Acute Kidney Injury after Open Repair of Intact Abdominal Aortic Aneurysms

Factors predicting acute kidney injury in patients after abdominal aortic aneurysm repair

INTRODUCTION

Postoperative acute kidney injury (AKI) is one of the most frequent complications in abdominal aortic aneurysm (AAA) patients after open and endovascular aortic aneurysm repair. AKI decreases the efficiency of kidney function, allowing accumulation of waste products in the body, and an imbalance of water, acid and electrolytes in the body. As a result, the functioning of various organs throughout the body is affected. These effects may raise the cost of treatment, length of stay, and mortality rate.

OBJECTIVE

This study aims to examine the predictive factors of AKI - preoperative of estimated glomerular filtration rate (eGFR), preoperative of hemoglobin level, types of abdominal aortic aneurysms repair, and intraoperative of cardiac arrhythmias - after open and endovascular aortic repair among AAA patients within 72 h.

METHODS

This is a retrospective study of 196 patients with AAA after elective open and endovascular aortic aneurysm repair within the first 72 h who met the inclusion criteria recruited from a tertiary care hospital in Bangkok, Thailand. Postoperative AKI after elective open and endovascular aortic repair among AAA patients is defined by the 2012 Kidney Disease Improving Global Outcomes (KDIGO) Clinical Practice Guidelines.

RESULTS

A total of 196 AAA patients, 75.5% were male with an average age of 75.12 years (SD = 8.45). Endovascular aortic aneurysm repair was used more frequently than open aortic aneurysm repair (64.8% vs 35.2%) and 37.2% of the AAA patients had intraoperative cardiac arrhythmias. The occurrence of AKI among the AAA patients after abdominal aortic aneurysm repair within 72 h was 54.1%. The AKI rate of EVAR patients was 69.8% while the AKI rate for OAR patients was 30.2%. The preoperative estimated glomerular filtration rate (eGFR) and hemoglobin level were found to jointly predict AKI and explain 32.2% of the variance (Nagelkerke R2 = 0.322, p < .05). However, the type of abdominal aortic aneurysms repair and intraoperative cardiac arrhythmias did not correlate with the incidence of AKI in AAA repair patients. The predictive factors for AKI among AAA patients after aortic aneurysm repair were preoperative eGFR < 60 mL/min/1.73 m2 (OR = 4.436, 95% CI: 2.202-8.928, p < .001) and preoperative hemoglobin level between 8.1-10.0 g/dL (OR = 4.496, 95% CI: 1.831-11.040, p = .001).

CONCLUSION

Preoperative eGFR < 60 mL/min/1.73 m2 and preoperative hemoglobin level between 8.1-10.0 g/dL were the predictive factors for AKI among AAA patients after both open and endovascular AAA repair. Therefore, healthcare providers should be aware of and monitor signs of AKI after surgery in AAA patients, especially those undergoing EVAR with lower eGFR and hemoglobin levels.

Mannitol Use is Renal Protective in Patients with Chronic Kidney Disease Requiring Suprarenal Aortic Clamping

OBJECTIVES

Objective: Mannitol is often administered during open juxtarenal or suprarenal aortic surgery to prevent ischemic injury to the kidneys. Prior evidence evaluating the benefits of intraoperative mannitol in reducing ischemia/reperfusion injury is conflicting and largely based on small, retrospective series. The aim of this study was to evaluate the effect of mannitol in preventing postoperative hemodialysis in patients undergoing open abdominal aortic aneurysm (AAA) repair where proximal control involved temporary renal ischemia.

METHODS

Methods: The Society for Vascular Surgery Quality Initiative database was queried for all patients undergoing elective open AAA repair between 2003 and 2020. Patients were included in the current analysis if the proximal aortic clamp was placed above at least one renal artery. Chronic kidney disease (CKD) was defined as Cr >1.8mg/dL. Primary endpoints were 30-day major morbidity (myocardial infarction, respiratory complications, lower extremity or intestinal ischemia, and the need for temporary or permanent hemodialysis) and mortality. Comparisons were made between the mannitol and non-mannitol cohorts and stratified by the presence of pre-existing CKD.

RESULTS

Results: During the study period, 4,156 patients underwent elective open AAA repair requiring clamp placement above one (32.7%) or both (67.3%) renal arteries; 182 patients (4.4%) had pre-existing CKD. Overall, 69.8% of patients received mannitol during their surgery. Mannitol was more frequently used in cases involving clamp placement above both renal arteries (70.3%) than one renal artery (61.5%). While prolonged ischemia time (greater than 40 minutes) was associated with higher risk of post-operative dialysis in patients without CKD, it was not significant in patients with baseline CKD. On univariate analysis, mannitol use in patients with CKD was associated with lower risk of post-operative dialysis (p=0.005). This remained significant on multivariate analysis (p=0.008). Mannitol use did not appear to confer renal protective effects in patients without baseline CKD.

