Acute Kidney Injury in Critically Ill Vascular Surgery Patients is Common and Associated with Increased Mortality

Persistent Acute Kidney Injury is Associated with Poor Outcomes and Increased Hospital Cost in Vascular Surgery

BACKGROUND

Postoperative acute kidney injury (AKI) is common after major surgery and is associated with increased morbidity, mortality, and cost. Additionally, there are recent studies demonstrating that time to renal recovery may have a substantial impact on clinical outcomes. We hypothesized that patients with delayed renal recovery after major vascular surgery will have increased complications, mortality, and hospital cost.

METHODS

A single-center retrospective cohort of patients undergoing nonemergent major vascular surgery between 6/1/2014 and 10/1/2020 was analyzed. Development of postoperative AKI (defined using Kidney Disease Improving Global Outcomes (KDIGO) criteria: >50% or > 0.3 mg/dl absolute increase in serum creatinine relative to reference after surgery and before discharge) was evaluated. Patients were divided into 3 groups: no AKI, rapidly reversed AKI (<48 hours), and persistent AKI (≥48 hours). Multivariable generalized linear models were used to evaluate the association between AKI groups and postoperative complications, 90-day mortality, and hospital cost.

RESULTS

A total of 1,881 patients undergoing 1,980 vascular procedures were included. Thirty five percent of patients developed postoperative AKI. Patients with persistent AKI had longer intensive care unit and hospital stays, as well as more mechanical ventilation days. In multivariable logistic regression analysis, persistent AKI was a major predictor of 90-day mortality (odds ratio 4.1, 95% confidence interval 2.4-7.1). Adjusted average cost was higher for patients with any type of AKI. The incremental cost of having any AKI ranged from $3,700 to $9,100, even after adjustment for comorbidities and other postoperative complications. The adjusted average cost for patients stratified by type of AKI was higher among patients with persistent AKI compared to those with no or rapidly reversed AKI.

CONCLUSIONS

Persistent AKI after vascular surgery is associated with increased complications, mortality, and cost. Strategies to prevent and aggressively treat AKI, specifically persistent AKI, in the perioperative setting are imperative to optimize care for this population.

Severity of acute kidney injury is associated with decreased survival after fenestrated and branched endovascular aortic aneurysm repair

OBJECTIVE

Acute kidney injury (AKI) occurs frequently in complex aortic surgery and has been implicated in perioperative and long-term survival. This study sought to characterize the relationship between AKI severity and mortality after fenestrated and branched endovascular aortic aneurysm repair (F/B-EVAR).

METHODS

Consecutive patients enrolled by the US Aortic Research Consortium in 10, prospective, nonrandomized, physician-sponsored investigational device exemption studies evaluating F/B-EVAR, between 2005 and 2023, were included in this study. Perioperative AKI during hospitalization was defined by and staged using the 2012 Kidney Disease Improving Global Outcomes criteria. Determinants of AKI were evaluated with backward stepwise mixed effects multivariable ordinal logistic regression. Survival was analyzed with conditionally adjusted survival curves and backward stepwise mixed effects Cox proportional hazards modelling.

