Remote Ischemic Preconditioning for Prevention of Acute Kidney Injury: A Meta-analysis of Randomized Controlled Trials

Nitric Oxide in Cardiac Surgery: A Review Article

Perioperative organ injury remains a medical, social and economic problem in cardiac surgery. Patients with postoperative organ dysfunction have increases in morbidity, length of stay, long-term mortality, treatment costs and rehabilitation time. Currently, there are no pharmaceutical technologies or non-pharmacological interventions that can mitigate the continuum of multiple organ dysfunction and improve the outcomes of cardiac surgery. It is essential to identify agents that trigger or mediate an organ-protective phenotype during cardiac surgery. The authors highlight nitric oxide (NO) ability to act as an agent for perioperative protection of organs and tissues, especially in the heart-kidney axis. NO has been delivered in clinical practice at an acceptable cost, and the side effects of its use are known, predictable, reversible and relatively rare. This review presents basic data, physiological research and literature on the clinical application of NO in cardiac surgery. Results support the use of NO as a safe and promising approach in perioperative patient management. Further clinical research is required to define the role of NO as an adjunct therapy that can improve outcomes in cardiac surgery. Clinicians also have to identify cohorts of responders for perioperative NO therapy and the optimal modes for this technology.

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).

The Effect of Remote Ischemic Preconditioning on Serum Creatinine in Patients Undergoing Partial Nephrectomy: A Randomized Controlled Trial

Renal function declines after partial nephrectomy due to ischemic reperfusion injury induced by surgical insult or renal artery clamping. The effect of remote ischemic preconditioning (RIPC) on reducing renal injury after partial nephrectomy has not been studied regarding urinary biomarkers. Eighty-one patients undergoing partial nephrectomy were randomly assigned to either RIPC or the control group. RIPC protocol consisted of four cycles of five-min inflation and deflation of a blood pressure cuff to 250 mmHg. Serum creatinine levels were compared at the following time points: preoperative baseline, immediate postoperative, on the first and third days after surgery, and two weeks after surgery. The incidence of acute kidney injury, other surgical complication rates, and urinary biomarkers, including urine creatinine, β-2 microglobulin, microalbumin, and N-acetyl-beta-D-glucosaminidase were compared. Split renal functions measured by renal scan were compared up to 18 months after surgery. There was no significant difference in the serum creatinine level on the first postoperative day (median (interquartile range) 0.87 mg/dL (0.72–1.03) in the RIPC group vs. 0.92 mg/dL (0.71–1.12) in the control group, p = 0.728), nor at any other time point. There was no significant difference in the incidence of acute kidney injury. Secondary outcomes, including urinary biomarkers, were not significantly different between the groups. RIPC showed no significant effect on the postoperative serum creatinine level of the first postoperative day. We could not reveal any significant difference in the urinary biomarkers and clinical outcomes. However, further larger randomized trials are required, because our study was not sufficiently powered for the secondary outcomes.

Urine Injury Biomarkers Are Not Associated With Kidney Transplant Failure

BACKGROUND

Kidneys transplanted from deceased donors with serum creatinine-defined acute kidney injury (AKI) have similar allograft survival as non-AKI kidneys but are discarded at a higher rate. Urine injury biomarkers are sensitive markers of structural kidney damage and may more accurately predict graft outcomes.

METHODS

In the 2010-2013 multicenter Deceased Donor Study of 2430 kidney transplant recipients from 1298 donors, we assessed the association of donor urine injury biomarkers microalbumin, neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, IL-18, and liver-type fatty acid binding protein with graft failure (GF) and death-censored GF (dcGF) using Cox proportional hazard models (median follow-up 4 y). We examined if serum creatinine-defined donor AKI modified this association to assess the relationship between subclinical donor AKI (elevated biomarkers without creatinine-defined AKI) and GF. Through chart review of a subcohort (1137 recipients), we determined associations between donor injury biomarkers and a 3-year composite outcome of GF, mortality, or estimated glomerular filtration rate ≤ 20mL/min/1.73m.

RESULTS

Risk of GF, dcGF, and 3-year composite outcome did not vary with donor injury biomarker concentrations after adjusting for donor, transplant, and recipient characteristics (adjusted hazard ratio ranged from 0.96 to 1.01 per log-2 increase in biomarker). Subclinical injury in transplanted kidneys without AKI was not associated with GF.

CONCLUSIONS

AKI measured using injury biomarkers was not associated with posttransplant graft outcomes (at median 4 y posttransplant). When assessing posttransplant graft viability, clinicians can prioritize other donor and recipient factors over donor kidney injury, measured by either serum creatinine or urine injury biomarkers.

Early Renal-Protective Effects of Remote Ischemic Preconditioning in Elderly Patients with Non-ST-Elevation Myocardial Infarction (NSTEMI)

Background

With the wide clinical application of angiography, contrast-enhanced nephropathy (CIN) has become the third-leading cause of acute kidney injury (AKI). Remote ischemic preconditioning (RIPC) is a non-fatal ischemia-reperfusion injury that can provide protection against lethal ischemia-reperfusion. This study aimed to assess the effect of RIPC on CIN in elderly patients with non-ST-elevation myocardial infarction (NSTEMI).

Material/Methods

Patients were randomly divided into 2 groups with 119 patients in each group treated with interventional therapy. Patients in the RIPC group received distal ischemic preconditioning 2 h before contrast exposure, while patients in the control group received a sham RIPC procedure. Incidence of CIN was the primary outcome. Changes in creatinine, NGAL, and KIM-1 after contrast administration were secondary outcomes.

Results

CIN occurred in a total of 27 (12.3%) patients, including 12 (10.1%) in the RIPC group and 15 (15.1%) in the control group (P=0.329). RIPC treatment significantly reduced the levels of NGAL (P=0.024) and KIM-1 (P=0.007) at 12 h after contrast administration, suggesting RIPC treatment reduces sub-clinical renal damage. Subgroup analysis revealed that significant reduction of KIM-1 and NGAL by RIPC, mainly occurring in patients with a Mehran risk score of 6–10.

Conclusions

Although RIPC did not significantly reduce CIN incidence in elderly patients with NSTEMI, the application of more sensitive biomarkers – NGAL and KIM-1 – indicated a reduction of sub-clinical renal damage by RIPC, especially in the early stage of injury. As a simple and well-tolerated method, RIPC may be a potentially feasible option to prevent CIN.

Prevalence and Predictors of Contrast-Induced Nephropathy (CIN) in Patients with ST-Segment Elevation Myocardial Infarction (STEMI) Undergoing Percutaneous Coronary Intervention (PCI): A Meta-Analysis

Background

Contrast-induced nephropathy (CIN) becomes more and more frequent after percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI). There have been no reported meta-analyses to determine the role of these risk factors in predicting CIN in patients with STEMI undergoing PCI. So we made this meta-analysis to summarize the incidence of CIN in patients with STEMI undergoing PCI and to study associations between CIN and several risk factors that are mentioned in most prevention guidelines.

Hypothesis

The overall incidence of CIN in patients with STEMI undergoing PCI is not low. Many risk factors could influence the occurrence of CIN, such as hypertension, diabetes mellitus (DM), and lower estimated glomerular filtration rate.

Methods

Databases, including PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), and Chinese BioMedical (CBM), were searched for articles published before May 21, 2019, to identify all relevant studies on CIN. The pooled data were analyzed using either fixed-effects or random-effects models depending on heterogeneity (assessed via the I ² index).

