N-acetylcysteine and fenoldopam protect the renal function of patients with chronic renal insufficiency undergoing cardiac surgery

Physiological principles underlying the kidney targeting of renal nanomedicines

Kidney disease affects more than 10% of the global population and is associated with considerable morbidity and mortality, highlighting a need for new therapeutic options. Engineered nanoparticles for the treatment of kidney diseases (renal nanomedicines) represent one such option, enabling the delivery of targeted therapeutics to specific regions of the kidney. Although they are underdeveloped compared with nanomedicines for diseases such as cancer, findings from preclinical studies suggest that renal nanomedicines may hold promise. However, the physiological principles that govern the in vivo transport and interactions of renal nanomedicines differ from those of cancer nanomedicines, and thus a comprehensive understanding of these principles is needed to design nanomedicines that effectively and specifically target the kidney while ensuring biosafety in their future clinical translation. Herein, we summarize the current understanding of factors that influence the glomerular filtration, tubular uptake, tubular secretion and extrusion of nanoparticles, including size and charge dependency, and the role of specific transporters and processes such as endocytosis. We also describe how the transport and uptake of nanoparticles is altered by kidney disease and discuss strategic approaches by which nanoparticles may be harnessed for the detection and treatment of a variety of kidney diseases.

Beneficial Impacts of Fenoldopam on Patients With or at Risk for Acute Renal Failure and Undergoing Surgery: A Meta-Analysis of Randomized Clinical Trials

This meta-analysis aims to determine the beneficial impacts of fenoldopam on patients with or at high risk of acute kidney injury (AKI) and undergoing surgery. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed while performing the present meta-analysis. Two investigators searched electronic databases including PubMed, EMBASE, and the Cochrane library, from inception until January 10, 2023, for relevant studies. The key terms used to search for relevant articles included "fenoldopam", "acute kidney injury" and "surgery". The primary outcome was the incidence of new AKI. Secondary outcomes included change in serum creatine from baseline (mg/dl), length of stay in ICU (days), renal replacement therapy (RRT), and all-cause mortality that included mortality before or at 30 days. A total of 10 studies involving 1484 patients were included in the present meta-analysis. The risk of AKI was lower in the fenoldopam group compared to the control group [risk ratio (RR): 0.73, 95% CI: 0.57-0.95]. The length of ICU stay was also shorter in the fenoldopam group [mean difference (MD): -0.35 days, 95% confidence interval (CI): -0.68, -0.03]. No significant differences were reported in terms of all-cause mortality, change in serum creatinine, and RRT. In conclusion, our meta-analysis of studies on the use of fenoldopam in adult patients undergoing major surgery showed that fenoldopam significantly reduces the risk of AKI and shortens ICU stays. However, there was no significant impact on all-cause mortality or RRT.

Strategies for post-cardiac surgery acute kidney injury prevention: A network meta-analysis of randomized controlled trials

Objects

Cardiac surgery is associated with acute kidney injury (AKI). However, the effects of various pharmacological and non-pharmacological strategies for AKI prevention have not been thoroughly investigated, and their effectiveness in preventing AKI-related adverse outcomes has not been systematically evaluated.

Methods

Studies from PubMed, Embase, and Medline and registered trials from published through December 2021 that evaluated strategies for preventing post-cardiac surgery AKI were identified. The effectiveness of these strategies was assessed through a network meta-analysis (NMA). The secondary outcomes were prevention of dialysis-requiring AKI, mortality, intensive care unit (ICU) length of stay (LOS), and hospital LOS. The interventions were ranked using the P-score method. Confidence in the results of the NMA was assessed using the Confidence in NMA (CINeMA) framework.

Results

A total of 161 trials (involving 46,619 participants) and 53 strategies were identified. Eight pharmacological strategies {natriuretic peptides [odds ratio (OR): 0.30, 95% confidence interval (CI): 0.19-0.47], nitroprusside [OR: 0.29, 95% CI: 0.12-0.68], fenoldopam [OR: 0.36, 95% CI: 0.17-0.76], tolvaptan [OR: 0.35, 95% CI: 0.14-0.90], N-acetyl cysteine with carvedilol [OR: 0.37, 95% CI: 0.16-0.85], dexmedetomidine [OR: 0.49, 95% CI: 0.32-0.76;], levosimendan [OR: 0.56, 95% CI: 0.37-0.84], and erythropoietin [OR: 0.62, 95% CI: 0.41-0.94]} and one non-pharmacological intervention (remote ischemic preconditioning, OR: 0.76, 95% CI: 0.63-0.92) were associated with a lower incidence of post-cardiac surgery AKI with moderate to low confidence. Among these nine strategies, five (fenoldopam, erythropoietin, natriuretic peptides, levosimendan, and remote ischemic preconditioning) were associated with a shorter ICU LOS, and two (natriuretic peptides [OR: 0.30, 95% CI: 0.15-0.60] and levosimendan [OR: 0.68, 95% CI: 0.49-0.95]) were associated with a lower incidence of dialysis-requiring AKI. Natriuretic peptides were also associated with a lower risk of mortality (OR: 0.50, 95% CI: 0.29-0.86). The results of a sensitivity analysis support the robustness and effectiveness of natriuretic peptides and dexmedetomidine.

