Postoperative neurocognitive dysfunction in patients undergoing cardiac surgery after remote ischemic preconditioning: a double-blind randomized controlled pilot study

Remote ischemic preconditioning and cognitive dysfunction following coronary artery bypass grafting: A systematic review and meta-analysis of randomized controlled trials

Introduction

Postoperative cognitive dysfunction (POCD) is a common neurological issue following cardiopulmonary bypass (CPB)-assisted heart surgery. Remote ischemic preconditioning (RIPC) increases the tolerance of vital organs to ischemia/reperfusion injury, leading to reduced brain injury biomarkers and improved cognitive control. However, the exact mechanisms underlying RIPC's neuroprotective effects remain unclear. This systematic review aimed to explore the hypothesis that RIPC lowers neurocognitive dysfunction in patients undergoing CPB surgery.

Method

All relevant studies were searched in PubMed, ScienceDirect, EBSCOhost, Google Scholar, Semantic Scholar, Scopus, and Cochrane Library database. Assessment of study quality was carried out by two independent reviewers individually using the Cochrane Risk of Bias (RoB-2) tool. Meta-analysis was performed using a fixed-effect model due to low heterogeneity among studies, except for those with substantial heterogeneity.

Results

A total of five studies with 1,843 participants were included in the meta-analysis. RIPC was not associated with reduced incidence of postoperative cognitive dysfunction (five RCTs, odds ratio [OR:] 0.79, 95% confidence interval [CI]: 0.56-1.11) nor its improvement (three RCTs, OR: 0.80, 95% CI: 0.50-1.27). In addition, the analysis of the effect of RIPC on specific cognitive function tests found that pooled SMD for RAVLT 1-3 and RAVLT LT were -0.07 (95% CI: -0.25,012) and -0.04 (95% CI: -0.25-0.12), respectively, and for VFT semantic and phonetic were -0.15 (95% CI: -0.33-0.04) and 0.11 (95% CI: -0.40-0.62), respectively.

Conclusion

The effect of RIPC on cognitive performance in CABG patients remained insignificant. Results from previous studies were unable to justify the use of RIPC as a neuroprotective agent in CABG patients.

Cognitive trajectories after surgery: Guideline hints for assessment and treatment

Elderly patients who undergo major surgery (not-neurosurgical) under general anaesthesia frequently complain about cognitive difficulties, especially during the first weeks after surgical "trauma". Although recovery usually occurs within a month, about one out of four patients develops full-blown postoperative Neurocognitive disorders (NCD) which compromise quality of life or daily autonomy. Mild/Major NCD affect approximately 10% of patients from three months to one year after major surgery. Neuroinflammation has emerged to have a critical role in the postoperative NCDs pathogenesis, through microglial activation and the release of pro-inflammatory cytokines which increase blood-brain-barrier permeability, enhance movement of leukocytes into the central nervous system (CNS) and favour the neuronal damage. Moreover, pre-existing Mild Cognitive Impairment, alcohol or drugs consumption, depression and other factors, together with several intraoperative and post-operative sequelae, can exacerbate the severity and duration of NCDs. In this context it is crucial rely on current progresses in serum and CSF biomarker analysis to frame neuroinflammation levels, along with establishing standard protocol for neuropsychological assessment (with specific set of tools) and to apply cognitive training or neuromodulation techniques to reduce the incidence of postoperative NCDs when required. It is recommended to identify those patients who would need such preventive intervention early, by including them in pre-operative and post-operative comprehensive evaluation and prevent the development of a full-blown dementia after surgery. This contribution reports all the recent progresses in the NCDs diagnostic classification, pathogenesis discoveries and possible treatments, with the aim to systematize current evidences and provide guidelines for multidisciplinary care.

Effect of remote ischemic preconditioning on postoperative cognitive dysfunction in adult patients with general anesthesia: a meta-analysis

BACKGROUND

Remote ischemic preconditioning (RIPC) is proven to have neuroprotective protective effects. Nevertheless, the impact of RIPC on postoperative cognitive dysfunction (POCD) in patients undergoing general anesthesia is controversial. This meta-analysis of randomized controlled trials (RCTs) aimed to assess the effect of RIPC on POCD in adults after general anesthesia.

METHODS

Relevant literature was obtained by searching Embase, PubMed, Web of Science, Cochrane Library, Wanfang, and China National Knowledge Infrastructure (CNKI) databases in July 2022. RCTs were included to assess the influences of RIPC on POCD in adults following general anesthesia. Two investigators independently performed literature screening, data extraction, and quality assessment based on the inclusion and exclusion criteria. The incidence of POCD, operation time, and hospital stay were analyzed by Review manager5.4 software.

RESULTS

Thirteen RCTs with 1122 participants were selected for this meta-analysis. Compared to the control group, RIPC decreased the incidence of POCD (OR = 0.50, 95% CI 0.31-0.82), as well as reduced the duration of hospitalization (MD = - 0.98, 95% CI - 1.69 to - 0.27), but did not prolong operative time (MD = - 2.65, 95% CI - 7.68 to 2.37).

CONCLUSION

RIPC reduced the incidence of POCD in adult patients after general anesthesia and accelerated their discharge.

Communication Regarding the Myocardial Ischemia/Reperfusion and Cognitive Impairment: A Narrative Literature Review

Coronary artery disease is a prevalent ischemic disease that results in insufficient blood supply to the heart muscle due to narrowing or occlusion of the coronary arteries. Various reperfusion strategies, including pharmacological thrombolysis and percutaneous coronary intervention, have been developed to enhance blood flow restoration. However, these interventions can lead to myocardial ischemia/reperfusion injury (MI/RI), which can cause unpredictable complications. Recent research has highlighted a compelling association between MI/RI and cognitive function, revealing pathophysiological mechanisms that may explain altered brain cognition. Manifestations in the brain following MI/RI exhibit pathological features resembling those observed in Alzheimer's disease (AD), implying a potential link between MI/RI and the development of AD. The pro-inflammatory state following MI/RI may induce neuroinflammation via systemic inflammation, while impaired cardiac function can result in cerebral under-perfusion. This review delves into the role of extracellular vesicles in transporting deleterious substances from the heart to the brain during conditions of MI/RI, potentially contributing to impaired cognition. Addressing the cognitive consequence of MI/RI, the review also emphasizes potential neuroprotective interventions and pharmacological treatments within the MI/RI model. In conclusion, the review underscores the significant impact of MI/RI on cognitive function, summarizes potential mechanisms of cardio-cerebral communication in the context of MI/RI, and offers ideas and insights for the prevention and treatment of cognitive dysfunction following MI/RI.

Effect of remote ischemic preconditioning on lung function after surgery under general anesthesia: a systematic review and meta-analysis

Remote ischemic preconditioning (RIPC) protects organs from ischemia-reperfusion injury. Recent trials showed that RIPC improved gas exchange in patients undergoing lung or cardiac surgery. We performed a systematic search to identify randomized controlled trials involving RIPC in surgery under general anesthesia. The primary outcome was the PaO2/FIO2 (P/F) ratio at 24 h after surgery. Secondary outcomes were A-a DO2, the respiratory index, duration of postoperative mechanical ventilation (MV), incidence of acute respiratory distress syndrome (ARDS), and serum cytokine levels. The analyses included 71 trials comprising 7854 patients. Patients with RIPC showed higher P/F ratio than controls (mean difference [MD] 36.6, 95% confidence interval (CI) 12.8 to 60.4, I2 = 69%). The cause of heterogeneity was not identified by the subgroup analysis. Similarly, A-a DO2 (MD 15.2, 95% CI - 29.7 to - 0.6, I2 = 87%) and respiratory index (MD - 0.17, 95% CI - 0.34 to - 0.01, I2 = 94%) were lower in the RIPC group. Additionally, the RIPC group was weaned from MV earlier (MD - 0.9 h, 95% CI - 1.4 to - 0.4, I2 = 78%). Furthermore, the incidence of ARDS was lower in the RIPC group (relative risk 0.73, 95% CI 0.60 to 0.89, I2 = 0%). Serum TNFα was lower in the RIPC group (SMD - 0.6, 95%CI - 1.0 to - 0.3 I2 = 87%). No significant difference was observed in interleukin-6, 8 and 10. Our meta-analysis suggested that RIPC improved oxygenation after surgery under general anesthesia.Clinical trial number: This study protocol was registered in the University Hospital Medical Information Network (registration number: UMIN000030918), https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000035305.