Results

Twelve articles encompassing a total of 6342 patients were included. The overall pooled CIN incidence was 13.3% (95% CI: 10.4-17.1). The forest plots showed positive associations between CIN and the presence of hypertension, diabetes mellitus, history of prior myocardial infarction, age, damaged left anterior descending artery, Killip class ≥2, decreased left ventricular ejection fraction, lower estimated glomerular filtration rate, and left ventricular ejection fraction <40%; the odds ratios for these factors were 1.85 (95% CI: 1.57-2.18; p < 0.00001), 1.83 (95% CI: 1.47-2.29; p < 0.00001), 2.14 (95% CI: 1.46-3.14; p < 0.0001), 7.79 (95% CI: 5.24-10.34; p < 0.00001), 1.92 (95% CI: 1.15-3.22; p=0.01), 3.12 (95% CI: 2.21-4.40; p < 0.00001), -6.15 (95% CI: -9.52 to -2.79; p=0.0003), -15.06 (95% CI: -24.75 to -5.36; p=0.002), and 5.53 (95% CI: 1.10-27.95; p=0.04), respectively.

Conclusion

The overall incidence of CIN in patients with STEMI undergoing PCI was not low and was closely associated with hypertension, diabetes mellitus, history of prior myocardial infarction, age, damaged left anterior descending artery, Killip class ≥2, decreased left ventricular ejection fraction, lower estimated glomerular filtration rate, and left ventricular ejection fraction <40%.

Remote ischaemic preconditioning for renal and cardiac protection in adult patients undergoing cardiac surgery with cardiopulmonary bypass: systematic review and meta-analysis of randomized controlled trials

Background

The main aim of this systematic review was to assess whether remote ischaemic preconditioning (RIPC) protects kidneys and the heart in cardiac surgery with cardiopulmonary bypass (CPB) and to investigate a possible role of anaesthetic agents.

Methods

Randomized clinical trials (RCTs) on the effects of RIPC through limb ischaemia in adult patients undergoing cardiac surgery with CPB were searched (1965-October 2016) in PubMed, Cochrane Library and article reference lists. A random effects model on standardized mean difference (SMD) for continuous outcomes and the Peto odds ratio (OR) for dichotomous outcomes were used to meta-analyse data. Subgroup analyses to evaluate the effects of different anaesthetic regimens were pre-planned.

Results

Thirty-three RCTs (5999 participants) were included. In the whole group, RIPC did not significantly reduce the incidence of acute kidney injury (AKI), acute myocardial infarction, atrial fibrillation, mortality or length of intensive care unit (ICU) and hospital stays. On the contrary, RIPC significantly reduced the area under the curve for myocardial injury biomarkers (MIBs) {SMD -0.37 [95% confidence interval (CI) -0.53 to - 0.21]} and the composite endpoint incidence [OR 0.85 (95% CI 0.74-0.97)]. In the volatile anaesthetic group, RIPC significantly reduced AKI incidence [OR 0.57 (95% CI 0.41-0.79)] and marginally reduced ICU stay. Conversely, except for MIBs, RIPC had fewer non-significant effects under propofol with or without volatile anaesthetics.

Conclusions

RIPC did not consistently reduce morbidity and mortality in adults undergoing cardiac surgery with CPB. In the subgroup on volatile anaesthetics only, RIPC markedly and significantly reduced the incidence of AKI and composite endpoint as well as myocardial injury.

Effect of Remote Ischemic Preconditioning on Complications After Elective Abdominal Aortic Aneurysm Repair: A Meta-Analysis With Randomized Control Trials

OBJECTIVE

This meta-analysis was to evaluate the effect of remote ischemic preconditioning (RIP) on complications after abdominal aortic aneurysm repair.

METHODS

A literature search was conducted in Google scholar, PubMed, Embase, and Web of Science databases up to February 2019. The pooled risk difference (RD) as well as their 95% confidence interval (CI) were calculated by RevMan 5.3 software.

RESULTS

A total of 249 patients receiving abdominal aortic aneurysm repair with RIP and 248 receiving abdominal aortic aneurysm repair without RIP in 7 included studies were reanalyzed in this meta-analysis. The results showed that RIP cannot significantly reduce the postoperative mortality (RD = -0.01, 95% CI: -0.07 to 0.06, P = .87), myocardial infarction (RD = -0.01, 95% CI, -0.09 to 0.07, P = .79), and renal impairment (RD = 0.06, 95% CI: -0.41 to 0.30, P = .89) and renal failure (RD = 0.04, 95% CI: -0.03 to 0.10, P = .30). Moreover, the pooled estimate indicated that the RIP significantly increased the risk of arrhythmia after abdominal aortic aneurysm repair surgery (RD = 0.08, 95% CI: 0.01 to -0.16, P = .03). Nevertheless, sensitivity analyses indicated unreliable results for risk of arrhythmia.

CONCLUSION

There is no evidence that RIP reduces mortality after abdominal aortic aneurysm repair. Moreover, the current evidence is not robust enough to prove the effect of RIP on kidney- and cardiac-related complications.

The effect of remote ischemic preconditioning on serum creatinine in patients undergoing partial nephrectomy: a study protocol for a randomized controlled trial

Background

Acute kidney injury (AKI) may develop during partial nephrectomy due to ischemic reperfusion injury induced by renal artery clamping or surgical insult. The effect of remote ischemic preconditioning (RIPC) on reducing the renal injury after partial nephrectomy has not been evaluated in terms of urinary biomarkers.

Methods/design

We will conduct a randomized controlled trial enrolling the patients who will undergo partial nephrectomy. In the study group, RIPC which consisted of four 5-min cycles of limb ischemia and reperfusion will be conducted after induction of anesthesia. Postoperative serum creatinine values, the incidence of AKI, and urinary biomarkers, including urinary creatinine, microalbumin, β-2 microglobulin, and N-acetyl-beta-D-glucosaminidase, will be compared between groups during the postoperative 2 weeks. Regional oxygen saturation on the skin of the contralateral kidney will be measured to evaluate the association between intraoperative regional oxygen saturation values and renal injury of the operating side.

Discussion

We expect that our trial may demonstrate the effect of RIPC on mitigating the immediate postoperative renal injury and improving patient outcomes after partial nephrectomy. Moreover, our patients will undergo ^99mTc-DTPA radionuclide scintigraphy to calculate glomerular filtration rate 6 and 12 months after surgery. This data should show the long-term effect of RIPC.

Trial registration

ClinicalTrials.gov, ID: NCT03273751. Registered on 6 September 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2820-3) contains supplementary material, which is available to authorized users.

Update on perioperative acute kidney injury

PURPOSE OF REVIEW

In this review, we discuss the latest updates on perioperative acute kidney injury (AKI) and the specific considerations that are relevant to different surgeries and patient populations.

RECENT FINDINGS

AKI diagnosis is constantly evolving. New biomarkers detect AKI early and shed a light on the possible cause of AKI. Hypotension, even for a short duration, is associated with perioperative AKI. The debate on the deleterious effects of chloride-rich solutions is still far from conclusion. Remote ischemic preconditioning is showing promising results in the possible prevention of perioperative AKI. No definite data show a beneficiary effect of statins, fenoldepam, or sodium bicarbonate in preventing AKI.

SUMMARY

Perioperative AKI is prevalent and associated with significant morbidity and mortality. Considering the lack of effective preventive or therapeutic interventions, this review focuses on perioperative AKI: measures for early diagnosis, defining risks and possible mechanisms, and summarizing current knowledge for intraoperative fluid and hemodynamic management to reduce risk of AKI.

Association between vascular access creation and deceleration of estimated glomerular filtration rate decline in late-stage chronic kidney disease patients transitioning to end-stage renal disease

Background

Prior studies have suggested that arteriovenous fistula (AVF) or graft (AVG) creation may be associated with slowing of estimated glomerular filtration rate (eGFR) decline. It is unclear if this is attributable to the physiological benefits of a mature access on systemic circulation versus confounding factors.

Methods

We examined a nationwide cohort of 3026 US veterans with advanced chronic kidney disease (CKD) transitioning to dialysis between 2007 and 2011 who had a pre-dialysis AVF/AVG and had at least three outpatient eGFR measurements both before and after AVF/AVG creation. Slopes of eGFR were estimated using mixed-effects models adjusted for fixed and time-dependent confounders, and compared separately for the pre- and post-AVF/AVG period overall and in patients stratified by AVF/AVG maturation. In all, 3514 patients without AVF/AVG who started dialysis with a catheter served as comparators, using an arbitrary 6-month index date before dialysis initiation to assess change in eGFR slopes.