Conclusion

Nine potentially effective strategies were identified. Natriuretic peptide therapy was the most effective pharmacological strategy, and remote ischemic preconditioning was the only effective non-pharmacological strategy. Preventive strategies might also help prevent AKI-related adverse outcomes. Additional studies are required to explore the optimal dosages and protocols for potentially effective AKI prevention strategies.

Efficacy of N-acetylcysteine in Preventing Acute Kidney Injury and Major Adverse Cardiac Events After Cardiac Surgery: A Meta-Analysis and Trial Sequential Analysis

Background

The effect of N-acetylcysteine (NAC), an antioxidant, on preventing acute kidney injury (AKI) and major adverse cardiac events (MACE) remains controversial. Therefore, we conducted this meta-analysis and trial sequential analysis to evaluate its efficacy on cardiac surgery-related adverse events.

Methods

PubMed, Embase, and Cochrane Library were searched for relevant studies from inception to June 2021. We selected randomized controlled trials comparing NAC with controls in patients undergoing cardiac surgery.

Results

Twenty-five studies including 2,444 patients met the inclusion criteria. The pooled results showed that there was no significant difference in the incidence of AKI between the NAC and control groups [relative risk (RR) = 0.91, 95% confidence interval (CI) = 0.77, 1.08, P = 0.28], but the trial sequential analysis (TSA) could not confirm this result. No difference was observed in the need for renal replacement therapy (RRT), all-cause mortality, MACE, length of stay in the intensive care unit (ICU), and length of stay in the hospital. Results of subgroup analysis results showed that intravenous infusion instead of oral NAC could significantly reduce the incidence of AKI and arrhythmia (RR = 0.84, 95% CI = 0.71, 0.99, P = 0.03, I² = 3% and RR = 0.74, 95% CI = 0.61, 0.91, P = 0.004, I² = 48%, respectively).

Conclusion

Intravenous administration of NAC can reduce the incidence of AKI and arrhythmia in patients after cardiac surgery, but cannot reduce all-cause mortality, AMI, cardiac insufficiency, and the number of patients using RRT. Oral NAC has no significant effect on the outcomes of patients after cardiac surgery.

Rationale and Design of Assessing the Effectiveness of Short-Term Low-Dose Lithium Therapy in Averting Cardiac Surgery-Associated Acute Kidney Injury: A Randomized, Double Blinded, Placebo Controlled Pilot Trial

Background: Burgeoning pre-clinical evidence suggests that therapeutic targeting of glycogen synthase kinase 3β (GSK3β), a convergence point of multiple cellular protective signaling pathways, confers a beneficial effect on acute kidney injury (AKI) in experimental models. However, it remains unknown if GSK3β inhibition likewise mitigates AKI in humans. Cardiac surgery associated acute kidney injury (CSA-AKI) poses a significant challenge for clinicians and currently the only treatment available is general supportive measures. Lithium, an FDA approved mood stabilizer, is the best-known GSK3β inhibitor and has been safely used for over half a century as the first line regimen to treat bipolar affective disorders. This study attempts to examine the effectiveness of short term low dose lithium on CSA-AKI in human patients.

Methods/Design: This is a single center, prospective, randomized, double blinded, placebo controlled pilot study on patients undergoing cardiac surgery with cardiopulmonary bypass. Patients will be randomized to receive a small dose of lithium or placebo treatment for three consecutive days. Renal function will be measured via creatinine as well as novel AKI biomarkers. The primary outcome is incidence of AKI according to Acute Kidney Injury Network (AKIN) criteria, and secondary outcomes include receipt of new dialysis, days on dialysis, days on mechanical ventilation, infections within 1 month of surgery, and death within 90 days of surgery.

Discussion: As a standard selective inhibitor of GSK3β, lithium has been shown to exert a beneficial effect on tissue repair and regeneration upon acute injury in multiple organ systems, including the central nervous system and hematopoietic system. In experimental AKI, lithium at small doses is able to ameliorate AKI and promote kidney repair. Successful completion of this study will help to assess the effectiveness of lithium in CSA-AKI and could potentially pave the way for large-scale randomized trials to thoroughly evaluate the efficacy of this novel regimen for preventing AKI after cardiac surgery.

Trial Registration: This study was registered prospectively on the 17th February 2017 at ClinicalTrials.gov (NCT03056248, https://clinicaltrials.gov/ct2/show/NCT03056248?term=NCT03056248&draw=2&rank=1).

Does Fenoldopam Protect Kidney in Cardiac Surgery? A Systemic Review and Meta-Analysis With Trial Sequential Analysis

PURPOSE

To assess the benefits and harms of fenoldopam for nephroprotective effects in adult patients undergoing cardiac surgery.

