Perioperative Acute Kidney Injury: An Under-Recognized Problem

Development and validation of a risk nomogram for postoperative acute kidney injury in older patients undergoing liver resection: a pilot study

BACKGROUND

Postoperative acute kidney injury (AKI) is associated with poor clinical outcomes. Early identification of high-risk patients of developing postoperative AKI can optimize perioperative renal management and facilitate patient survival. The present study aims to develop and validate a nomogram to predict postoperative AKI after liver resection in older patients.

METHODS

A retrospective observational study was conducted involving data from 843 older patients scheduled for liver resection at a single tertiary high caseload general hospital between 2012 and 2019. The data were randomly divided into training (70%, n = 599) and validation (30%, n = 244) datasets. The training cohort was used to construct a predictive nomogram for postoperative AKI with the logistic regression model which was confirmed by a validation cohort. The model was evaluated by receiver operating characteristic (ROC) curve, calibration plot, and decision curve analysis in the validation cohort. A summary risk score was also constructed for identifying postoperative AKI patients.

RESULTS

Postoperative AKI occurred in 155 (18.4%) patients and was highly associated with in-hospital mortality (5.2% vs. 0.7%, P <  0.001). The six predictors selected and assembled into the nomogram included age, preexisting chronic kidney disease (CKD), non-steroidal anti-inflammatory drugs (NSAIDs) usage, intraoperative hepatic inflow occlusion, blood loss, and transfusion. The predictive nomogram performed well in terms of discrimination with area under ROC curve (AUC) in training (0.73, 95% confidence interval (CI): 0.68-0.78) and validation (0.71, 95% CI: 0.63-0.80) datasets. The nomogram was well-calibrated with the Hosmer-Lemeshow chi-square value of 9.68 (P = 0.47). Decision curve analysis demonstrated a significant clinical benefit. The summary risk score calculated as the sum of points from the six variables (one point for each variable) performed as well as the nomogram in identifying the risk of AKI (AUC 0.71, 95% CI: 0.66-0.76).

CONCLUSION

This nomogram and summary risk score accurately predicted postoperative AKI using six clinically accessible variables, with potential application in facilitating the optimized perioperative renal management in older patients undergoing liver resection.

TRIAL REGISTRATION

NCT04922866 , retrospectively registered on clinicaltrials.gov on June 11, 2021.

Analysis of Risk Factors for Perioperative Acute Kidney Injury and Management Strategies

Acute kidney injury (AKI) is a serious clinical syndrome, and one of the common comorbidities in the perioperative period. AKI can lead to complications in surgical patients and is receiving increasing attention in clinical workup. In recent years, the analysis of perioperative risk factors has become more in-depth and detailed. In this review, the definition, diagnosis, and pathophysiological characteristics of perioperative AKI are reviewed, and the main risk factors for perioperative AKI are analyzed, including advanced age, gender, certain underlying diseases, impaired clinical status such as preoperative creatinine levels, and drugs that may impair renal function such as non-steroidal anti-inflammatory drugs (NASIDs), ACEI/ARB, and some antibiotics. Injectable contrast agents, some anesthetic drugs, specific surgical interventions, anemia, blood transfusions, hyperglycemia, and malnutrition are also highlighted. We also propose potential preventive and curative measures, including the inclusion of renal risk confirmation in the preoperative assessment, minimization of intraoperative renal toxin exposure, intraoperative management and hemodynamic optimization, remote ischemic preadaptation, glycemic control, and nutritional support. Among the management measures, we emphasize the need for careful perioperative clinical examination, timely detection and management of AKI complications, administration of dexmedetomidine for renal protection, and renal replacement therapy. We aim that this review can further increase clinicians' attention to perioperative AKI, early assessment and intervention to try to reduce the risk of AKI.

Hyperglycemia on Admission Predicts Acute Kidney Failure and Renal Functional Recovery among Inpatients

BACKGROUND

Hyperglycemia is associated with adverse outcomes in hospitalized patients. We aimed to assess the impact of glucose levels upon admission on the subsequent deterioration or improvement of kidney function in inpatients with a focus on diabetes or reduced baseline kidney function as possible modifiers of this effect.

METHODS

Running a retrospective cohort analysis, we compared patients with normal vs. high glucose levels upon admission. We applied multivariable logistic regression models to study the association between baseline glucose levels with subsequent renal and clinical outcomes. Interaction terms were used to study a possible modifier effect of diabetes.

RESULTS

Among 95,556 inpatients (52% males, mean age 61 years), 15,675 (16.5%) had plasma glucose higher than 180 mg/dL, and 72% of them were diabetics. Patients with higher glucose at presentation were older, with a higher proportion of co-morbid conditions. Rates of acute kidney injury (AKI), acute kidney functional recovery (AKR), and mortality were proportional to reduced renal function. AKI, AKR, and mortality were almost doubled in patients with high baseline glucose upon admission. Multivariable analysis with interaction terms demonstrated an increasing adjusted probability of all events as glucose increased, yet this association was observed principally in non-diabetic patients.

CONCLUSIONS

Hyperglycemia is associated with AKI, AKR, and mortality in non-diabetic inpatients in proportion to the severity of their acute illness. This association diminishes in diabetic patients, suggesting a possible impact of treatable and easily reversible renal derangement in this population.

The potential for artificial intelligence to predict clinical outcomes in patients who have acquired acute kidney injury during the perioperative period

Acute kidney injury (AKI) is a common medical problem in hospitalised patients worldwide that may result in negative physiological, social and economic consequences. Amongst patients admitted to ICU with AKI, over 40% have had either elective or emergency surgery prior to admission. Predicting outcomes after AKI is difficult and the decision on whom to initiate RRT with a goal of renal recovery or predict a long-term survival benefit still poses a challenge for acute care physicians. With the increasing use of electronic healthcare records, artificial intelligence may allow postoperative AKI prognostication and aid clinical management. Patients will benefit if the data can be readily accessed andregulatory, ethical and human factors challenges can be overcome.

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 of Postoperative Renal Failure in Radical Nephrectomy and Nephroureterectomy: A Validated Risk Prediction Model

INTRODUCTION

The study aimed to construct and validate a risk prediction model for incidence of postoperative renal failure (PORF) following radical nephrectomy and nephroureterectomy.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database years 2005-2014 were used for the derivation cohort. A stepwise multivariate logistic regression analysis was conducted, and the final model was validated with an independent cohort from the ACS-NSQIP database years 2015-2017.

RESULTS

In cohort of 14,519 patients, 296 (2.0%) developed PORF. The final 9-factor model included age, gender, diabetes, hypertension, BMI, preoperative creatinine, hematocrit, platelet count, and surgical approach. Model receiver-operator curve analysis provided a C-statistic of 0.79 (0.77, 0.82; p < 0.001), and overall calibration testing R2 was 0.99. Model performance in the validation cohort provided a C-statistic of 0.79 (0.76, 0.81; p < 0.001).

CONCLUSION

PORF is a known risk factor for chronic kidney disease and cardiovascular morbidity, and is a common occurrence after unilateral kidney removal. The authors propose a robust and validated risk prediction model to aid in identification of high-risk patients and optimization of perioperative care.

Decreased urinary uromodulin is potentially associated with acute kidney injury: a systematic review and meta-analysis

BACKGROUND

Urinary uromodulin (uUMOD) is one of the novel biomarkers for predicting AKI. However, currently available publications showed inconsistent results. We designed this meta-analysis to evaluate the potential association between uUMOD and AKI.

