Remote Ischemic Preconditioning To Reduce Contrast-Induced Nephropathy: A Randomized Controlled Trial

Prevention of Contrast-induced Nephropathy in Patients Undergoing Percutaneous Coronary Intervention

Contrast-induced nephropathy (CIN) or contrast-induced acute kidney injury has varying definitions, but in general, increased serum creatinine level by ≥ 0.3 mg/dL (26.5 µmol/L) or 1.5x of baseline value or urine output <0.5 mL/kg/h within 1-7 days after contrast media (CM) administration can be considered as CIN. CIN is one of the most common complications and is associated with increased mortality in patients undergoing percutaneous coronary intervention (PCI). Thus, risk stratification for CIN should be made and preventive strategies should be employed in which the intensity of the approach must be tailored to patient's risk profile. In all patients, adequate hydration is required, nephrotoxic medications should be discontinued, and pre-procedural high-intensity statin is recommended. In patients with an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2, IV hydration should be started 12 hours pre-procedure up until 12-24 hours after the procedure. Remote ischemic preconditioning may be performed pre-procedurally. Radial first approach for vascular access is recommended. During the procedure, low or iso-osmolar CM should be used and its volume should be limited to eGFR x 3.7. In patients at high risk for CIN, additional contrast-sparing strategies may be applied, such as using a contrast reduction system, 5 Fr catheter with no sideholes, CM dilution, limiting test injection, confirming placement using guidewire, use of stent enhancing imaging technology, using metallic/software roadmap to guide PCI, use of IVUS or dextran-based OCT, and coronary aspiration. A more advanced hydration technique based on central venous pressure, left ventricular end-diastolic pressure, or using furosemide-matched hydration, might be considered.

Is Renal Ischemic Preconditioning an Alternative to Ameliorate the Short- and Long-Term Consequences of Acute Kidney Injury?

Acute kidney injury (AKI) is a global health problem and has recently been recognized as a risk factor for developing chronic kidney disease (CKD). Unfortunately, there are no effective treatments to reduce or prevent AKI, which results in high morbidity and mortality rates. Ischemic preconditioning (IPC) has emerged as a promising strategy to prevent, to the extent possible, renal tissue from AKI. Several studies have used this strategy, which involves short or long cycles of ischemia/reperfusion (IR) prior to a potential fatal ischemic injury. In most of these studies, IPC was effective at reducing renal damage. Since the first study that showed renoprotection due to IPC, several studies have focused on finding the best strategy to activate correctly and efficiently reparative mechanisms, generating different modalities with promising results. In addition, the studies performing remote IPC, by inducing an ischemic process in distant tissues before a renal IR, are also addressed. Here, we review in detail existing studies on IPC strategies for AKI pathophysiology and the proposed triggering mechanisms that have a positive impact on renal function and structure in animal models of AKI and in humans, as well as the prospects and challenges for its clinical application.

Remote ischaemic preconditioning versus no remote ischaemic preconditioning for vascular and endovascular surgical procedures

BACKGROUND

Despite advances in perioperative care, elective major vascular surgical procedures still carry a significant risk of morbidity and mortality. Remote ischaemic preconditioning (RIPC) is the temporary blocking of blood flow to vascular beds remote from those targeted by surgery. It has the potential to provide local tissue protection from further prolonged periods of ischaemia. However, the efficacy and safety of RIPC in people undergoing major vascular surgery remain unknown. This is an update of a review published in 2011.  OBJECTIVES: To assess the benefits and harms of RIPC versus no RIPC in people undergoing elective major vascular and endovascular surgery.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov to 1 April 2022.

SELECTION CRITERIA

We included all randomised controlled trials that evaluated the role of RIPC in reducing perioperative mortality and morbidities in people undergoing elective major vascular or endovascular surgery.

DATA COLLECTION AND ANALYSIS

We collected data on the characteristics of the trial, methodological quality, and the remote ischaemic preconditioning stimulus used. Our primary outcome was perioperative mortality, and secondary outcomes included myocardial infarction, renal impairment, stroke, hospital stay, limb loss, and operating time or total anaesthetic time. We analysed the data using random-effects models. For each outcome, we calculated the risk ratio (RR) or mean difference (MD) with a 95% confidence interval (CI) based on an intention-to-treat analysis. In addition, we used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

We included 14 trials which randomised a total of 1295 participants (age range: 64.5 to 76 years; 84% male; study periods ranged from 2003 to 2019). In general, the included studies were at low to unclear risk of bias for most risk of bias domains. The certainty of evidence of main outcomes was moderate due to imprecision of results, moderate heterogeneity, or possible publication bias. We found that RIPC made no clear difference in perioperative mortality compared with no RIPC (RR 1.41, 95% CI 0.59 to 3.40; I2 = 0%; 10 studies, 965 participants; moderate-certainty evidence). Similarly, we found no clear difference between the two groups for myocardial infarction (RR 0.82, 95% CI 0.49 to 1.40; I2 = 7%; 11 studies, 1001 participants; moderate-certainty evidence), renal impairment (RR 1.07, 95% CI 0.62 to 1.86; I2 = 40%; 12 studies, 1054 participants; moderate-certainty evidence), stroke (RR 0.33, 95% CI 0.04 to 3.15; I2 = 0%; 4 studies, 392 participants; moderate-certainty evidence), limb loss (RR 0.74, 95% CI 0.05 to 10.61; I2 = 32%; 3 studies, 322 participants; low-certainty evidence), hospital stay (MD -0.94 day, 95% CI -1.95 to 0.07; I2 = 17%; 7 studies, 569 participants; moderate-certainty evidence), and operating time or total anaesthetic time (MD 5.76 minutes, 95% CI -3.25 to 14.76; I2 = 44%; 10 studies, 803 participants; moderate-certainty evidence).  AUTHORS' CONCLUSIONS: Overall, compared with no RIPC, RIPC probably leads to little or no difference in perioperative mortality, myocardial infarction, renal impairment, stroke, hospital stay, and operating time, and may lead to little or no difference in limb loss in people undergoing elective major vascular and endovascular surgery. Adequately powered and designed randomised studies are needed, focusing in particular on the clinical endpoints and patient-centred outcomes.