METHODS

We conducted a systematic review with meta-analysis of randomized controlled trials (RCTs) comparing fenoldopam with placebo in cardiac surgery. Trials were systematically searched from PubMed, EMBASE, CENTRAL, and CNKI databases, up to July 30, 2018. A trial sequential analysis (TSA) was used to determine whether the present evidence was valid and conclusive for the primary outcomes.

RESULTS

A total of seven randomized controlled trials involving 1,107 adult patients undergoing cardiac surgery fulfilled the inclusion criteria. The pooled analysis suggested that the use of fenoldopam was associated with a reduction in the incidence of AKI (18 of 216 [8.3%] in the fenoldopam group versus 45 of 222 [20.3%] in the placebo group, RR = 0.42 [0.26, 0.69], P = 0.0006) and with a higher rate of hypotension (92/357 [25.8%] versus 51/348 [14.7%], RR = 1.76 [1.29, 2.39], P = 0.0003). There was no significant effect on renal replacement therapy requirement (77 of 540 [14.3%] versus 75 of 536 [14.0%], P = 0.96) or hospital mortality (87/392 [22.2%] versus 83/383 [21.7%], P = 0.86). TSA supported the results of the conventional analysis on AKI.

CONCLUSIONS

Low-dose dopamine offers transient improvements in renal physiology, but no good evidence shows that it offers important clinical benefits to patients with or at risk for acute renal failure.Among patients treated with fenoldopam, there was a decrease in AKI and an increased incidence of hypotension, had no significant effect on RRT or mortality. Given that most studies were small and the definition of AKI was variable between studies, there is not enough evidence to support the systematic use of fenoldopam in cardiac surgery.

Fenoldopam Mesylate: A Narrative Review of Its Use in Acute Kidney Injury

Background:

Fenoldopam mesylate is a selective agonist of DA-1 receptors. It is currently used for the in-hospital treatment of severe hypertension. DA-1 receptors have high density in renal pa-renchyma and for this reason, a possible reno-protective role of Fenoldopam mesylate was investigated.

Methods:

We examined all studies regarding the role of Fenoldopam mesylate in Acute Kidney Injury (AKI); particularly, those involving post-surgical patients, intensive care unit patients and contrast-induced nephropathy.

Results:

Fenoldopam mesylate was found to be effective in reducing the onset of postoperative AKI, when used before the development of the kidney damage. Positive results were also obtained in the management of intensive care unit patients with AKI, although the clinical studies investigated were few and conducted on small samples.

Conclusion:

Conflicting results were achieved in contrast-induced nephropathy.

N-acetylcysteine use among patients undergoing cardiac surgery: A systematic review and meta-analysis of randomized trials

Background

Cardiac surgeries are complex procedures aiming to re-establish coronary flow and correct valvular defects. Oxidative stress, caused by inflammation and ischemia-reperfusion injury, is associated with these procedures, increasing the risk of adverse outcomes. N-acetylcysteine (NAC) acts as an antioxidant by replenishing the glutathione stores, and emerging evidence suggests that NAC may reduce the risk of adverse perioperative outcomes. We conducted a systematic review and meta-analysis to investigate the addition of NAC to a standard of care among adult patients undergoing cardiac surgery.

Methods

We searched four databases (PubMed, EMBASE, CENTRAL, LILACS) from inception to October 2018 and the grey literaure for randomized controlled trials (RCTs) investigating the effect of NAC on pre-defined outcomes including mortality, acute renal insufficiency (ARI), acute cardiac insufficiency (ACI), hospital length of stay (HLoS), intensive care unit length of stay (ICULoS), arrhythmia and acute myocardial infarction (AMI). Reviewers independently screened potentially eligible articles, extracted data and assessed the risk of bias among eligible articles. We used the GRADE approach to rate the overall certainty of evidence for each outcome.

Results

Twenty-nine RCTs including 2,486 participants proved eligible. Low to moderate certainty evidence demonstrated that the addition of NAC resulted in a non-statistically significant reduction in mortality (Risk Ratio (RR) 0.71; 95% Confidence Interval (CI) 0.40 to 1.25), ARI (RR 0.92; 95% CI 0.79 to 1.09), ACI (RR 0.77; 95% CI 0.44 to 1.38), HLoS (Mean Difference (MD) 0.21; 95% CI -0.64 to 0.23), ICULoS (MD -0.04; 95% CI -0.29 to 0.20), arrhythmia (RR 0.79; 95% CI 0.52 to 1.20), and AMI (RR 0.84; 95% CI 0.48 to 1.48).

Limitations

Among eligible trials, we observed heterogeneity in the population and interventions including patients with and without kidney dysfunction and interventions that differed in route of administration, dosage, and duration of treatment. This observed heterogeneity was not explained by our subgroup analyses.

Conclusions

The addition of NAC during cardiac surgery did not result in a statistically significant reduction in clinical outcomes. A large randomized placebo-controlled multi-centre trial is needed to determine whether NAC reduces mortality.

Registration

PROSPERO CRD42018091191.

Comparative Efficacy of Drugs for Preventing Acute Kidney Injury after Cardiac Surgery: A Network Meta-Analysis

BACKGROUND

Acute kidney injury (AKI) occurs frequently after cardiac surgery and has been associated with increased hospital length of stay, mortality, and costs.