METHODS

We searched research articles with no language restriction in Medline, Web of Science, Cochrane Library, Embase, and 3 Chinese datasets from inception to February 2021. We used random-effects models to estimate the standardized mean difference (SMD) between patients with AKI or not, while the leave-one-out method and random-effects meta-regression to evaluate the sensitivity and the impact of potential confounders such as age and surgery.

RESULTS

The meta-analysis comprising 3148 subjects from 11 studies showed that the uUMOD of the AKI group is significantly lower than the non-AKI group (SMD: - 0.71; 95% confidence interval (CI), - 1.00, - 0.42, P < 0. 001, I2 = 78.8%). Subgroup analysis revealed the difference is also significant in a different age, surgery condition, and assay time but not acute rejection (AR) group, especially in children (SMD: - 1.21, 95% CI: - 1.80, - 0.61; P < 0.001) and patients undergoing surgery (SMD: - 1.03, 95% CI: - 1.75, - 0.30; P < 0.001). Lower uromodulin is associated with higher odds for AKI incidence (odds ratio = 2.47, 95% CI: 1.12, 5.47; P < 0.001, I2 = 89%). Meta-reggression found that age was associated with the SMD of uUMOD. The study outcome was reliably confirmed by the sensitivity analysis.

CONCLUSION

The present study suggested a negative association between uUMOD and AKI especially in children and surgical patients.

Extracellular Vesicles: A New Paradigm for Cellular Communication in Perioperative Medicine, Critical Care, and Pain Management

Extracellular vesicles (EVs) play critical roles in many health and disease states, including ischemia, inflammation, and pain, which are major concerns in the perioperative period and in critically ill patients. EVs are functionally active, nanometer-sized, membrane-bound vesicles actively secreted by all cells. Cell signaling is essential to physiological and pathological processes, and EVs have recently emerged as key players in intercellular communication. Recent studies in EV biology have improved our mechanistic knowledge of the pathophysiological processes in perioperative and critical care patients. Studies also show promise in using EVs in novel diagnostic and therapeutic clinical applications. This review considers the current advances and gaps in knowledge of EVs in the areas of ischemia, inflammation, pain, and in organ systems that are most relevant to anesthesiology, perioperative medicine, critical care, and pain management. We expect the reader will better understand the relationship between EVs and perioperative and critical care pathophysiological states and their potential use as novel diagnostic and therapeutic modalities.

Impact of Inhaled Oxygen on Reactive Oxygen Species Production and Oxidative Damage during Spontaneous Ventilation in a Murine Model of Acute Renal Ischemia and Reperfusion

Introduction

Acute kidney injury (AKI) affects 10% of patients following major surgery and is independently associated with extra-renal organ injury, development of chronic kidney disease, and death. Perioperative renal ischemia and reperfusion (IR) contributes to AKI by, in part, increasing production of reactive oxygen species (ROS) and leading to oxidative damage. Variations in inhaled oxygen may mediate some aspects of IR injury by affecting tissue oxygenation, ROS production, and oxidative damage. We tested the hypothesis that provision of air (normoxia) compared to 100% oxygen (hyperoxia) during murine renal IR affects renal ROS production and oxidative damage.

Methods

We administered 100% oxygen or 21% oxygen (air) to 8-9 week-old FVB/N mice and performed dorsal unilateral nephrectomy with contralateral renal ischemia/reperfusion surgery while mice spontaneously ventilated. We subjected mice to 30 minutes of ischemia and 30 minutes of reperfusion prior to sacrifice. We obtained an arterial blood gas (ABG) by performing sternotomy and left cardiac puncture. We stained the kidney with pimonidazole, a marker of tissue hypoxia; 4-HNE, a marker of ROS-production; and we measured F2-isoprostanes in homogenized tissue to quantify oxidative damage.

Results

Hyperoxia during IR increased arterial oxygen content compared to normoxia, but both groups of mice were hypoventilating at the time of ABG sampling. Renal tissue hypoxia following reperfusion was similar in both treatment groups. ROS production was similar in the cortex of mice (3.8% area in hyperoxia vs. 3.1% in normoxia, P=0.19) but increased in the medulla of hyperoxia-treated animals (6.3% area in hyperoxia vs. 4.5% in nomoxia, P=0.02). Renal F2-isoprostanes were similar in treatment groups (2.2 pg/mg kidney in hyperoxia vs. 2.1 pg/mg in normoxia, P=0.40).

Conclusions

Hyperoxia during spontaneous ventilation in murine renal IR did not appear to affect renal hypoxia following reperfusion, but hyperoxia increased medullary ROS production compared to normoxia.

Sirtuin 5 depletion impairs mitochondrial function in human proximal tubular epithelial cells

Ischemia is a major cause of kidney damage. Proximal tubular epithelial cells (PTECs) are highly susceptible to ischemic insults that frequently cause acute kidney injury (AKI), a potentially life-threatening condition with high mortality. Accumulating evidence has identified altered mitochondrial function as a central pathologic feature of AKI. The mitochondrial NAD⁺-dependent enzyme sirtuin 5 (SIRT5) is a key regulator of mitochondrial form and function, but its role in ischemic renal injury (IRI) is unknown. SIRT5 expression was increased in murine PTECs after IRI in vivo and in human PTECs (hPTECs) exposed to an oxygen/nutrient deprivation (OND) model of IRI in vitro. SIRT5-depletion impaired ATP production, reduced mitochondrial membrane potential, and provoked mitochondrial fragmentation in hPTECs. Moreover, SIRT5 RNAi exacerbated OND-induced mitochondrial bioenergetic dysfunction and swelling, and increased degradation by mitophagy. These findings suggest SIRT5 is required for normal mitochondrial function in hPTECs and indicate a potentially important role for the enzyme in the regulation of mitochondrial biology in ischemia.

Prevention of hemorrhage-induced renal vasoconstriction and hypoxia by angiotensin II type 1 receptor antagonism in pigs

Angiotensin II (ANG II) is a potent vasoconstrictor and may reduce renal blood flow (RBF), causing renal hypoxia. Hypotensive hemorrhage elevates plasma ANG II levels and is associated with increased risk of acute kidney injury. We hypothesized that ANG II antagonism prevents renal vasoconstriction and hypoxia caused by hemorrhage. Pigs were anaesthetized, surgically prepared, and randomized to intravenous losartan (1.5 mg·kg^-1·h^-1, n = 8) or an equal volume of intravenous Ringer acetate (vehicle-treated, n = 8). Hemorrhage was induced by continuous aspiration of blood to reach and sustain mean arterial pressure of <50 mmHg for 30 min. Plasma ANG II levels, hemodynamics and oxygenation were assessed 60 min prehemorrhage, 30-min after the start of hemorrhage, and 60 min posthemorrhage. Erythropoietin mRNA was analyzed in cortical and medullary tissue sampled at the end of the experiment. Hypotensive hemorrhage increased plasma ANG II levels and decreased RBF and oxygen delivery in both groups. Losartan-treated animals recovered in RBF and oxygen delivery, whereas vehicle-treated animals had persistently reduced RBF and oxygen delivery. In accordance, renal vascular resistance increased over time post hemorrhage in vehicle-treated animals but was unchanged in losartan-treated animals. Renal oxygen extraction rate and cortical erythropoietin mRNA levels increased in the vehicle group but not in the losartan group. In conclusion, ANG II antagonism alleviates prolonged renal vasoconstriction and renal hypoxia in a large animal model of hypotensive hemorrhage.

