channel blockers, ACE inhibitors, NAC, ANP, sodium bicarbonate, antioxidants and EPO or selected hydration fluids. Some clinical heterogeneity and varying risk of bias were noted amongst the studies, although we were able to meaningfully interpret the data. Results showed significant heterogeneity and indicated that most interventions provided no benefit.Data on perioperative mortality were reported in 41 studies and data on acute renal injury in 44 studies (all interventions combined). Because of considerable clinical heterogeneity (different clinical scenarios, as well as considerable methodological variability amongst the studies), we did not perform a meta-analysis on the combined data.Subgroup analysis of major interventions and surgical procedures showed no significant influence of interventions on reported mortality and acute renal injury. For the subgroup of participants who had pre-existing renal damage, the risk of mortality from 10 trials (959 participants) was estimated as odds ratio (OR) 0.76, 95% confidence interval (CI) 0.38 to 1.52; the risk of acute renal injury (as reported in the trials) was estimated from 11 trials (979 participants) as OR 0.43, 95% CI 0.23 to 0.80. Subgroup analysis of studies that were rated as having low risk of bias revealed that 19 studies reported mortality numbers (1604 participants); OR was 1.01, 95% CI 0.54 to 1.90. Fifteen studies reported data on acute renal injury (criteria chosen by the individual studies; 1600 participants); OR was 1.03, 95% CI 0.54 to 1.97.

AUTHORS' CONCLUSIONS

No reliable evidence from the available literature suggests that interventions during surgery can protect the kidneys from damage. However, the criteria used to diagnose acute renal damage varied in many of the older studies selected for inclusion in this review, many of which suffered from poor methodological quality such as insufficient participant numbers and poor definitions of end points such as acute renal failure and acute renal injury. Recent methods of detecting renal damage such as the use of specific biomarkers and better defined criteria for identifying renal damage (RIFLE (risk, injury, failure, loss of kidney function and end-stage renal failure) or AKI (acute kidney injury)) may have to be explored further to determine any possible benefit derived from interventions used to protect the kidneys during the perioperative period.

Fluid balance and urine volume are independent predictors of mortality in acute kidney injury

Introduction

In ICUs, both fluid overload and oliguria are common complications associated with increased mortality among critically ill patients, particularly in acute kidney injury (AKI). Although fluid overload is an expected complication of oliguria, it remains unclear whether their effects on mortality are independent of each other. The aim of this study is to evaluate the impact of both fluid balance and urine volume on outcomes and determine whether they behave as independent predictors of mortality in adult ICU patients with AKI.

Methods

We performed a secondary analysis of data from a multicenter, prospective cohort study in 10 Italian ICUs. AKI was defined by renal sequential organ failure assessment (SOFA) score (creatinine >3.5 mg/dL or urine output (UO) <500 mL/d). Oliguria was defined as a UO <500 mL/d. Mean fluid balance (MFB) and mean urine volume (MUV) were calculated as the arithmetic mean of all daily values. Use of diuretics was noted daily. To assess the impact of MFB and MUV on mortality of AKI patients, multivariate analysis was performed by Cox regression.

Results

Of the 601 included patients, 132 had AKI during their ICU stay and the mortality in this group was 50%. Non-surviving AKI patients had higher MFB (1.31 ± 1.24 versus 0.17 ± 0.72 L/day; P <0.001) and lower MUV (1.28 ± 0.90 versus 2.35 ± 0.98 L/day; P <0.001) as compared to survivors. In the multivariate analysis, MFB (adjusted hazard ratio (HR) 1.67 per L/day, 95%CI 1.33 to 2.09; <0.001) and MUV (adjusted HR 0.47 per L/day, 95%CI 0.33 to 0.67; <0.001) remained independent risk factors for 28-day mortality after adjustment for age, gender, diabetes, hypertension, diuretic use, non-renal SOFA and sepsis. Diuretic use was associated with better survival in this population (adjusted HR 0.25, 95%CI 0.12 to 0.52; <0.001).

Conclusions

In this multicenter ICU study, a higher fluid balance and a lower urine volume were both important factors associated with 28-day mortality of AKI patients.

Renal and abdominal visceral complications after open aortic surgery requiring supra-renal aortic cross clamping

PURPOSE

The aim of this study was to assess renal or abdominal visceral complications after open aortic surgery (OAS) requiring supra-renal aortic cross clamping (SRACC).

METHODS

We retrospectively reviewed the medical records of 66 patients who underwent SRACC. Among them, 17 followed supra-celiac aortic cross clamping (SCACC) procedure, 42 supra-renal, and 7 inter-renal aorta. Postoperative renal, hepatic or pancreatic complications were investigated by reviewing levels of serum creatinine and hepatic and pancreatic enzymes. Preoperative clinical and operative variables were analyzed to determine risk factors for postoperative renal insufficiency (PORI).