Perioperative renal protection

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a common but underestimated syndrome in the perioperative setting. AKI can be induced by different causes and is associated with increased morbidity and mortality. Unfortunately, no specific treatment options are available at the moment.

RECENT FINDINGS

AKI is now understood as being a continuum ranging from normal kidney function over AKI and acute kidney disease to ultimately chronic kidney disease. The KDIGO organization recommend in 2012 implementation of preventive bundles in patients at high risk for AKI. In the perioperative setting, relevant measures include hemodynamic optimization, with careful consideration of blood pressure targets, adequate fluid therapy to maintain organ perfusion and avoidance of hyperglycaemia. These measures are most effective if patients at risk are identified as soon as possible and measures are implemented accordingly. Although current point of care functional biomarkers can detect patients at risk earlier than the established damage biomarkers, some components of the preventive bundle are still under investigation.

SUMMARY

Good evidence exists for the use of biomarkers to identify individual patients at risk for AKI and for the implementation of haemodynamic optimization, abdication of nephrotoxins, adequate fluid administration using balanced crystalloid solutions and glycaemic control. The data for using colloids or the degree of nephrotoxicity of contrast media still remain inconclusive.

Risk factors of contrast-induced nephropathy after percutaneous coronary intervention: a retrospective analysis

Objective

Contrast-induced nephropathy (CIN) is a serious complication in patients with acute coronary syndrome (ACS) and percutaneous coronary intervention (PCI). This study aimed to analyze the potential risk factors for CIN in patients undergoing PCI.

Methods

Patients with ACS who underwent PCI treatment from January 2017 to January 2020 were selected. The patients’ characteristics and medical information were collected and compared.

Results

A total of 1331 patients undergoing PCI were included. The incidence of CIN was 15.33%. Logistic regression analyses showed that a left ventricular ejection fraction ≤45% (odds ratio [OR] 4.18, 95% confidence interval [CI] 1.10–7.36), serum creatinine levels ≤60 μmol/L (OR 3.03, 95% CI 1.21–5.57), age ≥65 years (OR 2.75, 95% CI 1.32–4.60), log N-terminal pro-B-type natriuretic peptide levels ≥2.5 pg/mL (OR 2.31, 95% CI 1.18–5.13), uric acid levels ≥350 μmol/L (OR 2.29, 95% CI 1.04–5.30), emergency percutaneous intervention (OR 1.35, 95% CI 0.34–3.12), and triglyceride levels ≤1.30 mmol/L (OR 1.10, 95% CI 0.01–2.27) were independent risk factors for CIN in patients who underwent PCI.

Conclusions

Early prevention is required to reduce the occurrence of CIN in patients who undergo PCI and have risk factors for CIN.

Remote ischemic preconditioning for prevention of contrast-induced nephropathy - A randomized control trial

Background

There is a lack of sufficient data regarding the protective effects of remote ischemic preconditioning (RIPC) in patients at risk of developing contrast-induced nephropathy (CIN). Thus, this study was conducted to determine whether RIPC as an adjunct to standard therapy prevents CIN in high-risk patients undergoing coronary intervention.

Methods

In a single-center, double-blinded, randomized controlled trial, 162 patients who were at risk of CIN received standard hydration combined with RIPC or hydration with sham preconditioning. RIPC was accomplished by four cycles of 5 min ischemia and 5 min reperfusion of the forearm. The primary endpoint was a rise in serum creatinine (>0.5 mg/dL or >25%) from baseline to serum creatinine 48–72 h after contrast administration.

Results

Of the 162 patients, 81 were randomly allocated to receive sham preconditioning and 81 to receive RIPC. Significantly reduced serum creatinine levels were observed in patients with a Mehran moderate risk allocated to sham group compared to the RIPC group (0.070 ± 0.16 mg/dL vs. 0.107 ± 0.13 mg/dL, p = 0.001). With regards to the primary endpoint, a significantly higher change in serum creatinine from baseline to 48–72 h was observed in the sham group compared to the RIPC group (0.023 ± 0.2 μmol/L vs −0.064 ± 0.1 μmol/L, p < 0.001).

Conclusion

RIPC as an alternative to standard therapy, improved serum creatinine levels after contrast administration in patients at risk of CIN. However, present data indicate that RIPC might have beneficial effects in patients with a moderate or high risk of CIN.

Management of Acute Kidney Injury Following Major Abdominal Surgery: A Contemporary Review

Acute kidney injury (AKI) is a frequent occurrence following major abdominal surgery and is independently associated with both in-hospital and long-term mortality, as well as with a higher risk of progressing to chronic kidney disease (CKD) and cardiovascular events. Postoperative AKI can account for up to 40% of in-hospital AKI cases. Given the differences in patient characteristics and the pathophysiology of postoperative AKI, it is inappropriate to assume that the management after noncardiac and nonvascular surgery are the same as those after cardiac and vascular surgery. This article provides a comprehensive review on the available evidence on the management of postoperative AKI in the setting of major abdominal surgery.