Nonpharmacological Cognitive Impairment Prevention Interventions in Older Adults Undergoing Cardiac Surgery: A Systematic Review

BACKGROUND

More than 1 million individuals undergo cardiothoracic surgery for coronary artery bypass graft or valve repair/replacement annually in the United States. There is an increased risk of developing serious cognitive impairment post cardiothoracic surgery. Pharmacological interventions and surgical techniques were associated with improvements in cognitive function in previous systematic reviews. However, a gap in the literature exists regarding how nonpharmacological interventions can mitigate cognitive impairment in adults undergoing cardiac surgery.

OBJECTIVE

The aim of this study was to explore the effectiveness of nonpharmacological interventions to reduce the detrimental effects of cardiac surgery on cognitive function in patients after cardiothoracic surgery.

METHODS

CINAHL, MEDLINE, PubMed, EMBASE, PsycINFO, and Web of Science databases were searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines from January 2011 to February 2022.

RESULTS

Nineteen studies were included in this review. Researchers defined cognitive impairment differently across studies. Various interventions were used to reduce cognitive impairment post cardiothoracic surgery, with the most common being remote ischemic limb conditioning. The interventions used to reduce cognitive impairment were heterogeneous in outcomes, measurements, and time of assessment, but only 2 interventions were associated with a reduction in cognitive impairment.

CONCLUSIONS

This review is a unique synthesis of the quality of interventions that address broader components of cognition. Researchers used various interventions to reduce cognitive impairment; the outcomes, instruments, and time interval for measurements were heterogeneous. Researchers should conduct future studies at multiple time intervals, using a comprehensive measure of cognitive impairment to better understand the impact of cognitive impairment interventions postoperatively.

Effects of perioperative intravenous glucocorticoids on perioperative neurocognitive disorders in adults after surgery: A PRISMA-compliant meta-analysis of randomized controlled trials

BACKGROUND

Randomized controlled trials (RCTs) have shown uncertain clinical benefits from perioperative intravenous glucocorticoids for perioperative neurocognitive disorders (PND). Thus, this meta-analysis was performed to evaluate whether perioperative intravenous glucocorticoids can decrease the occurrence of PND among adults undergoing surgery.

METHODS

We searched 4 databases (MEDLINE, Embase, CENTRAL and Web of Science) for RCTs that assessed the incidence of PND in adults (aged ≥ 18 years old) after surgery. Two reviewers independently assessed the studies for eligibility, extracted data, and assessed the risk of bias in each study. We assessed the certainty of evidence using GRADEpro software.

RESULTS

A total of 10 studies (N = 14,967) were eligible. Compared with controls, glucocorticoids were not associated with reducing the risk of postoperative cognitive dysfunction (POCD) (risk ratio [RR]: 0.79 95% confidence interval [CI]: 0.41-1.55, P = .50, I2 = 85%), risk of postoperative delirium (POD) (RR: 0.87 95% CI: 0.74-1.03, P = .10, I2 = 36%), the length of stay in intensive care unit (ICU) (mean difference [MD] -0.21 95% CI: -1.20 to 0.79, P = .68, I2 = 84%), 30-day mortality (RR: 0.92 95% CI: 0.59-1.46, P = .73, I2 = 0%), or postoperative atrial fibrillation (RR: 0.94 95% CI: 0.86-1.01, P = .11, I2 = 25%). However, there was significant difference between glucocorticoids and control group in the length of hospital stay (LOS) (MD: -0.39 95% CI: -0.62 to -0.16, P = .001, I2 = 0%), and postoperative infections (RR: 0.65 95% CI: 0.56-0.76, P < .00001, I2 = 0%).

CONCLUSIONS

Perioperative intravenous glucocorticoids did not reduce the risk of PND in adults after surgery but might be associated with shorter the LOS and lower the incidence of postoperative infections. More, larger, higher-quality RCTs including neurological surgery or hip fracture surgery and different doses of glucocorticoids compared with placebos are needed to explore the intervention effects.

Effects of Remote Ischemic Preconditioning on Postoperative Cognitive Dysfunction in Elderly Patients with Laparoscopic Cholecystectomy

Purpose

We hypothesized that remote ischemic preconditioning (RIPC) could improve postoperative cognitive dysfunction (POCD) in elderly patients following laparoscopic cholecystectomy (LC).

Patients and Methods

Eighty-eight patients were randomly assigned to either the control or the RIPC group. The RIPC was applied on the right upper limb using a blood pressure cuff inflating 200 mmHg, consisting of 3 cycles of 5 min ischemia and 5 min reperfusion. Serum concentrations of Neuron-specific Enolase (NSE) and Brain-Derived Neurotrophic Factor (BDNF) were collected at one-day preoperative (T0), at the end of the operation (T4) and one-day postoperative (T5). Z score was tested at T0 and 3 days after the operation (T6). POCD was determined if there were two Z scores ≥1.96 at the same time or an average Z score ≥1.96.

Results

There was no significant difference in the Z score of each test between the two groups at T0 (P > 0.05). Notably, the duration of Stroop test C was significantly shorter in the RIPC group than that in the Control group at T6 (P = 0.01). POCD occurred in 1/44 (2.3%) patients in the RIPC group and 8/44 (18.2%) patients in the control group at T6 (P=0.035). In addition, serum NSE concentration was significantly decreased, but serum BDNF concentration was increased compared with the control group at T4 and T5 (P<0.001).

Conclusion

RIPC could reduce the incidence of POCD in elderly patients after laparoscopic cholecystectomy.

Effects of remote ischemic conditioning on cognitive performance: A systematic review

The aging process leads to subtle decline in cognitive function, and in some overt dementia. Like physical activity Remote Ischemic Conditioning (RIC) may ameliorate these changes on cognitive impairment in humans. The purpose of this study was to compared the effects of single, repeated short-term and long-term treatment RIC, and analyze its effect registered as immediate vs. long-term on cognitive performance in humans. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered with PROSPERO, number (CRD42021285668). A systematic review was conducted to identify relevant studies through six healthcare science databases (Cochrane, PubMed, EMBASE, EBSCO, Scopus, and Web of Science) up to December 2021. Eligibility criteria included (1) a study sample of participants aged ≥18 years, (2) post-intervention changes on cognitive performance in humans, and (3) this systematic review included only randomized controlled trials of RIC in humans. The quality of the included studies was assessed by GRADEpro tool. A total of 118 articles were initially identified, 35 of which met the inclusion criteria. Based on title/abstract, age and RIC protocol, 14 articles were included in this review: 5 studies investigated the immediate and long-term effect of a single RIC (n = 370 patients), 4 studies examined intermittent short-term RIC (n = 174 patients) and 5 studies evaluated repeated long-term RIC (n = 228 patients). A single pre-operative RIC treatment had an immediate effect that disappeared at one week. Short-term RIC showed either a positive or no effects on cognitive function. The majority of studies examining long-term RIC treatment showed improvements in cognitive performance, particularly in very old adults and older patients with cognitive impairments. Single RIC treatment did not show any persisting effect on cognition. However, repeated short term RIC showed some improvement and long-term RIC may improve cognitive performance after stroke or enhance neuropsychological tests in patients diagnosed with vascular dementia. The mixed results might be explained by different RIC treatment protocols and populations investigated.

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

Objects

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

Methods

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

Results

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

Conclusion

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

Neuroprotective effect of remote ischemic preconditioning in patients undergoing cardiac surgery: A randomized controlled trial

Background

The neuroprotective effect of remote ischemic preconditioning (RIPC) in patients undergoing elective cardiopulmonary bypass (CPB)-assisted coronary artery bypass graft (CABG) or valvular cardiac surgery remains unclear.

Methods

A randomized, double-blind, placebo-controlled superior clinical trial was conducted in patients undergoing elective on-pump coronary artery bypass surgery or valve surgery. Before anesthesia induction, patients were randomly assigned to RIPC (three 5-min cycles of inflation and deflation of blood pressure cuff on the upper limb) or the control group. The primary endpoint was the changes in S-100 calcium-binding protein β (S100-β) levels at 6 h postoperatively. Secondary endpoints included changes in Neuron-specific enolase (NSE), Mini-mental State Examination (MMSE), and Montreal Cognitive Assessment (MoCA) levels.

Results

A total of 120 patients [mean age, 48.7 years; 36 women (34.3%)] were randomized at three cardiac surgery centers in China. One hundred and five patients were included in the modified intent-to-treat analysis (52 in the RIPC group and 53 in the control group). The primary result demonstrated that at 6 h after surgery, S100-β levels were lower in the RIPC group than in the control group (50.75; 95% confidence interval, 67.08 to 64.40 pg/ml vs. 70.48; 95% CI, 56.84 to 84.10 pg/ml, P = 0.036). Compared to the control group, the concentrations of S100-β at 24 h and 72 h and the concentration of NSE at 6 h, 24 h, and 72 h postoperatively were significantly lower in the RIPC group. However, neither the MMSE nor the MoCA revealed significant between-group differences in postoperative cognitive performance at 7 days, 3 months, and 6 months after surgery.