Results

Of the 3026 patients with AVF/AVG (mean age 67 years, 98% male, 75% diabetic), 71% had a mature AVF/AVG at dialysis initiation. eGFR decline accelerated in the last 6 months prior to dialysis in patients with a catheter (median, from -6.0 to -16.3 mL/min/1.73 m2/year, P < 0.001), while a significant deceleration of eGFR decline was seen after vascular access creation in those with AVF/AVG (median, from -5.6 to -4.1 mL/min/1.73 m2/year, P < 0.001). Findings were independent of AVF/AVG maturation status and were robust in adjusted models.

Conclusions

The creation of pre-dialysis AVF/AVG appears to be associated with eGFR slope deceleration and, consequently, may delay the onset of dialysis initiation in advanced CKD patients.

Adrenomedullin serves a role in the humoral pathway of delayed remote ischemic preconditioning via a hypoxia-inducible factor-1α-associated mechanism

Remote ischemic preconditioning (RIPC) is a minimally invasive method that provides protection by reducing injury to the heart, kidneys, brain and other tissues or organs. RIPC may improve the outcome in patients undergoing surgery. Although the role of RIPC has been studied, the results remain controversial. It is difficult to confirm whether RIPC has a kidney protective effect and the understanding of the preconditioning signal pathway involved remains unclear. In the present study, the effect of RIPC in urology was evaluated. The protection against renal damage was assessed by investigating the potential mediator, hypoxia-inducible factor-1α (HIF-1α), and the functional adrenomedullin (ADM) pathway. Male Sprague-Dawley (SD) rats were used in the present study. The animal model of kidney damage induced by ischemia reperfusion (IR) was used to investigate the protective effect of the acute and delayed phase RIPC. Furthermore, the protective effects of RIPC mediated by a HIF-1α-ADM pathway were assessed. The indexes of renal function and oxidative damage indicators were measured by Cr, BUN, mALB, β2-MG, MPO, MDA and SOD assays, and the expression of HIF-1α and ADM were detected by western blot analysis, immunohistochemistry and ELISA assays. Tubular score, determined using hematoxylin and eosin staining, was used to evaluate renal tissue damage. Applying RIPC prevented IR-induced renal dysfunction and oxidative damage by decreasing Cr, BUN, mALB, β2-MG, MPO, MDA levels and increasing SOD activity. Findings showed that delayed RIPC had an improved effect compared with acute treatment. Delayed RIPC also upregulated the expression of HIF-1α and ADM, indicating that the protective effect of the delayed RIPC may be associated with a HIF-1α-ADM-mediated mechanism. The effect of the delayed RIPC to reduce IR-induced renal damage and increase ADM expression was enhanced by HIF-1α agonists DMOG and BAY 85–3934, whereas the effect was whittled by HIF-1α antagonists YC-1 and 2-MeOE2. Furthermore, receiving ADM also offered protection to the kidney in comparison with the IR+Vehicle group. These findings suggest that RIPC prevents IR-mediated renal damage by HIF-1α via an ADM humoral pathway. In the present study, RIPC provided an effective renal protection. ADM could also offer protection regulated by HIF-1α in renal tissue. However, the mechanism of ADM as a protective factor in RIPC requires further research.

Protective effect of vascular endothelial growth factor against cardiopulmonary bypass-associated acute kidney injury in beagles

The present study aimed to examine the hypothesis that vascular endothelial growth factor (VEGF) has a protective effect against cardiopulmonary bypass (CPB)-associated acute kidney injury (AKI). Eighteen male beagles were randomly allocated to three groups (n=6 per group): Sham group, animals received sternotomy without going through CPB; CPB group, animals received CPB only; VEGF group, animals received CPB and VEGF. VEGF infusion was completed 1 h prior to the initiation of CPB. Renal microcirculation perfusion, serum creatinine (SCr) and blood urea nitrogen (BUN), histopathological injury score and apoptotic index were determined. Hypoxia inducible factor-1α, VEGF, phosphorylated (p)-Akt serine/threonine kinase (Akt), p-endothelial nitric oxide synthase (eNOS), cleaved caspase-3, B-cell lymphoma 2 (Bcl-2) and cluster of differentiation (CD)95 expression levels were assessed by western blot analysis, Enzyme-linked immunosorbent assay quantitative assays were used to evaluate tumor necrosis factor (TNF)-α, interleukin (IL)-6, superoxide dismutase and malondialdehyde levels. Renal microcirculation perfusion of the VEGF group was higher than that of the CPB group (P<0.05) and lower than that of the sham surgery group (P<0.05). SCr and BUN were significantly elevated after CPB in the CPB and VEGF groups, with significantly lower levels in group VEGF than group CPB. Renal pathology scores and apoptotic indices were significantly lower in the VEGF group than the CPB group. Levels of TNF-α, IL-6 in the VEGF group were significantly lower than in the CPB group. Levels of VEGF, p-Akt, p-eNOS and Bcl-2 expression in the VEGF group increased significantly in comparison with group CPB. Cleaved caspase-3 in the VEGF group was significantly lower than in the group CPB. CPB-associated reduction of renal microcirculation perfusion may predispose to AKI. VEGF appears to provide a protective effect on the kidneys through improvement in renal microperfusion.

Remote ischaemic preconditioning reduces acute kidney injury in adult patients undergoing cardiac surgery with cardiopulmonary bypass: a meta-analysis

This article represents the first attempt to perform a pooled analysis about remote ischaemic preconditioning (RIPC) in reduction of acute kidney injury (AKI) of adult patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). A systematic search was performed using PubMed (1966-5 January 2016), the Cochrane Library (1996-5 January 2016), the Web of Science (1986-5 January 2016) and Chinese database (SinoMed) (1978-5 January 2016) to identify studies that have described the effect of RIPC on AKI in adult patients undergoing cardiac surgery with CPB. The outcomes used for this analysis included the incidence of AKI and the need for renal replacement therapy (RRT). Thirteen randomized controlled trials (4370 participants) were included in this analysis. RIPC significantly reduced the risk of AKI (risk ratio, 0.81; 95% confidence interval, [0.66, 0.99]; P = 0.04; I2 = 46%) for adult patients compared with control group. However, there was no significant difference with respect to the incidence of RRT between the two groups. The present meta-analysis found that RIPC may reduce the incidence of AKI among adult patients following cardiac surgery with CPB. Adequately powered trials are warranted to provide further corroboration of our findings in the future.

Prevention of acute kidney injury and protection of renal function in the intensive care unit: update 2017 : Expert opinion of the Working Group on Prevention, AKI section, European Society of Intensive Care Medicine

BACKGROUND

Acute kidney injury (AKI) in the intensive care unit is associated with significant mortality and morbidity.

OBJECTIVES

To determine and update previous recommendations for the prevention of AKI, specifically the role of fluids, diuretics, inotropes, vasopressors/vasodilators, hormonal and nutritional interventions, sedatives, statins, remote ischaemic preconditioning and care bundles.

METHOD

A systematic search of the literature was performed for studies published between 1966 and March 2017 using these potential protective strategies in adult patients at risk of AKI. The following clinical conditions were considered: major surgery, critical illness, sepsis, shock, exposure to potentially nephrotoxic drugs and radiocontrast. Clinical endpoints included incidence or grade of AKI, the need for renal replacement therapy and mortality. Studies were graded according to the international GRADE system.

RESULTS

We formulated 12 recommendations, 13 suggestions and seven best practice statements. The few strong recommendations with high-level evidence are mostly against the intervention in question (starches, low-dose dopamine, statins in cardiac surgery). Strong recommendations with lower-level evidence include controlled fluid resuscitation with crystalloids, avoiding fluid overload, titration of norepinephrine to a target MAP of 65-70 mmHg (unless chronic hypertension) and not using diuretics or levosimendan for kidney protection solely.