RESULTS

In the study period, 2413 patients with a median (interquartile range [IQR]) age of 74 years (IQR, 69-79 years) underwent F/B-EVAR. The median follow-up duration was 2.2 years (IQR, 0.7-3.7 years). The median baseline estimated glomerular filtration rate (eGFR) and creatinine were 68 mL/min/1.73 m2 (IQR, 53-84 mL/min/1.73 m2) and 1.1 mg/dL (IQR, 0.9-1.3 mg/dL), respectively. Stratification of AKI identified 316 patients (13%) with stage 1 injury, 42 (2%) with stage 2 injury, and 74 (3%) with stage 3 injury. Renal replacement therapy was initiated during the index hospitalization in 36 patients (1.5% of cohort, 49% of stage 3 injuries). Thirty-day major adverse events were associated with AKI severity (all P ≤ .0001). Multivariable predictors of AKI severity included baseline eGFR (proportional odds ratio, 0.9 per 10 mL/min/1.73 m2 [95% confidence interval (CI), 0.85-0.95 per 10 mL/min/1.73 m2]; P < .0001), baseline serum hematocrit (0.58 per 10% [95% CI, 0.48-0.71 per 10%]; P < .0001), renal artery technical failure during aneurysm repair (3 [95% CI,1.61-5.72]; P = .0006), and total operating time (1.05 per 10 minutes [95% CI, 1.04-1.07 per 10 minutes]; P < .0001). One-year unadjusted survivals for AKI severity strata were 91% (95% CI, 90%-92%) for no injury, 80% (95% CI, 76%-85%) for stage 1 injury, 72% (95% CI, 59-87%) for stage 2 injury, and 46% (95% CI, 35-59%) for stage 3 injury (P<.0001). Multivariable determinants of survival included AKI severity (stage 1, hazard ratio [HR], 1.6 [95% CI, 1.3-2]); stage 2, HR, 2.2 [95% CI, 1.4-3.4]); stage 3 HR, 4 [95% CI, 2.9-5.5]; P < .0001), decreased eGFR (HR, 1.1 [95% CI, 0.9-1.3]; P = .4), patient age (HR, 1.6 per 10 years [95% CI, 1.4-1.8 per 10 years]; P < .0001), baseline chronic obstructive pulmonary disease (HR, 1.5 [95% CI, 1.3-1.8]; P < .0001), baseline congestive heart failure (HR, 1.7 [95% CI, 1.6-2.1]; P < .0001), postoperative paraplegia (HR, 2.1 [95% CI, 1.1-4]; P = .02), and procedural technical success (HR, 0.6 [95% CI, 0.4-0.8]; P = .003).

CONCLUSIONS

AKI, as defined by the 2012 Kidney Disease Improving Global Outcomes criteria, occurred in 18% of patients after F/B-EVAR. Greater severity of AKI after F/B-EVAR was associated with decreased postoperative survival. The predictors of AKI severity identified in these analyses suggest a role for improved preoperative risk mitigation and staging of interventions in complex aortic repair.

NAD+ Biosynthesis Impairment and Acute Kidney Injury after Major Vascular Surgery

Acute kidney injury (AKI) is a serious complication after vascular surgery. Reduced synthesis of nicotinamide adenine dinucleotide (NAD+) from tryptophan is associated with an increased risk of AKI in critically ill patients, patients hospitalized with COVID-19, and cardiac surgery patients, and is marked by elevated urinary quinolinate and quinolinate to tryptophan ratios. We measured quinolinate concentrations in vascular surgery patients to determine if impaired NAD+ synthesis was associated with AKI in this patient population. Eight preoperative and eight postoperative vascular surgery patients who developed AKI were selected from a parent study to participate in this single-center case-control study. They were matched with controls who did not develop AKI based on age, sex, BMI, eGFR, hypertension, and diabetes. Urinary quinolinate and tryptophan concentrations were measured at anesthetic induction and on postoperative day one. Two-sided Mann-Whitney U tests were used to compare quinolinate and quinolinate to tryptophan ratios. Multivariate linear regression modeling was used to estimate the relationship between quinolinate and serum creatinine. There was no difference in preoperative or postoperative urine quinolinate concentrations or the preoperative quinolinate to tryptophan ratio between patients that did and did not develop AKI (p = 0.07, 0.50, and 0.32, respectively). However, postoperative quinolinate to tryptophan ratios were higher in AKI patients (p = 0.04). Further, after adjustment for AKI risk factors, higher preoperative quinolinate concentrations and higher postoperative quinolinate to tryptophan ratios were associated with greater postoperative creatinine increases (p = 0.04 and 0.04, respectively). These data suggest that impaired NAD+ synthesis may contribute to AKI development in vascular surgery patients.