Conclusion

In patients undergoing CPB-assisted cardiac surgery, RIPC attenuated brain damage as indicated with the decreased release of brain damage biomarker S100-β and NSE.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT01231789].

Remote ischemic preconditioning improves cognitive control in healthy adults: Evidence from an event-related potential study

It is suggested that remote ischemic preconditioning (RIPC) may be a promising treatment for improving healthy adults’ cognitive control. However, direct empirical evidence was absent. Therefore, this study aims to provide evidence for the impact of RIPC on cognitive control. Sixty healthy young male volunteers were recruited, and 30 of them received 1-week RIPC treatment (RIPC group), while the rest did not receive RIPC (control group). Their cognitive control before and after RIPC treatment was evaluated using the classic Stroop task, and the scalp electricity activity was recorded by event-related potentials (ERPs). The behavioral results showed a conventional Stroop interference effect of both reaction times (RTs) and the accuracy rate (ACC), but the Stroop interference effect of RTs significantly decreased in the posttest compared to the pretest. Furthermore, at the electrophysiological level, ERP data showed that N450 and SP for incongruent trials were larger than that for congruent trials. Importantly, the SP differential amplitude increased after RIPC treatment, whereas there was no significant change in the control group. These results implied that RIPC treatment could improve cognitive control, especially conflict resolving in the Stroop task.

Influences of remote ischemic preconditioning on postoperative delirium and cognitive dysfunction in adults after cardiac surgery: a meta-analysis of randomized controlled trials

Background

Remote ischemic preconditioning (RIPC) has been suggested to confer neuroprotective effect. However, influences of RIPC on postoperative delirium (POD) and cognitive dysfunction (POCD) in adults after cardiac surgery are less known. We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the effects of RIPC on POD and POCD.

Methods

Relevant studies were obtained by search of PubMed, Embase, and Cochrane’s Library databases. A random-effect model was used to pool the results.

Results

Ten RCTs including 2303 adults who received cardiac surgery were included. Pooled results showed that RIPC did not significantly affect the incidence of POD (six RCTs, odds ratio [OR] 1.07, 95% confidence interval [CI] 0.81 to 1.40, P = 0.65) with no significant heterogeneity (I² = 0%). In addition, combined results showed that RIPC did not significantly reduce the incidence of POCD either (six RCTs, OR 0.64, 95% CI 0.37 to 1.11, P = 0.11) with moderate heterogeneity (I² = 44%). Sensitivity analysis by excluding one RCT at a time showed consistent results (P values all > 0.05).

Conclusions

Current evidence from RCTs did not support that RIPC could prevent the incidence of POD or POCD in adults after cardiac surgery. Although these findings may be validated in large-scale RCTs, particularly for the results of POCD, based on these findings, RIPC should not be routinely used as a preventative measure for POD and POCD in adult patients after cardiac surgery.

Neurologic Dysfunction and Neuroprotection in Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation (TAVI) is a fast-growing procedure. Expanding to low-risk patients, it has surpassed surgical aortic valve implantation in frequency and has been associated with excellent outcomes. Stroke is a devastating complication after transcatheter aortic valve implantation. Silent brain infarcts identified by diffusion-weighted magnetic resonance imaging are present in most patients following TAVI. Postoperative delirium and cognitive dysfunction are common neurologic complications. The stroke and silent brain infarcts are likely caused by particulate emboli released during the procedure. Intravascularly positioned cerebral embolic protection devices are designed to prevent debris from entering the aortic arch vessels to avoid stroke. Despite promising design, randomized clinical trials have not demonstrated a reduction in stroke in patients receiving cerebral embolic protection devices. Similarly, the association of cerebral embolic protection devices with silent brain infarcts, postoperative delirium, and cognitive dysfunction is uncertain. Monitored anesthesia care or conscious sedation is as safe as general anesthesia and is associated with lower cost, but different anesthetic techniques have not been shown to decrease stroke risk, postoperative delirium, or cognitive dysfunction. Anesthesiologists play important roles in providing perioperative care including management of neurologic events in patients undergoing TAVI. Large randomized clinical trials are needed that focus on the correlation between perioperative interventions and neurologic outcomes.

Remote Ischemic Preconditioning Reduces Acute Kidney Injury After Cardiac Surgery: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Results from previous studies evaluating the effects of remote ischemic preconditioning (RIPC) on morbidity and mortality after cardiac surgery are inconsistent. This meta-analysis of randomized controlled trials (RCTs) aims to determine whether RIPC improves cardiac and renal outcomes in adults undergoing cardiac surgery.

METHODS

PubMed, EMBASE, and Cochrane Library were comprehensively searched to identify RCTs comparing RIPC with control in cardiac surgery. The coprimary outcomes were the incidence of postoperative myocardial infarction (MI) and the incidence of postoperative acute kidney injury (AKI). Meta-analyses were performed using a random-effect model. Subgroup analyses were conducted according to volatile only anesthesia versus propofol anesthesia with or without volatiles, high-risk patients versus non-high-risk patients, and Acute Kidney Injury Network (AKIN) or Kidney Disease Improving Global Outcomes (KDIGO) criteria versus other criteria for AKI diagnosis.

RESULTS

A total of 79 RCTs with 10,814 patients were included. While the incidence of postoperative MI did not differ between the RIPC and control groups (8.2% vs 9.7%; risk ratio [RR] = 0.87, 95% confidence interval [CI], 0.76-1.01, P = .07, I2 = 0%), RIPC significantly reduced the incidence of postoperative AKI (22% vs 24.4%; RR = 0.86, 95% CI, 0.77-0.97, P = .01, I2 = 34%). The subgroup analyses showed that RIPC was associated with a reduced incidence of MI in non-high-risk patients, and that RIPC was associated with a reduced incidence of AKI in volatile only anesthesia, in non-high-risk patients, and in the studies using AKIN or KDIGO criteria for AKI diagnosis.

CONCLUSIONS

This meta-analysis demonstrates that RIPC reduces the incidence of AKI after cardiac surgery. This renoprotective effect of RIPC is mainly evident during volatile only anesthesia, in non-high-risk patients, and when AKIN or KDIGO criteria used for AKI diagnosis.

Photobiomodulation Regulation as One Promising Therapeutic Approach for Myocardial Infarction

Myocardial infarction refers to myocardial necrosis caused by acute or persistent coronary ischemia and hypoxia. It is considered to be one of the significant crises threatening human health in the world. Following myocardial infarction, collagen gradually replaces the original tissue due to the loss of many cardiomyocytes, myocardial contractile function decreases, and myocardial fibrosis eventually leads to heart failure. Phototherapy is a new treatment which has shown superior efficacy on the nerve, skeletal muscle, skin, and other tissues. Likewise, there is growing evidence that phototherapy also has many positive effects on the heart. Therefore, this article introduces the progress of research on phototherapy as a new therapeutic strategy in the treatment of myocardial infarction. The wavelength of photobiomodulation in the treatment of myocardial infarction is specific, and the influence of light source power and light duration on the tissue presents a bell-shaped distribution. Under these conditions, phototherapy can promote ATP synthesis and angiogenesis, inhibit the inflammatory response, improve heart function, reduce infarct size, and protect myocardium. In addition, we summarized the molecular mechanisms of phototherapy. According to the location of photoreceptors, they can be divided into mitochondrial and nonmitochondrial parts.

Remote Ischemic Preconditioning to Prevent Acute Kidney Injury After Cardiac Surgery: A Meta-Analysis of Randomized Controlled Trials

Objective: Randomized controlled trials (RCTs) evaluating the influence of remote ischemic preconditioning (RIPC) on acute kidney injury (AKI) after cardiac surgery showed inconsistent results. We performed a meta-analysis to evaluate the efficacy of RIPC on AKI after cardiac surgery.

Methods: Relevant studies were obtained by search of PubMed, Embase, and Cochrane's Library databases. A random-effect model was used to pool the results. Meta-regression and subgroup analyses were used to determine the source of heterogeneity.

Results: Twenty-two RCTs with 5,389 patients who received cardiac surgery −2,702 patients in the RIPC group and 2,687 patients in the control group—were included. Moderate heterogeneity was detected (p for Cochrane's Q test = 0.03, I² = 40%). Pooled results showed that RIPC significantly reduced the incidence of AKI compared with control [odds ratio (OR): 0.76, 95% confidence intervals (CI): 0.61–0.94, p = 0.01]. Results limited to on-pump surgery (OR: 0.78, 95% CI: 0.64–0.95, p = 0.01) or studies with acute RIPC (OR: 0.78, 95% CI: 0.63–0.97, p = 0.03) showed consistent results. Meta-regression and subgroup analyses indicated that study characteristics, including study design, country, age, gender, diabetic status, surgery type, use of propofol or volatile anesthetics, cross-clamp time, RIPC protocol, definition of AKI, and sample size did not significantly affect the outcome of AKI. Results of stratified analysis showed that RIPC significantly reduced the risk of mild-to-moderate AKI that did not require renal replacement therapy (RRT, OR: 0.76, 95% CI: 0.60–0.96, p = 0.02) but did not significantly reduce the risk of severe AKI that required RRT in patients after cardiac surgery (OR: 0.73, 95% CI: 0.50–1.07, p = 0.11).