CONCLUSION

The results of recent randomised controlled trials have allowed the formulation of new recommendations and/or increase the strength of previous recommendations. On the other hand, in many domains the available evidence remains insufficient, resulting from the limited quality of the clinical trials and the poor reporting of kidney outcomes.

Remote Ischemic Conditioning and Renal Protection

Over the course of the last 2 decades, the concept of remote ischemic conditioning (RIC) has attracted considerable research interest, because RIC, in most of its embodiments offers an inexpensive way of protecting tissues against ischemic damage inflicted by a number of medical conditions or procedures. Acute kidney injury (AKI) is a common side effect in the context of various medical procedures, and RIC has been suggested as a means of reducing its incidence. Outcomes regarding kidney function have been reported in numerous studies that evaluated the effects of RIC in a variety of settings (eg, cardiac surgery, interventions requiring intravenous administration of contrast media). Although several individual studies have implied a beneficial effect of RIC in preserving kidney function, 3 recently published randomized controlled trials evaluating more than 1000 patients each (Effect of Remote Ischemic Preconditioning in the Cardiac Surgery, Remote Ischaemic Preconditioning for Heart Surgery, and ERICCA) were negative. However, AKI or any other index of renal function was not a stand-alone primary end point in any of these trials. On the other hand, a range of meta-analyses (each including thousands of participants) have reported mixed results, with the most recent among them showing benefit from RIC, pinpointing at the same time a number of shortcomings in published studies, adversely affecting the quality of available data. The present review provides a critical appraisal of the current state of this field of research. It is the opinion of the authors of this review that there is a clear need for a common clinical trial framework for ischemic conditioning studies. If the current babel of definitions, procedures, outcomes, and goals persists, it is most likely that soon ischemic conditioning will be "yesterday's news" with no definitive conclusions having been reached in terms of its real clinical utility.

Age and Surgical Complexity impact on Renoprotection by Remote Ischemic Preconditioning during Adult Cardiac Surgery: A Meta analysis

We aimed to conduct an up-to-date meta-analysis to comprehensively assess the renoprotective effect of remote ischemic preconditioning (RIPC) in patients undergoing adult cardiac surgery. 21 randomized controlled trials (RCTs) with a total of 6302 patients were selected and identified. Compared with controls, RIPC significantly reduced the incidence of acute kidney injury (AKI) [odds ratio (OR) = 0.79; P = 0.02; I² = 38%], and in particular, AKI stage I (OR = 0.65; P = 0.01; I² = 55%). RIPC significantly shortened mechanical ventilation (MV) duration [weighted mean difference (WMD) = −0.79 hours; P = 0.002; I² = 53%), and reduced intensive care unit (ICU) stay (WMD = −0.23 days; P = 0.07; I² = 96%). Univariate meta-regression analyses showed that the major sources of heterogeneity for AKI stage I were age (coefficient = 0.06; P = 0.01; adjusted R2 = 0.86) and proportion of complex surgery (coefficient = 0.02; P = 0.03; adjusted R2 = 0.81). Subsequent multivariate regression and subgroup analyses also confirmed these results. The present meta-analysis suggests that RIPC reduces the incidence of AKI in adults undergoing cardiac surgery and this benefit was more pronounced in younger patients undergoing non-complex cardiac surgery. RIPC may also shorten MV duration and ICU stay. Future RCTs tailored for those most likely to benefit from RIPC warrants further investigation.

[Renal protection in intensive care : Myths and facts]

BACKGROUND

Acute kidney injury (AKI) is a common and severe complication in patients on the intensive care unit with a significant impact on patient mortality, morbidity and costs of care; therefore, renal protective therapy is most important in these severely ill patients.

AIM OF THE REVIEW

Many renal protective strategies have been postulated during the last decades, which are sometimes still in place as a kind of "myth" but which are not always proven by evidence-based "facts". The aim of this review is therefore to question and compare some of these "myths" with the available "facts".

RECENT FINDINGS

Most important for renal protection is the early identification of patients at risk for AKI or with acute kidney damage before renal function deteriorates further. A stage-based management of AKI comprises more general measures, such as discontinuation of nephrotoxic agents and adjustment of diuretic doses but most importantly early hemodynamic stabilization with crystalloid volume replacement solutions and vasopressors, such as noradrenaline. The aim is to ensure optimal renal perfusion and perfusion pressure. Patients with known arterial hypertension potentially need higher perfusion pressures. Large amounts of hyperchloremic solutions should be avoided. Volume overload and renal vasodilatory substances can also lead to further deterioration of kidney function. There is still no specific pharmacological therapy for renal protection.

Ischaemic preconditioning for the reduction of renal ischaemia reperfusion injury

BACKGROUND

Ischaemia reperfusion injury can lead to kidney dysfunction or failure. Ischaemic preconditioning is a short period of deprivation of blood supply to particular organs or tissue, followed by a period of reperfusion. It has the potential to protect kidneys from ischaemia reperfusion injury.

OBJECTIVES

This review aimed to look at the benefits and harms of local and remote ischaemic preconditioning to reduce ischaemia and reperfusion injury among people with renal ischaemia reperfusion injury.

SEARCH METHODS

We searched Cochrane Kidney and Transplant's Specialised Register to 5 August 2016 through contact with the Information Specialist using search terms relevant to this review.

SELECTION CRITERIA

We included all randomised controlled trials measuring kidney function and the role of ischaemic preconditioning in patients undergoing a surgical intervention that induces kidney injury. Kidney transplantation studies were excluded.

DATA COLLECTION AND ANALYSIS

Studies were assessed for eligibility and quality; data were extracted by two independent authors. We collected basic study characteristics: type of surgery, remote ischaemic preconditioning protocol, type of anaesthesia. We collected primary outcome measurements: serum creatinine and adverse effects to remote ischaemic preconditioning and secondary outcome measurements: acute kidney injury, need for dialysis, neutrophil gelatinase-associated lipocalin, hospital stay and mortality. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes.

MAIN RESULTS

We included 28 studies which randomised a total of 6851 patients. Risk of bias assessment indicated unclear to low risk of bias for most studies. For consistency regarding the direction of effects, continuous outcomes with negative values, and dichotomous outcomes with values less than one favour remote ischaemic preconditioning. Based on high quality evidence, remote ischaemic preconditioning made little or no difference to the reduction of serum creatinine levels at postoperative days one (14 studies, 1022 participants: MD -0.02 mg/dL, 95% CI -0.05 to 0.02; I2 = 21%), two (9 studies, 770 participants: MD -0.04 mg/dL, 95% CI -0.09 to 0.02; I2 = 31%), and three (6 studies, 417 participants: MD -0.05 mg/dL, 95% CI -0.19 to 0.10; I2 = 68%) compared to control.Serious adverse events occurred in four patients receiving remote ischaemic preconditioning by iliac clamping. It is uncertain whether remote ischaemic preconditioning by cuff inflation leads to increased adverse effects compared to control because the certainty of the evidence is low (15 studies, 3993 participants: RR 3.47, 95% CI 0.55 to 21.76; I2 = 0%); only two of 15 studies reported any adverse effects (6/1999 in the remote ischaemic preconditioning group and 1/1994 in the control group), the remaining 13 studies stated no adverse effects were observed in either group.Compared to control, remote ischaemic preconditioning made little or no difference to the need for dialysis (13 studies, 2417 participants: RR 0.85, 95% CI 0.37 to 1.94; I2 = 60%; moderate quality evidence), length of hospital stay (8 studies, 920 participants: MD 0.17 days, 95% CI -0.46 to 0.80; I2 = 49%, high quality evidence), or all-cause mortality (24 studies, 4931 participants: RR 0.86, 95% CI 0.54 to 1.37; I2 = 0%, high quality evidence).Remote ischaemic preconditioning may have slightly improved the incidence of acute kidney injury using either the AKIN (8 studies, 2364 participants: RR 0.76, 95% CI 0.57 to 1.00; I2 = 61%, high quality evidence) or RIFLE criteria (3 studies, 1586 participants: RR 0.91, 95% CI 0.75 to 1.12; I2 = 0%, moderate quality evidence).