OBJECTIVE

We aimed to evaluate the efficacy of pharmacologic strategies for preventing AKI after cardiac surgery.

METHODS

We searched PubMed, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL) up to 6 May 2017 and the reference lists of relevant articles about trials. The outcome was the occurrence of AKI. This is the first network meta-analysis of the different prevention strategies using Bayesian methodology.

RESULTS

The study included 63 articles with 19,520 participants and evaluated the effect of ten pharmacologic strategies to prevent AKI in patients undergoing cardiac surgery. Compared with placebo, the odds ratio (OR) for the occurrence of AKI was 0.24 [95% confidence interval (CI) 0.16-0.34] with natriuretic peptide, 0.33 (95% CI 0.14-0.70) with fenoldopam, 0.54 (95% CI 0.31-0.84) with dexmedetomidine, 0.56 (95% CI 0.29-0.95) with low-dose erythropoietin, 0.63 (95% CI 0.43-0.88) with levosimendan, 0.76 (95% CI 0.52-1.10) with steroids, 0.83 (95% CI 0.48-1.40) with high-dose erythropoietin, 0.85 (95% CI 0.64-1.14) with N-acetylcysteine, 0.96 (95% CI 0.69-1.29) with sodium bicarbonate, and 1.05 (95% CI 0.70-1.41) with statins. The surface under the cumulative ranking curve probabilities indicated that natriuretic peptide was the best treatment therapy and that fenoldopam ranked second.

CONCLUSIONS

Natriuretic peptide is probably the preferred pharmacologic strategy to prevent AKI in adult patients undergoing cardiac surgery, especially in those at high risk of AKI.

Cardiac surgery-associated acute kidney injury

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

Bridging translation for acute kidney injury with better preclinical modeling of human disease

The current lack of effective therapeutics for patients with acute kidney injury (AKI) represents an important and unmet medical need. Given the importance of the clinical problem, it is time for us to take a few steps back and reexamine current practices. The focus of this review is to explore the extent to which failure of therapeutic translation from animal studies to human studies stems from deficiencies in the preclinical models of AKI. We will evaluate whether the preclinical models of AKI that are commonly used recapitulate the known pathophysiologies of AKI that are being modeled in humans, focusing on four common scenarios that are studied in clinical therapeutic intervention trials: cardiac surgery-induced AKI; contrast-induced AKI; cisplatin-induced AKI; and sepsis associated AKI. Based on our observations, we have identified a number of common limitations in current preclinical modeling of AKI that could be addressed. In the long term, we suggest that progress in developing better preclinical models of AKI will depend on developing a better understanding of human AKI. To this this end, we suggest that there is a need to develop greater in-depth molecular analyses of kidney biopsy tissues coupled with improved clinical and molecular classification of patients with AKI.

A comparison between the effects of metformin and N-acetyl cysteine (NAC) on some metabolic and endocrine characteristics of women with polycystic ovary syndrome

OBJECTIVE

To compare N-acetyl cysteine (NAC) and metformin on polycystic ovary syndrome (PCOS).

METHOD

Study was performed as a randomized double-blind clinical trial on women with diagnosis of PCOS without additional complications. In one group, oral NAC 600 mg, three times a day and in the other group, 500 mg oral metformin, three times a day were prescribed. Duration of treatment was 24 weeks, and after finishing this period of treatment, fasting blood glucose (FBS) and insulin, lipid profile and Homeostasis Model Assessment (HOMA) index were measured (all the blood samples were taken while fasting) and were compared in the two groups.

RESULTS

Forty-six women in NAC group and 48 women in metformin group finished the study. The two groups did not show significant difference according to age, body mass index (BMI) of more than 30; mean BMI, AUB, FBS, fasting blood insulin, lipid profile and HOMA index before treatment. After 24 weeks of treatment; BMI >30 [17 (35.4%) versus 7 (15.2%), p = 0.033], mean BMI [(28.36 ± 2.27) versus (27.11 ± 3.55), p = 0.44], number of women with the complain of abnormal uterine bleeding (AUB) [24 (50%) versus 13 (28.3%), p = 0.037], FBS [(90.02 ± 6.24) versus (86.61 ± 7.81), p = 0.021], fasting insulin (10.40 ± 2.64 versus 8.89 ± 2.20, p = 0.004), HOMA Index (2.09 ± 0.69 versus 1.71 ± 0.45, p = 0.001), low density lipoprotein (LDL) (141.83 ± 26.98 versus 127.89 ± 28.70, p = 0.017) were less in NAC group. Triglyceride (TG) and total cholesterol did not show significant difference between the two groups after treatment. High-density lipoprotein (HDL) was higher in NAC group.

CONCLUSION

NAC can improve lipid profile and fasting blood sugar (FBS) and fasting blood insulin better than metformin.

Fenoldopam to prevent acute kidney injury after major surgery-a systematic review and meta-analysis

Background

Acute kidney injury (AKI) after surgery is associated with increased mortality and healthcare costs. Fenoldopam is a selective dopamine-1 receptor agonist with renoprotective properties. We conducted a systematic review and meta-analysis of randomised controlled trials comparing fenoldopam with placebo to prevent AKI after major surgery.