Remote Ischemic Preconditioning and Contrast-Induced Acute Kidney Injury in Patients Undergoing Elective Percutaneous Coronary Intervention: A Randomized Clinical Trial

Background

Contrast-induced acute kidney injury (CI-AKI) is a common cause of hospital-acquired AKI and a serious complication of percutaneous coronary intervention.

Objective

The aim of the present study was to assess whether remote ischemic preconditioning (RIPC) reduces the incidence of CI-AKI.

Methods

We conducted a prospective, randomized, sham-controlled clinical study. The study included 101 patients admitted to the Intensive Cardiac Therapy Clinic of Medical University of Lodz for elective percutaneous coronary intervention. The participants were randomly assigned in a 1:1 ratio to either a control group (n = 51) or an RIPC group (n = 50). In the latter, RIPC was achieved before percutaneous coronary intervention by 4 cycles of 5-minute inflation of a cuff on the left upper arm to 200 mm Hg followed by 5-minute deflation. In the control group, a deflated cuff was placed on the left arm for 40 minutes. Serum creatinine concentration was measured to check for the presence of CI-AKI within 48 to 72 hours of percutaneous coronary intervention. Serum neutrophil gelatinase-associated lipocalin level was also measured within 3 hours.

Results

CI-AKI occurred in 2 patients from the RIPC group (4%) and 3 patients from the control group (5.9%), but the difference was not significant (P = 0.98). The patients who developed CI-AKI also demonstrated increased serum neutrophil gelatinase-associated lipocalin concentrations (the area under the receiver operator characteristic curve = 0.97; 95% CI, 0.938–1.00; P < 0.00) and the optimal cutoff point value was 118.9 ng/mL.

Conclusions

The use of RIPC before elective percutaneous coronary intervention was not found to prevent CI-AKI. ClinicalTrials.gov identifier: NCT03761368. (Curr Ther Res Clin Exp. 2020; 81:XXX–XXX)

Effects of Remote Ischemic Pre-Conditioning to Prevent Contrast-Induced Nephropathy after Intravenous Contrast Medium Injection: A Randomized Controlled Trial

Objective

We aimed to assess the effects of remote ischemic pre-conditioning (RIPC) on the incidence of contrast-induced nephropathy (CIN) after an intravenous (IV) or intra-arterial injection of contrast medium (CM) in patient and control groups.

Materials and Methods

This prospective, randomized, single-blinded, controlled trial included 26 patients who were hospitalized for the evaluation of the feasibility of transcatheter aortic valve implantation and underwent investigations including contrast-enhanced computed tomography (CT), with Mehran risk scores greater than or equal to six. All the patients underwent four cycles of five minute-blood pressure cuff inflation followed by five minutes of total deflation. In the RIPC group (n = 13), the cuff was inflated to 50 mm Hg above the patient's systolic blood pressure (SBP); in the control group (n = 13), it was inflated to 10 mm Hg below the patient's SBP. The primary endpoint was the occurrence of CIN. Additionally, variation in the serum levels of cystatin C was assessed.

Results

One case of CIN was observed in the control group, whereas no cases were detected in the RIPC group (p = 0.48, analysis of 25 patients). Mean creatinine values at the baseline, 24 hours after injection of CM, and 48 hours after injection of CM were 88 ± 32 µmol/L, 91 ± 28 µmol/L and 82 ± 29 µmol/L, respectively (p = 0.73) in the RIPC group, whereas in the control group, they were 100 ± 36 µmol/L, 110 ± 36 µmol/L, and 105 ± 34 µmol/L, respectively (p = 0.78). Cystatin C values (median [Q1, Q3]) at the baseline, 24 hours after injection of CM, and 48 hours after injection of CM were 1.10 [1.08, 1.18] mg/L, 1.17 [0.97, 1.35] mg/L, and 1.12 [0.99, 1.24] mg/L, respectively (p = 0.88) in the RIPC group, whereas they were 1.11 [0.97, 1.28] mg/L, 1.13 [1.08, 1.25] mg/L, and 1.16 [1.03, 1.31] mg/L, respectively (p = 0.93), in the control group.

Conclusion

The risk of CIN after an IV injection of CM is very low in patients with Mehran risk score greater than or equal to six and even in the patients who are unable to receive preventive hyperhydration. Hence, the Mehran risk score may not be an appropriate method for the estimation of the risk of CIN after IV CM injection.

Acute Kidney Injury: From Diagnosis to Prevention and Treatment Strategies

Acute kidney injury (AKI) is characterized by an acute decrease in renal function that can be multifactorial in its origin and is associated with complex pathophysiological mechanisms. In the short term, AKI is associated with an increased length of hospital stay, health care costs, and in-hospital mortality, and its impact extends into the long term, with AKI being associated with increased risks of cardiovascular events, progression to chronic kidney disease (CKD), and long-term mortality. Given the impact of the prognosis of AKI, it is important to recognize at-risk patients and improve preventive, diagnostic, and therapy strategies. The authors provide a comprehensive review on available diagnostic, preventive, and treatment strategies for AKI.

Limb ischemic preconditioning ameliorates renal microcirculation through activation of PI3K/Akt/eNOS signaling pathway after acute kidney injury

Purpose

Contrast-induced acute kidney injury (CI-AKI) resulting from administration of iodinated contrast media (CM) is the third leading cause of hospital-acquired acute kidney injury and is associated with substantial morbidity and mortality. Deteriorated renal microcirculation plays an important role in CI-AKI. Limb ischemic preconditioning (LIPC), where brief and non-injurious ischemia/reperfusion is applied to a limb prior to the administration of the contrast agent, is emerging as a promising strategy for CI-AKI prevention. However, it is not known whether the renal protection of LIPC against CI-AKI is mediated by regulation of renal microcirculation and the molecular mechanisms remain largely unknown.

