Acute kidney injury after gastric bypass surgery

Effect of pre-transplantation use of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in kidney transplant recipients-propensity score-matched analysis

BACKGROUND

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers (ACEi/ARBs) can cause acute kidney injury under dehydratation or in hemodynamically unstable conditions. Regarding kidney transplantation (KT), the risk of using ACEi/ARBs before surgery is not well established. Therefore, we evaluated the clinical outcomes to determine the effect of preoperative use of ACEi/ARBs on KT.

METHODS

We retrospectively collected 1187 patients who received living-donor KT between January 2017 and December 2021. We conducted a propensity score-matched analysis between the ACEi/ARB(+) and ACEi/ARB(-) groups and evaluated the effects of ACEi/ARBs on delayed graft function, post-KT renal function, hyperkalemia events, rejection, and graft survival.

RESULTS

The ACEi/ARB(+) group showed a similar incidence of delayed graft function as the ACEi/ARB(-) group (1.8% vs. 1.0%, P = 0.362). The risk of delayed graft function was not upregulated in the ACEi/ARB(+) group after propensity score-matching (odds ratio: 0.50, 95% confidence interval (CI) 0.13-2.00). Postoperative creatinine levels and the slope of creatinine levels after KT also were not significantly different between the two groups (creatinine slope from POD#0 to POD#7: - 0.73 ± 0.35 vs. - 0.75 ± 0.32 mg/dL/day, P = 0.464). Hyperkalemia did not occur more often in the ACEi/ARB(+) group than in the ACEi/ARB(-) group during perioperative days. Rejection-free survival (P = 0.920) and graft survival (P = 0.621) were not significantly different between the two groups.

CONCLUSIONS

In KT, the preoperative use of ACEi/ARBs did not significantly affect clinical outcomes including delayed graft function, postoperative renal function, hyperkalemia events, incidence of rejection, and graft survival rates compared to the patients who did not receive ACEi/ARBs.

Obesity aggravates acute kidney injury resulting from ischemia and reperfusion in mice

In critically ill patients, overweight and obesity are associated with acute respiratory distress syndrome and acute kidney injury (AKI). However, the effect of obesity on ischemia-reperfusion injury (IRI)-induced AKI is unknown. We hypothesized that obesity would aggravate renal IRI in mice. We fed mice a standard or high-fat diet for eight weeks. The mice were divided into four groups and submitted to sham surgery or IRI: obese, normal, normal + IRI, obese, and obese + IRI. All studies were performed 48 h after the procedures. Serum glucose, cholesterol, and creatinine clearance did not differ among the groups. Survival and urinary osmolality were lower in the obese + IRI group than in the normal + IRI group, whereas urinary neutrophil gelatinase-associated lipocalin levels, tubular injury scores, and caspase 3 expression were higher. Proliferating cell nuclear antigen expression was highest in the obese + IRI group, as were the levels of oxidative stress (urinary levels of thiobarbituric acid-reactive substances and renal heme oxygenase-1 protein expression), whereas renal Klotho protein expression was lowest in that group. Expression of glutathione peroxidase 4 and peroxiredoxin 6, proteins that induce lipid peroxidation, a hallmark of ferroptosis, was lower in the obese + IRI group. Notably, among the mice not induced to AKI, macrophage infiltration was greater in the obese group. In conclusion, greater oxidative stress and ferroptosis might aggravate IRI in obese individuals, and Klotho could be a therapeutic target in those with AKI.

Predictors and outcomes of acute kidney injury after bariatric surgery: analysis of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program data registry

BACKGROUND

Acute kidney injury (AKI) after surgery increases long-term risk of kidney dysfunction. The major risk factor for AKI after bariatric surgery is having preoperative renal insufficiency. Little is known about the outcomes and risk factors for developing AKI in patients undergoing bariatric surgery with normal renal function.

OBJECTIVE

We aimed to describe factors that may increase risk of AKI after primary bariatric surgery in patients without history of kidney disease.

SETTING

Academic hospital, United States.

METHODS

We performed a retrospective analysis of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program data registry for patients aged ≥18 years undergoing laparoscopic sleeve gastrectomy and laparoscopic Roux-en-Y gastric bypass (LRYGB) from 2015 to 2019. Patients with diagnosis of chronic kidney disease were excluded. The primary outcome was incidence of AKI. Secondary outcomes included 30-day complications, readmissions, reoperations, and mortality. Univariate and multivariate analyses were performed to identify differences between patients with and without AKI.

RESULTS

A total of 747,926 patients were included in our analysis (laparoscopic sleeve gastrectomy = 73.1%, LRYGB = 26.8%). Mean age was 44.40 ± 11.94 years, with female predominance (79.7%). AKI occurred in 446 patients (.05%). Patients with postoperative AKI had higher rates of complications, readmissions, reoperations, and mortality. Significant predictors of AKI were male sex, history of venous thromboembolism, hypertension, limitation for ambulation, and LRYGB. High albumin levels and White race were protective factors.

CONCLUSIONS

New-onset AKI was associated with adverse 30-day outcomes in patients undergoing bariatric surgery. Male sex, venous thromboembolism, hypertension, limited ambulation, and LRYGB were independent predictors of AKI. Prospective studies are needed to better describe these results.