High-Density Lipoproteins and Acute Kidney Injury

High-density lipoprotein (HDL) particles, best known for their anti-atherosclerotic effects, also may play a beneficial role during acute renal stress. HDL from healthy human beings also shows anti-inflammatory and anti-oxidant capacities, promotes endothelial function and repair, and serves as a systemic signaling mechanism facilitating rapid interorgan communication during times of physiologic stress. Higher concentrations of HDL are associated with less acute kidney injury after sepsis, cardiac and vascular surgery, and contrast-exposure during percutaneous coronary interventions. A better understanding of the interplay between HDL and the kidney both under homeostatic conditions and under acute physiologic stress could lead to the identification of novel risk factors and therapeutic targets for acute kidney injury prevention and treatment in the future.

Apolipoprotein L1 (APOL1) Coding Variants Are Associated With Creatinine Rise After Cardiac Surgery

OBJECTIVE

Acute kidney injury (AKI) is a complication of cardiac surgery that is considerably more common in African Americans (1.5-fold). Although homozygous status for apolipoprotein L1 (APOL1) risk alleles is associated with chronic kidney disease in individuals of African ancestry, whether these coding variants confer AKI risk is unknown. The present study examined whether APOL1 homozygous risk allele status was associated with AKI in African Americans after cardiac surgery.

DESIGN

Retrospective analysis of a cohort.

SETTING

Single-center university hospital.

PARTICIPANTS

African American patients from the CATHeterization GENetics study cohort who underwent cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

Genotyping of APOL1 alleles.

MEASUREMENTS AND MAIN RESULTS

Data from 125 African American patients included 12 APOL1 risk (ie, homozygous for risk alleles) patients and 113 APOL1 control (ie, wildtype or heterozygous for risk alleles) patients. The primary outcome to reflect AKI was peak serum creatinine rise after surgery relative to the preoperative creatinine (%ΔCr). The secondary outcome was Kidney Disease: Improving Global Outcomes (KDIGO) AKI criteria. In the primary analysis, peak creatinine rise was higher in risk compared with control patients in both univariate (%ΔCr 69.1 v 29.6%; p = 0.005) and multivariate regression (%ΔCr 88.5 v 43.7%; p = 0.006) analyses. For the secondary outcome, a trend toward KDIGO AKI development was noted in APOL1 risk patients, but this was not statistically significant.

CONCLUSIONS

African American cardiac surgery patients homozygous for APOL1 chronic kidney disease risk variants averaged a more than 2-fold higher postoperative creatinine rise even after adjustment for other risk factors, suggesting these alleles also are independent risk factors for AKI.

Renal Stent Complications and Impact on Renal Function after Standard Fenestrated Endovascular Aneurysm Repair

BACKGROUND

To report renal outcomes including long-term patency, secondary interventions, and related renal function after fenestrated endovascular aortic repair (fEVAR).

METHODS

Single-center retrospective review of patients undergoing fEVAR between 2012 and 2018 using the Cook ZFEN device. Renal stent complications, defined as any stenosis, occlusion, kink, renal stent-related endoleak, and reinterventions were tabulated. Estimated glomerular filtration rate (eGFR) was estimated using the Modification of Diet in Renal Disease formula.