CONCLUSIONS

Conclusion: Mannitol use was associated with a decreased risk of need for post-operative hemodialysis in patients with CKD undergoing suprarenal aortic clamping for open aneurysm repair. In appropriately selected patients, particularly those with underlying renal insufficiency, mannitol may confer a renal protective effect in open repair of pararenal AAA requiring suprarenal clamping.

Relationship between intraoperative dopamine infusion and postoperative acute kidney injury in patients undergoing open abdominal aorta aneurysm repair

Background

Acute kidney injury (AKI) is one of the most common complications in patients undergoing open abdominal aortic aneurysm (AAA) repair. Dopamine has been frequently used in these patients to prevent AKI. We aimed to clarify the relationship between intraoperative dopamine infusion and postoperative AKI in patients undergoing open AAA repair.

Methods

We analyzed 294 patients who underwent open AAA repair at a single tertiary center from 2009 to 2018, retrospectively. The primary outcome was the incidence of postoperative AKI, determined by the Kidney Disease Improving Global Outcomes definition, after open AAA repair. Secondary outcomes included survival outcome, hospital and intensive care unit length of stay, and postoperative renal replacement therapy (RRT).

Results

Postoperative AKI occurred in 21.8% (64 out of 294 patients) The risk of postoperative AKI by intraoperative dopamine infusion was greater after adjusting for risk factors (odds ratio [OR] 2.56; 95% confidence interval [CI], 1.09–5.89; P = 0.028) and after propensity score matching (OR 3.22; 95% CI 1.12–9.24; P = 0.030). On the contrary, intraoperative norepinephrine use was not associated with postoperative AKI (use vs. no use; 19.3 vs. 22.4%; P = 0.615). Patients who used dopamine showed higher requirement for postoperative RRT (6.8 vs. 1.2%; P = 0.045) and longer hospital length of stay (18 vs. 16 days, P = 0.024).

Conclusions

Intraoperative dopamine infusion was associated with more frequent postoperative AKI, postoperative RRT, and longer hospital length of stay in patients undergoing AAA repair, when compared to norepinephrine. Further prospective randomized clinical trial may be necessary for this topic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01624-6.

Trimetazidine an emerging paradigm in renal therapeutics: Preclinical and clinical insights

Trimetazidine (TMZ) is a well-known anti-ischemic agent used for the treatment of angina pectoris. In the past decades, the efficacy of this drug has been tested in a wide range of kidney injuries, including drug-induced nephrotoxicity (DIN), radio-contrast agent-induced nephropathy, and surgically induced renal ischemic injury. TMZhas renoprotective effects by attenuating oxidative stress, inflammatory cytokine release, maintaining oxygen and energy balance. Moreover, TMZ administration prevented kidney graft rejection in the porcine model by suppressing the infiltration of mononuclear cells, preserving mitochondrial functions, and maintaining Ca+ homeostasis. In DIN and diabetic kidney diseases,TMZ treatment prevents renal injury by inactivating immune cells, attenuating renal fibrosis, inflammation, apoptosis, and histological abnormalities. Interestingly, the clinical therapeutic efficacy of TMZ has also been documented in pre-existing kidney disease patients undergoing contrast exposure for diagnostic intervention. However, the mechanistic insights into the TMZ mediated renoprotective effects in other forms of renal injuries, including type-2 diabetes, drug-induced nephrotoxicity, and hypertension-induced chronic kidney diseases, remain uninvestigated and incomplete. Moreover, the clinical utility of TMZ as a renoprotective agent in radio-contrast-induced nephrotoxicity needs to be tested in a large patient population. Nevertheless, the available pieces of evidence suggest that TMZ is a promising and emerging renal therapy for the treatment and management of kidney diseases of variable etiologies. This review discusses the various pre-clinical and clinical findings and provides mechanistic insights into the TMZ mediated beneficial effects in various kidney diseases.

Short-term outcomes of open surgical abdominal aortic aneurysm repair from the Dutch Surgical Aneurysm Audit

Background

The sharp decrease in open surgical repair (OSR) for abdominal aortic aneurysm (AAA) has raised concerns about contemporary postoperative outcomes. The study was designed to analyse the impact of complications on clinical outcomes within 30 days following OSR.

Methods

Patients who underwent OSR for intact AAA registered prospectively between 2016 and 2019 in the Dutch Surgical Aneurysm Audit were included. Complications and outcomes (death, secondary interventions, prolonged hospitalization) were evaluated. The adjusted relative risk (aRr) and 95 per cent confidence intervals were computed using Poisson regression. Subsequently, the population-attributable fraction (PAF) was calculated. The PAF reflects the expected percentage reduction of an outcome if a complication were to be completely prevented.