Management of a Case of Aortic Valve Replacement with Left Ventricle Clot Removal Developing Acute Kidney Injury in Postoperative Period

Cardiac surgery associated-acute kidney injury (AKI) is a common and a serious complication of cardiac surgery requiring cardiopulmonary bypass and it is the second most common cause of AKI in intensive care unit. Recently, two consensus conferences have suggested new diagnostic criteria to define AKI and risk score to better identify patients who will develop AKI after cardiac surgery. In fact, prompt recognition of high-risk patients could allow a more aggressive management at a reversible stage of an incoming ARF. In this case report, we have discussed a case of 21-year-old patient with bicuspid aortic valve with severe aortic stenosis with ejection fraction 15% and left ventricle (LV) clot undergoing surgery for aortic valve replacement with LV clot removal. In the postoperative period, he developed AKI that was managed successfully by early intervention by slow low efficiency dialysis and diafiltration and hemodialysis and patient discharged successfully from hospital.

Preoperative proteinuria may be a risk factor for postoperative acute kidney injury：a meta-analysis

Objective

To investigate the relationship between preoperative proteinuria and postoperative acute kidney injury (AKI).

Methods

We performed a search on databases included PubMed, Embase, the Cochrane Library, and Web of Science, from December 2009 to September 2020. Data extracted from eligible studies were synthesized to calculate the odds ratio (OR) and 95% confidence interval (CI). A fixed or random effects model was applied to calculate the pooled OR based on heterogeneity through the included studies.

Results

This meta-analysis of 11 observational studies included 203,987 participants, of whom 21,621 patients suffered from postoperative AKI and 182,366 patients did not suffer from postoperative AKI. The combined results demonstrated that preoperative proteinuria is an independent risk factor for postoperative AKI (adjusted OR = 1.65, 95%CI:1.44–1.89, p < 0.001). Subgroup analysis showed that both preoperative mild proteinuria (adjusted OR = 1.30, 95%CI:1.24–1.36, p < 0.001) and preoperative heavy proteinuria (adjusted OR = 1.93, 95%CI:1.65–2.27, p < 0.001) were independent risk factors for postoperative AKI. The heterogeneity was combined because its values were lower. Further subgroup analysis found that preoperative proteinuria measured using dipstick was an independent risk factor for postoperative AKI (adjusted OR = 1.48, 95%CI:1.37–1.60, p < 0.001). Finally, preoperative proteinuria was an independent risk factor for postoperative AKI in the non-cardiac surgery group (adjusted OR = 2.06, 95%CI:1.31–3.24, p = 0.002) and cardiac surgery group (adjusted OR = 1.69, 95%CI:1.39–2.06, p < 0.001)

Conclusion

Preoperative proteinuria is an independent risk factor for postoperative AKI and in instances when proteinuria is detected using dipsticks.

Outcome of Organ Dysfunction in the Perioperative Period

While intraoperative mortality has diminished greatly over the last several decades, the risk of death within 30 days of surgery remains stubbornly high and is ultimately related to perioperative organ failure. Perioperative strokes, while rare (<2% in noncardiac surgery), are associated with a more than 10-fold increase in mortality. Rapid identification and treatment are key to maximizing long-term outcomes. Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) are separate but related perioperative neurological disorders, both of which are associated with poor long-term outcomes. To date, there are few known interventions that can ameliorate the risk of perioperative central nervous system dysfunction. Major adverse cardiac events (MACE) are a major contributor to adverse clinical outcomes following surgical procedures. Recently, advances in diagnostic strategies (eg, high-sensitivity cardiac troponin [hs-cTn] assays) have improved our understanding of MACE. Recently, the dabigatran in patients with myocardial injury after noncardiac surgery (MINS; Management of myocardial injury After NoncArdiac surGEry) trial demonstrated that a direct thrombin inhibitor could improve outcomes following MINS. While the risk of acute respiratory distress syndrome (ARDS) after surgery is approximately 0.2%, other less severe complications (eg, pneumonia, reintubation) are closer to 2%. While intensive care unit (ICU) concepts related to ARDS have migrated into the operating room, whether or not adverse pulmonary outcomes impact long-term outcomes in surgical patients remains a matter of debate. The standardization of acute kidney injury (AKI) definition has improved the ability of clinicians to measure and study the incidence of this important source of perioperative morbidity. AKI is associated with increased mortality as well as nonrenal morbidity (eg, myocardial infarction) after major surgery. Gastrointestinal complications after surgery range from ileus (common in abdominal procedures and associated with an increased length of stay) to less common complications such as mesenteric ischemia and gastrointestinal bleeding, both of which are associated with very high mortality. Outside of cardiothoracic surgery, the incidence of perioperative hepatic injury is not well described but, in this population, is associated with worsened long-term outcomes. Hyperglycemia is a common perioperative complication and occurs in patients undergoing both cardiac and noncardiac surgery. Both hyper- and hypoglycemia are associated with worsened long-term outcomes in cardiac and noncardiac surgery. Better diagnosis and increased understanding of perioperative organ injury has led to an increased appreciation for the specific role that particular organ systems play in poor long-term outcomes and has set the stage for targeted therapeutic interventions.

How new biomarkers aid the anesthetist to detect and prevent perioperative acute kidney injury

PURPOSE OF REVIEW

Acute kidney injury (AKI) is underestimated but common in the perioperative setting. Although the association of this syndrome with an increased morbidity and mortality has been well established, little progress has been made in the diagnosis or prevention of AKI in recent years. This is partly due to the late detection of AKI by conventional criteria based of functional biomarkers, serum creatinine, and urine output. In addition, conceptually AKI is now recognized as being part of a continuum, in which preventive intervention is time critical. This review will summarize the current best available evidence and explain why timely perioperative management does have impact on the development of AKI and overall outcomes for patients.

RECENT FINDINGS

Damage biomarkers can reliably identify AKI earlier than conventional functional biomarkers, facilitating more timely preventive intervention. Although the interventions published in the Kidney Disease: Improving Global Outcomes guideline are all important, the most relevant preventive options perioperatively include maintenance of adequate volume status and perfusion pressure, and the focus on balanced crystalloid solutions as maintenance fluid.

SUMMARY

AKI is a time critical syndrome that requires timely detection and damage biomarkers can help to adjust the perioperative management to prevent further injury.

Perioperative use of serum creatinine and postoperative acute kidney injury: a single-centre, observational retrospective study to explore physicians' perception and practice

BACKGROUND

Postoperative acute kidney injury (PO-AKI) is a leading cause of short- and long-term morbidity and mortality, as well as progression to chronic kidney disease (CKD). The aim of this study was to explore the physicians' attitude toward the use of perioperative serum creatinine (sCr) for the identification of patients at risk for PO-AKI and long-term CKD. We also evaluated the incidence and risk factors associated with PO-AKI and renal function deterioration in patients undergoing major surgery for malignant disease.