RESULTS

Indications for SRACC were 25 juxta-renal aortic occlusion and 41 aortic aneurysms (24 juxta-renal, 12 supra-renal and 5 type IV thoraco-abdominal). The mean duration of renal ischemic time (RIT) was 30.1 ± 22.2 minutes (range, 3 to 120 minutes). PORI developed in 21% of patients, including four patients requiring hemodialysis (HD). However, chronic HD was required for only one patient (1.5%) who had preoperative renal insufficiency. RIT ≥ 25 minutes and SCACC were significant risk factors for PORI development by univariate analysis, but not by multivariate analysis. Serum pancreatic and hepatic enzyme was elevated in 41% and 53% of the 17 patients who underwent SCACC, respectively.

CONCLUSION

Though postoperative renal or abdominal visceral complications developed often after SRACC, we found that most of those complications resolved spontaneously unless there was preexisting renal disease or the aortic clamping time was exceptionally long.

Perioperative acute kidney injury

Acute kidney injury (AKI) is a serious complication in the perioperative period, and is consistently associated with increased rates of mortality and morbidity. Two major consensus definitions have been developed in the last decade that allow for easier comparison of trial evidence. Risk factors have been identified in both cardiac and general surgery and there is an evolving role for novel biomarkers. Despite this, there has been no real change in outcomes and the mainstay of treatment remains preventive with no clear evidence supporting any therapeutic intervention as yet. This review focuses on definition, risk factors, the emerging role of biomarkers and subsequent management of AKI in the perioperative period, taking into account new and emerging strategies.

Intraoperative mannitol use does not improve long-term renal function outcomes after minimally invasive partial nephrectomy

OBJECTIVE

To evaluate intravenous mannitol during minimally invasive partial nephrectomy (PN) by comparing the renal function outcomes of the patients who received it versus those who did not.

METHODS

Of 285 consecutive elective minimally invasive PN cases from February 2005 to July 2010, 164 patients (58%) were treated with mannitol. We compared the renal function recovery using a multivariate generalized estimating equation linear model of estimated glomerular filtration rate (eGFR) controlling for nephrometry complexity, preoperative eGFR, American Society of Anesthesiologists score, ischemia time, estimated blood loss, age, and sex. Sensitivity analyses were performed to adjust for cold ischemia and individual surgeon differences corrected for year of surgery.

RESULTS

Of the 285 patients who underwent minimally invasive treatment, 164 received mannitol and 121 did not. Those who received mannitol had a better preoperative eGFR (median 72 vs 69 mL/min/m(2), P = .046), less complex nephrometry scores (P = 0.051), and were less likely to have an American Society of Anesthesiologists score of ≥ 3 (42% vs 54%, P = .005). Renal function recovery was similar in both groups (estimated effect of mannitol -0.7 mL/min/m(2), 95% confidence interval -3.6-2.2, P = .6). At no point in the postoperative period did mannitol make a significant difference in the eGFR according to the generalized estimating equation model after adjusting for multiple potential renal function confounders.

CONCLUSION

Mannitol use did not influence renal function recovery within 6 months of minimally invasive PN as measured by the eGFR in our analysis. An appropriately designed prospective study of mannitol is being conducted to validate its use during PN.

Fenoldopam and acute renal failure in cardiac surgery: a meta-analysis of randomized placebo-controlled trials

OBJECTIVE

Because at present no pharmacologic prevention or treatment of acute kidney injury seems to be available, the authors updated a meta-analysis to investigate the effects of fenoldopam in reducing acute kidney injury in patients undergoing cardiac surgery, focusing on randomized placebo-controlled studies only.

DESIGN

A meta-analysis of randomized, placebo-controlled trials.

SETTING

Hospitals.

PARTICIPANTS

A total of 440 patients from 6 studies were included in the analysis.

INTERVENTIONS

None. The ability of fenoldopam to reduce acute kidney injury in the perioperative period when compared with placebo was investigated.

MEASUREMENTS AND MAIN RESULTS

Google Scholar and PubMed were searched (updated January 1, 2012). Authors and external experts were contacted. Pooled estimates showed that fenoldopam consistently and significantly reduced the risk of acute kidney injury (odds ratio [OR] = 0.41; 95% confidence interval [CI], 0.23-0.74; p = 0.003), with a higher rate of hypotensive episodes and/or use of vasopressors (30/109 [27.5%] v 21/112 [18.8%]; OR = 2.09; 95% CI, 0.98-4.47; p = 0.06) and no effect on renal replacement therapy, survival, and length of intensive care unit or hospital stay.