Results

A total of 1657 patients were analysed. Bowel ischaemia and renal complications had the largest impact on death (aRr 12·44 (95 per cent c.i. 7·95 to 19·84) at PAF 20 (95 per cent c.i. 8·4 to 31·5) per cent and aRr 5·07 (95 per cent c.i. 3·18 to 8.07) at PAF 14 (95 per cent c.i. 0·7 to 27·0) per cent, respectively). Arterial occlusion had the greatest impact on secondary interventions (aRr 11·28 (95 per cent c.i. 8·90 to 14·30) at PAF 21 (95 per cent c.i. 14·7 to 28·1) per cent), and pneumonia (aRr 2·52 (95 per cent c.i. 2·04 to 3·10) at PAF 13 (95 per cent c.i. 8·3 to 17·8) per cent) on prolonged hospitalization. Small effects were observed on outcomes for other complications.

Conclusion

The greatest clinical impact following OSR can be made by focusing on measures to reduce the occurrence of bowel ischaemia, arterial occlusion and pneumonia.

Diseases of the Aorta and Kidney Disease: Conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Chronic kidney disease (CKD) is an independent risk factor for the development of abdominal aortic aneurysm (AAA), as well as for cardiovascular and renal events and all-cause mortality following surgery for AAA or thoracic aortic dissection. In addition, the incidence of acute kidney injury (AKI) after any aortic surgery is particularly high, and this AKI per se is independently associated with future cardiovascular events and mortality. On the other hand, both development of AKI after surgery and the long-term evolution of kidney function differ significantly depending on the type of AAA intervention (open surgery vs. the various subtypes of endovascular repair). Current knowledge regarding AAA in the general population may not be always applicable to CKD patients, as they have a high prevalence of co-morbid conditions and an elevated risk for periprocedural complications. This summary of a Kidney Disease: Improving Global Outcomes Controversies Conference group discussion reviews the epidemiology, pathophysiology, diagnosis, and treatment of Diseases of the Aorta in CKD and identifies knowledge gaps, areas of controversy, and priorities for future research.

Central and peripheral arterial diseases in chronic kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Chronic kidney disease (CKD) affects about 10% of all populations worldwide, with about 2 million people requiring dialysis. Although patients with CKD are at high risk of cardiovascular disease and events, they are often underrepresented or excluded in clinical trials, leading to important knowledge gaps about how to treat these patients. KDIGO (Kidney Disease: Improving Global Outcomes) convened the fourth clinical Controversies Conference on the heart, kidney and vasculature in Dublin, Ireland, in February 2020, entitled Central and Peripheral Arterial Diseases in Chronic Kidney Disease. A global panel of multidisciplinary experts from the fields of nephrology, cardiology, neurology, surgery, radiology, vascular biology, epidemiology, and health economics attended. The objective was to identify key issues related to the optimal detection, management, and treatment of cerebrovascular diseases, central aortic disease, renovascular disease, and peripheral artery disease in the setting of CKD. This report outlines the common pathophysiology of these vascular processes in the setting of CKD, describes best practices for their diagnosis and management, summarizes areas of uncertainty, addresses ongoing controversial issues, and proposes a research agenda to address key gaps in knowledge that, when addressed, could improve patient care and outcomes.

Systematic Review and Meta-Analysis of Preventative Strategies for Acute Kidney Injury in Patients Undergoing Abdominal Aortic Aneurysm Repair

BACKGOUND

To assess the effect of various preventative interventions for reducing the incidence of postoperative acute kidney injury (AKI) in patients undergoing elective abdominal aortic aneurysm (AAA) repair.

METHODS

We included randomized controlled trials of 10 patients or more which tested a preventative intervention versus standard therapy or placebo in patients undergoing elective AAA repair using the open or endovascular approach. Studies including mixed patient populations such as those with aortic occlusive disease, thoracoabdominal aneurysms or ruptured aneurysms were ineligible for review. We searched Medline (1966-2019), EMBASE (1947-2019), CINAHL (1961-2019), Web of Science (1945-2019), Scopus (1966-2019), and The Cochrane Library (1996-2019) for trials available as published manuscripts in English. Study quality was assessed using the Cochrane Collaboration risk of bias tool. Where possible we pooled the results of similar interventions using random effects meta-analysis.

RESULTS

We included 17 trials involving 1443 participants. Most trials were small, single-center studies, with varying definitions of AKI and a high or moderate risk of bias. The preventative strategies with possible protective effects were mannitol, a composite of antioxidant supplements, an open extraperitoneal approach, and human atrial natriuretic peptide (hANP). Curcumin, methylprednisolone, carbon dioxide contrast medium, hemodynamic monitoring and N-acetylcysteine were found to be ineffective. Six trials with a total of 355 participants reported on remote ischemic preconditioning (RIPC) and our meta-analysis showed no statistically significant difference between RIPC and standard treatment (OR 1.20, 95% CI 0.37, 3.89); although the results should be interpreted with caution due to considerable statistical heterogeneity (I² = 70%). None of the interventions studied significantly reduced receipt of renal replacement therapy (RRT).