Methods

In this study, we examined the renal cortical and medullary blood flow in a stable CI-AKI model using 5/6-nephrectomized (NE) rat. The LIPC and sham procedures were performed prior to the injection of CM. Furthermore, we analyzed renal medulla hypoxia using in vivo labeling of hypoxyprobe. Pharmacological inhibitions and western blotting were used to determine the underlying molecular mechanisms.

Results

In this study, we found LIPC significantly ameliorated CM-induced reduction of medullary blood flow and attenuated CM-induced hypoxia. PI3K inhibitor (wortmannin) treatment blocked the regulation of medullary blood flow and the attenuation of hypoxia of LIPC. Phosphorylation of Akt/eNOS was significantly decreased via wortmannin treatment compared with LIPC. Nitric oxide synthase-inhibitor [Nω-nitro-l-arginine methyl ester (L-NAME)] treatment abolished the above effects and decreased phosphorylation of eNOS, but not Akt.

Conclusions

Collectively, the results demonstrate that LIPC ameliorates CM-induced renal vasocontraction and is mediated by activation of PI3K/Akt/eNOS signaling pathway.

The efficacy of remote ischemic conditioning in preventing contrast-induced nephropathy among patients undergoing coronary angiography or intervention: An updated systematic review and meta-analysis

Background

Numerous trials have investigated the effect of remote ischemic conditioning (RIC) in preventing contrast‐induced nephropathy (CIN) in patients receiving contrast medium (CM). This meta analysis aims to validate the role of RIC in preventing CIN.

Methods

We searched the PubMed, EMBASE, and Web of Science databases for eligible randomized controlled trials (RCTs) published before April 27, 2019. Two investigators independently extracted basic characteristics from each study. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to examine the treatment effect.

Results

A total of 18 studies comprising 2,503 patients were included in our meta‐analysis. Compared with conventional therapy, RIC significantly reduced the risk of CIN (OR = 0.43, 95% CI: 0.33, 0.56, p < .05). Subgroup analyses showed that the protective effect of RIC was stronger in the low‐osmolar contrast media group (OR = 0.32; 95% CI: 0.23, 0.45, p < .05) and the nondiabetic group (OR = 0.39; 95% CI: 0.29, 0.53 p < .05). RIC also significantly reduced major adverse cardiovascular events within the first 6 months (OR = 0.39; p < .05), but the influence was not present after long‐term follow‐up.

Conclusions

Our meta‐analysis showed that RIC could effectively reduce CIN risk and decrease the short‐term incidence of relevant adverse events. Furthermore, the effects of CIN are more pronounced in nondiabetic patients and with the use of low‐osmolar contrast medium. This meta‐analysis of small trials suggests a possible protective effect of RIC on contrast‐induced nephropathy and favors the performance of a large randomized trial to further investigate this strategy.

Remote ischemic preconditioning reduces the incidence of contrast-induced nephropathy in patients undergoing coronary angiography/intervention: Systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Contrast-induced nephropathy (CIN) is associated with increased mortality and morbidity in patients undergoing coronary angiography (CAG) and percutaneous coronary intervention (PCI). We aimed to assess the latest evidence on the effect of remote ischemic preconditioning (RIPC) on the incidence of CIN in patients undergoing CAG/PCI.

METHODS

We performed a comprehensive search on topics assessing RIPC and CIN in CAG/PCI patients from inception up until July 2019 through several electronic databases.

RESULTS

There were a total of 1,925 subjects from 14 randomized controlled trials. Remote ischemic preconditioning was associated with reduced CIN incidence in patients undergoing CAG/PCI (OR 0.41 [0.30, 0.55], p < .001; I² : 22%). The nephroprotective effect was also demonstrated in those at moderate-high risk for CIN subgroup (OR 0.41 [0.29, 0.58], p < .001; I² : 26%) and PCI-only subgroup (OR 0.41 [0.29, 0.58], p < .001; I² : 0%). Time from RIPC to CAG/PCI has similar effectiveness among ≤45, ≤60, and ≤120 min. Mortality, rehospitalization, hemodialysis, and major adverse events were lower in the RIPC group (OR 0.50 [0.33, 0.76], p = .001; I² : 0%). Grading of recommendations assessment, development and evaluation (GRADE) assessment showed that RIPC has high evidence certainty for reducing CIN in patients undergoing PCI/CAG, moderate-high risk subgroup, and PCI-only subgroup with absolute reduction of 97 per 1,000, 129 per 1,000, and 121 per 1,000, respectively. Harbord test showed no evidence for the presence of small-study effects (p = .157).

CONCLUSIONS

Remote ischemic preconditioning is an effective procedure to reduce the risk of CIN and should be considered in patients with moderate-high risk at developing CIN.

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.