Conclusions: Current evidence supports RIPC as an effective strategy to prevent AKI after cardiac surgery, which seems to be mainly driven by the reduced mild-to-moderate AKI events that did not require RRT. Efforts are needed to determine the influences of patient characteristics, procedure, perioperative drugs, and RIPC protocol on the outcome.

Neurologic complications of heart surgery

Cardiac surgeries are commonly associated with neurologic complications. The type and complexity of the surgery, as well as patients' comorbidities, determine the risk for these complications. Awareness and swift recognition of these complications may have significant implications on management and prognosis. Recent trials resulted in an expansion of the time window to treat patients with acute ischemic stroke with intravenous thrombolysis and/or mechanical thrombectomy using advanced neuroimaging for screening. The expanded time window increases the reperfusion treatment options for patients that suffer a periprocedural ischemic stroke. Moreover, there is now limited data available to help guide management of intracerebral hemorrhage in patients undergoing treatment with anticoagulation for highly thrombogenic conditions, such as left ventricular assist devices and mechanical valves. In addition to cerebrovascular complications patients undergoing heart surgery are at increased risk for seizures, contrast toxicity, cognitive changes, psychological complications, and peripheral nerve injuries. We review the neurological complications associated with the most common cardiac surgeries and discuss clinical presentation, diagnosis and management strategies.

Methylene blue reduces incidence of early postoperative cognitive disorders in elderly patients undergoing major non-cardiac surgery: An open-label randomized controlled clinical trial

STUDY OBJECTIVE

The purpose of the present study was to investigate whether methylene blue (MB) could reduce the incidences of postoperative delirium (POD) and early postoperative cognitive dysfunction (POCD) in elderly patients undergoing major non-cardiac surgery.

DESIGN

Prospective, randomized, open-label clinical trial.

SETTING

University-affiliated hospital.

PATIENTS

Two hundred and forty-eight elderly patients scheduled for non-cardiac surgery.

INTERVENTIONS

Elderly patients undergoing non-cardiac major surgery were randomly assigned to MB group (n = 124), who receiving intravenous infusion of 2 mg/kg MB within 60 min immediately after anesthetic induction, or control group (n = 124), who receiving equal volume saline in the same way.

MEASUREMENTS

All patients were evaluated with delirium and neuropsychological batteries before and after surgery, as well as perioperative adverse events. Two plasma biomarkers superoxide dismutase (SOD) and homocysteine (HCY) were measured pre- and post-operatively.

MAIN RESULTS

There were total 39 cases(15.7%)experienced POD. The incidence of POD in MB group was significantly less than that in control group (7.3% vs. 24.2%, OR = 0.24, 95%CI: 0.11-0.53, p < 0.001). The incidence of early POCD at postoperative 7th day in MB group was also less than that in control group (16.1% vs. 40.2%, OR = 0.30, 95% CI: 0.16-0.57, p < 0.001). The adverse events were comparable in both groups. In addition, there was no significant correlation between POD/POCD and levels of SOD or HCY.

CONCLUSION

We conclude that intraoperative intravenous 2 mg/kg MB could significantly reduce the incidences of POD and early POCD in elderly surgical patients, while not remarkably increase incidence of perioperative adverse events, suggesting MB may be clinically effective and safe for prevention of early postoperative neurocognitive disorders.

The Future of Cardioprotection-Pointing Toward Patients at Elevated Risk as the Target Populations

Translation of the cardioprotective effect by pharmacological and mechanical conditioning therapies into improvement of clinical outcome for the patients has been disappointing. Confounding factors like comorbidity and comedications may explain some of the loss in translation. However, the substantial improvement of outcome in disease states involving ischemia-reperfusion injury, that is, planned cardiac surgery, elective percutaneous coronary intervention, and even primary percutaneous coronary intervention for ST-segment myocardial infarction (STEMI), is the most plausible explanation for the missed demonstration of a clinical benefit. Remote ischemic conditioning has demonstrated consistent cardioprotective effect in experimental and in clinical proof-of-concept studies. As an adjunctive cardioprotective treatment beyond reperfusion, remote ischemic conditioning should address target populations at risk of extensive tissue damage, including patients who experience complications, which may induce profound myocardial ischemia in relation to cardiac surgery or elective percutaneous coronary intervention. Moreover, patients with STEMI and predictable impaired clinical outcome due to delayed hospital admission, high Killip class, cardiogenic shock, and cardiac arrest remain target groups. For high-risk patients, daily remote ischemic conditioning or the corollary of blood flow-restricted exercise may be alternative cardioprotective options during postoperative and post-myocardial infarct rehabilitation.

Remote ischemic preconditioning and its role in the prevention of new onset atrial fibrillation post-cardiac surgery. A meta-analysis of randomized control trials

BACKGROUND

The denouement of remote ischemic preconditioning on new onset atrial fibrillation (NOAF) post-cardiac surgery is not well-established. An updated meta-analysis of randomized control trials was performed by comparing remote ischemic preconditioning with controls and the outcome of interest was NOAF.

METHODS

The systemic review was performed in accordance with the PRISMA (Preferred reporting items for systemic review) and AHA (American Heart Association) guidelines. PubMed database was searched to include relevant randomized control trials from inception to July 2019. We used Mantel-Haenzsel method with random error model to calculate risk ratio (RR) with 95% confidence interval (CI). Heterogeneity was assessed using the I 2 test> 50% or χ 2 P < .05. Publication bias was visually assessed using a funnel plot.

RESULTS

Twelve randomized control trials were included in the final analysis. Remote ischemic preconditioning did not alter the risk of NOAF post-cardiac surgery [RR: 0.95, CI: 0.83-1.09, P = .48, I 2 = 37%, χ 2 P = .09].

CONCLUSION

In conclusion, the present meta-analysis failed to provide any evidence for the beneficial effect of remote ischemic preconditioning in the prevention of NOAF.

Postoperative Delirium and Postoperative Cognitive Dysfunction: Overlap and Divergence

BACKGROUND

Postoperative delirium and postoperative cognitive dysfunction share risk factors and may co-occur, but their relationship is not well established. The primary goals of this study were to describe the prevalence of postoperative cognitive dysfunction and to investigate its association with in-hospital delirium. The authors hypothesized that delirium would be a significant risk factor for postoperative cognitive dysfunction during follow-up.

METHODS

This study used data from an observational study of cognitive outcomes after major noncardiac surgery, the Successful Aging after Elective Surgery study. Postoperative delirium was evaluated each hospital day with confusion assessment method-based interviews supplemented by chart reviews. Postoperative cognitive dysfunction was determined using methods adapted from the International Study of Postoperative Cognitive Dysfunction. Associations between delirium and postoperative cognitive dysfunction were examined at 1, 2, and 6 months.

RESULTS

One hundred thirty-four of 560 participants (24%) developed delirium during hospitalization. Slightly fewer than half (47%, 256 of 548) met the International Study of Postoperative Cognitive Dysfunction-defined threshold for postoperative cognitive dysfunction at 1 month, but this proportion decreased at 2 months (23%, 123 of 536) and 6 months (16%, 85 of 528). At each follow-up, the level of agreement between delirium and postoperative cognitive dysfunction was poor (kappa less than .08) and correlations were small (r less than .16). The relative risk of postoperative cognitive dysfunction was significantly elevated for patients with a history of postoperative delirium at 1 month (relative risk = 1.34; 95% CI, 1.07-1.67), but not 2 months (relative risk = 1.08; 95% CI, 0.72-1.64), or 6 months (relative risk = 1.21; 95% CI, 0.71-2.09).

CONCLUSIONS

Delirium significantly increased the risk of postoperative cognitive dysfunction in the first postoperative month; this relationship did not hold in longer-term follow-up. At each evaluation, postoperative cognitive dysfunction was more common among patients without delirium. Postoperative delirium and postoperative cognitive dysfunction may be distinct manifestations of perioperative neurocognitive deficits.

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.

Hyperhomocysteinemia is key for increased susceptibility to PND in aged mice

Background

Postoperative neurocognitive disorder (PND) is a severe postoperative complication with no effective therapy that affects up to 19–52% of senior patients. Age and surgery type have been identified as risk factors. However, what caused the increased risk in the elderly is poorly understood.