RESULTS

During the study period, 114 patients underwent elective fEVAR. Of 329 total target vessels, 193 renal arteries were stented (133 Atrium iCAST, 60 Gore VBX). Technical success was achieved in 97.4%, and the mean follow-up was 23.3 months. Seventeen renal complications occurred in 14 patients (12.3%), including 4 occlusions, 9 stenosis, 3 dislocations, and 1 type III endoleak. All stent complications underwent endovascular reintervention with a median hospital stay of 1 day (0-10) and a technical success of 94.2%. One patient suffered renal hemorrhage that warranted embolization. Patients with occlusion were treated the day of diagnosis, and mean time from diagnosis to intervention for stenosis was 21.5 days. Estimated primary patency was 92.1 % and 81.5% at 24 and 48 months, respectively. On multivariate analysis, larger native renal artery diameter was the only independent protective factor against patency loss (HR 0.23 (0.09-0.59)). Secondary patency at latest follow-up was 99.4%. Mean eGFR was not significantly different at latest follow-up between patients with renal complications versus those without (43.75 vs. 55.58 mL/min/1.73 m², P = 0.09). Comparing patients with and without renal stent complications, 81.4% and 72.7% of patients had stable or improved renal disease by chronic kidney disease staging compared with baseline (P = 0.51).

CONCLUSIONS

fEVAR is a durable option for the treatment of juxtarenal aortic aneurysms and is associated with excellent secondary patency. Renal stent complications have no significant impact on renal function, but smaller native renal arteries are at higher risk of stent-graft complications.

Single versus Multiple Vessel Endovascular Tibial Artery Revascularization for Critical Limb Ischemia: A Review of the Literature

Vascular interventionalists have long debated on whether one or multiple patent tibial arteries (run-off) are necessary to treat critical limb ischemia, including ischemic rest pain and tissue loss. This review article seeks to clarify data surrounding this topic by including literature from retrospective studies, prospective studies, meta-analyses, and randomized controlled trials. Our conclusion is that revascularizing a single tibial artery to the foot is adequate for wound healing.

Perioperative urinary heat shock protein 72 as an early marker of acute kidney injury in dogs

OBJECTIVE

Acute kidney injury (AKI) may be a complication in dogs undergoing surgery. Urinary heat shock protein 72 (uHSP72) is a sensitive biomarker of canine AKI. To assess the occurrence of perioperative AKI, based on uHSP72 compared with serum creatinine (sCr), and whether its occurrence is associated with the American Society of Anesthesiology physical status (ASA status).

STUDY DESIGN

Clinical prospective study.

ANIMALS

A total of 80 client-owned and shelter dogs.

METHODS

Dogs scheduled for elective or emergency surgery were assigned ASA status (ASA I-IV). Preoperative and 24 hour postoperative serum and urine samples were collected. sCr, uHSP72 and urinary creatinine (uCr) were measured.

RESULTS

Postoperative uHSP72/uCr concentration [median (range)] of all dogs undergoing surgery [2.40 (0.14-252) ng mg^-1] was significantly increased compared with preoperative uHSP72/uCr [1.30 (0.11-142) ng mg^-1] concentration (p < 0.001). Conversely, postoperative sCr concentration of all dogs [0.88 (0.3-1.6) mg dL^-1] significantly decreased compared with preoperative sCr concentration [0.8 (0.2-5.0) mg dL^-1; p = 0.001]. Median uHSP72/uCr concentration differed both preoperatively (p = 0.007) and postoperatively (p = 0.019) among the ASA status groups. Increased uHSP/uCr was measured in 20 dogs preoperatively and 33 dogs postoperatively, whereas only five dogs fulfilled the criteria of AKI based on sCr.

CONCLUSIONS

The occurrence of increased uHSP72/uCr perioperatively suggests that the proportion of dogs with AKI is considerably higher than perceived.

CLINICAL RELEVANCE

Dogs undergoing surgery should be closely monitored for AKI before and after anesthesia, using currently available markers (e.g., sCr) and more sensitive markers.

Malate Protects the Kidneys From Hemorrhagic Shock-Induced Injury in an Experimental Rat Model

BACKGROUND

In the past, protective effects in terms of prolonged survival of malate-containing solutions were demonstrated in the treatment of experimental hemorrhagic shock (HS). The objective of the present study was to investigate malate's impact on the kidneys. Therefore, renal function and morphological and histological anomalies were examined.