METHODS

Adult oncological patients who underwent major abdominal surgery from November 2016 to February 2017 were considered for this single-centre, observational retrospective study. Routinely available sCr values were used to define AKI in the first three postoperative days. Long-term kidney dysfunction (LT-KDys) was defined as a reduction in the estimated glomerular filtration rate by more than 10 ml/min/m² at 12 months postoperatively. A questionnaire was administered to 125 physicians caring for the enrolled patients to collect information on local attitudes regarding the use of sCr perioperatively and its relationship with PO-AKI.

RESULTS

A total of 423 patients were observed. sCr was not available in 59 patients (13.9%); the remaining 364 (86.1%) had at least one sCr value measured to allow for detection of postoperative kidney impairment. Among these, PO-AKI was diagnosed in 8.2% of cases. Of the 334 patients who had a sCr result available at 12-month follow-up, 56 (16.8%) developed LT-KDys. Data on long-term kidney function were not available for 21% of patients. Interestingly, 33 of 423 patients (7.8%) did not have a sCr result available in the immediate postoperative period or long term. All the physicians who participated in the survey (83 out of 125) recognised that postoperative assessment of sCr is required after major oncological abdominal surgery, particularly in those patients at high risk for PO-AKI and LT-KDys.

CONCLUSION

PO-AKI after major surgery for malignant disease is common, but clinical practice of measuring sCr is variable. As a result, the exact incidence of PO-AKI and long-term renal prognosis are unclear, including in high-risk patients.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT04341974 .

Perioperative Clinical Trials in AKI

To characterize current evidence and current foci of perioperative clinical trials, we systematically reviewed Medline and identified perioperative trials involving 100 or more adult patients undergoing surgery and reporting renal end points that were published in high-impact journals since 2004. We categorized the 101 trials identified based on the nature of the intervention and summarized major trial findings from the five categories most applicable to perioperative management of patients. Trials that targeted ischemia suggested that increasing perioperative renal oxygen delivery with inotropes or blood transfusion does not reliably mitigate acute kidney injury (AKI), although goal-directed therapy with hemodynamic monitors appeared beneficial in some trials. Trials that have targeted inflammation or oxidative stress, including studies of nonsteroidal anti-inflammatory drugs, steroids, N-acetylcysteine, and sodium bicarbonate, have not shown renal benefits, and high-dose perioperative statin treatment increased AKI in some patient groups in two large trials. Balanced crystalloid intravenous fluids appear safer than saline, and crystalloids appear safer than colloids. Liberal compared with restrictive fluid administration reduced AKI in a recent large trial in open abdominal surgery. Remote ischemic preconditioning, although effective in several smaller trials, failed to reduce AKI in two larger trials. The translation of promising preclinical therapies to patients undergoing surgery remains poor, and most interventions that reduced perioperative AKI compared novel surgical management techniques or existing processes of care rather than novel pharmacologic interventions.

Mild increases in plasma creatinine after intermediate to high-risk abdominal surgery are associated with long-term renal injury

BACKGROUND

The potential relationship between a mild acute kidney injury (AKI) observed in the immediate postoperative period after major surgery and its effect on long term renal function remains poorly defined. According to the "Kidney Disease: Improving Global Outcomes" (KDIGO) classification, a mild injury corresponds to a KIDIGO stage 1, characterized by an increase in creatinine of at least 0.3 mg/dl within a 48-h window or 1.5 to 1.9 times the baseline level within the first week post-surgery. We tested the hypothesis that patients who underwent intermediate-to high-risk abdominal surgery and developed mild AKI in the following days would be at an increased risk of long-term renal injury compared to patients with no postoperative AKI.

METHODS

All consecutive adult patients with a plasma creatinine value ≤1.5 mg/dl who underwent intermediate-to high-risk abdominal surgery between 2014 and 2019 and who had at least three recorded creatinine measurements (before surgery, during the first seven postoperative days, and at long-term follow up [6 months-2 years]) were included. AKI was defined using a "modified" (without urine output criteria) KDIGO classification as mild (stage 1 characterised by an increase in creatinine of > 0.3 mg/dl within 48-h or 1.5-1.9 times baseline) or moderate-to-severe (stage 2-3 characterised by increase in creatinine 2 to 3 times baseline or to ≥4.0 mg/dl). The exposure (postoperative kidney injury) and outcome (long-term renal injury) were defined and staged according to the same KDIGO initiative criteria. Development of long-term renal injury was compared in patients with and without postoperative AKI.

RESULTS

Among the 815 patients included, 109 (13%) had postoperative AKI (81 mild and 28 moderate-to-severe). The median long-term follow-up was 360, 354 and 353 days for the three groups respectively (P = 0.2). Patients who developed mild AKI had a higher risk of long-term renal injury than those who did not (odds ratio 3.1 [95%CI 1.7-5.5]; p < 0.001). In multivariable analysis, mild postoperative AKI was independently associated with an increased risk of developing long-term renal injury (adjusted odds ratio 4.5 [95%CI 1.8-11.4]; p = 0.002).

CONCLUSIONS

Mild AKI after intermediate-to high-risk abdominal surgery is associated with a higher risk of long-term renal injury 1 y after surgery.

Urinary neprilysin for early detection of acute kidney injury after cardiac surgery: A prospective observational study

BACKGROUND

Acute kidney injury (AKI) predicts adverse outcomes after cardiac surgery. The accuracy of using changes in serum creatinine for diagnosis and grading of AKI is limited in the peri-operative cardiac surgical setting and AKI may be underdiagnosed due to haemodilution from cardiopulmonary bypass priming and the need for intra-operative and postoperative volume resuscitation.

OBJECTIVES

To determine whether the urinary biomarker neprilysin can be used as a marker for the early detection of AKI after cardiac surgery.

DESIGN

Prospective, observational cohort study.

SETTING

Austrian tertiary referral centre.

PATIENTS

96 Patients undergoing elective cardiac surgery with cardiopulmonary bypass.

MAIN OUTCOME MEASURES

Differences and discriminatory power of neprilysin levels early after cardiac surgery and on postoperative day 1 between patients with or without AKI, as defined by the Kidney Disease Improving Global Outcomes Group.

RESULTS

AKI was found in 27% (n=26). The median neprilysin levels on postoperative day 1 were significantly higher in the AKI than in the non-AKI group, 4.0 [interquartile range (IQR): 2 to 6.25] vs. 2.0 ng ml [IQR: 1.0 to 4.5], P = 0.0246, respectively. In addition, the median neprilysin levels at the end of surgery were significantly different between both groups, 5.0 [IQR: 2.0 to 9.0] vs. 2.0 ng ml [IQR: 1.0 to 4.0], P = 0.0055, respectively. The discriminatory power of neprilysin for detecting early AKI corresponded to an area under the curve of 0.77 (95% confidence interval, 0.65 to 0.90).

CONCLUSION

Urinary neprilysin has potential as a biomarker for the early detection of AKI after cardiac surgery and has comparable discriminatory power to recently studied AKI biomarkers.

TRIAL REGISTRATION

The trial was registered at ClinicalTrials.gov (NCT03854825, https://clinicaltrials.gov/ct2/show/NCT03854825).

Dl-3-n-butylphthalide pretreatment attenuates renal ischemia/reperfusion injury

BACKGROUND

Renal ischemia reperfusion injury (IRI) has become a growing concern in clinical practice with high morbidity and mortality rates. There is currently no effective prophylactic regimen available to prevent its occurrence and to improve its clinical prognosis. Dl-3-n-butylphthalide (NBP) has been used for stroke treatment in China for years. Little is known about its role in preventing kidney injury.