Methods

We utilized a PND model in aged mice undergoing experimental laparotomy with general anesthesia to evaluate the causal relationship between hyperhomocysteinemia and increased PND susceptibility. PND was assessed by Novel Object Tasks, Fear Conditioning Tests, and Barnes Maze Tests. Serum homocysteine (Hcy) as well as vitamin B12 and folate acid levels were tested before, immediately after surgery and from day 1 to day 29 after surgery by ELISA. The effectiveness of preventative strategy including diet supplementation of vitamin B12 + folic acid (Vit B12 + FA) and S‐adenosylmethionine (SAM) injection targeting hyperhomocysteinemia were also tested.

Results

PND in aged mice lasted for at least 2 weeks after experimental laparotomy, which was not observed in young adult mice. Serum Hcy results indicated a significant correlation between postoperative cognitive performance and perioperative Hcy level. Preoperative supplementation with VB12 and folic acid (FA) in the diet or S‐adenosylmethionine (SAM) injection reduced perioperative serum Hcy level and inhibited the development of PND in aged mice.

Conclusions

Serum homocysteine accumulation is a fundamental cause for increased susceptibility of PND in aged mice. Preoperative diet supplementation of VitB12 + FA can effectively reduce PND in aged mice, which may be a promising prophylaxis treatment in clinical settings.

Remote ischaemic preconditioning does not modulate the systemic inflammatory response or renal tubular stress biomarkers after endotoxaemia in healthy human volunteers: a single-centre, mechanistic, randomised controlled trial

BACKGROUND

Remote ischaemic preconditioning (RIPC) consists of repeated cycles of limb ischaemia and reperfusion, which may reduce perioperative myocardial ischaemic damage and kidney injury. We hypothesised that RIPC may be beneficial by attenuating the systemic inflammatory response. We investigated whether RIPC affects the response in humans to bacterial endotoxin (lipopolysaccharide [LPS]) by measuring plasma cytokines and renal cell-cycle arrest mediators, which reflect renal tubular stress.

METHODS

Healthy male volunteers were randomised to receive either daily RIPC for 6 consecutive days (RIPC_multiple, n=10) plus RIPC during the 40 min preceding i.v. LPS (2 ng kg^-1), RIPC only during the 40 min before LPS (RIPC_single, n=10), or no RIPC preceding LPS (control, n=10). As a surrogate marker of renal tubular stress, the product of urinary concentrations of two cell-cycle arrest markers was calculated (tissue inhibitor of metalloproteinases-2 [TIMP2]*insulin-like growth factor binding protein-7 [IGFBP7]). Data are presented as median (inter-quartile range).

RESULTS

In both RIPC groups, RIPC alone increased [TIMP2]*[IGFBP7]. LPS administration resulted in fever, flu-like symptoms, and haemodynamic alterations. Plasma cytokine concentrations increased profoundly during endotoxaemia (control group: tumor necrosis factor alpha [TNF-α] from 14 [9-16] pg ml^-1 at baseline to 480 [284-709] pg ml^-1 at 1.5 h after LPS; interleukin-6 [IL-6] from 4 [4-4] pg ml^-1 at baseline to 659 [505-1018] pg ml^-1 at 2 h after LPS). LPS administration also increased urinary [TIMP2[*[IGFBP7]. RIPC had no effect on LPS-induced cytokine release or [TIMP2]*[IGFBP7].

CONCLUSIONS

RIPC neither modulated systemic cytokine release nor attenuated inflammation-induced tubular stress after LPS. However, RIPC alone induced renal markers of cell-cycle arrest.

CLINICAL TRIAL REGISTRATION

NCT02602977.

Volatile anesthetics versus propofol in the cardiac surgical setting of remote ischemic preconditioning: a secondary analysis of a Cochrane Systematic Review

INTRODUCTION

So far, the concept of remote ischemic preconditioning (RIPC) failed its translation from experimental to clinical studies. In addition to our Cochrane Systematic Review, we systematically assessed the use of the intravenous anesthetic propofol, as a potential confounding factor.

EVIDENCE ACQUISITION

We searched CENTRAL, MEDLINE, Embase and Web of Science. We included randomized controlled trials comparing RIPC with no RIPC in adult patients scheduled for coronary artery bypass graft surgery (with or without valve surgery) receiving either exclusively propofol or exclusively volatile anesthetics. Two authors independently assessed methodological quality and extracted data. We report odds ratios (ORs) with 95% confidence intervals as our summary statistics are based on random-effects models.

EVIDENCE SYNTHESIS

We included 14 studies involving 4060 participants. We found no difference in treatment effect between the propofol and volatile anesthetic groups when RIPC or no RIPC is applied on a composite endpoint (all-cause mortality, non-fatal myocardial infarction and/or any new stroke), all-cause mortality, non-fatal myocardial infarction, stroke, or length of stay on ICU. On cardiac markers, RIPC did show a treatment effect on cardiac troponin T measured as AUC 72 hours (SMD -0.80, CI -1.34, -0.25) in the propofol group. However, these findings have to be interpreted with great caution, to date only a very limited number of patients received volatile anesthetics in RIPC trials (minimum N.=15, maximum N.=232).

CONCLUSIONS

Present data do not permit a final assessment regarding the role of volatile or intravenous anesthetics as a possible confounding factor in RIPC trials.

A high risk of sleep apnea is associated with less postoperative cognitive dysfunction after intravenous anesthesia: results of an observational pilot study

Background

The obstructive sleep apnea syndrome (OSAS) is characterized by temporary cerebral hypoxia which can cause cognitive dysfunction. On the other hand, hypoxia induced neurocognitive deficits are detectable after general anesthesia.

The objective of this study was to evaluate the impact of a high risk of OSAS on the postoperative cognitive dysfunction after intravenous anesthesia.

Methods

In this single center trial between June 2012 and June 2013 43 patients aged 55 to 80 years with an estimated hospital stay of at least 3 days undergoing surgery were enrolled. Patients were screened for a high risk of OSAS using the STOP-BANG test. The cognitive function was assessed using a neuropsychological test battery, including the DemTect test for cognitive impairment and the RMBT test for memory, the day before surgery and within 36 h after extubation.

Results

Twenty-two of the 43 analyzed patients were identified as patients with a high risk of OSAS. Preoperatively, OSAS patients showed a significant worse performance only for the DemTect (p = 0.0043). However, when comparing pre- and postoperative test results, the OSAS patients did not show a significant loss in any test but significantly improved in RMBT test, whereas the control group showed a significant worse performance in three of eight tests. In five tests, we found a significant difference between the two groups with respect to the change from pre- to postoperative cognitive function.

Conclusion

Patients with a high risk of OSAS showed a less impairment of memory function and work memory performance after intravenous anesthesia. This might be explained by a beneficial effect of intrinsic hypoxic preconditioning in these patients.

Neuroprotective Effects of Cerebral Ischemic Preconditioning in a Rat Middle Cerebral Artery Occlusion Model: The Role of the Notch Signaling Pathway

Cerebral ischemia-reperfusion (I/R) injury is a major problem worldwide. The Notch signaling pathway plays an important role in neural progenitor cell differentiation and in the inflammatory response after central nervous system injury. This study evaluated whether the neuroprotective effect of cerebral ischemic preconditioning (cIPC) is mediated by the preactivation of the Notch signaling pathway. A rat middle cerebral artery occlusion/reperfusion (MCAO/R) model and glucose deprivation/reoxygenation (OGD/R) cell model were constructed to detect the neuroprotective effects of cIPC. In in vivo experiments, cIPC reduces the neurological functional deficit, cerebral infarction, and cellular apoptosis in the hippocampus induced by middle cerebral artery occlusion/reperfusion (MCAO/R), thus indicating that cIPC can improve neurologic function. Moreover, cIPC can reveal the expression peak of Jagged1, Notch1, NICD, and Hes1 protein, thereby indicating that cIPC can preactivate Notch signaling. However, cIPC-induced improvements in neurologic function are compromised by the γ-secretase inhibitor N-(N-(3,5-difluorophenacetyl)-1-alanyl)-S-phenylglycine t-butyl ester (DAPT). In in vitro experiments, OGD preconditioning (OGDPC) can clearly upregulate Notch1 expression in the OGD/R-treated neuron and neural stem cell. Notch1 pre-overexpression can decrease neuron death and apoptosis under OGD/R treatment. Notch1 pre-overexpression can decrease the percentage of G1 stage cells and increase the percentage of S stage cells in OGD/R-treated neural stem cell. Furthermore, Notch1 pre-knockdown has the opposite effect on cell survival, apoptosis, and cycle in both OGD/R-treated neuron and neural stem cell. In conclusion, our results demonstrate that the neuroprotective effects of cIPC in a rat MCAO/R model are mediated by the preactivation of the Notch signaling pathway.