CONCLUSIONS

Interventions that have shown some potential to reduce AKI after AAA repair include mannitol, a composite of antioxidant supplements, an open extraperitoneal approach and hANP. These conclusions are limited by the small size, high risk of bias and inconsistency of the included trials. Large, high quality, multi-center randomized trials will help determine which interventions are effective in reducing the incidence of postoperative AKI among patients undergoing elective AAA repair.

(TIMP2) x (IGFBP7) as early renal biomarker for the prediction of acute kidney injury in aortic surgery (TIGER). A single center observational study

Objective

Postoperative acute kidney injury (po-AKI) is frequently observed after major vascular surgery and impacts on mortality rates. Early identification of po-AKI patients using the novel urinary biomarkers insulin-like growth factor-binding-protein 7 (IGFBP7) and tissue inhibitor of metalloproteinases-2 (TIMP-2) might help in early identification of individuals at risk of AKI and enable timely introduction of preventative or therapeutic interventions with the aim of reducing the incidence of po-AKI. We investigated whether biomarker-based monitoring would allow for early detection of po-AKI in patients undergoing abdominal aortic interventions.

Methods

In an investigator-initiated prospective single-center observational study in a tertiary care academic center, adult patients with emergency/ elective abdominal aortic repair were included. Patients were tested for concentrations of urinary (TIMP-2) x (IGFBP7) at baseline, after surgical interventions (PO), and in the mornings of the first postoperative day (POD1). The primary endpoint was a difference in urinary (TIMP-2) x (IGFBP7) levels at POD1 in patients with/ without po-AKI (all KDIGO stages, po-AKI until seven days after surgery). Secondary endpoints included sensitivity/ specificity analyses of previously proposed cut-off levels and clinical outcome measures (e.g. need for renal replacement therapy).

Results

93 patients (n = 71 open surgery) were included. Po-AKI was observed in 33% (31/93) of patients. Urinary (TIMP-2) x (IGFBP7) levels at POD1 did not differ between patients with/ without AKI (median 0.39, interquartile range [IQR] 0.13–1.05 and median 0.23, IQR 0.14–0.53, p = .11, respectively) and PO (median 0.2, IQR 0.08–0.42, 0.18, IQR 0.09–0.46; p = .79). Higher median (TIMP-2) x (IGFBP7) levels were noted in KDIGO stage 3 pAKI patients at POD1 (3.75, IQR 1.97–6.92; p = .003). Previously proposed cutoff levels (0.3, 2) showed moderate sensitivity/ specificity (0.58/0.58 and 0.16/0.98, respectively).

Conclusion

In a prospective monocentric observational study in patients after abdominal aortic repair, early assessment of urinary (TIMP-2) x (IGFBP7) did not appear to have adequate sensitivity/ specificity to identify patients that later developed postoperative AKI.

Clinicaltrials.gov

NCT03469765, registered March 19, 2018.

The risk of renal function deterioration in abdominal aortic stent graft patients with and without previous kidney function failure - an analysis of risk factors

Purpose

Kidney failure influences the treatment outcomes of abdominal aortic aneurysm (AAA). A prospective study of renal function before and after aortic stent-graft treatment was performed. Special attention was paid to the influence of preoperative kidney function as well as the impact of the radiological follow-up.

Material and methods

A total of 214 endovascularly treated AAA patients were included. In all cases, pre- and postope-rative estimated glomerular filtration rate (eGFR) and serum creatinine were noted. Patients were prospectively followed up for a minimum of two years.

Results

The baseline eGFR was 69.38 ± 16.29 ml/min/1.73 m². Chronic kidney disease at baseline was noted in 29% of patients. In the direct postoperative period, acute kidney injury was identified in 8.4% of cases. Additional endo-vascular procedures within two years of observation were performed in 5.6% of cases, and over the two years of follow-up, in the study group from one to six angio-computed tomographic scans (angio-CT) per patient were performed. The mean eGFR value after the 24-month follow-up was significantly lower than the preoperative value. Among the factors influencing kidney function, an angio-CT during the same hospital stay of the primary stent-graft procedures was identified. The type of stent-graft, contrast volume during the primary procedure, need for reintervention, concomitant disease presence, and statin use did not show statistical significance.

Conclusions

Angio-CT followed by stent-graft implantation over a short time interval (within the same hospitalisation) significantly worsened renal function in the late follow-up and should be avoided in elective AAA cases.