MATERIALS AND METHODS

Male Wistar rats were subjected to severe HS by dropping the mean arterial blood pressure to 25-30 mmHg. The depth was held for 60 min. Subsequently, reperfusion with Ringer's solution or a 10 mM malate-containing solution was performed both together with blood in a 2:1 relation, followed by an observation period of 150 min.

RESULTS

Compared with the control group (Ringer's solution), malate increased diuresis and, thus, enhanced excretion of creatinine and urea. Shock-induced histopathological changes were reduced by malate administration. Renal hemorrhages in the straight proximal tubule and in the distal tubule were reduced and even significantly reduced in the proximal convoluted tubule. Malate significantly preserved the endothelial glycocalyx in the proximal tubule. Surprisingly, malate induced glucosuria in the absence of a significant renal dysfunction, morphological damage, or hyperglycemia.

CONCLUSIONS

The protective effect of malate observed in the treatment of severe HS in the rat may be explained by a certain protective effect of this substance for the kidney.

Eosinopenia and post-hospital outcomes in critically ill non-cardiac vascular surgery patients

BACKGROUND AND AIMS

Eosinopenia is a marker for acute inflammation. We hypothesized that eosinopenia at Intensive Care Unit (ICU) admission in vascular surgery patients who receive critical care, would be associated with increased mortality following hospital discharge.

METHODS AND RESULTS

We performed a two-center observational cohort study of critically ill, non-cardiac adult vascular surgery patients who received treatment in Boston between 1997 and 2012 and survived hospital admission. The consecutive sample included 5083 patients (male 57%, white 82%, mean age [SD] 61.6 [17.4] years). The exposure was Absolute eosinophil count measured within 24 h of admission to the ICU and categorized as ≤10 cells/μL, 11-50 cells/μL, 51-100 cells/μL, 101-350 cells/μL (normal range), and >350 cells/μL. The primary outcome was all-cause mortality within 90 days of hospital discharge. The secondary outcome was discharge to home following hospitalization. 90-day post-discharge mortality was 6.7%, and 12.9% of patients were readmitted within 30 days. After multivariable adjustment, patients with eosinopenia (≤10 cells/μL) have a 90-day post-discharge mortality OR of 1.97 (95%CI 1.42, 2.73; P < 0.001) relative to patients with an absolute eosinophil count of 101-350 cells/μL. Further, after multivariable adjustment, patients with eosinopenia (≤10 cells/μL) have a 25% lower odds of discharge to home compared to patients with an absolute eosinophil count of 101-350 cells/μL [OR = 0.71 (CI 95% 0.59-0.85); P < 0.001].

CONCLUSION

Eosinopenia at ICU admission is a robust predictor of increased mortality and lower likelihood of discharge to home in vascular surgery patients treated with critical care who survive hospitalization.

Acute kidney injury in major abdominal surgery: incidence, risk factors, pathogenesis and outcomes

Acute kidney injury (AKI) is a common complication in patients undergoing major abdominal surgery. Various recent studies using modern standardized classifications for AKI reported a variable incidence of AKI after major abdominal surgery ranging from 3 to 35%. Several patient-related, procedure-related factors and postoperative complications were identified as risk factors for AKI in this setting. AKI following major abdominal surgery has been shown to be associated with poor short- and long-term outcomes. Herein, we provide a contemporary and critical review of AKI after major abdominal surgery focusing on its incidence, risk factors, pathogeny and outcomes.

Stratification and Risk Reduction of Perioperative Acute Kidney Injury

Perioperative acute kidney injury (AKI) is associated with an increased morbidity and mortality. The incidence of AKI varies depending on preoperative risk factors and the surgical setting. Preoperative risk stratification is critical for informed consent and perioperative planning. Perioperative renal protection strategies are potentially invaluable in the prevention of AKI. Current advances in the development of biomarkers may offer the opportunity for early diagnosis and the implementation of therapeutic strategies. Increased awareness and concerted efforts by all perioperative physicians are needed to provide an improved outcome for surgical patients.