AUTHORS' CONCLUSIONS

Remote ischaemic preconditioning by cuff inflation appears to be a safe method, and probably leads to little or no difference in serum creatinine, adverse effects, need for dialysis, length of hospital stay, death and in the incidence of acute kidney injury. Overall we had moderate-high certainty evidence however the available data does not confirm the efficacy of remote ischaemic preconditioning in reducing renal ischaemia reperfusion injury in patients undergoing major cardiac and vascular surgery in which renal ischaemia reperfusion injury may occur.

Remote ischaemic pre-conditioning for the prevention of acute kidney injury

Acute kidney injury (AKI) is a common complication associated with high morbidity and mortality in hospitalized patients. One potential mechanism underlying renal injury is ischaemia/reperfusion injury (IRI), which attributed the organ damage to the inflammatory and oxidative stress responses induced by a period of renal ischaemia and subsequent reperfusion. Therapeutic strategies that aim at minimizing the effect of IRI on the kidneys may prevent AKI and improve clinical outcomes significantly. In this review, we examine the technique of remote ischaemic preconditioning (rIPC), which has been shown by several trials to confer organ protection by applying transient, brief episodes of ischaemia at a distant site before a larger ischaemic insult. We provide an overview of the current clinical evidence regarding the renoprotective effect of rIPC in the key clinical settings of cardiac or vascular surgery, contrast-induced AKI, pre-existing chronic kidney disease (CKD) and renal transplantation, and discuss key areas for future research.

Effects of ischaemic conditioning on major clinical outcomes in people undergoing invasive procedures: systematic review and meta-analysis

OBJECTIVE

 To summarise the benefits and harms of ischaemic conditioning on major clinical outcomes in various settings.

DESIGN

 Systematic review and meta-analysis.

DATA SOURCES

 Medline, Embase, Cochrane databases, and International Clinical Trials Registry platform from inception through October 2015.

STUDY SELECTION

 All randomised controlled comparisons of the effect of ischaemic conditioning on clinical outcomes were included.

DATA EXTRACTION

 Two authors independently extracted data from individual reports. Reports of multiple intervention arms were treated as separate trials. Random effects models were used to calculate summary estimates for all cause mortality and other pre-specified clinical outcomes. All cause mortality and secondary outcomes with P<0.1 were examined for study quality by using the GRADE assessment tool, the effect of pre-specified characteristics by using meta-regression and Cochran C test, and trial sequential analysis by using the Copenhagen Trial Unit method.

RESULTS

 85 reports of 89 randomised comparisons were identified, with a median 80 (interquartile range 60-149) participants and median 1 (range 1 day-72 months) month intended duration. Ischaemic conditioning had no effect on all cause mortality (68 comparisons; 424 events; 11 619 participants; risk ratio 0.96, 95% confidence interval 0.80 to 1.16; P=0.68; moderate quality evidence) regardless of the clinical setting in which it was used or the particular intervention related characteristics. Ischaemic conditioning may reduce the rates of some secondary outcomes including stroke (18 trials; 5995 participants; 149 events; risk ratio 0.72, 0.52 to 1.00; P=0.048; very low quality evidence) and acute kidney injury (36 trials; 8493 participants; 1443 events; risk ratio 0.83, 0.71 to 0.97; P=0.02; low quality evidence), although the benefits seem to be confined to non-surgical settings and to mild episodes of acute kidney injury only.

CONCLUSIONS

 Ischaemic conditioning has no overall effect on the risk of death. Possible effects on stroke and acute kidney injury are uncertain given methodological concerns and low event rates. Adoption of ischaemic conditioning cannot be recommended for routine use unless further high quality and well powered evidence shows benefit.

Remote Ischemic Preconditioning for Prevention of Acute Kidney Injury in Patients Undergoing On-Pump Cardiac Surgery: A Systematic Review and Meta-Analysis

Remote ischemic preconditioning (RIPC) may attenuate acute kidney injury (AKI). However, results of studies evaluating the effect of RIPC on AKI after cardiac surgery have been controversial and contradictory.The aim of this meta-analysis is to examine the association between RIPC and AKI after on-pump cardiac surgery.The authors searched relevant studies in PubMed, EMBASE, and the Cochrane Library through December 2015.We considered for inclusion all randomized controlled trials that the role of RIPC in reducing AKI and renal replacement therapy (RRT) among patients underwent on-pump cardiac surgical procedures.We collected the data on AKI, initiation of RRT, serum creatinine (sCr) levels, and in-hospital mortality. Random- and fixed-effect models were used for pooling data.Nineteen trials including 5100 patients were included. The results of this meta-analysis showed a significant benefit of RIPC for reducing the incidence of AKI after cardiac interventions (odds ratio [OR] = 0.84; 95% confidence interval [CI], 0.73-0.98; P = 0.02). No significant difference was found in the incidence of RRT between RIPC and control (OR, 0.76, 95% CI, 0.46-1.24; P = 0.36). In addition, compared with standard medical care, RIPC showed no significant difference in postoperative sCr (IV 0.07; 95% CI, -0.03 to 0.16; P = 0.20; postoperative day 1; IV 0.00; 95% CI, -0.08 to 0.09; P = 0.92; postoperative day 2; IV 0.04; 95% CI, -0.05 to 0.12; P = 0.39; postoperative day 3), and in-hospital mortality (OR, 1.21, 95% CI, 0.64-2.30; P = 0.56).According to the results from present meta-analysis, RIPC was associated with a significant reduction AKI after on-pump cardiac surgery but incidence of RRT, postoperative sCr, and in-hospital mortality. Further high-quality randomized controlled trials and experimental researches comparing RIPC are desirable.

Remote Ischemic Preconditioning in the PICU: A Simple Concept With a Complex Past

OBJECTIVE

In this study, we will review the most recently proposed mechanisms for remote ischemic preconditioning and summarize the past 10 years of clinical studies, as well as potential reasons for why, despite over 20 years of research on remote ischemic preconditioning, it is not routinely used in the pediatric critical care patient. In addition, future directions for remote ischemic preconditioning research will be discussed.

DATA SOURCES

We searched the PubMed database for relevant literature.

STUDY SELECTION AND DATA EXTRACTION

In PubMed, the search terms "ischemic preconditioning" and "remote preconditioning" were used. Randomized controlled trials published from 2006 until the present time that used a blood pressure cuff to induce remote ischemic preconditioning were included. We also reviewed the reference lists of the articles found in the PubMed search and included those thought to contribute to the objectives. All studies pertaining to remote ischemic preconditioning that included pediatric patients were reviewed.

DATA SYNTHESIS AND CONCLUSIONS

Differences in study outcomes in the effect of remote ischemic preconditioning on organ protection have been reported and may have played a large role in limiting the translation of findings into routine clinical practice. Ongoing efforts to protocolize the remote ischemic preconditioning technique in large multicenter trials with clearly delineated patient risk groups, including the use of biomarkers for enrichment, may help to ultimately determine if this procedure can be safely and effectively used for critically ill children.