Methods

We searched EMBASE, PubMed, meta-Register of randomised controlled trials and Cochrane CENTRAL databases for trials comparing fenoldopam with placebo in patients undergoing major surgery. The primary outcome was incidence of new AKI. Secondary outcomes were requirement for renal replacement therapy and hospital mortality.

Results

Eighty-three publications were screened; 23 studies underwent full data extraction and scoring. Six trials were suitable for inclusion in the data synthesis (total of 507 subjects undergoing cardiovascular surgery, partial nephrectomy, liver transplant surgery). Five studies were rated at high risk of bias. Data on post-operative incidence of AKI were available in five of the six trials (total of 471 patients) but definitions of AKI varied between studies. Of the 238 patients receiving fenoldopam, 45 (18.9 %) developed AKI compared to 62 (26.6 %) of the 233 patients who received placebo (p = 0.004, I² = 0 %; random-effects model odds ratio 0.46, 95 % confidence interval 0.27–0.79). In patients treated with fenoldopam, there was no difference in renal replacement therapy (n = 478; p = 0.11, I² = 47 %; fixed-effect model odds ratio 0.27, 95 % confidence interval 0.06–1.19) or hospital mortality (p = 0.60, I² = 0 %; fixed-effect model odds ratio 1.0, 95 % confidence interval 0.14–7.37).

Conclusions

In this analysis, peri-operative treatment with fenoldopam was associated with a significant reduction in post-operative AKI but it had no impact on renal replacement therapy or hospital mortality. Equipoise remains for further large trials in this area since the studies were conducted in three types of surgery, the majority of studies were rated at high risk of bias and the criteria for AKI varied between trials.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1166-4) contains supplementary material, which is available to authorized users.

Double-blinded, randomized controlled trial of N-acetylcysteine for prevention of acute kidney injury in high risk patients undergoing off-pump coronary artery bypass

AIM

The aim of this study was to investigate the influence of perioperative N-acetylcysteine (NAC) administration, a known antioxidant, on the incidence of acute kidney injury (AKI) after off-pump coronary bypass surgery (OPCAB) in patients with known risk factors of AKI.

METHODS

One hundred and seventeen patients with ≥1 of the following risk factors of AKI were randomized into either the control (n = 57) or the NAC (n = 60) group; (i) preoperative serum creatinine >1.4 mg/dL; (ii) left ventricular ejection fraction <35% or congestive heart failure (iii) age >70 years (iv) diabetes or (v) re-operation. Patients in the NAC group received 150 mg/kg of NAC IV bolus at anaesthetic induction followed by a continuous infusion at 150 mg/kg per day for 24 h. AKI was diagnosed based on Acute Kidney Injury Network criteria during 48 h postoperatively.

RESULTS

The incidence of AKI was 32% (19/60) and 35% (20/57) in the control and the NAC group, respectively (P = 0.695). The serum concentrations of creatinine and cystatin C were similar between the groups throughout the study period. Fluid balance including the amount of blood loss and transfusion requirement were similar between the groups except the amount of postoperative urine output, which was higher in the control group compared with the NAC group (5528 ± 1247 mL vs. 4982 ± 1185 mL, control vs. NAC, P = 0.017).

CONCLUSION

Perioperative administration of NAC did not prevent the development of postoperative AKI after OPCAB in highly susceptible patients to AKI.

Addition of N-acetyl cysteine to carvedilol decreases the incidence of acute renal injury after cardiac surgery

BACKGROUND

Oxidative stress and inflammation during cardiac surgery may be associated with acute renal injury (ARI). N-acetyl cysteine (NAC) and carvedilol have antioxidant and anti-inflammatory properties.

HYPOTHESIS

A combination of carvedilol and NAC should decrease the incidence of ARI more than metoprolol or carvedilol.

METHODS

Patients undergoing cardiac surgery were randomized to metoprolol, carvedilol, or carvedilol plus NAC. End points were occurrence of ARI and change in preoperative to postoperative peak creatinine levels.

RESULTS

ARI incidence was lower in the carvedilol plus NAC group compared with the metoprolol (21.0% vs 42.1%; P = 0.002) or carvedilol (21.0% vs 38.6%; P = 0.006) groups, but was similar between the metoprolol and carvedilol groups (P = 0.62). Preoperative and postoperative day 1 creatinine levels were similar among the metoprolol (1.02 [0.9-1.2] and 1.2 [0.92-1.45]) the carvedilol (1.0 [0.88-1.08] and 1.2 [0.9-1.5]) and the carvedilol plus NAC groups (1.06 [0.9-1.18] and 1.1 [1.0-1.21] mg/dL; all P values >0.05). Postoperative day 3, day 5, and peak creatinine levels were lower in the carvedilol plus NAC group (1.11 [1.0-1.23], 1.14 [1.0-1.25] and 1.15 [1.0-1.25]) as compared with the metoprolol (1.4 [1.3-1.49], 1.3 [1.0-1.54] and 1.3 [1.0-1.54]) or carvedilol groups (1.2 [1.0-1.52], 1.25 [1.0-1.52] and 1.25 [1.0-1.55] mg/dL; all P values <0.05), but were similar between the metoprolol and carvedilol groups (all P values >0.05).