Remote ischemic conditioning: a promising therapeutic intervention for multi-organ protection

Despite decades of formidable exploration, multi-organ ischemia-reperfusion injury (IRI) encountered, particularly amongst elderly patients with clinical scenarios, such as age-related arteriosclerotic vascular disease, heart surgery and organ transplantation, is still an unsettled conundrum that besets clinicians. Remote ischemic conditioning (RIC), delivered via transient, repetitive noninvasive IR interventions to distant organs or tissues, is regarded as an innovative approach against IRI. Based on the available evidence, RIC holds the potential of affording protection to multiple organs or tissues, which include not only the heart and brain, but also others that are likely susceptible to IRI, such as the kidney, lung, liver and skin. Neuronal and humoral signaling pathways appear to play requisite roles in the mechanisms of RIC-related beneficial effects, and these pathways also display inseparable interactions with each other. So far, several hurdles lying ahead of clinical translation that remain to be settled, such as establishment of biomarkers, modification of RIC regimen, and deep understanding of underlying minutiae through which RIC exerts its powerful function. As this approach has garnered an increasing interest, herein, we aim to encapsulate an overview of the basic concept and postulated protective mechanisms of RIC, highlight the main findings from proof-of-concept clinical studies in various clinical scenarios, and also to discuss potential obstacles that remain to be conquered. More well designed and comprehensive experimental work or clinical trials are warranted in future research to confirm whether RIC could be utilized as a non-invasive, inexpensive and efficient adjunct therapeutic intervention method for multi-organ protection.

Effects of remote ischemic conditioning on kidney injury in at-risk patients undergoing elective coronary angiography (PREPARE study): a multicenter, randomized clinical trial

The ability of remote ischemic preconditioning (RIPC) to prevent contrast-induced nephropathy (CIN) following percutaneous coronary angiography in at-risk patients is controversial. No evidence exists regarding potential RIPC positive effects on renal function and clinical outcomes in the long-term. The PREPARE study was a randomized, prospective, multicenter, and double-blinded trial. A total of 222 patients scheduled for coronary angiography and/or percutaneous transluminal coronary angioplasty with an estimated glomerular filtration rate (eGFR) < 40 mL/min/1.73 m², or eGFR between 40 and 60 mL/min/1.73 m² and two further risk factors were allocated to RIPC or control groups. Preventive measures were applied to all patients, including continuous intravenous saline infusion, withdrawal of nephrotoxic drugs, and limited volume of contrast medium. The primary endpoint, namely incidence of CIN, was 3.8% in the control group and 5.1% in the RIPC group (p = 0.74). The secondary endpoints, i.e., changes in serum creatinine and eGFR levels from baseline to 48 hours and from baseline to 12 months following contrast medium exposure, did not differ between both groups. The incidences of all major clinical events at 12 months were similar in both groups. In this population at risk of CIN, preventive strategies were associated with low CIN incidence. RIPC impacted neither the CIN incidence nor both the renal function and clinical outcomes at 1-year follow-up.

A systematic review and meta-analysis of remote ischemic preconditioning for vascular surgery

BACKGROUND

Remote ischemic preconditioning (RIPC) is a method of preparing the body for a later prolonged ischemic episode to protect against subsequent detrimental effects. This study aimed to identify the effects of RIPC in vascular surgery.

METHODS

A standard Preferred Reporting Items for Systematic Reviews and Meta-Analyses search was conducted of randomized controlled trials of RIPC in patients undergoing open or endovascular aneurysm repair, carotid endarterectomy, or lower limb bypass reporting on mortality and renal or cardiac outcomes. Random-effects meta-analysis was performed using Review Manager 5.3 (The Nordic Cochrane Center, Copenhagen, Denmark).

RESULTS

A total of 13 randomized controlled trials in the meta-analysis included 548 patients in the RIPC cohort and 549 controls. There was no significant difference in mortality, renal dysfunction, myocardial infarction, myocardial injury, or length of stay between the groups, with subgroup and sensitivity analysis showing no significant difference.

CONCLUSIONS

Current evidence demonstrates no benefit of RIPC in vascular surgery. Further large multicenter trials of RIPC in major vascular surgery should be considered.

Remote Ischemic Preconditioning in Renal Protection During Elective Percutaneous Coronary Intervention

Remote ischemic preconditioning (RIPC) exerts protection in remote organs. The purpose of this study was to investigate the potential of RIPC to prevent contrast induced nephropathy. One hundred and twenty four patients were randomized to elective percutaneous coronary intervention with or without RIPC. RIPC was performed using three cycles of 5-min inflation to 200 mmHg of a standard upper arm blood pressure cuff. The time between the last inflation cycle and the coronary intervention was less than 2 h. The primary endpoint was the incidence of contrast-induced nephropathy based on the standard criteria of the serum creatinine (SC) and cystatin C (CC) levels. The rates of major cardiac and cerebral adverse events (MACCE) during 1 year follow-up were evaluated. We found that contrast-induced nephropathy assessed by SC occurred in 4.9% (3/61) patients with RIPC and in 12.1% (7/58) patients without it (p = 0.20). Nephropathy assessed by CC occurred in 1.7% (1/58) patients with RIPC and 3.5% (2/57) patients without it (p = 0.62). There was no coincidence between the diagnosis of contrast-induced nephropathy based on SC and CC (McNemar test 0.012, κ = 0.28); SC was a more sensitive marker of nephropathy than CC (ten and three cases, respectively). The MACCE rate during the year of follow-up tended to be lower with the ischemic preconditioning than without it, four vs. six cases, respectively. We conclude that RIPC prior to percutaneous coronary intervention has no major influence on the development of contrast-induced nephropathy and does not improve the one-year outcome.

The impact of preinfarct angina on the incidence of acute kidney injury in patients with myocardial infarction: interaction with pre-existent chronic kidney disease

AIM

Remote ischemic conditioning may reduce acute kidney injury (AKI) in patients undergoing a coronary intervention. As preinfarct angina (PIA) might act as a preconditioning stimulus in patients with ST-elevation myocardial infarction (STEMI), we aimed to study whether PIA reduces AKI in accordance to pre-existing chronic kidney disease.