METHODS

The kidneys of male C57BL/6J mice were subjected to 33 min of ischemia followed by 24 h of reperfusion. NBP was administered by gavage prior to surgery. The reno-protective effect of NBP was evaluated by serum creatinine, kidney injury markers and renal pathological changes. Furthermore, the inflammation, oxidative stress, and apoptosis markers in kidney tissue were examined. In vitro, HK2 cells were treated prophylactically with NBP and then exposed to hypoxia/reoxygenation (H/R). Cell viability and apoptosis related protein were quantified to verify the protective effect of NBP. Pro-inflammation genes expression as well as ROS generation were further investigated also.

RESULTS

NBP pretreatment significantly improved renal dysfunction and alleviated pathological injury, renal inflammation response, oxidative stress and cell apoptosis. Consistently, NBP attenuated H/R induced increases in ROS, pro-inflammatory genes expression, apoptosis and cleaved caspase-3 levels in HK2 cells.

CONCLUSION

Our promising results validated for the first time that NBP could ameliorate renal IRI via attenuating inflammation, oxidative stress, and apoptosis, which indicated that NBP might be a good candidate against AKI.

Perioperative acute kidney injury following major abdominal surgery

Major abdominal surgery is associated with significant morbidity, not least the development of acute kidney injury. As a common perioperative complication, acute kidney injury is associated with increased length of stay, increased risk of perioperative infection and the potential development of chronic kidney disease. Moreover, the development of acute kidney injury is independently associated with an increased risk of death. Perioperative acute kidney injury is not a single entity, but describes a clinical syndrome with multiple causes including physical causes related to the surgical procedure, ischaemia-reperfusion injury and the use of potential nephrotoxins. Currently, acute kidney injury is defined by changes in serum creatinine level and urine output criteria, which although robust in heterogenous populations, may not perform as accurately in the perioperative period. This article discusses these issues including the potential role of novel biomarkers for early detection of perioperative acute kidney injury, as well as the use of predictive modelling. Treatment is mainly supportive but evidence suggests that more targeted therapy may lead to improved outcomes.

Perioperative Pain Management and Opioid Stewardship: A Practical Guide

Surgical procedures are key drivers of pain development and opioid utilization globally. Various organizations have generated guidance on postoperative pain management, enhanced recovery strategies, multimodal analgesic and anesthetic techniques, and postoperative opioid prescribing. Still, comprehensive integration of these recommendations into standard practice at the institutional level remains elusive, and persistent postoperative pain and opioid use pose significant societal burdens. The multitude of guidance publications, many different healthcare providers involved in executing them, evolution of surgical technique, and complexities of perioperative care transitions all represent challenges to process improvement. This review seeks to summarize and integrate key recommendations into a "roadmap" for institutional adoption of perioperative analgesic and opioid optimization strategies. We present a brief review of applicable statistics and definitions as impetus for prioritizing both analgesia and opioid exposure in surgical quality improvement. We then review recommended modalities at each phase of perioperative care. We showcase the value of interprofessional collaboration in implementing and sustaining perioperative performance measures related to pain management and analgesic exposure, including those from the patient perspective. Surgery centers across the globe should adopt an integrated, collaborative approach to the twin goals of optimal pain management and opioid stewardship across the care continuum.

Fighting Oxidative Stress with Sulfur: Hydrogen Sulfide in the Renal and Cardiovascular Systems

Hydrogen sulfide (H2S) is an essential gaseous signaling molecule. Research on its role in physiological and pathophysiological processes has greatly expanded. Endogenous enzymatic production through the transsulfuration and cysteine catabolism pathways can occur in the kidneys and blood vessels. Furthermore, non-enzymatic pathways are present throughout the body. In the renal and cardiovascular system, H2S plays an important role in maintaining the redox status at safe levels by promoting scavenging of reactive oxygen species (ROS). H2S also modifies cysteine residues on key signaling molecules such as keap1/Nrf2, NFκB, and HIF-1α, thereby promoting anti-oxidant mechanisms. Depletion of H2S is implicated in many age-related and cardiorenal diseases, all having oxidative stress as a major contributor. Current research suggests potential for H2S-based therapies, however, therapeutic interventions have been limited to studies in animal models. Beyond H2S use as direct treatment, it could improve procedures such as transplantation, stem cell therapy, and the safety and efficacy of drugs including NSAIDs and ACE inhibitors. All in all, H2S is a prime subject for further research with potential for clinical use.

The incidence, risk, presentation, pathophysiology, treatment, and effects of perioperative acute kidney injury

PURPOSE

Present clinical updates, current research findings, and consensus statements relevant to the care of the acute kidney injury (AKI) patient.

PRINCIPAL FINDINGS

Acute kidney injury is one of the most frequent and debilitating complications of surgery and critical illness. Consensus criteria use serum creatinine and urine output measurements to diagnose AKI and allow for objective diagnosis and more accurate comparisons across populations. New serum and urine biomarkers may provide earlier evidence of AKI, but their clinical utility, while increasing, remains limited. Avoidance of nephrotoxins, intravascular fluid management, and maintenance of renal perfusion are the mainstays of preventive management and treatment of AKI. Optimal timing for the initiation of renal replacement therapy is controversial and remains under investigation.

CONCLUSIONS

Acute kidney injury continues to affect large numbers of patients receiving surgery or in the intensive care unit, but specific advances in resuscitation techniques, endpoint refinements, epidemiology, biomarkers, and pathology are providing the necessary framework to reduce AKI and associated morbidity.

Intraoperative venous congestion and acute kidney injury in cardiac surgery: an observational cohort study

BACKGROUND

Increased intravascular volume has been associated with protection from acute kidney injury (AKI), but in patients with congestive heart failure, venous congestion is associated with increased AKI. We tested the hypothesis that intraoperative venous congestion is associated with AKI after cardiac surgery.

METHODS

In patients enrolled in the Statin AKI Cardiac Surgery trial, venous congestion was quantified as the area under the curve (AUC) of central venous pressure (CVP) >12, 16, or 20 mm Hg during surgery (mm Hg min). AKI was defined using Kidney Disease Improving Global Outcomes (KDIGO) criteria and urine concentrations of tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 ([TIMP-2]⋅[IGFBP7]), a marker of renal stress. We measured associations between venous congestion, AKI and [TIMP-2]⋅[IGFBP7], adjusted for potential confounders. Values are reported as median (25th-75th percentile).

RESULTS

Based on KDIGO criteria, 104 of 425 (24.5%) patients developed AKI. The venous congestion AUCs were 273 mm Hg min (81-567) for CVP >12 mm Hg, 66 mm Hg min (12-221) for CVP >16 mm Hg, and 11 mm Hg min (1-54) for CVP >20 mm Hg. A 60 mm Hg min increase above the median venous congestion AUC above each threshold was independently associated with increased AKI (odds ratio=1.06; 95% confidence interval [CI], 1.02-1.10; P=0.008; odds ratio=1.12; 95% CI, 1.02-1.23; P=0.013; and odds ratio=1.30; 95% CI, 1.06-1.59; P=0.012 for CVP>12, >16, and >20 mm Hg, respectively). Venous congestion before cardiopulmonary bypass was also associated with increased [TIMP-2]⋅[IGFBP7] measured during cardiopulmonary bypass and after surgery, but neither venous congestion after cardiopulmonary bypass nor venous congestion throughout surgery was associated with postoperative [TIMP-2]⋅[IGFBP7].