Kidney protection in thoracoabdominal aortic aneurysm surgery

Acute kidney injury (AKI) is a common complication of both open and endovascular repair of thoracoabdominal aortic aneurysms (TAAA). Its definition varies across difference studies, some standardized definitions (RIFLE, AKIN, KDIGO) have been proposed but still not uniformly employed in published papers. Acute kidney injury is multifactorial and is associated with increased in-hospital mortality, long-term mortality and late renal function decline. In addition, AKI is also associated with perioperative spinal cord ischemia. No specific pharmacological strategy has received a strong recommendation with high level of evidence as a protective measure. Fenoldopam, methylprednisolone or mannitol use to prevent AKI is commonly employed, but not supported by literature data. Avoiding nephrotoxic drugs and maintaining an adequate MAP, during and after the procedure plays a key role in preserving kidney function. During open TAAA surgery, renal arteries may be reimplanted using different techniques. The choice of the best option must be tailored to the patient, to reduce ischemic time and guarantee long-term patency. Current experience suggests that cold crystalloid solutions are the best substrates in preventing ischemia-reperfusion injury. Renal perfusion using Custodiol^® (Dr Franz-Kohler Chemie GmbH; Bensheim, Germany) 4 °C, even if currently considered off-label, represents an encouraging organ protection tool. In endovascular TAAA repair, techniques such as fusion imaging, use of diluted contrast, and CO<inf>2</inf> subtraction angiography have the potential to reduce postoperative AKI. Visceral vessels patency is closely related to the anatomy. Therefore, accurate endograft design according to these characteristics is crucial for long-term preservation of renal function.

Patient Safety Indicators are an insufficient performance metric to track and grade outcomes of open aortic repair

OBJECTIVE

National rankings of hospitals rely on outcomes-based evaluation to assess the performance of surgical programs, particularly those performing high-risk elective surgical procedures such as open aortic repair. Various classification systems exist for tracking outcomes, but increasingly the International Classification of Diseases, Tenth Revision-based Agency for Healthcare Research and Quality Patient Safety Indicators (PSIs) are used as a publicly reported comparison measure of hospital quality performance. We sought to critically evaluate the accuracy of the existing vehicles to assess open aortic repair outcomes in an established program.

METHODS

This is a case-control study of patients who underwent open abdominal aortic aneurysm repair at the Johns Hopkins Medical Institutions from 2004 to 2018. Patients' characteristics and outcomes were collected as part of a prospectively maintained retrospective database. For each case, hemorrhagic, cardiac, respiratory, renal, wound, and thromboembolic complications were identified with the unique definitions used for open abdominal aortic aneurysm repair by the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database, the Society for Vascular Surgery Vascular Quality Initiative (VQI) database, and the Agency for Healthcare Research and Quality PSI initiative.

RESULTS

Of the 154 patients included in the study, 79 (51.0%) were identified as having a complication as defined by the VQI, 46 (29.7%) according to the NSQIP, and 15 (9.7%) according to the PSI system (P < .001). Patients most likely to incur a complication in the PSI system were those with a pararenal or more extensive aneurysm, with baseline congestive heart failure, requiring a supramesenteric clamp (all P < .01), or with an aneurysm >6.5 cm in diameter (P = .02). The NSQIP and VQI systems both identified more postoperative hemorrhagic, respiratory, renal, and wound complications than the PSI system did (P < .05). The VQI system identified the most renal complications (52; P < .001); factors unique to incurring a complication in the VQI include use of a suprarenal clamp and performance of an aortorenal bypass procedure as part of the repair (P < .01). Particularly weak correlation was noted between the PSI system and the VQI with respect to renal outcomes (ρ = 0.163).

CONCLUSIONS

The PSI system identified fewer important complications than either of the clinically focused databases, with the VQI capturing the most postoperative events, mostly because of its stringent definition of renal injury. We conclude that the PSI system should not form the basis of grading hospital performance in comparing clinically relevant complications of open aortic surgery programs.

Acute Kidney Injury Following Elective Open Aortic Repair with Suprarenal Clamping

Objective: To investigate predictors of acute kidney injury (AKI) following open aortic repair (OAR) requiring suprarenal clamping.

Methods: The study included 833 nonhemodialysis patients who had undergone elective OAR (with suprarenal clamping, n=73; with infrarenal clamping, n=760). We evaluated AKI as defined by the criteria of the Kidney Disease Improving Global Outcomes (KDIGO) and compared in-hospital outcomes between the two groups. We also investigated the effects of AKI on outcomes, factors related to post-suprarenal clamping AKI, and efficacy of hypothermic renal perfusion (HRP) in the suprarenal clamping group.