Effect of Remote Ischemic Preconditioning on Outcomes in Adult Cardiac Surgery: A Systematic Review and Meta-analysis of Randomized Controlled Studies

BACKGROUND

Remote ischemic preconditioning (RIPC) has been demonstrated to prevent organ dysfunction in cardiac surgery patients. However, recent large, prospective, multicenter, randomized controlled trials (RCTs) had controversial results. Thus, a meta-analysis of RCTs was performed to investigate whether RIPC can reduce the incidence of acute myocardial infarction (AMI), acute kidney injury (AKI), and mortality in adult cardiac surgery patients.

METHODS

Study data were collected from Medline, Elsevier, Cochrane Central Register of Controlled Trials and Web of Science databases. RCTs involving the effect of RIPC on organ protection in cardiac surgery patients, which reported the concentration or total release of creatine kinase-myocardial band, troponin I/troponin T (TNI/TNT) after operation, or the incidence of AMI, AKI, or mortality, were selected. Two reviewers independently extracted data using a standardized data extraction protocol where TNI or TNT concentrations; total TNI released after cardiac surgery; and the incidence of AKI, AMI, and mortality were recorded. Review Manager 5.3 software was used to analyze the data.

RESULTS

Thirty trials, including 7036 patients were included in the analyses. RIPC significantly decreased the concentration of TNI/TNT (standard mean difference [SMD], -0.25 ng/mL; 95% confidence interval [CI], -0.41 to -0.048 ng/mL; P = .004), creatine kinase-myocardial band (SMD, -0.22; 95% CI, -0.07-0.35 ng/mL; P = .46), and the total TNI/TNT release (SMD, -0.49 ng/mL; 95% CI, -0.93 to -0.55 ng/mL; P = .03) in cardiac surgery patients after a procedure. However, RIPC could not reduce the incidence of AMI (relative risk, 0.89; 95% CI, 0.70-1.13; P = .34) and AKI (relative risk, 0.88; 95% CI, 0.72-1.06; P = .18), and there was also no effect of RIPC on mortality in adult cardiac surgery patients. Interestingly, subgroup analysis showed that RIPC reduced incidence of AKI and mortality of cardiac surgery patients who received volatile agent anesthesia.

CONCLUSIONS

Our meta-analysis demonstrated that RIPC reduced TNI/TNT release after cardiac surgery. RIPC did not significantly reduce the incidence of AKI, AMI, and mortality. However, RIPC could reduce mortality in patients receiving volatile inhalational agent anesthesia.

RIPHeart (Remote Ischemic Preconditioning for Heart Surgery) Study: Myocardial Dysfunction, Postoperative Neurocognitive Dysfunction, and 1 Year Follow-Up

BACKGROUND

Remote ischemic preconditioning (RIPC) has been suggested to protect against certain forms of organ injury after cardiac surgery. Previously, we reported the main results of RIPHeart (Remote Ischemic Preconditioning for Heart Surgery) Study, a multicenter trial randomizing 1403 cardiac surgery patients receiving either RIPC or sham-RIPC.

METHODS AND RESULTS

In this follow-up paper, we present 1-year follow-up of the composite primary end point and its individual components (all-cause mortality, myocardial infarction, stroke and acute renal failure), in a sub-group of patients, intraoperative myocardial dysfunction assessed by transesophageal echocardiography and the incidence of postoperative neurocognitive dysfunction 5 to 7 days and 3 months after surgery. RIPC neither showed any beneficial effect on the 1-year composite primary end point (RIPC versus sham-RIPC 16.4% versus 16.9%) and its individual components (all-cause mortality [3.4% versus 2.5%], myocardial infarction [7.0% versus 9.4%], stroke [2.2% versus 3.1%], acute renal failure [7.0% versus 5.7%]) nor improved intraoperative myocardial dysfunction or incidence of postoperative neurocognitive dysfunction 5 to 7 days (67 [47.5%] versus 71 [53.8%] patients) and 3 months after surgery (17 [27.9%] versus 18 [27.7%] patients), respectively.

CONCLUSIONS

Similar to our main study, RIPC had no effect on intraoperative myocardial dysfunction, neurocognitive function and long-term outcome in cardiac surgery patients undergoing propofol anesthesia.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01067703.

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.

Remote Ischemic Preconditioning and Clinical Outcomes in On-Pump Coronary Artery Bypass Grafting: A Meta-Analysis of 14 Randomized Controlled Trials

The purpose of this article is to perform the first pooled analysis on remote ischemic preconditioning (RIPC) used for the improvement of clinical outcomes of patients only undergoing on-pump coronary artery bypass grafting (CABG) in randomized controlled trials (RCTs). A systematic search was performed using PubMed, the Cochrane Library, and the Web of Science to identify studies that described the effect of RIPC on postoperative mortality in patients only undergoing on-pump CABG. The outcomes included postoperative mortality, postoperative morbidity (including incidence of myocardial infarction, atrial fibrillation, stroke, acute kidney injury, and renal replacement therapy), mechanical ventilation (MV), intensive care unit length of stay (ICU LOS), and hospital length of stay (HLOS). A total of 14 RCTs (2830 participants) were included. Our meta-analysis found that RIPC failed to reduce the postoperative mortality in patients only undergoing on-pump CABG compared with control individuals (odds ratio, 0.81; 95% confidence interval, [0.40, 1.64]; P = 0.55; I²  = 25%). Moreover, there were no differences in postoperative morbidity, ICU LOS, and HLOS between the two groups. However, MV in the RIPC group was shorter than that in control individuals (standard mean difference, -0.41; 95% confidence interval, [-0.80, -0.01]; P = 0.04; I²  = 73%). The present meta-analysis found that RIPC failed to improve most of clinical outcomes in patients only undergoing on-pump CABG; however, MV was reduced. Adequately powered trials are warranted to provide more evidence in the future.

Impact of ischemic preconditioning on surgical treatment of brain tumors: a single-center, randomized, double-blind, controlled trial

BACKGROUND

Postoperative ischemia is a frequent phenomenon in patients with brain tumors and is associated with postoperative neurological deficits and impaired overall survival. Particularly in the field of cardiac and vascular surgery, the application of a brief ischemic stimulus not only in the target organ but also in remote tissues can prevent subsequent ischemic damage. We hypothesized that remote ischemic preconditioning (rIPC) in patients with brain tumors undergoing elective surgical resection reduces the incidence of postoperative ischemic tissue damage and its consequences.

METHODS

Sixty patients were randomly assigned to two groups, with 1:1 allocation, stratified by tumor type (glioma or metastasis) and previous treatment with radiotherapy. rIPC was induced by inflating a blood pressure cuff placed on the upper arm three times for 5 min at 200 mmHg in the treatment group after induction of anesthesia. Between the cycles, the blood pressure cuff was released to allow reperfusion. In the control group no preconditioning was performed. Early postoperative magnetic resonance images (within 72 h after surgery) were evaluated by a neuroradiologist blinded to randomization for the presence of ischemia and its volume.

RESULTS

Fifty-eight of the 60 patients were assessed for occurrence of postoperative ischemia. Of these 58 patients, 44 had new postoperative ischemic lesions. The incidence of new postoperative ischemic lesions was significantly higher in the control group (27/31) than in the rIPC group (17/27) (p = 0.03). The median infarct volume was 0.36 cm³ (interquartile range (IR): 0.0-2.35) in the rIPC group compared with 1.30 cm³ (IR: 0.29-3.66) in the control group (p = 0.09).

CONCLUSIONS

Application of rIPC was associated with reduced incidence of postoperative ischemic tissue damage in patients undergoing elective brain tumor surgery. This is the first study indicating a benefit of rIPC in brain tumor surgery.

TRIAL REGISTRATION

German Clinical Trials Register, DRKS00010409 . Retrospectively registered on 13 October 2016.

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.

Remote ischaemic preconditioning for coronary artery bypass grafting (with or without valve surgery)

BACKGROUND

Despite substantial improvements in myocardial preservation strategies, coronary artery bypass grafting (CABG) is still associated with severe complications. It has been reported that remote ischaemic preconditioning (RIPC) reduces reperfusion injury in people undergoing cardiac surgery and improves clinical outcome. However, there is a lack of synthesised information and a need to review the current evidence from randomised controlled trials (RCTs).

OBJECTIVES

To assess the benefits and harms of remote ischaemic preconditioning in people undergoing coronary artery bypass grafting, with or without valve surgery.