CONCLUSION

Intraoperative venous congestion was independently associated with increased AKI after cardiac surgery.

Postoperative acute kidney injury in adult non-cardiac surgery: joint consensus report of the Acute Disease Quality Initiative and PeriOperative Quality Initiative

Postoperative acute kidney injury (PO-AKI) is a common complication of major surgery that is strongly associated with short-term surgical complications and long-term adverse outcomes, including increased risk of chronic kidney disease, cardiovascular events and death. Risk factors for PO-AKI include older age and comorbid diseases such as chronic kidney disease and diabetes mellitus. PO-AKI is best defined as AKI occurring within 7 days of an operative intervention using the Kidney Disease Improving Global Outcomes (KDIGO) definition of AKI; however, additional prognostic information may be gained from detailed clinical assessment and other diagnostic investigations in the form of a focused kidney health assessment (KHA). Prevention of PO-AKI is largely based on identification of high baseline risk, monitoring and reduction of nephrotoxic insults, whereas treatment involves the application of a bundle of interventions to avoid secondary kidney injury and mitigate the severity of AKI. As PO-AKI is strongly associated with long-term adverse outcomes, some form of follow-up KHA is essential; however, the form and location of this will be dictated by the nature and severity of the AKI. In this Consensus Statement, we provide graded recommendations for AKI after non-cardiac surgery and highlight priorities for future research.

Perioperative Renoprotection: General Mechanisms and Treatment Approaches

In the perioperative setting, acute kidney injury (AKI) is a frequent complication, and AKI itself is associated with adverse outcomes such as higher risk of chronic kidney disease and mortality. Various risk factors are associated with perioperative AKI, and identifying them is crucial to early interventions addressing modifiable risk and increasing monitoring for nonmodifiable risk. Different mechanisms are involved in the development of postoperative AKI, frequently picturing a multifactorial etiology. For these reasons, no single renoprotective strategy will be effective for all surgical patients, and efforts have been attempted to prevent kidney injury in different ways. Some renoprotective strategies and treatments have proven to be useful, some are no longer recommended because they are ineffective or even harmful, and some strategies are still under investigation to identify the best timing, setting, and patients for whom they could be beneficial. With this review, we aim to provide an overview of recent findings from studies examining epidemiology, risk factors, and mechanisms of perioperative AKI, as well as different renoprotective strategies and treatments presented in the literature.

Disease Mechanisms of Perioperative Organ Injury

Despite substantial advances in anesthesia safety within the past decades, perioperative mortality remains a prevalent problem and can be considered among the top causes of death worldwide. Acute organ failure is a major risk factor of morbidity and mortality in surgical patients and develops primarily as a consequence of a dysregulated inflammatory response and insufficient tissue perfusion. Neurological dysfunction, myocardial ischemia, acute kidney injury, respiratory failure, intestinal dysfunction, and hepatic impairment are among the most serious complications impacting patient outcome and recovery. Pre-, intra-, and postoperative arrangements, such as enhanced recovery after surgery programs, can contribute to lowering the occurrence of organ dysfunction, and mortality rates have improved with the advent of specialized intensive care units and advances in procedures relating to extracorporeal organ support. However, no specific pharmacological therapies have proven effective in the prevention or reversal of perioperative organ injury. Therefore, understanding the underlying mechanisms of organ dysfunction is essential to identify novel treatment strategies to improve perioperative care and outcomes for surgical patients. This review focuses on recent knowledge of pathophysiological and molecular pathways leading to perioperative organ injury. Additionally, we highlight potential therapeutic targets relevant to the network of events that occur in clinical settings with organ failure.

Management of Common Postoperative Complications

Postoperative complications are common. Major guidelines have been published on stratifying and managing adverse cardiovascular events and thromboembolic events, but there is often less literature supporting management of other, more common, postoperative complications, including acute kidney injury, gastrointestinal complications, postoperative anemia, fever, and delirium. These common conditions are frequently seen in hospital and can contribute to longer lengths of stay and rising health care costs. These complications are often due to the interplay between both patient-specific and surgery-specific risk factors. Identifying these risk factors, while addressing and optimizing modifiable risks, can mitigate the likelihood of developing these postoperative complications. Often, a multidisciplinary approach, including care team members through all phases of the surgical encounter, is needed. Cardiovascular and thrombotic complications have been addressed in prior articles in this perioperative series. We aim to cover other common postoperative complications, such as acute renal failure, postoperative gastrointestinal complications, anemia, fever, and delirium that often contribute to longer lengths of stay, rising health care costs, and increased morbidity and mortality for patients.

Pre-treatment with the angiotensin receptor 1 blocker losartan protects renal blood flow and oxygen delivery after propofol-induced hypotension in pigs

Hypotensive events are strongly correlated to the occurrence of perioperative acute kidney injury, but the underlying mechanisms for this are not completely elucidated. We hypothesised that anaesthesia-induced hypotension causes renal vasoconstriction and decreased oxygen delivery via angiotensin II-mediated renal vasoconstriction. Pigs were anaesthetised, surgically prepared and randomised to vehicle/losartan treatment (0.15 mg*kg⁻¹). A deliberate reduction in arterial blood pressure was caused by infusion of propofol (30 mg*kg⁻¹) for 10 min. Renal function and haemodynamics were recorded 60 min before and after hypotension. Propofol induced hypotension in all animals (p < 0.001). Renal blood flow (RBF) and renal oxygen delivery (RDO₂) decreased significantly regardless of treatment but more so in vehicle-treated compared to losartan-treated (p = 0.001, p = 0.02, respectively). During recovery RBF and RDO₂ improved to a greater extent in the losartan-treated compared to vehicle-treated (+ 28 ml*min⁻¹, 95%CI 8–50 ml*min⁻¹, p = 0.01 and + 3.1 ml*min⁻¹, 95%CI 0.3–5.8 ml*min⁻¹, p = 0.03, respectively). Sixty minutes after hypotension RBF and RDO₂ remained depressed in vehicle-treated, as renal vascular resistance was still increased (p < 0.001). In losartan-treated animals RBF and RDO₂ had normalised. Pre-treatment with losartan improved recovery of renal blood flow and renal oxygen delivery after propofol-induced hypotension, suggesting pronounced angiotensin II-mediated renal vasoconstriction during blood pressure reductions caused by anaesthesia.

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.

Perioperative Risk Factors Associated With Acute Kidney Injury in Patients After Brain Tumor Resection

BACKGROUND

Acute kidney injury (AKI) is a serious complication after surgery. The aim of this study is to identify risk factors for postoperative AKI in patients undergoing brain tumor surgery.

METHODS

This single-center, retrospective, matched case-control study included patients undergoing elective brain tumor surgery between January 2016 and December 2018 at Beijing Tiantan Hospital, Capital Medical University, China. Patients developing postoperative AKI were compared with controls without AKI matched by age, sex, and date of surgery in a ratio of 1:3. AKI was defined using the Kidney Disease Improving Global Outcomes criteria.