Results: For the suprarenal vs. infrarenal clamping group, in-hospital mortality was 0% (0/73) vs. 0.5% (4/760). The incidence of AKI was greater in the suprarenal clamping group (37% vs. 15%, P<0.001), and the hospital stay for patients with AKI was longer than for those patients without AKI (median, 21 days vs. 16 days; P=0.005). Renal ischemia time and bleeding volume >1,000 mL were associated with post-suprarenal clamping AKI. Renal ischemia time was longer with HRP (n=15) than without HRP (n=58) (median, 51 min vs. 33 min; P=0.011), and HRP did not decrease the incidence of AKI (40% vs. 36%; P=0.78).

Conclusion: Prolonged renal ischemia and substantial intraoperative bleeding are associated with postoperative AKI following suprarenal clamping.

Mannitol for the Prevention of Peri-Operative Acute Kidney Injury: A Systematic Review

OBJECTIVE/BACKGROUND

Post-operative acute kidney injury (AKI) is a frequent peri-operative complication that negatively affects morbidity and mortality. Mannitol is frequently used peri-operatively for renal protection, although evidence for its use is ambiguous. A systematic review was conducted to clarify whether there is evidence supporting peri-operative mannitol administration for the prevention of post-operative AKI.

METHODS

A systematic literature search was performed in MEDLINE/Pubmed, Embase, the Cochrane Library, Clinical Trials registry, and the Cochrane Central Register of Controlled Trials (CENTRAL). Eligibility criteria were (i) population (studies involving adult patients undergoing surgery or a related intervention); (ii) intervention (intravenous mannitol administered in either the pre- or intra-operative period with comparison to controls); and (iii) predefined outcomes (post-operative AKI or respective renal end points/surrogates).

RESULTS

In total, 1,538 articles published between January 1990 and October 2018 were identified. After checking for eligibility, 22 studies, including 17 prospective and/or randomised controlled trials and five retrospective studies, were included. The investigations involved various fields of surgery, such as aortic surgery, cardiac surgery with cardiopulmonary bypass, and urological procedures, including partial nephrectomy. Significant heterogeneity, limited sample size, and mostly short follow up periods were noted.

CONCLUSION

Given the available evidence, the peri-operative use of mannitol to prevent AKI cannot be considered an evidence based intervention in cardiac surgery, partial nephrectomy, and/or other major surgery. Further research is required with a focus on patients at high risk of post-operative AKI.

Preoperative Albuminuria and Intraoperative Chloride Load: Predictors of Acute Kidney Injury Following Major Abdominal Surgery

Background: Postoperative Acute Kidney Injury (AKI) is a common and serious complication associated with significant morbidity and mortality. While several pre- and intra-operative risk factors for AKI have been recognized in cardiac surgery patients, relatively few data are available regarding the incidence and risk factors for perioperative AKI in other surgical operations. The aim of the present study was to determine the risk factors for perioperative AKI in patients undergoing major abdominal surgery. Methods: This was a prospective, observational study of patients undergoing major abdominal surgery in a tertiary care center. Postoperative AKI was diagnosed according to the Acute Kidney Injury Network criteria within 48 h after surgery. Patients with chronic kidney disease stage IV or V were excluded. Logistic regression analysis was used to evaluate the association between perioperative factors and the risk of developing postoperative AKI. Results: Eleven out of 61 patients developed postoperative AKI. Four intra-operative variables were identified as predictors of AKI: intra-operative blood loss (p = 0.002), transfusion of fresh frozen plasma (p = 0.004) and red blood cells (p = 0.038), as well as high chloride load (p = 0.033, cut-off value > 500 mEq). Multivariate analysis demonstrated an independent association between AKI development and preoperative albuminuria, defined as a urinary Albumin to Creatinine ratio ≥ 30 mg·g⁻¹ (OR = 6.88, 95% CI: 1.43–33.04, p = 0.016) as well as perioperative chloride load > 500 mEq (OR = 6.87, 95% CI: 1.46–32.4, p = 0.015). Conclusion: Preoperative albuminuria, as well as a high intraoperative chloride load, were identified as predictors of postoperative AKI in patients undergoing major abdominal surgery.

Predictors of acute kidney injury after infrarenal abdominal aortic aneurysm repair in octogenarians

OBJECTIVE

Acute kidney injury (AKI) is a common postoperative complication after abdominal aortic aneurysm (AAA) repair and is associated with significant morbidity and mortality. However, limited studies have investigated this complication in elderly patients. This study aims to evaluate AKI in octogenarians after open endovascular AAA repair (OAR) and endovascular AAA repair (EVAR).

METHODS

Data were obtained from the Vascular Quality Initiative database on all patients who underwent elective infrarenal AAA repair between January 2003 and April 2017. Univariate analysis was used to compare AKI rates as well as failure to rescue after AKI between octogenarians and nonoctogenarians in OAR and EVAR. Stepwise multivariable logistic regression analysis was implemented to identify independent predictors and develop a risk calculator of AKI in octogenarians undergoing AAA repair.