PATIENTS AND METHODS

We conducted a retrospective study including 891 consecutive STEMI patients who underwent primary coronary intervention from January 2008 to March 2016. AKI was determined on the basis of KDIGO criteria. The impact of PIA was evaluated in three groups according to the baseline glomerular filtration rate: less than 45 ml/min/1.73 m (group 1, n = 89), 45-59 ml/min/1.73 m (group 2, n = 117), and greater than or equal to 60 ml/min/1.73 m (group 3, n = 642). Univariate and multivariate predictors for AKI were determined.

RESULTS

AKI developed in 13.8% of patients (n = 117) and was more prevalent in patients with worse baseline renal function (35% in group 1; 22% in group 2; and 9% in group 3, P < 0.01). The prevalence of PIA was similar across groups (28-34%, P = 0.2). Only in group 1 did patients with PIA have a significantly lower rate of AKI than patients without PIA (19 vs. 42%, P = 0.033). In multivariate analysis, the absence of PIA in group 1 patients conferred an almost three-fold risk of developing AKI (odds ratio = 2.92, P = 0.009), whereas no differences were found for the other groups. Age, total ischemic time, and intra-aortic balloon pump utilization were also related independently to AKI.

CONCLUSION

In our series, STEMI patients with at least stage 3B chronic kidney disease had a three-fold risk of developing AKI in the absence of PIA. These findings suggest that patients with worse renal function may be more susceptible to the renoprotective effect of myocardial ischemic preconditioning.

Remote ischemic preconditioning to reduce contrast-induced acute kidney injury in chronic kidney disease: a randomized controlled trial

BACKGROUND

The impact of contrast-induced acute kidney injury (CI-AKI) on patients with chronic renal disease is well-known. Remote ischemic preconditioning (RIPC) is a non-invasive method that can reduce the risk of CI-AKI, but studies on RIPC have had different results. The aim of the present study was to assess the potential impact of RIPC on CI-AKI.

METHODS

In a randomized, double blinded, controlled trial, 132 patients with chronic renal dysfunction (glomerular filtration rate < 60 mL/min/m2) who underwent coronary angiography or angioplasty received adequate hydration. RIPC was performed in 66 patients by applying an upper arm blood pressure cuff. The cuff was inflated four times for 5 min to 50 mmHg above the systolic blood pressure, followed by deflation for 5 min. In the control group, the blood pressure cuff was inflated only to 10 mmHg below the patient's diastolic blood pressure. The primary endpoint was an increase in serum cystatin C ≥ 10% from baseline to 48-72 h after exposure to the contrast.

RESULTS

The primary endpoint was achieved in 48 (36.4%) patients (24 in each group). RIPC did not show any significant effect on the occurrence of the primary endpoint (P = 1). In addition, when the results were analyzed based on the Mehran risk score for subgroups of patients, RIPC did not reduce the occurrence of the primary endpoint (P = 0.97).

CONCLUSIONS

In patients at moderate-to-high risk of developing CI-AKI when an adequate hydration protocol is performed, RIPC does not have an additive effect to prevent the occurrence of CI-AKI.

TRIAL REGISTRATION

The clinical trial was registered on (Identification number IRCT2016050222935N2 , on December 19, 2016 as a retrospective IRCT).

Effectiveness of contrast-associated acute kidney injury prevention methods; a systematic review and network meta-analysis

BACKGROUND

Different methods to prevent contrast-associated acute kidney injury (CA-AKI) have been proposed in recent years. We performed a mixed treatment comparison to evaluate and rank suggested interventions.

METHODS

A comprehensive Systematic review and a Bayesian network meta-analysis of randomised controlled trials was completed. Results were tabulated and graphically represented using a network diagram; forest plots and league tables were shown to rank treatments by the surface under the cumulative ranking curve (SUCRA). A stacked bar chart rankogram was generated. We performed main analysis with 200 RCTs and three analyses according to contrast media and high or normal baseline renal profile that includes 173, 112 & 60 RCTs respectively.

RESULTS

We have included 200 trials with 42,273 patients and 44 interventions. The primary outcome was CI-AKI, defined as ≥25% relative increase or ≥ 0.5 mg/dl increase from baseline creatinine one to 5 days post contrast exposure. The top ranked interventions through different analyses were Allopurinol, Prostaglandin E1 (PGE1) & Oxygen (0.9647, 0.7809 & 0.7527 in the main analysis). Comparatively, reference treatment intravenous hydration was ranked lower but better than Placebo (0.3124 VS 0.2694 in the main analysis).

CONCLUSION

Multiple CA-AKI preventive interventions have been tested in RCTs. This network evaluates data for all the explored options. The results suggest that some options (particularly allopurinol, PGE1 & Oxygen) deserve further evaluation in a larger well-designed RCTs.

Remote ischemic preconditioning for prevention of contrast induced nephropathy-Insights from an Indian study

Objectives

To study if four cycles of remote ischemic preconditioning (RIPC) could offer protection against contrast induced nephropathy (CIN) and post procedural renal dysfunction in high risk patients undergoing percutaneous coronary intervention (PCI).

Methods

This was a prospective single blind randomized sham controlled trial where patients undergoing coronary angioplasty with stage III chronic kidney disease were randomized into sham preconditioning and remote ischemic preconditioning. The primary outcome was the reduction in the incidence of CIN. The secondary outcomes were the maximum improvement in eGFR, maximum reduction in serum creatinine and composite of requirement of hemodialysis, death and rehospitalization for heart failure up to 6 weeks after PCI.