Acute kidney injury, long-term renal function and mortality in patients undergoing major abdominal surgery: a cohort analysis

Background

Acute kidney injury (AKI) is frequent during hospitalization and may contribute to adverse consequences. We aimed to evaluate long-term adverse renal function and mortality after postoperative AKI in a cohort of patients undergoing major abdominal surgery.

Methods

We performed a retrospective analysis of adult patients who underwent major non-vascular abdominal surgery between January 2010 and February 2011 at the Department of Surgery II of Hospital de Santa Maria–Centro Hospitalar Lisboa Norte, Portugal. Exclusion criteria were as follows: chronic kidney disease on renal replacement therapy, undergoing renal replacement therapy the week before surgery, death before discharge and loss to follow-up through January 2014. Patients were categorized according to the development of postoperative AKI in the first 48 h after surgery using the Kidney Disease: Improving Global Outcomes classification. AKI was defined by an increase in absolute serum creatinine (SCr) ≥0.3 mg/dL or by a percentage increase in SCr ≥50% and/or by a decrease in urine output to <0.5 mL/kg/h for >6 h. Adverse renal outcomes (need for long-term dialysis and/or a 25% decrease in estimated glomerular filtration rate after hospital discharge) and mortality after discharge were evaluated. Cumulative mortality was analysed with the Kaplan–Meier method and log-rank test and outcome predictive factors with the Cox regression. Significance was set at P < 0.05.

Results

Of 390 selected patients, 72 (18.5%) developed postoperative AKI. The median follow-up was 38 months. Adverse renal outcomes and death after hospital discharge were more frequent among AKI patients (47.2 versus 22.0%, P < 0.0001; and 47.2 versus 20.5%, P < 0.0001, respectively). The 4 year cumulative probability of death was 44.4% for AKI patients, while it was 19.8% for patients with no AKI (log-rank test, P < 0.0001). In multivariate analysis, AKI was a risk factor for adverse renal outcomes (adjusted hazard ratio 1.6, P = 0.046) and mortality (adjusted hazard ratio 1.4, P = 0.043).

Conclusions

AKI after major abdominal surgery was independently associated with the risk of long-term need for dialysis and/or renal function decline and with the risk of death after hospital discharge.

Vascular Surgery Kidney Injury Predictive Score: A Historical Cohort Study

OBJECTIVES

To develop a risk-prediction model for acute kidney injury (AKI) in patients undergoing vascular surgery.

DESIGN

A retrospective cohort study.

SETTING

A tertiary referral center.

PARTICIPANTS

Participants included 845 adult patients who underwent vascular surgery between January 3, 2003, and May 29, 2008.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The median age of patients was 72 years (interquartile range 65-80 years), and 653 patients (77%) were male. AKI developed in 258 (30.5%) patients. Patients with AKI had lower estimated glomerular filtration rates (60±21 v 72±21, p<0.001), were older (73 [68-78] years v 71 [65-80] years, p = 0.01), had a higher prevalence of hypertension (81% v 73%, p = 0.02), and were more likely to undergo emergency surgery (5% v 2%, p = 0.02). Patients with AKI also received more diuretics (p<0.001) and β-blockers (p = 0.003) prior to surgery. The multivariate AKI risk-prediction model with preoperative variables (estimated glomerular filtration rate, previous vascular interventions, use of preoperative diuretics and β-blockers, and emergency surgery) showed an area under the receiver operating characteristic curve of 0.67 (95% confidence interval, 0.628-0.710); a model with additional intraoperative variables (procedure duration, fluid balance, and plasma and platelet transfusion) had an area under the receiver operating characteristic curve of 0.72 (95% confidence interval, 0.685-0.760).

CONCLUSIONS

As AKI is a very common complication after vascular surgery, a risk-prediction model was derived to assess the likelihood of postoperative AKI. If validated in an independent cohort, this model may be used to facilitate targeted interventions in vascular surgery patients at high risk for AKI.