CONCLUSIONS

Combined carvedilol and NAC decreased ARI incidence as compared with carvedilol or metoprolol. No difference was detected between carvedilol and metoprolol.

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.

N-acetylcysteine for sepsis and systemic inflammatory response in adults

BACKGROUND

Death is common in systemic inflammatory response syndrome (SIRS) or sepsis-induced multisystem organ failure and it has been thought that antioxidants such as N-acetylcysteine could be beneficial.

OBJECTIVES

We assessed the clinical effectiveness of intravenous N-acetylcysteine for the treatment of patients with SIRS or sepsis.

SEARCH METHODS

We searched the following databases: Cochrane Central Register of Clinical Trials (CENTRAL) (The Cochrane Library 2011, Issue 12); MEDLINE (January 1950 to January 2012); EMBASE (January 1980 to January 2012); CINAHL (1982 to January 2012); the NHS Trusts Clinical Trials Register and Current Controlled Trials (www.controlled-trials.com); LILACS; KoreaMED; MEDCARIB; INDMED; PANTELEIMON; Ingenta; ISI Web of Knowledge and the National Trials Register to identify all relevant randomized controlled trials available for review.

SELECTION CRITERIA

We included only randomized controlled trials (RCTs) in the meta-analysis.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, quality assessment and data extraction. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic.

MAIN RESULTS

We included 41 fully published studies (2768 patients). Mortality was similar in the N-acetylcysteine group and the placebo group (RR 1.06, 95% CI 0.79 to 1.42; I(2) = 0%). Neither did N-acetylcysteine show any significant effect on length of stay, duration of mechanical ventilation or incidence of new organ failure. Early application of N-acetylcysteine to prevent the development of an oxidato-inflammatory response did not affect the outcome, nor did late application that is after 24 hours of developing symptoms. Late application was associated with cardiovascular instability.

AUTHORS' CONCLUSIONS

Overall, this meta-analysis puts doubt on the safety and utility of intravenous N-acetylcysteine as an adjuvant therapy in SIRS and sepsis. At best, N-acetylcysteine is ineffective in reducing mortality and complications in this patient population. At worst, it can be harmful, especially when administered later than 24 hours after the onset of symptoms, by causing cardiovascular depression. Unless future RCTs provide evidence of treatment effect, clinicians should not routinely use intravenous N-acetylcysteine in SIRS or sepsis and academics should not promote its use.

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.

Pharmacological therapies for the prevention of acute kidney injury following cardiac surgery: a systematic review

Post-cardiac surgery acute kidney injury (AKI) is common and is associated with a significant increase in morbidity and mortality. We aimed to systematically review randomised trials that assessed the renoprotective utility of pharmacological agents in patients undergoing cardiac surgery. We searched PubMed, Embase and the Cochrane Central Register of Controlled Trials for randomised controlled trials comparing renoprotective pharmacological interventions with control in adult patients undergoing cardiac surgery with cardiopulmonary bypass. We extracted data for mortality, need for renal replacement therapy (RRT), incidence of AKI, and creatinine clearance at 24-48 h. About 49 randomised controlled trials involving 4605 patients were included. Pharmacological interventions included dopamine, fenoldopam, calcium channel antagonists, natriuretic peptides, diuretics, and N-acetylcysteine. Most trials were of poor quality, with small sample sizes, under-reporting of randomisation procedure, allocation concealment and method of blinding. No pharmacological intervention significantly reduced mortality. Fenoldopam and Atrial Natriuretic Peptide (ANP) reduced the need for renal replacement therapy by 5% (NNT 20, 95% CI 11.3, 83.0) and 3.5% (NNT 29, 95% CI 17.1, 84.4), respectively. Brain Natriuretic Peptide resulted in a 10% reduction in the incidence of AKI (NNT 11, 95% CI 6.2, 32.0). Dopamine caused a significant reduction in creatinine clearance (-4.26 ml/min, 95% CI -7.14, -1.39). The quality of studies that have assessed pharmacological renoprotective agents in cardiac surgery is generally poor. Fenoldopam, ANP and BNP show evidence of renoprotection. Randomised studies evaluating the effect of novel renoprotective agents that are powered to detect clinically relevant differences in outcomes are required.

Acute kidney injury: not just acute renal failure anymore?

Until recently, no uniform standard existed for diagnosing and classifying acute renal failure. To clarify diagnosis, the Acute Dialysis Quality Initiative group stated its consensus on the need for a clear definition and classification system of renal dysfunction with measurable criteria. Today the term acute kidney injury has replaced the term acute renal failure, with an understanding that such injury is a common clinical problem in critically ill patients and typically is predictive of an increase in morbidity and mortality. A classification system, known as RIFLE (risk of injury, injury, failure, loss of function, and end-stage renal failure), includes specific goals for preventing acute kidney injury: adequate hydration, maintenance of renal perfusion, limiting exposure to nephrotoxins, drug protective strategies, and the use of renal replacement therapies that reduce renal injury.