Results

Eleven out of fifty patients in the study group developed CIN (22%) compared to eighteen out of the fifty control patients (36%) (p = 0.123). There was a statistically significant improvement in the post procedure creatinine values at 24 h (p = 0.013), 48 h (p = 0.015), 2 weeks (p = 0.003), 6 weeks (p = 0.003) and post procedure glomerular filtration rate (eGFR) values at 24 h (p = 0.026), 48 h (p = 0.044), 2 weeks (p = 0.015) and 6 weeks (p = 0.011) in study group compared to control group. The secondary outcome composite of requirement of hemodialysis, death and rehospitalization for heart failure was not statistically significant (p: 0.646).

Conclusion

RIPC does not result in significant reduction of CIN. However RIPC helps in the prevention of post procedural worsening in eGFR and serum creatinine even up to 6 weeks.

Ischaemic preconditioning - Current knowledge and potential future applications after 30 years of experience

Ischaemic preconditioning (IPC) phenomenon has been known for thirty years. During that time several studies showed that IPC provided by brief ischaemic and reperfusion episodes prior to longer ischaemia can bestow a protective effect to both preconditioned and also remote organs. IPC affecting remote organs is called remote ischaemic preconditioning. Initially, most IPC studies were focused on enhancing myocardial resistance to subsequent ischaemia and reperfusion injury. However, preconditioning was found to be a universal phenomenon and was observed in various organs and tissues including the heart, liver, brain, retina, kidney, skeletal muscles and intestine. Currently, there are a lot of simultaneous studies are underway aiming at finding out whether IPC can be helpful in protecting these organs. The mechanism of local and remote IPC is complex and not well known. Several triggers, intracellular pathways and effectors, humoral, neural and induced by genetic changes may be considered potential pathways in the protective activity of local and remote IPC. Local and remote IPC mechanism may potentially serve as heart protection during cardiac surgery and may limit the infarct size of the myocardium, can be a strategy for preventing the development of acute kidney injury development and liver damage during transplantation, may protect the brain against ischaemic injury. In addition, the method is safe, non-invasive, cheap and easily applicable. The main purpose of this review article is to present new advances which would help to understand the potential mechanism of IPC. It also discusses both its potential applications and utility in clinical settings.

Remote ischemic conditioning for the prevention of contrast-induced acute kidney injury in patients undergoing intravascular contrast administration: a meta-analysis and trial sequential analysis of 16 randomized controlled trials

Objective

We conducted this meta-analysis to examine the effect of remote ischemic conditioning (RIC) on contrast-induced acute kidney injury (CI-AKI) in patients undergoing intravascular contrast administrationon.

Methods

Pubmed, Embase, and Cochrane Library were comprehensively searched to identify all eligible studies by 15th March, 2017. Risk ratio (RR) and weighted mean difference with the corresponding 95% confidence intervals (CI) were used to examine the treatment effect. The heterogeneity and statistical significance were assessed with Q-test and Z-test, respectively.

Results

A total of 16 RCTs including 2175 patients were eventually analyzed. Compared with the control group, RIC could significantly decrease the incidence of CI-AKI (RR=0.58; 95% CI: 0.46, 0.74; P < 0.001), which was further confirmed by the trial sequential analysis. Subgroup analyses showed that remote ischemic preconditioning (RIPrC) and remote ischemic postconditioning (RIPoC) were both obviously effective, and perioperative hydration might enhance the efficiency of RIC. RIC also significantly reduced the major adverse cardiovascular events within six months.

Conclusion

RIC, whether RIPrC or RIPoC, could effectively exert renoprotective role in intravascular contrast administration and reduce the incidence of relevant adverse events.

Nephroprotective effects of remote ischemic preconditioning in coronary angiography

BACKGROUND

Contrast-induced nephropathy (CIN) is a formidable side effect of iodinated contrast medium use in subjects undergoing coronary angiogram (CAG). Remote ischemic preconditioning (RIPC) may reduce the risk of CIN.

AIM

The aim of the study was to investigate the nephroprotective effects of RIPC in coronary heart disease (CHD) in patients, undergoing CAG, with mild to moderate lowered estimated glomerular filtration rate (eGFR).

MATERIALS

In the randomized, blinded, sham RIPC (sRIPC) controlled study 51 patients with CHD and GFR less than 80 mL/min/m2, undergoing CAG, were investigated. The patients were randomized for RIPC (n = 26, 60.5±2.0 years) or sRIPC (n = 25, 62.96±1.7). RIPC was performed before the CAG by means of 3-5-minute cycle cuff pumped on the upper arm + 50 mm Hg above the systolic blood pressure (BP), while in sRIPC it corresponded to diastolic BP. The primary endpoint was the development of CIN and secondary - change of biomarkers (creatinine, urea, neutrophil gelatinase-associated lipocalin (NGAL), cystatin-C).

RESULTS

In RIPC group, CIN occurred in 28% of cases, while in sRIPC - 3.8%. All investigated markers increased in sRIPC and declined in RIPC; the difference was significant in markers between the groups before and after CAG.

CONCLUSIONS

RIPC proved nephroprotective effect in prevention of contrast-induced nephropathy in CHD subjects with mild to moderate lowered eGFR.

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.

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.

Remote Ischemic Preconditioning for the Prevention of Contrast-Induced Acute Kidney Injury in Diabetics Receiving Elective Percutaneous Coronary Intervention

Objective

Remote ischemic preconditioning (RIPC) induces transient episodes of ischemia by the occlusion of blood flow in non-target tissue, before a subsequent ischemia-reperfusion injury. When RIPC is applied before percutaneous coronary intervention (PCI), the kidneys may be protected against ischemia-reperfusion injury and subsequently contrast-induced acute kidney injury (CI-AKI). The aim of this study was to evaluate the efficacy of RIPC for the prevention of CI-AKI in patients with diabetes with pre-existing chronic kidney disease (CKD) undergoing elective PCI.