The Impact of Remote Ischemic Preconditioning on Arterial Stiffness and Heart Rate Variability in Patients with Angina Pectoris

Remote ischemic preconditioning (RIPC) is the set of ischemia episodes that protects against subsequent periods of prolonged ischemia through the cascade of adaptive responses; however, the mechanisms of RIPC are not entirely clear. Here, we aimed to study the impact of RIPC in patients with stable angina pectoris and compare it with healthy individuals with respect to arterial stiffness and heart rate variability. In the randomized, sham-controlled, crossover blind design study, a group of 30 coronary heart disease (CHD) patients (63.9 ± 1.6 years) with stable angina pectoris NYHA II-III and a control group of 20 healthy individuals (58.2 ± 2.49) were both randomly allocated for remote RIPC or sham RIPC. Arterial stiffness, pulse wave velocity (Spygmacor, Australia), and heart rate variability (HRV) were recorded before and after the procedure followed by the crossover examination. In the group of healthy individuals, RIPC showed virtually no impact on the cardiovascular parameters, while, in the CHD group, the systolic and central systolic blood pressure, central pulse pressure, and augmentation decreased, and total power of HRV improved. We conclude that ischemic preconditioning reduces not only systolic blood pressure, but also reduces central systolic blood pressure and improves arterial compliance and heart rate modulation reserve, which may be associated with the antianginal effect of preconditioning.

Protection of remote ischemic preconditioning against acute kidney injury: a systematic review and meta-analysis

Background

Remote ischemic preconditioning (RIPC) is a promising approach to preventing acute kidney injury (AKI), but its efficacy is controversial.

Methods

A systematic review of 30 randomized controlled trials was conducted to investigate the effects of RIPC on the incidence and outcomes of AKI. Random effects model meta-analyses and meta-regressions were used to generate summary estimates and explore sources of heterogeneity. The primary outcome was incidence of AKI and hospital mortality.

Results

The total pooled incidence of AKI in the RIPC group was 11.5 %, significantly less than the 23.3 % incidence in the control group (P = 0.009). Subgroup analyses indicated that RIPC significantly reduced the incidence of AKI in the contrast-induced AKI (CI-AKI) subgroup from 13.5 % to 6.5 % (P = 0.000), but not in the ischemia/reperfusion-induced AKI (IR-AKI) subgroup (from 29.5 % to 24.7 %, P = 0.173). Random effects meta-regression indicated that RIPC tended to strengthen its renoprotective effect (q = 3.95, df = 1, P = 0.047) in these trials with a higher percentage of diabetes mellitus. RIPC had no significant effect on the incidence of stages 1–3 AKI or renal replacement therapy, change in serum creatinine and estimated glomerular filtration rate (eGFR), hospital or 30-day mortality, or length of hospital stay. But RIPC significantly increased the minimum eGFR in the IR-AKI subgroup (P = 0.006) compared with the control group. In addition, the length of ICU stay in the RIPC group was significantly shorter than in the control group (2.6 vs 2.0 days, P = 0.003).

Conclusions

We found strong evidence to support the application of RIPC to prevent CI-AKI, but not IR-AKI.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1272-y) contains supplementary material, which is available to authorized users.

Effect of remote ischemic preconditioning on postoperative acute kidney injury among patients undergoing cardiac and vascular interventions: a meta-analysis

It is currently controversial whether remote ischemic preconditioning (RIPC) reduces the incidence of acute kidney injury (AKI) in patients undergoing cardiovascular interventions. The main objective of this meta-analysis was to investigate whether RIPC provides renal protection for patients undergoing cardiac or vascular surgery. We searched the PubMed database (1966-Oct 2015), Embase database (1966-Oct 2015), Google Scholar, Cochrane Library, ClinicalTrials Database and Open Grey. Then we conducted a meta-analysis of the randomized controlled trials that met the inclusion criteria of our study. The interventions included use of an inflatable tourniquet around the limbs or cross-clamping of the iliac arteries before surgery (RIPC groups) and general cardiovascular intervention (control groups). The main outcomes examined included the incidence of AKI; changes in acute kidney injury biomarkers; and use of renal replacement therapy. Other outcomes examined included in-hospital mortality and the lengths of hospital stay and intensive care unit (ICU) stay. Finally, we screened 26 eligible studies containing 6699 patients who underwent cardiac or vascular interventions with RIPC (n = 3343) or without RIPC (n = 3356). The AKI incidence was decreased in the RIPC group as was the length of ICU stay. There were no differences in the changes in AKI biomarkers, use of renal replacement therapy or in-hospital mortality between the two groups. Remote ischemic preconditioning may decrease the occurrence of AKI in cardiovascular surgery patients. Since studies included have a significant heterogeneity, meta-analyses using a stricter inclusion criteria are needed to clarify the renoprotection effect of RIPC.

Remote ischemic conditioning for kidney protection: A meta-analysis

BACKGROUND

Results from randomized controlled trials (RCTs) concerning kidney effect of remote ischemic conditioning (RIC) are inconsistent.

METHODS

We searched for relevant studies in Medline, Embase, the Cochrane Library, Google Scholar and Chinese database (SinoMed), as well as relevant references from their inception to November 2015. We performed a systematic review and meta-analysis of all eligible RCTs of RIC with kidney events.

RESULTS

We included 37 RCTs from 2007 to 2015 involving 8168 patients. Pooled analyses of all RCTs showed RIC significantly reduced the incidence of investigator-defined acute kidney injury (AKI) compared with control groups (RR 0.84, 95% CI 0.73-0.96, P = .009) (I(2) = 25%). However, the difference was not significant when only RIFLE (Risk, Injury, Failure, Loss, End Stage), AKIN (Acute Kidney Injury Network), or KDIGO (Kidney Disease Improving Global Outcomes) criteria were applied to the definition of AKI (RR 0.87, 95% CI 0.74-1.02, P = .08) (I(2) = 22%). In subgroup analysis, RIC showed a significant benefit on reducing investigator-defined AKI in patients following percutaneous coronary intervention (RR 0.64, 95% CI 0.46-0.87), but not after cardiac surgery (RR 0.93, 95% CI 0.82-1.06). There was no difference for changes in the incidence of renal replacement therapy, estimated glomerular filtration rate or serum creatinine.

CONCLUSIONS

RIC might be beneficial for the prevention of investigator-defined AKI; however, the effect is likely small. Moreover, due to lack of an effect on use of renal replacement therapy, estimated glomerular filtration rate, RIFLE, AKIN, or KDIGO-defined AKI, and serum creatinine, the evidence for RIC is not robust. Finally, recent large-scale RCTs of RIC focusing on patient-centered outcomes do not support the wider application of RIC.

Acute kidney injury: highlights from the ERA-EDTA Congress in London

The ERA-EDTA 52nd Congress was held in London, 28-31 May 2015. In the scientific programme, overall, during the symposium, there were 18 lectures, 3 minilectures, 15 free communications and 135 poster presentations on acute kidney injury (AKI). Among many excellent reports and presentations, I selected three hot topics on AKI for the readership of Nephrology Dialysis Transplantation.

[Neuroprotective and nephroprotective effects of remote postconditioning: Prospects for clinical use]

The results of experimental and clinical studies strongly suggest that remote ischemic preconditioning (RIP) has no neuroprotective effect during cardiac surgery performed under extracorporeal circulation. Remote preconditioning (RP) has no neuroprotective effect in hemorrhagic stroke. A randomized multicenter study is needed to evaluate the efficiency RIP in patients with ischemic stroke. RP reduces the severity of ischemia/reperfusion kidney injury during transplantation. RIP has been established to prevent contrast-induced nephropathy. There is a need for a multicenter trial to evaluate the efficiency of RIP in patients with abdominal aortic aneurysm repair. Analysis of the presented data indicates that RIP fails to prevent cardiorenal syndrome in infants and children during cardiac surgery. The data available in the literature on the capacity of RIP to provide nephroprotective effect in patients after coronary artery bypass surgery are discordant and indicative of the advisability of a multicenter study.

Effects of remote ischemic preconditioning in high-risk patients undergoing cardiac surgery (Remote IMPACT): a randomized controlled trial

BACKGROUND

Remote ischemic preconditioning is a simple therapy that may reduce cardiac and kidney injury. We undertook a randomized controlled trial to evaluate the effect of this therapy on markers of heart and kidney injury after cardiac surgery.