Novel aspects of pharmacological therapies for acute renal failure

Acute renal failure (ARF) comprises several syndromes that are associated with a sudden decrease in renal function. ARF is common among critically ill patients, is typically multifactorial and is of great prognostic significance. Indeed, even moderate changes in renal function significantly add to the morbidity and worsen mortality associated with ARF. Recent definitions, namely the renal Risk, Injury, Failure, Loss of renal function and End-stage kidney disease (RIFLE) classification or Acute Kidney Injury Network (AKIN) criteria, which incorporate the levels of oliguria in addition to fractional serum creatinine elevation, are important because the magnitude of kidney injury according to those definitions correlates very well with both short- and long-term patient survival. However, preventive strategies are most effective when started before oliguria or elevated serum creatinine is detectable, as those criteria already reflect established renal tubular cell injury. New biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP) or kidney injury molecule-1 (KIM-1) that increase prior to the serum creatinine elevation are promising and have been proven to be useful in this regard in a few clinical trials. In addition, genetic profiling may define patients at risk earlier and help to individualize preventive strategies. Well established strategies include limiting dehydration and hypotension by the use of intravenous isotonic fluids at an optimal and individualized rate, as well as avoiding exposure to nephrotoxins, which include aminoglycosides, amphotericin or non-ionic contrast. Generally accepted and evidence-based pharmacological preventive or therapeutic options have not yet been established, although many drugs (e.g. renal vasodilators, diuretics and HMG-CoA reductase inhibitors [statins]) have been tested. New promising agents interfere with the apoptotic signalling that can occur in the setting of toxin exposure or ischaemia-reperfusion injury, limit inflammatory responses or modulate endothelial cell activation. In the future, these new approaches will enable us to extend our therapeutic repertoire.

Prevention and treatment of acute kidney injury in patients undergoing cardiac surgery: a systematic review

BACKGROUND

Acute kidney injury (AKI) is common in patients undergoing cardiac surgery and is associated with a high rate of death, long-term sequelae and healthcare costs. We conducted a systematic review of randomized controlled trials for strategies to prevent or treat AKI in cardiac surgery.

METHODS

We screened Medline, Scopus, Cochrane Renal Library, and Google Scholar for randomized controlled trails in cardiac surgery for prevention or treatment of AKI in adults.

RESULTS

We identified 70 studies that contained a total of 5,554 participants published until November 2008. Most studies were small in sample size, were single-center, focused on preventive strategies, and displayed wide variation in AKI definitions. Only 26% were assessed to be of high quality according to the Jadad criteria. The types of strategies with possible protective efficacy were dopaminergic agents, vasodilators, anti-inflammatory agents, and pump/perfusion strategies. When analyzed separately, dopamine and N-acetylcysteine did not reduce the risk for AKI.

CONCLUSIONS

This summary of all the literature on prevention and treatment strategies for AKI in cardiac surgery highlights the need for better information. The results advocate large, good-quality, multicenter studies to determine whether promising interventions reliably reduce rates of acute renal replacement therapy and mortality in the cardiac surgery setting.

Outcome definitions in non-dialysis intervention and prevention trials in acute kidney injury (AKI)

BACKGROUND

The risk, injury, failure, loss-of-function, end-stage-renal-failure (RIFLE) and acute kidney injury network (AKIN) consensus definitions of acute kidney injury (AKI) were established in part to facilitate comparison of trials. Contrast-induced nephropathy (CIN) has traditionally used a less demanding definition.

OBJECTIVES

To review use of RIFLE and AKIN as AKI trial outcome variables and contrast these with outcomes for CIN.

METHODS

We conducted a search of PubMed from 1 January 2005 to 31 December 2008 and 9 trial registries for randomized control trials for preventional or interventional treatment of AKI and CIN.

RESULTS

RIFLE or AKIN were outcome variables in 36% (n = 8) of the published (n = 22) and 18% (n = 4) of the current (n = 22) AKI trials. RIFLE was used to triage to intervention in three trials. The urine output definition of RIFLE and AKIN was an outcome in only two trials. In 18% (n = 8) of AKI trials, the CIN definition (increase in serum creatinine of > or =25% and/or > or =44 micromol/l) was the primary outcome. This was also the primary outcome in 56% (n = 13) of published (n = 12) and current (n = 11) CIN trials. Three published CIN trials used RIFLE or AKIN as an outcome (13%). The duration over which outcomes were determined varied from 24 h to 7 days.

CONCLUSIONS

Considerable heterogeneity remains in outcome variables of AKI and CIN clinical trials. Even when the RIFLE or AKIN criteria were used, they were not applied consistently. There is a need for further consensus on surrogate outcome variables.

Efficacy of N-acetylcysteine in preventing renal injury after heart surgery: a systematic review of randomized trials

AIMS

The aim of this study was to assess whether perioperative N-acetylcysteine (NAC), an antioxidant, prevents acute renal injury (ARI) after cardiac surgery.