Methods

This randomized, double-blind, sham-controlled study enrolled patients with diabetes scheduled for elective PCI with eGFR ≤60 ml/min/1.73 m² or urinary albumin creatinine ratio of >300 mg/g to receive either RIPC or the sham ischemic preconditioning.

Results

One hundred and two patients (68.9 ± 8.2 years old, 47.1% men) were included. Baseline eGFR, creatinine and serum NGAL was similar between RIPC and control groups (48.5 ± 12 ml/min vs. 46.6 ± 10 ml/min, p = 0.391; 1.42 ± 0.58 mg/dl vs. 1.41 ± 0.34 mg/dl, p = 0.924; and 136.0 ± 45.0 ng/ml vs. 137.6 ± 43.3 ng/ml, p = 0.961, respectively). CI-AKI occurred in 13.7% (14/102) of the total subjects, with both RIPC and control groups having an equal incidence of 13.7% (7/51). No significant differences were seen in creatinine, NGAL, cardiac enzymes (troponin T, CKMB) and hs-CRP between the groups post-procedure.

Conclusions

In this study, RIPC applied prior to elective PCI was not effective in preventing CI-AKI in patients with diabetes with pre-existing CKD.

Trial Registration

ClinicalTrials.gov NCT02329444

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.

Renoprotection by remote ischemic conditioning during elective coronary revascularization: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Remote ischemic conditioning (RIC) has been recognized an emerging non-invasive approach for preventing acute kidney injury (AKI) in patients undergoing either elective coronary artery bypass graft (CABG) surgery or percutaneous coronary intervention (PCI). On the other hand, accumulating evidence has indicated the involving role of pre-CABG contrast usage for coronary angiography in post-surgery AKI risk. Along with the shortening time delay of CABG after coronary angiography, and the prevalent hybrid coronary revascularization (HCR), the AKI prevention by RIC has faced challenges following coronary revascuralization.

METHODS

Randomized controlled trials (RCTs) were searched from Pubmed, EMBase, and Cochrane library (until May 2016). The primary outcome was postoperative AKI. The second outcomes were included the requirement for renal replacement therapy (RRT), and in-hospital or 30-day mortality.

RESULTS

Twenty eligible RCTs (CABG, 3357 patients; PCI, 1501 patients) were selected. RIC significantly halved the incidence of AKI following PCI when compared with controls [n=1501; odds ratio (OR)=0.51; 95% CI, 0.32 to 0.82; P=0.006; I(2)=29.6%]. However, RIC did not affect the incidence of AKI following CABG (n=1850; OR=0.94; 95% CI, 0.73 to 1.19; P=0.586; I(2)=12.4%). The requirement for RRT and in-hospital mortality was not affected by RIC in CABG (n=2049, OR=1.04, P=0.87; n=1920, OR=0.89, P=0.7; respectively).

CONCLUSIONS

Our meta-analysis suggests that RIC for preventing AKI following CABG has faced with challenges in terms of AKI, the requirement for RRT, and mortality. However, RIC shows a renoprotective benefit for PCI. Hence, our findings may infer the preserved renal effects of RIC in CABG with preconditioning before the coronary angiography, or in HCR.

Limb ischemic preconditioning protects against contrast-induced nephropathy via renalase

Clinical trials shows that remote ischemic preconditioning (IPC) can protect against contrast induced nephropathy (CIN) in risky patients, however, the exact mechanism is unclear. In this study, we explored whether renalase, an amine oxidase that has been previously shown to mediate reno-protection by local IPC, would also mediate the same effect elicited by remote IPC in animal model. Limb IPC was performed for 24 h followed by induction of CIN. Our results indicated that limb IPC prevented renal function decline, attenuated tubular damage and reduced oxidative stress and inflammation in the kidney. All those beneficial effects were abolished by silencing of renalase with siRNA. This suggests that similar to local IPC, renalase is also critically involved in limb IPC-elicited reno-protection. Mechanistic studies showed that limb IPC increased TNFα levels in the muscle and blood, and up-regulated renalase and phosphorylated IκBα expression in the kidney. Pretreatment with TNFα antagonist or NF-κB inhibitor, largely blocked renalase expression. Besides, TNFα preconditioning increased expression of renal renalase in vivo and in vitro, and attenuated H₂O₂ induced apoptosis in renal tubular cells. Collectively, our results suggest that limb IPC-induced reno-protection in CIN is dependent on increased renalase expression via activation of the TNFα/NF-κB pathway.

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Limb ischemic preconditioning (IPC) leads to renalase upregulation in kidney tissue.

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Renalase is critically involved in limb IPC-elicited renal protection in contrast induced nephropathy.

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Limb IPC induces renalase upregulation via activation of the tumor necrosis factor α (TNFα)/ nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway.

Renalase, a kidney-secreted protein, serves as extracellular pro-survival signals and has been reported to participate in the local ischemic preconditioning (IPC) induced renal protection against ischemia-reperfusion injury. Whether renalase contributes to the beneficial effects of limb IPC on contrast induced nephropathy (CIN) remains unknown. This study revealed that limb IPC induced reno-protection in CIN was at least in part dependent on increased renalase expression, which is evidenced by our observations that knockdown of renalase abolished reno-protective effects conferred by limb IPC. The upregulation of renalase elicited by limb IPC may be mediated by activation of TNFα/NF-κB pathway.

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.

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.