RESULTS

A total of 27,993 patients (12% OAR and 88% EVAR) were included, of which 6708 (24%) were octogenarians (OAR, 332; EVAR, 6376). Postoperative AKI was more common in octogenarians as compared with nonoctogenarians in OAR (15.1% vs 10.1%; P = .01) and EVAR (4.2% vs 2.7%; P < .001). Similarly, failure to rescue, defined as 30-day mortality after postoperative AKI, was higher in octogenarians whether undergoing OAR (28.0% vs 8.8%; P < .001) or EVAR (14.1% vs 7.5%; P < .01). On multivariable analysis, octogenarians undergoing OAR had a 3.5 times higher odds of AKI compared with those undergoing EVAR (odds ratio [OR], 3.52; 95% confidence interval [CI], 2.36-5.23; P < .001). Other independent risk factors for postoperative AKI in octogenarians included chronic obstructive pulmonary disease (OR, 1.48; 95% CI, 1.14-1.93), chronic kidney disease stage III (OR, 2.17; 95% CI, 1.26-3.76) and chronic kidney disease stage IV-V (OR, 5.7; 95% CI, 3.0-10.9), peripheral artery disease (OR, 1.99; 95% CI, 1.34-2.94), preoperative β-blocker use (OR, 1.85; 95% CI, 1.45-2.38), and aneurysm diameter (OR, 1.25; 95% CI, 1.11-1.41). These predictors were incorporated in an interactive risk calculator of AKI after AAA repair in octogenarians (C-statistic = 0.728).

CONCLUSIONS

AKI is a serious complication after AAA repair, especially in octogenarians, and is associated with high failure to rescue rates. A careful assessment of risk factors for AKI in elderly patients should be performed to inform clinical decision making.

Severe Infrarenal Atheroma Load in Open Aortic Aneurysm Repair Is Not a Risk Factor for Postoperative Acute Kidney Injury

BACKGROUND

Acute kidney injury (AKI) after open aortic repair is subject to multiple patient- and operation-related variables. Hostile neck morphology in open aneurysm repair is thought to contribute to this AKI risk postoperatively. The aim of this study was to evaluate if large neck atheroma is a possible risk factor in the postoperative development of AKI.

METHODS

Retrospectively 137 patients were evaluated for neck atheroma and AKI incidence. Atheroma load measurements were performed by 2 different techniques. Results were compared, and secondly a univariate analysis was performed for multiple additional risk factors regarding AKI occurrence.

RESULTS

Significant (>30%) neck atheroma was not associated with a higher risk for developing AKI (odds ratio [OR]: 1.81; 95% confidence intervals: 0.74-4.44). Overall incidence of AKI based upon Acute Kidney Injury Network criteria was 19.7%. In univariate analysis coronary artery disease and the presence of a renal artery stenosis were both significantly associated with AKI (OR: 2.38, 3.31, respectively) as well as the use of B-blockers and angiotensin converting enzyme inhibitors (OR 3.05, 2.48, respectively).

CONCLUSIONS

Cross-clamping in case of significant neck atheroma during open aortic aneurysm repair is not associated with increased risk of AKI. Defining high-risk patients based on additional risk factors must be a part of preoperative patient selection.

Has Anatomic Complexity of Abdominal Aortic Aneurysms Undergoing Open Surgical Repair Changed after the Introduction of Endovascular Treatment? Systematic Review and Meta-analysis of Comparative Studies

BACKGROUND

At a time when endovascular aneurysm repair (EVAR) is increasingly used to treat abdominal aortic aneurysms (AAAs), lesions undergoing open surgical repair (OSR) may present significant differences compared with those treated before wide EVAR availability. We aim to record discrepancies in AAAs surgically treated before and after the introduction of EVAR.

METHODS

We conducted a systematic review of the literature and meta-analysis of comparative studies. The MEDLINE, CENTRAL, and OpenGrey databases were searched up to October 2017. Outcome measures were anatomic complexity, procedural details, and postoperative outcomes. The random-effects model was used to calculate combined overall effect sizes. Data are presented as odds ratio (OR) or mean difference (MD) with 95% confidence intervals (CIs).

RESULTS

Five observational studies were included. These involved 1,091 patients treated in the pre-EVAR era and 802 in the post-EVAR era. In general, patients undergoing OSR during the first period presented more comorbidities. Increased anatomic complexity was found among patients in the second group as demonstrated by the increased rate of suprarenal clamping (10.5% vs. 22.3%; OR, 0.34; 95% CI, 0.24-0.50), left renal vein division (10.3% vs. 18.8%; OR, 0.46; 95% CI, 0.25-0.88), iliac aneurysm (28.3% vs. 44.9%; OR, 0.48; 95% CI, 0.37-0.64), and iliac occlusive disease (13.1% vs. 20.2%; OR, 0.59; 95% CI, 0.39-0.88). Intraoperative use of blood products was greater during the latter period, but this difference did not reach statistical significance. Procedural duration was slightly increased in the same group. Morbidity and mortality were similar among the groups.