METHODS AND RESULTS

We performed a systematic review of randomized controlled trials (RCTs) of NAC in adult cardiac surgery patients. The RCTs were identified by searching MEDLINE (1960-2008), clinicaltrials.gov website, and hand-searching references of relevant publications. Primary outcome was ARI (absolute increase >0.5 mg/dL or relative increase >25%, in serum creatinine from baseline within 5 days after surgery). Random effects model was used to perform a meta-analysis. Forest plots and I(2) test were used to assess heterogeneity among studies. Ten RCTs (n = 1163 patients) were included. Mean age was 70 +/- 7.4 years, 71% were male, and 66% underwent coronary artery bypass surgery. N-Acetylcysteine did not reduce ARI incidence [35% NAC vs. 37% placebo; relative risk (RR) 0.91, 95% CI 0.79-1.06, P = 0.24]. Overall, 3.3% of patients required haemodialysis (NAC vs. placebo; RR = 1.13, 95% CI 0.59-2.17) and 3% died (RR = 1.10, 95% CI 0.56-2.16). There was a trend towards reduced ARI incidence among patients with baseline chronic kidney disease assigned to intravenous NAC (RR = 0.80, 95% CI 0.64-1.01, P = 0.06).

CONCLUSION

This meta-analysis of RCTs showed that prophylactic perioperative NAC in cardiac surgery does not reduce ARI, haemodialysis, or death.

N-acetylcysteine to reduce renal failure after cardiac surgery: a systematic review and meta-analysis

PURPOSE

To assess the effect of N-acetylcysteine (NAC) on acute renal failure and important clinical outcomes after cardiac surgery.

METHODS

Two reviewers performed literature searches, using EMBASE and PubMed, of randomized controlled trials investigating the renoprotective effect of N-acetylcysteine in cardiac surgery. Treatment effects were calculated as relative risks (RR) with 95% confidence intervals (CI). Heterogeneity and publication bias were assessed using the I(2) test and funnel plots, respectively. Meta regression was performed to assess the effect of baseline renal function and the use of aprotinin on renal function.

RESULTS

Seven randomized controlled trials (RCTs) (n = 1000) were identified. No study could demonstrate, either independently or meta-analytically, an improvement in the postoperative increase in creatinine, mortality (RR 0.93, 95% CI 0.4 to 2.07), renal failure requiring renal replacement therapy (RR 1.01, 95% CI 0.49 to 2.12), myocardial infarction (RR 0.88, 95% CI 0.36 to 1.88), atrial fibrillation (RR 0.88, 95% CI 0.70 to 1.10), or stroke (RR 0.69, 95% CI 0.27 to 1.69). There was a small, though significant increase in postoperative blood loss among patients treated with NAC (weighted mean difference 119 mL 95% CI 51, 187). After meta regression neither increase in postoperative creatinine (r(2) = 0.33) nor renal replacement therapy (r(2) = 0.04) was associated with the baseline creatinine or with NAC dose (r(2) =0.04).

CONCLUSION

This analysis did not find that treatment with NAC was associated with clinical renal protection during cardiac surgery, or improvement in other clinical outcomes.

N-acetylcysteine in cardiovascular-surgery-associated renal failure: a meta-analysis

BACKGROUND

Clinical trials with N-acetylcysteine (NAC) in perioperative cardiovascular settings have shown inconsistent effects for renal endpoints. We aimed to systematically review these trials to ascertain its role in prevention of post-cardiovascular surgery acute renal failure.

METHODS

We searched MEDLINE, EMBASE, Cochrane Renal Health Library, and Google Scholar for randomized controlled studies that evaluated NAC in adult patients undergoing cardiovascular surgery. Acute renal failure, acute renal failure requiring dialysis, and mortality were the primary outcomes. Additional outcomes studied were length of intensive care unit stay, postoperative serum creatinine, creatinine clearance, renal biomarkers, and adverse effects of NAC.

RESULTS

Twelve studies comprising 1,324 patients were found to be eligible. Meta-analytic estimates showed that NAC was not associated with reduction in acute renal failure (odds ratio [OR]: 0.89, 95% confidence interval [CI]: 0.68 to 1.15), acute renal failure requiring dialysis (OR: 1.09, 95% CI: 0.57 to 2.09) or mortality (OR: 0.95, 95% CI: 0.53 to 1.71). N-acetylcysteine was well tolerated but was not associated with any reduction in the length of intensive care unit stay. It had inconsistent effects on postoperative serum creatinine, creatinine clearance, and renal biomarkers. Subgroup analysis restricted to studies using intravenous NAC preparation showed a nonsignificant trend toward reduction in acute renal failure (OR: 0.81, 95% CI: 0.61 to 1.08) without any significant change in other outcomes.

CONCLUSIONS

Overall analysis of the existent literature shows that NAC is not beneficial in the prevention of post-cardiovascular surgery renal dysfunction. Routine use of NAC for this indication should be avoided.