RESULTS

A total of 9933 patients were identified for review, of which 115 (1.16%) developed AKI; 345 matched patients were included in the control group. AKI occurred most commonly within the first 24 hours (41/97, 42.3%) and 48 hours (33/94, 35.1%) after surgery. Preoperative administration of mannitol (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.04-2.60; P= 0.034), American Society of Anesthesiologists physical status III or higher (OR, 5.50; 95% CI, 2.23-13.59; P<0.001), preoperative blood glucose (OR, 2.53; 95% CI, 1.23-5.22; P=0.012), craniopharyngioma (OR, 8.96; 95% CI, 3.55-22.63; P<0.001), nonsteroidal anti-inflammatory drug administration (OR, 3.74; 95% CI, 1.66-8.42; P<0.001), and intraoperative hypotension (OR, 2.13; 95% CI, 1.21-3.75; P=0.009) were independent risk factors for postoperative AKI.

CONCLUSION

Multiple factors, including preoperative administration of mannitol, are independently associated with the development of postoperative AKI in patients undergoing brain tumor surgery.

Restrictive intraoperative fluid management was associated with higher incidence of composite complications compared to less restrictive strategies in open thoracotomy: A retrospective cohort study

Restrictive fluid management has been recommended for thoracic surgery. However, specific guidelines are lacking, and there is always concern regarding impairment of renal perfusion with a restrictive policy. The objective of this study was to find the net intraoperative fluid infusion rate which shows the lowest incidence of composite complications (either pulmonary complications or acute kidney injury) in open thoracotomy. We hypothesized that a certain range of infusion rate would decrease the composite complications within postoperative 30 days. All patients (n = 1,031) who underwent open thoracotomy at a tertiary care university hospital were included in this retrospective study. The time frame of fluid monitoring was from the start of operation to postoperative 24 hours. The cutoff value of the intraoperative net fluid amount was 4–5 ml.kg⁻¹.h⁻¹ according to the minimum p-value method, thus, patients were divided into Low (≤3 ml.kg⁻¹.h⁻¹), Cutoff (4–5 ml.kg⁻¹.h⁻¹) and High (≥6 ml.kg⁻¹.h⁻¹) groups. The Cutoff group showed the lowest composite complication rate (19%, 12%, and 13% in the Low, Cutoff, and High groups, respectively, P = 0.0283; Low vs. Cutoff, P = 0.0324, Bonferroni correction). Acute respiratory distress syndrome occurred least frequently in the Cutoff group (7%, 3%, and 6% for the Low, Cutoff, and High groups, respectively, P = 0.0467; Low vs. Cutoff, P = 0.0432, Bonferroni correction). In multivariable analysis, intraoperative net fluid infusion rate was associated with composite complications, and the Cutoff group decreased risk (odds ratio 0.54, 95% confidence interval: 0.35–0.81, P = 0.0035). In conclusion, maintaining intraoperative net fluid infusion at 4–5 ml.kg⁻¹.h⁻¹ was associated with better results in open thoracotomy, in terms of composite complications, compared to more restrictive fluid management.

Community Health Care Quality Standards to Prevent Acute Kidney Injury and Its Consequences

As the incidence of acute kidney injury (AKI) increases, prevention strategies are needed across the health care continuum, which begins in the community. Recognizing this knowledge gap, the 22nd Acute Disease Quality Initiative (ADQI) was tasked to discuss the evidence for quality-of-care measurement and care processes to prevent AKI and its consequences in the community. Using a modified Delphi process, an international and interdisciplinary group provided a framework to identify and monitor patients with AKI in the community. The recommendations propose that risk stratification involve both susceptibilities (eg, chronic kidney disease) and exposures (eg, coronary angiography), with the latter triggering a Kidney Health Assessment. This assessment should include blood pressure, serum creatinine, and urine dipstick, followed by a Kidney Health Response to prevent AKI that encompasses cessation of unnecessary medications, minimization of nephrotoxins, patient education, and ongoing monitoring until the exposure resolves. These recommendations give community health care providers and health systems a starting point for quality improvement initiatives to prevent AKI and its consequences in the community.

ACUTE KIDNEY INJURY FOLLOWING SURGERY FOR HIP FRACTURE

Objective:

An observational study was carried out to determine the rate of acute kidney injury (AKI) following surgery for hip fracture at our institution and to look for factors associated with AKI.

Methods:

Preoperative creatinine values were compared to post-operative results for all patients who underwent surgery for hip fracture at our institution between 1^st January 2015 and 30^th September 2016. AKI was defined as an increase in postoperative creatinine, greater than or equal to 1.5 times the preoperative value within 7 days. Chi-squared test and Student’s t-test were used to look for factors associated with AKI.

Results:

Out of 500 patients, 96 developed an AKI (19.2%). Patients with chronic kidney disease (CKD) were more likely to develop AKI (30.8%) that those without it (17.2%, p = 0.018). Similarly, patients with 2 or more comorbidities were more likely to develop AKI (22.0%) than those without it (12.4%, p = 0.009). No statistically significant association was observed between type of surgery and AKI.

Conclusion:

A large proportion of patients following surgery for hip fracture developed AKI. Patients with CKD and the presence of 2 or more comorbidities had significantly higher rates of AKI. Level III evidence, Retrospective comparative study.

Perioperative acute kidney injury: Stratification and risk reduction strategies

Perioperative acute kidney injury (AKI) is associated with increased morbidity and mortality. Patient comorbidities, the type of surgery, timing of surgery, and exposure to nephrotoxins are important contributors for developing acute kidney injury. Urgent or emergent surgery, cardiac, and organ transplantation procedures are associated with a higher risk of acute kidney injury. Nephrotoxic drugs, contrast dye, and diuretics can worsen preexisting kidney dysfunction or act as an additive and/or synergistic insult to perioperative injury. A history of preoperative chronic kidney disease is the main risk factor for developing AKI, conferring as much as a 10-fold risk. However, beyond the preoperative renal function, the development of AKI is a complex phenomenon that involves a combination of patient-related and surgery-related factors.

Postoperative Complications After Colorectal Surgery: Where Are We in the Era of Enhanced Recovery?

PURPOSE OF REVIEW

Individual elements in enhanced recovery pathways may be associated with specific complication risks. In this review, we highlight three areas of controversy surrounding complications in enhanced recovery: (1) whether enhanced recovery is associated with increased rates of acute kidney injury, (2) whether NSAID use is associated with anastomotic leaks, and (3) whether early urinary catheter removal is justified following colorectal surgery.

RECENT FINDINGS

Acute kidney injury has been reported at several institutions following implementation of enhanced recovery pathways highlighting the importance of institutional data tracking. NSAID use has been implicated in anastomotic leak rates for non-elective colorectal procedures, and criteria for its use should be implemented. Early urinary catheter removal has been supported despite increased urinary retention rates in order to decrease urinary tract infections. Enhanced recovery protocols will continue to evolve, and risk profiles associated with individual elements should continue to be evaluated.

Acute Kidney Injury Associated with Cardiac Surgery: a Comprehensive Literature Review

Objective

To comprehensively understand cardiac surgeryassociated acute kidney injury (CSA-AKI) and methods of prevention of such complication in cardiac surgery patients.

Methods

A comprehensive literature search was performed using the electronic database to identify articles describing acute kidney injury (AKI) in patients that undergone cardiac surgery. There was neither time limit nor language limit on the search. The results were narratively summarized.

Results

All the relevant articles have been extracted; results have been summarized in each related section. CSA-AKI is a serious postoperative complication and it can contribute to a significant increase in perioperative morbidity and mortality rates. Optimization of factors that can reduce CSA-AKI, therefore, contributes to a better postoperative outcome.