CONCLUSIONS

This analysis suggests that fenoldopam reduces acute kidney injury in patients undergoing cardiac surgery. Because the number of the enrolled patients was small and there was no effect on renal replacement therapy or survival, a large, multicenter, and appropriately powered trial is needed to confirm these promising results.

[Risk factors for postoperative acute kidney injury in a cohort of 2378 patients from 59 hospitals]

OBJECTIVES

To assess risk factors for postoperative acute kidney injury (AKI) in adults with normal renal function hospitalized for major surgery. To analyze mortality and length of hospital stay in patients who develop postoperative AKI.

PATIENTS AND METHODS

Data for analysis were drawn from the 2006 ARISCAT study. The dependent variable was postoperative AKI defined as a decline in renal function demonstrated by a rise in plasma creatinine level to twice the baseline measurement or a 50% reduction in the glomerular filtration rate. Bivariate and multivariate analyses were used to identify preoperative and intraoperative risk factors.

RESULTS

We analyzed 2378 of the ARISCAT cases, which had been enrolled from 59 participating hospitals; 25 patients (1.1%) developed AKI. Analysis identified 5 risk factors: age, peripheral arterial disease, type of surgical incision, blood loss, and infusion of colloids. The area under the receiver operating characteristic curve was 0.88% (95% confidence interval, 0.79%-0.69%). Duration of hospital stay was longer for patients with postoperative AKI (21.8 days, vs 5.5 days for other patients; P=.007). Mortality was higher in patients with AKI at 30 days (36% vs 0.9%) and at 3 months (48% vs 1.7%).

CONCLUSIONS

The incidence of postoperative AKI was slightly over 1%. Knowledge of postoperative AKI risk factors can facilitate the planning of surgical interventions and anesthesia to reduce subsequent morbidity and mortality and length of hospital stay.

Sphingosine kinase 1 protects against renal ischemia-reperfusion injury in mice by sphingosine-1-phosphate1 receptor activation

The roles of sphingosine kinases SK1 and SK2 in ischemia-reperfusion injury have not been fully elucidated since studies have found beneficial effects of SK1 while others showed no role in this injury. To help resolve this, we used SK1 or SK2 knockout mice and confirmed that renal ischemia-reperfusion injury induced SK1, but not SK2, in the kidneys. Furthermore, knockout or pharmacological inhibition of SK1 increased injury after renal ischemia-reperfusion injury. In contrast, lack of SK2 conferred renal protection following injury. In addition, we used lentiviral gene delivery to selectively express enhanced green fluorescent protein (EGFP) or human SK1 coexpressed with EGFP (EGFP-huSK1) in the kidney. Mice with kidney-specific overexpression of EGFP-huSK1 had significantly improved renal function with lower plasma creatinine, renal necrosis, apoptosis, and inflammation. Moreover, EGFP-huSK1 overexpression in cultured human proximal tubule (HK-2) cells protected against peroxide-induced necrosis. Selective overexpression of EGFP-huSK1 led to increased HSP27 mRNA and protein expression in vivo and in vitro. Functional protection as well as induction of HSP27 with EGFP-huSK1 overexpression in vivo was blocked with sphingosine-1-phosphate-1 receptor(1) (S1P(1)) antagonism. Thus, our findings suggest that SK1 is renoprotective by S1P(1) activation and perhaps HSP27 induction. Kidney-specific expression of SK1 through lentiviral delivery may be a viable therapeutic option to attenuate renal ischemia-reperfusion injury.

Risk factors of acute kidney injury according to RIFLE criteria after lung cancer surgery

BACKGROUND

Perioperative acute kidney injury (AKI) is associated with increased mortality and morbidity. Our aim was to evaluate the incidence and determinants of AKI using the risk, injury, failure, loss of function, and end-stage kidney disease (RIFLE) criteria in thoracic surgical patients.

METHODS

We retrospectively analyzed a cohort of patients undergoing lung cancer surgery from 1996 to 2009. Patient management was protocol-driven, and postoperative complications were prospectively collected. The primary outcome was AKI within 3 days after surgery. A variety of patient comorbidities and operative characteristics were evaluated as potential predictors of AKI using a multiple logistic regression model.

RESULTS

Complete data were obtained from 1,345 patients, and the incidence of AKI was 6.8%. Four independent risk factors for AKI were identified: American Society of Anesthesiologists classes 3 and 4 (odds ratio [OR] 2.60, 95% confidence interval [CI]: 1.03 to 6.55), forced expiratory volume in 1 second (OR 0.55, 95% CI: 0.32 to 0.96), the use of vasopressors (OR 1.015, 95% CI: 0.998 to 1.035), and the duration of anesthesia (OR 1.044, 95% CI: 1.001 to 1.008). Patients who experienced AKI were more frequently admitted to the intensive care unit (24.2% versus 3.5% for patients without AKI, p < 0.05); they had increased mortality (19.8% versus 1.1%, p < 0.05) and a threefold to fourfold higher incidence of cardiopulmonary complications.