METHODS

Patients at high risk of death within 30 days after cardiac surgery were randomly assigned to undergo remote ischemic preconditioning or a sham procedure after induction of anesthesia. The preconditioning therapy was three 5-minute cycles of thigh ischemia, with 5 minutes of reperfusion between cycles. The sham procedure was identical except that ischemia was not induced. The primary outcome was peak creatine kinase-myocardial band (CK-MB) within 24 hours after surgery (expressed as multiples of the upper limit of normal, with log transformation). The secondary outcome was change in creatinine level within 4 days after surgery (expressed as log-transformed micromoles per litre). Patient-important outcomes were assessed up to 6 months after randomization.

RESULTS

We randomly assigned 128 patients to remote ischemic preconditioning and 130 to the sham therapy. There were no significant differences in postoperative CK-MB (absolute mean difference 0.15, 95% confidence interval [CI] -0.07 to 0.36) or creatinine (absolute mean difference 0.06, 95% CI -0.10 to 0.23). Other outcomes did not differ significantly for remote ischemic preconditioning relative to the sham therapy: for myocardial infarction, relative risk (RR) 1.35 (95% CI 0.85 to 2.17); for acute kidney injury, RR 1.10 (95% CI 0.68 to 1.78); for stroke, RR 1.02 (95% CI 0.34 to 3.07); and for death, RR 1.47 (95% CI 0.65 to 3.31).

INTERPRETATION

Remote ischemic precnditioning did not reduce myocardial or kidney injury during cardiac surgery. This type of therapy is unlikely to substantially improve patient-important outcomes in cardiac surgery.

TRIAL REGISTRATION

ClinicalTrials.gov, no. NCT01071265.

Marked protection against acute renal and hepatic injury after nitrited myoglobin + tin protoporphyrin administration

The phenomenon known as renal "ischemic preconditioning," whereby an initial ischemic insult induces resistance against subsequent kidney damage, has been well established in the experimental literature. However, a clinically applicable way to safely recapitulate this state has not been defined. We hypothesized that a unique combination of agents (nitrited myoglobin [N-Mgb] + tin protoporphyrin [SnPP]) can achieve these ends safely and synergistically, increasing cytoprotective proteins (eg, heme oxygenase 1 [HO-1], interleukin 10 [IL-10], and haptoglobin) in kidney cells. To test this hypothesis, CD-1 mice received 1 mg of N-Mgb and 1 μmol of SnPP, either alone or in combination. Renal cortical HO-1, haptoglobin, and IL-10 gene expressions (messenger RNA [mRNA], protein levels) were determined 4 and 18 hours later. Cytoresistance to 3 forms of acute kidney injury (AKI; glycerol-induced rhabdomyolysis, maleate nephrotoxicity, and postischemic AKI progression to chronic kidney disease [CKD]) was assessed. To ascertain whether cytoresistance might emerge in extrarenal organs, hepatic HO-1, IL-10, and haptoglobin levels were also measured, and resistance to 25 minutes of hepatic ischemia-reperfusion injury and hepatotoxicity (intraperitoneal glycerol injection) was sought. N-Mgb + SnPP induced additive or synergistic increases in renal HO-1, haptoglobin, and IL-10 mRNA and protein levels (up to 20-fold) without inducing any apparent renal or extrarenal damage. After 18 hours of post-treatment, marked or complete protection against glycerol-induced AKI, maleate-induced AKI, and postischemic AKI progression to CKD had emerged. Combined N-Mgb + SnPP was more protective than either agent alone (assessed in glycerol model). N-Mgb + SnPP also upregulated cytoprotective pathways in liver and induced marked protection against both hepatic ischemia-reperfusion and toxic liver damage. In conclusion, we posit that "preconditioning" with combined administration of N-Mgb + SnPP represents a promising approach for protecting against diverse forms of renal and nonrenal (hepatic) forms of tissue damage.

Remote Ischemic Preconditioning May Attenuate Renal Ischemia-Reperfusion Injury in a Porcine Model of Supraceliac Aortic Cross-Clamping

AIM

The effect of remote ischemic preconditioning (RIPC) in decreasing renal ischemia-reperfusion injury (IRI) during a suprarenal aortic cross-clamping was examined in a swine model.

MATERIALS AND METHODS

Four groups of pigs were examined: (a) ischemia-reperfusion (IR) group, renal IRI produced by 30 min of supraceliac aortic cross-clamping; (b) RIPC I group, the same renal IRI following RIPC by brief occlusion of the infrarenal aorta (15 min ischemia and 15 min reperfusion); (c) RIPC II group, the same renal IRI following RIPC by brief occlusion of the infrarenal aorta (3 cycles of 5 min ischemia and 5 min reperfusion); (d) sham group. Renal function was assessed before and after IRI by examining creatinine, neutrophil gelatinase-associated lipocalin (NGAL), TNF-α, malondialdehyde (MDA), cystatin C and C-reactive protein (CRP) from renal vein blood samples at specific time intervals.

RESULTS

Both RIPC groups presented significantly less impaired results compared to the IR group when considering MDA, cystatin C, CRP and creatinine. Between the two RIPC groups, RIPC II presented a better response with regard to CRP, NGAL, TNF-α, MDA and cystatin C.

CONCLUSIONS

Remote IR protocols and mainly repetitive short periods of cycles of IR ameliorate the biochemical kidney effects of IRI in a model of suprarenal aortic aneurysm repair.

Associations between Deceased-Donor Urine Injury Biomarkers and Kidney Transplant Outcomes

Assessment of deceased-donor organ quality is integral to transplant allocation practices, but tools to more precisely measure donor kidney injury and better predict outcomes are needed. In this study, we assessed associations between injury biomarkers in deceased-donor urine and the following outcomes: donor AKI (stage 2 or greater), recipient delayed graft function (defined as dialysis in first week post-transplant), and recipient 6-month eGFR. We measured urinary concentrations of microalbumin, neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), IL-18, and liver-type fatty acid binding protein (L-FABP) from 1304 deceased donors at organ procurement, among whom 112 (9%) had AKI. Each biomarker strongly associated with AKI in adjusted analyses. Among 2441 kidney transplant recipients, 31% experienced delayed graft function, and mean±SD 6-month eGFR was 55.7±23.5 ml/min per 1.73 m(2) In analyses adjusted for donor and recipient characteristics, higher donor urinary NGAL concentrations associated with recipient delayed graft function (highest versus lowest NGAL tertile relative risk, 1.21; 95% confidence interval, 1.02 to 1.43). Linear regression analyses of 6-month recipient renal function demonstrated that higher urinary NGAL and L-FABP concentrations associated with slightly lower 6-month eGFR only among recipients without delayed graft function. In summary, donor urine injury biomarkers strongly associate with donor AKI but provide limited value in predicting delayed graft function or early allograft function after transplant.

Remote ischaemic conditioning on recipients of deceased renal transplants, effect on immediate and extended kidney graft function: a multicentre, randomised controlled trial protocol (CONTEXT)

INTRODUCTION

Delayed graft function due to ischaemia-reperfusion injury is a frequent complication in deceased donor renal transplantation. Experimental evidence indicates that remote ischaemic conditioning (RIC) provides systemic protection against ischaemia-reperfusion injury in various tissues.

METHODS AND ANALYSIS

'Remote ischaemic conditioning in renal transplantation--effect on immediate and extended kidney graft function' (the CONTEXT study) is an investigator initiated, multicentre, randomised controlled trial investigating whether RIC of the leg of the recipient improves short and long-term graft function following deceased donor kidney transplantation. The study will include 200 kidney transplant recipients of organ donation after brain death and 20 kidney transplant recipients of organ donation after circulatory death. Participants are randomised in a 1:1 design to RIC or sham-RIC (control). RIC consists of four cycles of 5 min occlusion of the thigh by a tourniquet inflated to 250 mm Hg, separated by 5 min of deflation. Primary end point is the time to a 50% reduction from the baseline plasma creatinine, estimated from the changes of plasma creatinine values 30 days post-transplant or 30 days after the last performed dialysis post-transplant. Secondary end points are: need of dialysis post-transplant, measured and estimated-glomerular filtration rate (GFR) at 3 and 12 months after transplantation, patient and renal graft survival, number of rejection episodes in the first year, and changes in biomarkers of acute kidney injury and inflammation in plasma, urine and graft tissue.