Conclusion

Several factors can significantly increase the rate of AKI; identification and minimization of such factors can lead to lower rates of CSA-AKI and lower perioperative morbidity and mortality rates.

Remote Ischaemic Preconditioning Reduces Kidney Injury Biomarkers in Patients Undergoing Open Surgical Lower Limb Revascularisation: A Randomised Trial

Background and Aims

Perioperative kidney injury affects 12.7% of patients undergoing lower limb revascularisation surgery. Remote ischaemic preconditioning (RIPC) is a potentially protective procedure against organ damage and consists of short nonlethal episodes of ischaemia. The main objective of this substudy was to evaluate the effect of RIPC on kidney function, inflammation, and oxidative stress in patients undergoing open surgical lower limb revascularisation. Materials and Methods. This is a subgroup analysis of a randomised, sham-controlled, double-blinded, single-centre study. A RIPC or a sham procedure was performed noninvasively along with preparation for anaesthesia in patients undergoing open surgical lower limb revascularisation. The RIPC protocol consisted of 4 cycles of 5 minutes of ischaemia, with 5 minutes of reperfusion between every episode. Blood was collected for analysis preoperatively, 2, 8, and 24 hours after surgery, and urine was collected preoperatively and 24 hours after surgery.

Results

Data of 56 patients were included in the analysis. Serum creatinine, cystatin C, and beta-2 microglobulin increased, and eGFR decreased across all time points significantly more in the sham group than in the RIPC group (p = 0.021, p = 0.021, p = 0.021, p = 0.021, p = 0.021,

Conclusions

Our finding of reduced release of kidney injury biomarkers may indicate the renoprotective effect of RIPC in patients undergoing open surgical lower limb revascularisation. The trial is registered with ClinicalTrials.gov NCT02689414.

A narrative review of the impact of surgery and anaesthesia on acute kidney injury

The epidemiology of peri-operative acute kidney injury varies depending on the definition, type of surgery and acute and chronic comorbidities. Haemodynamic instability, disturbance of the microcirculation, endothelial dysfunction, inflammation and tubular cell injury are the main factors contributing to the pathogenesis. There are no specific therapies. The most effective strategies to protect renal function during the peri-operative period are: the avoidance of nephrotoxic insults; optimisation of haemodynamics; prevention of hypotension; and meticulous fluid management, including avoidance of both hypovolaemia and hypervolaemia. Peri-operative acute kidney injury is associated with an increased risk of short- and long-term postoperative complications, including a longer stay in hospital, development of premature chronic kidney disease and increased mortality. Resource utilisation and healthcare costs are also higher. In future, the development of advanced clinical prediction scores, new imaging and monitoring techniques and the application of new biomarkers for acute kidney injury have the prospect of identifying acute kidney injury earlier and allowing a more personalised management approach with the aim of reducing the global burden of acute kidney injury.

Perioperative Acute Kidney Injury

Perioperative organ injury is among the leading causes of morbidity and mortality of surgical patients. Among different types of perioperative organ injury, acute kidney injury occurs particularly frequently and has an exceptionally detrimental effect on surgical outcomes. Currently, acute kidney injury is most commonly diagnosed by assessing increases in serum creatinine concentration or decreased urine output. Recently, novel biomarkers have become a focus of translational research for improving timely detection and prognosis for acute kidney injury. However, specificity and timing of biomarker release continue to present challenges to their integration into existing diagnostic regimens. Despite many clinical trials using various pharmacologic or nonpharmacologic interventions, reliable means to prevent or reverse acute kidney injury are still lacking. Nevertheless, several recent randomized multicenter trials provide new insights into renal replacement strategies, composition of intravenous fluid replacement, goal-directed fluid therapy, or remote ischemic preconditioning in their impact on perioperative acute kidney injury. This review provides an update on the latest progress toward the understanding of disease mechanism, diagnosis, and managing perioperative acute kidney injury, as well as highlights areas of ongoing research efforts for preventing and treating acute kidney injury in surgical patients.

Preventive effects of fraxin on ischemia/reperfusion-induced acute kidney injury in rats

AIM

Kidney ischemia reperfusion (IR) injury is an important health problem resulting in acute kidney failure. The oxidative stress and inflammatory process are the underlying mechanisms of IR injury. It has been purposed in this study to research the possible protective effects of fraxin on kidney injury induced by IR.

MATERIAL AND METHODS

32 Sprague Dawley male rats were divided into 4 groups. The groups were organized as follows; sham, IR, IR + fraxin 10 mg/kg, and IR + 50 mg/kg fraxin groups. Some oxidant, antioxidant and inflammatory parameters were evaluated in kidney tissues removed at the end of our experimental study.

KEY FINDINGS

It was detected that the oxidant and proinflammatory markers increased and antioxidant parameters decreased in IR group but the results significantly reversed in treatment groups compared to IR group. And also, 8-OHdG, NF-κB, HAVCR1 immunopositivities were at severe levels and these results attenuated in IR fraxin + 10 mg/kg, and IR + fraxin 50 mg/kg groups.

SIGNIFICANCE

These presented results have shown that fraxin performed protective effects against kidney injury induced by IR.

Anesthesiologists Guide to the 2019 AHA/ACC/HRS Focused Update for the Management of Patients With Atrial Fibrillation

Perioperative physicians should be well versed in atrial fibrillation (AF) management because it is the most common sustained arrythmia in the United States. In this narrative review of the 2019 American Heart Association/American College of Cardiologists/Heart Rhythm Society Focused Update on Atrial Fibrillation, the authors detail the emergence of new evidence from completed studies that may affect the management of patients with AF presenting for surgery. Updates regarding non-vitamin K oral anticoagulants (NOACs) comprise the bulk of the update with newer evidence emerging regarding their equivalence and/or superiority compared to Coumadin. Apixaban is now the preferred drug of choice for first line stroke prevention in nonvalvular AF over Coumadin. Renal dysfunction and the management of patients with AF on hemodialysis is examined; in patients on hemodialysis with AF, the focused update recommends administration of either warfarin or dose-reduced apixaban. Evidence from new trials addressing the appropriate bridging of NOACs before surgery is discussed. Patients with nonvalvular AF may not exhibit an added benefit from bridging of anticoagulation, and perioperative physicians should balance the risks of stroke and major bleeding before surgery. Advances in nonpharmacologic treatment and management of AF are outlined, including left atrial appendage occlusion devices, catheter ablations, and electrical cardioversion. Anesthesiologists' understanding of these 2019 updated guidelines will allow for more adept optimization of patients with AF presenting for surgery.

Postoperative ward monitoring - Why and what now?

The postoperative ward is considered an ideal nursing environment for stable patients transitioning out of the hospital. However, approximately half of all in-hospital cardiorespiratory arrests occur here and are associated with poor outcomes. Current monitoring practices on the hospital ward mandate intermittent vital sign checks. Subtle changes in vital signs often occur at least 8-12 h before an acute event, and continuous monitoring of vital signs would allow for effective therapeutic interventions and potentially avoid an imminent cardiorespiratory arrest event. It seems tempting to apply continuous monitoring to every patient on the ward, but inherent challenges such as artifacts and alarm fatigue need to be considered. This review looks to the future where a continuous, smarter, and portable platform for monitoring of vital signs on the hospital ward will be accompanied with a central monitoring platform and machine learning-based pattern detection solutions to improve safety for hospitalized patients.