SEARCH METHODS

In May 2016 we searched CENTRAL, MEDLINE, Embase and Web of Science. We also conducted a search of ClinicalTrials.gov and the International Clinical Trials Registry Platform (ICTRP). We also checked reference lists of included studies. We did not apply any language restrictions.

SELECTION CRITERIA

We included RCTs in which people scheduled for CABG (with or without valve surgery) were randomly assigned to receive RIPC or sham intervention before surgery.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data and checked them for accuracy. We calculated mean differences (MDs), standardised mean differences (SMDs) and risk ratios (RR) using a random-effects model. We assessed quality of the trial evidence for all primary outcomes using the GRADE methodology. We completed a 'Risk of bias' assessment for all studies and performed sensitivity analysis by excluding studies judged at high or unclear risk of bias for sequence generation, allocation concealment and incomplete outcome data. We contacted authors for missing data. Our primary endpoints were 1) composite endpoint (including all-cause mortality, non-fatal myocardial infarction or any new stroke, or both) assessed at 30 days after surgery, 2) cardiac troponin T (cTnT, ng/L) at 48 hours and 72 hours, and as area under the curve (AUC) 72 hours (µg/L) after surgery, and 3) cardiac troponin I (cTnI, ng/L) at 48 hours, 72 hours, and as area under the curve (AUC) 72 hours (µg/L) after surgery.

MAIN RESULTS

We included 29 studies involving 5392 participants (mean age = 64 years, age range 23 to 86 years, 82% male). However, few studies contributed data to meta-analyses due to inconsistency in outcome definition and reporting. In general, risk of bias varied from low to high risk of bias across included studies, and insufficient detail was provided to inform judgement in several cases. The quality of the evidence of key outcomes ranged from moderate to low quality due to the presence of moderate or high statistical heterogeneity, imprecision of results or due to limitations in the design of individual studies.Compared with no RIPC, we found that RIPC has no treatment effect on the rate of the composite endpoint with RR 0.99 (95% confidence interval (CI) 0.78 to 1.25); 2 studies; 2463 participants; moderate-quality evidence. Participants randomised to RIPC showed an equivalent or better effect regarding the amount of cTnT release measured at 72 hours after surgery with SMD -0.32 (95% CI -0.65 to 0.00); 3 studies; 1120 participants; moderate-quality evidence; and expressed as AUC 72 hours with SMD -0.49 (95% CI -0.96 to -0.02); 3 studies; 830 participants; moderate-quality evidence. We found the same result in favour of RIPC for the cTnI release measured at 48 hours with SMD -0.21 (95% CI -0.40 to -0.02); 5 studies; 745 participants; moderate-quality evidence; and measured at 72 hours after surgery with SMD -0.37 (95% CI -0.59 to -0.15); 2 studies; 459 participants; moderate-quality evidence. All other primary outcomes showed no differences between groups (cTnT release measured at 48 hours with SMD -0.14, 95% CI -0.33 to 0.06; 4 studies; 1792 participants; low-quality evidence and cTnI release measured as AUC 72 hours with SMD -0.17, 95% CI -0.48 to 0.14; 2 studies; 159 participants; moderate-quality evidence).We also found no differences between groups for all-cause mortality after 30 days, non-fatal myocardial infarction after 30 days, any new stroke after 30 days, acute renal failure after 30 days, length of stay on the intensive care unit (days), any complications and adverse effects related to ischaemic preconditioning. We did not assess many patient-centred/salutogenic-focused outcomes.

AUTHORS' CONCLUSIONS

We found no evidence that RIPC has a treatment effect on clinical outcomes (measured as a composite endpoint including all-cause mortality, non-fatal myocardial infarction or any new stroke, or both, assessed at 30 days after surgery). There is moderate-quality evidence that RIPC has no treatment effect on the rate of the composite endpoint including all-cause mortality, non-fatal myocardial infarction or any new stroke assessed at 30 days after surgery, or both. We found moderate-quality evidence that RIPC reduces the cTnT release measured at 72 hours after surgery and expressed as AUC (72 hours). There is moderate-quality evidence that RIPC reduces the amount of cTnI release measured at 48 hours, and measured 72 hours after surgery. Adequately-designed studies, especially focusing on influencing factors, e.g. with regard to anaesthetic management, are encouraged and should systematically analyse the commonly used medications of people with cardiovascular diseases.

Biochemical signaling by remote ischemic conditioning of the arm versus thigh: Is one raise of the cuff enough?

Remote Ischemic Conditioning (RIC), induced by brief cycles of ischemia and reperfusion, protects vital organs from a prolonged ischemic insult. While several biochemical mediators have been implicated in RIC's mechanism of action, it remains unclear whether the localization or “dose” of RIC affects the extent of protective signaling. In this randomized crossover study of healthy individuals, we tested whether the number of cycles of RIC and its localization (arm versus thigh) determines biochemical signaling and cytoprotection. Subjects received either arm or thigh RIC and then were crossed over to receive RIC in the other extremity. Blood flow, tissue perfusion, concentrations of the circulating protective mediator nitrite, and platelet mitochondrial function were measured after each RIC cycle. We found that plasma nitrite concentration peaked after the first RIC cycle and remained elevated throughout RIC. This plasma nitrite conferred cytoprotection in an in vitro myocyte model of hypoxia/reoxygenation. Notably, though plasma nitrite returned to baseline at 24 h, RIC conditioned plasma still mediated protection. Additionally, no difference in endpoints between RIC in thigh versus arm was found. These data demonstrate that localization and “dose” of RIC does not affect cytoprotection and further elucidate the mechanisms by which nitrite contributes to RIC-dependent protection.

Clinical Outcomes of Remote Ischemic Preconditioning Prior to Cardiac Surgery: A Meta-Analysis of Randomized Controlled Trials

Background

Multiple randomized controlled trials of remote ischemic preconditioning (RIPC) prior to cardiac surgery have failed to demonstrate clinical benefit. The aim of this updated meta‐analysis was to evaluate the effect of RIPC on outcomes following cardiac surgery.

Methods and Results

Searches of PubMed, Cochrane, EMBASE, and Web of Science databases were performed for 1970 to December 13, 2015. Randomized controlled trials comparing RIPC with a sham procedure prior to cardiac surgery performed with cardiopulmonary bypass were assessed. All‐cause mortality, acute kidney injury (AKI), and myocardial infarction were the primary outcomes of interest. We identified 21 trials that randomized 5262 patients to RIPC or a sham procedure prior to undergoing cardiac surgery. The majority of patients were men (72.6%) and the mean or median age ranged from 42.3 to 76.3 years. Of the 9 trials that evaluated mortality, 188 deaths occurred out of a total of 4210 randomized patients, with 96 deaths occurring in 2098 patients (4.6%) randomized to RIPC and 92 deaths occurring in 2112 patients (4.4%) randomized to a sham control procedure, demonstrating no significant reduction in all‐cause mortality (risk ratio [RR], 0.987; 95% CI, 0.653–1.492, P=0.95). Twelve studies evaluated AKI in 4209 randomized patients. In these studies, AKI was observed in 516 of 2091 patients (24.7%) undergoing RIPC and in 577 of 2118 patients (27.2%) randomized to a sham procedure. RIPC did not result in a significant reduction in AKI (RR, 0.839; 95% CI, 0.703–1.001 [P=0.052]). In 6 studies consisting of 3799 randomized participants, myocardial infarction occurred in 237 of 1891 patients (12.5%) randomized to RIPC and in 282 of 1908 patients (14.8%) randomized to a sham procedure, resulting in no significant reduction in postoperative myocardial infarction (RR, 0.809; 95% CI, 0.615–1.064 [P=0.13]). A subgroup analysis was performed a priori based on previous studies suggesting that propofol may mitigate the protective benefits of RIPC. Three studies randomized patients undergoing cardiac surgery to RIPC or sham procedure in the absence of propofol anesthesia. Most of these patients were men (60.3%) and the mean or median age ranged from 57.0 to 70.6 years. In this propofol‐free subgroup of 434 randomized patients, 71 of 217 patients (32.7%) who underwent RIPC developed AKI compared with 103 of 217 patients (47.5%) treated with a sham procedure. In this cohort, RIPC resulted in a significant reduction in AKI (RR, 0.700; 95% CI, 0.527–0.930 [P=0.014]). In studies of patients who received propofol anesthesia, 445 of 1874 (23.7%) patients randomized to RIPC developed AKI compared with 474 of 1901 (24.9%) who underwent a sham procedure. The RR for AKI was 0.928 (95% CI, 0.781–1.102; P=0.39) for RIPC versus sham. There was no significant interaction between the two subgroups (P=0.098).