CONCLUSIONS

After the wide availability of endoluminal grafting, more compromised patients tend to be managed with EVAR, leaving a fitter patient population to undergo OSR. At the same time, anatomic complexity of AAAs undergoing open surgery has considerably increased, requiring advanced proximal aortic surgical expertise to deal with these complex aortic pathologies Overall, morbidity and mortality remained unchanged, possibly due to the counterbalancing effects of these factors.

Low mortality rates after endovascular aortic repair expand use to high-risk patients

OBJECTIVE

The 2010 endovascular aneurysm repair (EVAR) trial 2 (EVAR 2) reported that patients with comorbidity profiles rendering them unfit for open aneurysm repair who underwent EVAR did not experience a survival advantage compared with those who did not undergo intervention. These patients experienced a 30-day mortality of 7.3%, whereas reports from similar cohorts reported far lower mortality rates. The primary objective of our study was to compare the incidence of 30-day mortality in low- and high-risk patients undergoing EVAR in a contemporary data set, using patient risk stratification criteria from EVAR 2. Secondarily, we sought to identify risk factors associated with a disproportionate contribution to 30-day mortality risk.

METHODS

Data were obtained from the 2005 to 2013 American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) Participant Use Data Files (N = 24,813). Patients were included in the high-risk cohort with the presence of renal, respiratory, or cardiac preoperative criteria alone or in combination. Renal impairment criteria were defined as dialysis and creatinine concentration >2.26 mg/dL. Respiratory impairment criteria included history of chronic obstructive pulmonary disease and preoperative ventilator support. Cardiac impairment criteria included history of myocardial infarction, congestive heart failure, angina, and prior coronary intervention. Patient and procedural characteristics and 30-day postoperative outcomes were compared using Pearson χ2 tests for categorical variables and Wilcoxon rank sum tests for continuous variables.

RESULTS

Among 24,813 patients undergoing EVAR, 12,043 (48%) patients were characterized as high risk (at least one impairment criterion); 12,770 (52%) patients were stratified as low risk. The 30-day mortality rate was 1.9% in the high-risk cohort compared with the 7.3% reported by EVAR 2, and it was higher in the high-risk cohort compared with the low-risk cohort (1.9% vs 0.9%; P < .001). Whereas the presence of each comorbidity increased the odds of 30-day mortality (respiratory odds ratio [OR], 1.62; 95% confidence interval [CI], 1.16-2.26; P = .005; cardiac OR, 1.55; 95% CI, 1.14-2.10; P = .005), the presence of renal criteria disproportionately increased the odds of mortality threefold (OR, 3.42; 95% CI, 2.31-5.09; P < .001).

CONCLUSIONS

Contemporary 30-day mortality after EVAR in high-risk patients is substantially lower than that reported in the EVAR 2 trial. Whereas low- and high-risk stratification by current comorbidity criteria is appropriate, attention needs to be paid to disproportionate risk contribution from renal disease to mortality compared with cardiac and pulmonary comorbidities. Given the lower mortality risk than previously described, patients stratified as high risk should be thoughtfully considered for definitive EVAR.

Comparison of acute kidney injury of different etiology reveals in-common mechanisms of tissue damage

Acute kidney injury (AKI) is a syndrome of reduced glomerular filtration rate and urine production caused by a number of different diseases. It is associated with renal tissue damage. This tissue damage can cause tubular atrophy and interstitial fibrosis that leads to nephron loss and progression of chronic kidney disease (CKD). This review describes the in-common mechanisms behind tissue damage in AKI caused by different underlying diseases. Comparing six high-quality microarray studies of renal gene expression after AKI in disease models (gram-negative sepsis, gram-positive sepsis, ischemia-reperfusion, malignant hypertension, rhabdomyolysis, and cisplatin toxicity) identified 5,254 differentially expressed genes in at least one of the AKI models; 66% of genes were found only in one model, showing that there are unique features to AKI depending on the underlying disease. There were in-common features in the form of four genes that were differentially expressed in all six models, 49 in at least five, and 215 were found in common between at least four models. Gene ontology enrichment analysis could be broadly categorized into the injurious processes hypoxia, oxidative stress, and inflammation, as well as the cellular outcomes of cell death and tissue remodeling in the form of epithelial-to-mesenchymal transition. Pathway analysis showed that MYC is a central connection in the network of activated genes in-common to AKI, which suggests that it may be a central regulator of renal gene expression in tissue injury during AKI. The outlining of this molecular network may be useful for understanding progression from AKI to CKD.