CONCLUSIONS

The RIFLE classification is a valuable tool to assess AKI after lung cancer surgery. The severity of perioperative renal impairment is associated with increased mortality and morbidity.

Fluid balance, diuretic use, and mortality in acute kidney injury

BACKGROUND AND OBJECTIVES

Management of volume status in patients with acute kidney injury (AKI) is complex, and the role of diuretics is controversial. The primary objective was to elucidate the association between fluid balance, diuretic use, and short-term mortality after AKI in critically ill patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using data from the Fluid and Catheter Treatment Trial (FACTT), a multicenter, randomized controlled trial evaluating a conservative versus liberal fluid-management strategy in 1000 patients with acute lung injury (ALI), we evaluated the association of post-renal injury fluid balance and diuretic use with 60-day mortality in patients who developed AKI, as defined by the AKI Network criteria.

RESULTS

306 patients developed AKI in the first 2 study days and were included in our analysis. There were 137 in the fluid-liberal arm and 169 in the fluid-conservative arm (P=0.04). Baseline characteristics were similar between groups. Post-AKI fluid balance was significantly associated with mortality in both crude and adjusted analysis. Higher post-AKI furosemide doses had a protective effect on mortality but no significant effect after adjustment for post-AKI fluid balance. There was no threshold dose of furosemide above which mortality increased.

CONCLUSIONS

A positive fluid balance after AKI was strongly associated with mortality. Post-AKI diuretic therapy was associated with 60-day patient survival in FACTT patients with ALI; this effect may be mediated by fluid balance.

Anesthetic concerns in patients presenting with renal failure

Anesthesiologists often care for patients with renal insufficiency or renal failure. These patients may present to the operating room for a minor procedure such as an inguinal hernia repair or an arteriovenous fistula/graft. Alternatively, they may present for major abdominal operations or coronary artery bypass grafting. Critically ill patients presenting to the operating room may have acute kidney injury. It is imperative that the anesthesiologist understands the ramifications of renal failure and adjusts the anesthetic plan accordingly. Hemodynamic monitoring and fluid management can be challenging in this patient population. Various metabolic abnormalities can ensue that the anesthesiologist must be able to manage in the acute setting of the operating room.

Atrial natriuretic peptide for preventing and treating acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is common in hospitalised patients and is associated with significant morbidity and mortality. Despite recent advances, outcomes have not substantially changed in the last four decades. Atrial natriuretic peptide (ANP) has shown promise in animal studies, however randomised controlled trials (RCTs) have shown inconsistent clinical benefits.

OBJECTIVES

To assess the benefits and harms of ANP for preventing and treating AKI.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE and EMBASE and reference lists of retrieved articles.

SELECTION CRITERIA

RCTs that investigated all forms of ANP versus any other treatment in adult hospitalised patients with or "at risk" of AKI.

DATA COLLECTION AND ANALYSIS

Results were expressed as risk ratios (RR) with 95% confidence intervals (CI) or mean difference (MD). Outcomes were analysed separately for low and high dose ANP for preventing or treating AKI.

MAIN RESULTS

Nineteen studies (11 prevention, 8 treatment; 1,861 participants) were included. There was no difference in mortality between ANP and control in either the low or high dose prevention studies. Low (but not high) dose ANP was associated with a reduced need for RRT in the prevention studies (RR 0.32, 95% CI 0.14 to 0.71). Length of hospital and ICU stay were significantly shorter in the low dose ANP group. For established AKI, there was no difference in mortality with either low or high dose ANP. Low (but not high) dose ANP was associated with a reduction in the need for RRT (RR 0.54, 95% CI 0.30 to 0.98). High dose ANP was associated with more adverse events (hypotension, arrhythmias). After major surgery there was a significant reduction in RRT requirement with ANP in the prevention studies (RR 0.56, 95% CI 0.32 to 0.99), but not in the treatment studies. There was no difference in mortality between ANP and control in either the prevention or treatment studies. There was a reduced need for RRT with low dose ANP in patients undergoing cardiovascular surgery (RR 0.35, 95% CI 0.18 to 0.70). ANP was not associated with outcome improvement in either radiocontrast nephropathy or oliguric AKI.

AUTHORS' CONCLUSIONS

ANP may be associated with improved outcomes when used in low doses for preventing AKI and in managing postsurgery AKI and should be further explored in these two settings. There were no significant adverse events in the prevention studies, however in the high dose ANP treatment studies there were significant increases hypotension and arrhythmias.