Conclusions

RIPC does not reduce morbidity or mortality in patients undergoing cardiac surgery with cardiopulmonary bypass. In the subgroup of studies in which propofol was not used, a reduction in AKI was seen, suggesting that propofol may interact with the protective effects of RIPC. Future studies should evaluate RIPC in the absence of propofol anesthesia.

A Role for Photobiomodulation in the Prevention of Myocardial Ischemic Reperfusion Injury: A Systematic Review and Potential Molecular Mechanisms

Myocardial ischemia reperfusion injury is a negative pathophysiological event that may result in cardiac cell apoptosis and is a result of coronary revascularization and cardiac intervention procedures. The resulting loss of cardiomyocyte cells and the formation of scar tissue, leads to impaired heart function, a major prognostic determinant of long-term cardiac outcomes. Photobiomodulation is a novel cardiac intervention that has displayed therapeutic effects in reducing myocardial ischemia reperfusion related myocardial injury in animal models. A growing body of evidence supporting the use of photobiomodulation in myocardial infarct models has implicated multiple molecular interactions. A systematic review was conducted to identify the strength of the evidence for the therapeutic effect of photobiomodulation and to summarise the current evidence as to its mechanisms. Photobiomodulation in animal models showed consistently positive effects over a range of wavelengths and application parameters, with reductions in total infarct size (up to 76%), decreases in inflammation and scarring, and increases in tissue repair. Multiple molecular pathways were identified, including modulation of inflammatory cytokines, signalling molecules, transcription factors, enzymes and antioxidants. Current evidence regarding the use of photobiomodulation in acute and planned cardiac intervention is at an early stage but is sufficient to inform on clinical trials.

Cognitive Outcomes of Cardiovascular Surgical Procedures in the Old: An Important but Neglected Area

Older individuals can now undergo invasive cardiovascular procedures without serious concern about mortality, and the numbers and proportions of the over 65s and 85s doing so in Australia has been increasing over the last 20 years. There is overwhelming evidence linking cardiovascular conditions to late-life (65 years and over) cognitive impairment and dementia including Alzheimer's Disease, primarily due to impaired cerebrovascularisation and cascading neuropathological processes. Somewhat paradoxically, these cardiovascular interventions, carried out with the primary aim of revascularisation, are not usually associated with short- or long-term improvements in cognitive function in older adults. We discuss factors associated with cognitive outcomes post-cardiovascular surgeries in patients over 65 years of age. There are many opportunities for future research: we know almost nothing about cognitive outcomes following invasive cardiac procedures in the oldest old (85 years and over) nor how to predict the cognitive/delirium outcome using pre-surgical data, and lastly, intervention opportunities exist both pre and postoperatively that have not been tested. As our population ages with increased cardiovascular burden and rates of cardiovascular interventions and surgeries, it is critical that we understand the cognitive consequences of these procedures, who is at greatest risk, and ways to optimise cognition.

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.

Time to Give Up on Cardioprotection?

The mortality from acute myocardial infarction (AMI) remains significant, and the prevalence of post-myocardial infarction heart failure is increasing. Therefore, cardioprotection beyond timely reperfusion is needed. Conditioning procedures are the most powerful cardioprotective interventions in animal experiments. However, ischemic preconditioning cannot be used to reduce infarct size in patients with AMI because its occurrence is not predictable; several studies in patients undergoing surgical coronary revascularization report reduced release of creatine kinase and troponin. Ischemic postconditioning reduces infarct size in most, but not all, studies in patients undergoing interventional reperfusion of AMI, but may require direct stenting and exclusion of patients with >6 hours of symptom onset to protect. Remote ischemic conditioning reduces infarct size in patients undergoing interventional reperfusion of AMI, elective percutaneous or surgical coronary revascularization, and other cardiovascular surgery in many, but not in all, studies. Adequate dose-finding phase II studies do not exist. There are only 2 phase III trials, both on remote ischemic conditioning in patients undergoing cardiovascular surgery, both with neutral results in terms of infarct size and clinical outcome, but also both with major problems in trial design. We discuss the difficulties in translation of cardioprotection from animal experiments and proof-of-concept trials to clinical practice. Given that most studies on ischemic postconditioning and all studies on remote ischemic preconditioning in patients with AMI reported reduced infarct size, it would be premature to give up on cardioprotection.

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.

Remote ischemic preconditioning in patients undergoing cardiovascular surgery: Evidence from a meta-analysis of randomized controlled trials

BACKGROUND

Remote ischemic preconditioning (RIPC) has been associated with reduced risk of myocardial injury in patients undergoing cardiovascular surgery, but uncertainty about clinical outcomes remains, particularly in the light of 2 recent large randomized clinical trials (RCTs) which were neutral. We performed a meta-analysis to evaluate the efficacy of RIPC on clinically relevant outcomes in patients undergoing cardiovascular surgery.

METHODS

We searched PubMed, Cochrane CENTRAL, EMBASE, EBSCO, Web of Science and CINAHL databases from inception through November 30, 2015. RCTs that compared the effects of RIPC vs. control in patients undergoing cardiac and/or vascular surgery were selected. We calculated summary random-effect odds ratios (ORs) and 95% confidence intervals (CI).

RESULTS

The analysis included 5652 patients from 27 RCTs. RIPC reduced the risk of myocardial infarction (MI) (OR 0.72, 95% CI, 0.52 to 1.00; p=0.05; number needed to treat (NNT)=42), acute renal failure (OR 0.73, 95% CI, 0.53 to 1.00; p=0.05; NNT=44) as well as the composite of all cause mortality, MI, stroke or acute renal failure (OR 0.60, 95% CI, 0.39 to 0.90; p=0.01; NNT=25). No significant difference between RIPC and the control groups was observed for the outcome of all-cause mortality (OR 1.10, 95% CI, 0.81 to 1.51). Randomization to RIPC group was also associated with significantly shorter hospital stay (weighted mean difference -0.15days; 95% CI -0.27 to -0.03days).

CONCLUSIONS

RIPC did not decrease overall mortality, but was associated with less MI and acute renal failure and shorter hospitalizations in patients undergoing cardiac or vascular surgery.

Postoperative cognitive dysfunction and neuroinflammation; Cardiac surgery and abdominal surgery are not the same

Postoperative cognitive dysfunction (POCD) is a debilitating surgical complication, with cardiac surgery patients at particular risk. To gain insight in the mechanisms underlying the higher incidence of POCD after cardiac versus non-cardiac surgery, systemic and central inflammatory changes, alterations in intraneuronal pathways, and cognitive performance were studied after cardiac and abdominal surgery in rats. Male Wistar rats were subjected to ischemia reperfusion of the upper mesenteric artery (abdominal surgery) or the left coronary artery (cardiac surgery). Control rats remained naïve, received anesthesia only, or received thoracic sham surgery. Rats were subjected to affective and cognitive behavioral tests in postoperative week 2. Plasma concentrations of inflammatory factors, and markers for neuroinflammation (NGAL and microglial activity) and the BDNF pathway (BDNF, p38MAPK and DCX) were determined. Spatial memory was impaired after both abdominal and cardiac surgery, but only cardiac surgery impaired spatial learning and object recognition. While all surgical procedures elicited a pronounced acute systemic inflammatory response, NGAL and TNFα levels were particularly increased after abdominal surgery. Conversely, NGAL in plasma and the paraventricular nucleus of the hypothalamus and microglial activity in hippocampus and prefrontal cortex on postoperative day 14 were increased after cardiac, but not abdominal surgery. Both surgery types induced hippocampal alterations in BDNF signaling. These results suggest that POCD after cardiac surgery, compared to non-cardiac surgery, affects different cognitive domains and hence may be more extended rather than more severe. Moreover, while abdominal surgery effects seem limited to hippocampal brain regions, cardiac surgery seems associated with more wide spread alterations in the brain.

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.

Neuroprotective Effects Against POCD by Photobiomodulation: Evidence from Assembly/Disassembly of the Cytoskeleton

Postoperative cognitive dysfunction (POCD) is a decline in memory following anaesthesia and surgery in elderly patients. While often reversible, it consumes medical resources, compromises patient well-being, and possibly accelerates progression into Alzheimer's disease. Anesthetics have been implicated in POCD, as has neuroinflammation, as indicated by cytokine inflammatory markers. Photobiomodulation (PBM) is an effective treatment for a number of conditions, including inflammation. PBM also has a direct effect on microtubule disassembly in neurons with the formation of small, reversible varicosities, which cause neural blockade and alleviation of pain symptoms. This mimics endogenously formed varicosities that are neuroprotective against damage, toxins, and the formation of larger, destructive varicosities and focal swellings. It is proposed that PBM may be effective as a preconditioning treatment against POCD; similar to the PBM treatment, protective and abscopal effects that have been demonstrated in experimental models of macular degeneration, neurological, and cardiac conditions.