ETHICS AND DISSEMINATION

The study is approved by the local ethical committees and national data security agencies. Results are expected to be published in 2016.

TRIAL REGISTRATION NUMBER

NCT01395719.

Remote ischemic preconditioning for kidney protection: GSK3β-centric insights into the mechanism of action

Preventing acute kidney injury (AKI) in high-risk patients following medical interventions is a paramount challenge for clinical practice. Recent data from animal experiments and clinical trials indicate that remote ischemic preconditioning, represented by limb ischemic preconditioning, confers a protective action on the kidney. Ischemic preconditioning is effective in reducing the risk for AKI following cardiovascular interventions and the use of iodinated radiocontrast media. Nevertheless, the underlying mechanisms for this protective effect are elusive. A protective signal is conveyed from the remote site undergoing ischemic preconditioning, such as the limb, to target organs, such as the kidney, by multiple potential communication pathways, which may involve humoral, neuronal, and systemic mechanisms. Diverse transmitting pathways trigger a variety of signaling cascades, including the reperfusion injury salvage kinase and survivor activating factor enhancement pathways, all of which converge on glycogen synthase kinase 3β (GSK3β). Inhibition of GSK3β subsequent to ischemic preconditioning reinforces the Nrf2-mediated antioxidant defense, diminishes the nuclear factor-κB-dependent proinflammatory response, and exerts prosurvival effects ensuing from the desensitized mitochondria permeability transition. Thus, therapeutic targeting of GSK3β by ischemic preconditioning or by pharmacologic preconditioning with existing US Food and Drug Administration-approved drugs having GSK3β-inhibitory activities might represent a pragmatic and cost-effective adjuvant strategy for kidney protection and prophylaxis against AKI.

Multiorgan protection of remote ischemic perconditioning in valve replacement surgery

BACKGROUND

Remote ischemic perconditioning (RIPerc) is a new alternative of remote ischemic conditioning and has not been well studied. RIPerc attenuates myocardial injury when applied during cardiac surgery. However, its protective effects on other organs remain unknown.

MATERIALS AND METHODS

Patients with rheumatic heart disease undergoing valve replacement surgery were randomized into the RIPerc group (n = 101) or the control group (n = 100). RIPerc was achieved by three cycles of 5-min ischemia-5-min reperfusion in the right thigh during surgery. Clinical data and the levels of injury biomarkers for the heart, lungs, liver, and kidneys within 48 h after surgery were compared using one-way or repeated measurement analysis of variance.

RESULTS

In the RIPerc group, the release of serum cardiac troponin I (128.68 ± 102.56 versus 172.33 ± 184.38, P = 0.04) and the inotropic score (96.4 ± 73.8 versus 121.5 ± 89.6, P = 0.032) decreased compared with that of the control; postoperative drainage (458.2 ± 264.2 versus 545.1 ± 349.0 ml, P = 0.048) and the incidence of acute lung injury was reduced (36.6% versus 51%, P = 0.04), and the extent of hyperbilirubinemia was also attenuated. No significant difference was observed in the levels of biomarkers for renal injury and systemic inflammation response.

CONCLUSIONS

RIPerc applied during the valve replacement surgery induced multiple beneficial effects postoperatively including reduced drainage and myocardial damage, lower incidence of acute lung injury, and attenuated hyperbilirubinemia.

Remote Ischemic Conditioning for Preventing Contrast-Induced Acute Kidney Injury in Patients Undergoing Percutaneous Coronary Interventions/Coronary Angiography: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

It is uncertain whether remote ischemic conditioning (RIC) has a protective effect on contrast-induced acute kidney injury (CI-AKI) after percutaneous coronary intervention (PCI)/coronary artery angiography (CAG). We performed a meta-analysis of randomized controlled trials (RCTs) to assess the effect of RIC on CI-AKI in such patients.

METHODS

PubMed, MEDLINE, EMBASE, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials databases were searched for RCTs that assessed the effect of RIC on CI-AKI in patients undergoing PCI/CAG.

RESULTS

Ten RCTs with 1389 patients (RIC group, 757 and control, 632) were included. The RIC group significantly exerted a lower risk of CI-AKI compared to the controls (odds ratio [OR] = 0.52, 95% confidence interval [CI] = 0.34-0.77, P = .001), and they had the similar effect on major adverse cardiovascular events within 1 year (OR = 0.36, 95% CI = 0.20-0.66, P < .001). The RIC reduced the rates of death within 30 days, but this was not significant (OR = 0.16, 95% CI = 0.02-1.34, P = .091). The RIC was associated with a significantly lower incidence of CI-AKI in patients following elective PCI/CAG (OR = 0.54, 95% CI = 0.33-0.87, P = .011). The RIC before not after the intervention was effective in reducing the occurrence of CI-AKI (OR: 0.37 vs 1.05, P = .022). The RIC of the upper arm has statistically significant effect on protecting CI-AKI but not that of the lower limb (OR: 0.41 vs 1.41, P = .004). The effect of RIC on CI-AKI was similar between patients with a mean estimated glomerular filtration rate <60 mL/min/1.73 m(2) and those with mean rates ≥60 (OR: 0.23 vs 0.41, P = .333).

CONCLUSION

The RIC reduced the incidence of CI-AKI in those receiving PCI/CAG. And RIC of the upper arm significantly reduced the risk of CI-AKI but not RIC of the lower limb in patients undergoing PCI/CAG.

Using remote ischemic conditioning to reduce acute kidney injury in patients undergoing percutaneous coronary intervention: a meta-analysis

BACKGROUND AND AIMS

It remains uncertain whether remote ischemic conditioning (RIC) could prevent acute kidney injury (AKI) in patients undergoing percutaneous coronary intervention (PCI). Thus, this meta-analysis aiming to explore the renoprotective role of RIC in patients undergoing PCI was carried out.

METHODS

PubMed, Web of Science, and Cochrane Library were searched from inception to 31 December 2014 to identify eligible randomized controlled trials. Pooled risk ratio, mean, standard deviation and 95% CI were used to assess the effect by fixed- or random-effect models. Heterogeneity was assessed by the Cochran Q and I( 2) statistics.

RESULTS

Nine trials were included in this study. RIC decreased the AKI incidence in patients undergoing PCI compared with control individuals (P < 0.001; RR, 0.53; 95% CI, 0.39-0.71; P for heterogeneity = 0.15; heterogeneity χ(2 )= 13.38; I(2 )= 33%). Besides, limb conditioning attenuated AKI (P = 0.001; RR, 0.57; 95% CI, 0.41-0.81; P for heterogeneity = 0.13; heterogeneity χ(2 )= 12.48; I(2 )= 36%). Remote postconditioning may reduce the AKI incidence (P = 0.03; RR, 0.65; 95% CI, 0.44-0.97; P for heterogeneity = 0.15; heterogeneity χ(2 )= 5.36; I(2 )= 44%); remote preconditioning could also play a renoprotective role (P < 0.001; RR, 0.42; 95% CI, 0.27-0.65; P for heterogeneity = 0.31; heterogeneity χ(2 )= 5.98; I(2 )= 16%).

CONCLUSIONS

RIC may not only confer cardioprotection, but also reduce the incidence of AKI in patients undergoing PCI, ultimately leading to better clinical outcomes. RIC may potentially be a powerful approach conferring protection in patients undergoing PCI in future clinical practice. More large-scale trials are required to obtain a more reliable conclusion.