Bariatric Surgery Outcomes in Patients with Chronic Kidney Disease

Obesity increases the risk of developing chronic kidney disease (CKD), which has a major negative impact on global health. Bariatric surgery (BS) has demonstrated a substantial improvement of obesity-related comorbidities and thus, it has emerged as a potential therapeutic tool in order to prevent end-stage renal disease. A limited number of publications to date have examined the beneficial effects and risks of BS in patients with non-advanced stages of CKD. We aimed to investigate the safety of BS in patients with CKD stages 3-4 (directly related or not to obesity) and both the metabolic/renal outcomes post-BS. A total of 57 individuals were included (n = 19 for CKD-group; n = 38 for patients with obesity, but normal eGFR [control-group]). Weight loss and obesity comorbidities resolution after BS were similar in both groups. Renal function (eGFR [CKD-EPI]) improved significantly at the 1-year follow-up: Δ10.2 (5.2-14.9) (p < 0.001) for CKD-group and Δ4.0 (-3.9-9.0) mL/min/1.73 m2 (p = 0.043) for controls. Although this improvement tended to decrease in the 5-year follow-up, eGFR remained above its basal value for the CKD-group. Noteworthy, eGFR also improved in those patients who presented CKD not directly attributed to obesity. For patients with CKD, BS appears to be safe and effective regarding weight loss and obesity comorbidities resolution, irrespective of the main cause of CKD (related or not to obesity).

Impact of Intraoperative Fluid Balance and Norepinephrine on Postoperative Acute Kidney Injury after Cystectomy and Urinary Diversion over Two Decades: A Retrospective Observational Cohort Study

The use of norepinephrine and the restriction of intraoperative hydration have gained increasing acceptance over the last few decades. Recently, there have been concerns regarding the impact of this approach on renal function. The objective of this study was to examine the influence of norepinephrine, intraoperative fluid administration and their interaction on acute kidney injury (AKI) after cystectomy. In our cohort of 1488 consecutive patients scheduled for cystectomies and urinary diversions, the overall incidence of AKI was 21.6% (95%-CI: 19.6% to 23.8%) and increased by an average of 0.6% (95%-CI: 0.1% to 1.1%, p = 0.025) per year since 2000. The fluid and vasopressor regimes were characterized by an annual decrease in fluid balance (-0.24 mL·kg^-1·h^-1, 95%-CI: -0.26 to -0.22, p < 0.001) and an annual increase in the amount of norepinephrine of 0.002 µg·kg^-1·min^-1 (95%-CI: 0.0016 to 0.0024, p < 0.001). The interaction between the fluid balance and norepinephrine levels resulted in a U-shaped association with the risk of AKI; however, the magnitude and shape depended on the reference categories of confounders (age and BMI). We conclude that decreased intraoperative fluid balance combined with increased norepinephrine administration was associated with an increased risk of AKI. However, other potential drivers of the observed increase in AKI incidence need to be further investigated in the future.

Association of intraoperative hypotension and severe postoperative complications during non-cardiac surgery in adult patients: A systematic review and meta-analysis

Background

Intraoperative hypotension (IOH) is a common side effect of non-cardiac surgery that might induce poor postoperative outcomes. The relationship between the IOH and severe postoperative complications is still unclear. Thus, we summarized the existing literature to evaluate whether IOH contributes to developing severe postoperative complications during non-cardiac surgery.

Methods

We conducted a comprehensive search of PubMed, Embase, Cochrane Library, Web of Science, and the CBM from inception to 15 September 2022. The primary outcomes were 30-day mortality, acute kidney injury (AKI), major adverse cardiac events (myocardial injury or myocardial infarction), postoperative cognitive dysfunction (POCD), and postoperative delirium (POD). Secondary outcomes included surgical-site infection (SSI), stroke, and 1-year mortality.

Results

72 studies (3 randomized; 69 non-randomized) were included in this study. Low-quality evidence showed IOH resulted in an increased risk of 30-day mortality (OR, 1.85; 95% CI, 1.30-2.64; P < .001), AKI (OR, 2.69; 95% CI, 2.15-3.37; P < .001), and stroke (OR, 1.33; 95% CI, 1.21-1.46; P < .001) after non-cardiac surgery than non-IOH. Very low-quality evidence showed IOH was associated with a higher risk of myocardial injury (OR, 2.00; 95% CI, 1.17-3.43; P = .01), myocardial infarction (OR, 2.11; 95% CI, 1.41-3.16; P < .001), and POD (OR, 2.27; 95% CI, 1.53-3.38; P < .001). Very low-quality evidence showed IOH have a similar incidence of POCD (OR, 2.82; 95% CI, 0.83-9.50; P = .10) and 1-year-mortality (OR, 1.66; 95% CI, 0.65-4.20; P = .29) compared with non-IOH in non-cardiac surgery.

Conclusion

Our results suggest IOH was associated with an increased risk of severe postoperative complications after non-cardiac surgery than non-IOH. IOH is a potentially avoidable hazard that should be closely monitored during non-cardiac surgery.

Implementation of a new definition for acute kidney injury in the National Surgical Quality Improvement Project: What is the impact?

BACKGROUND

The National Surgical Quality Improvement Project is the preeminent surgical quality database, but it undercaptures acute kidney injury. Recently, the National Surgical Quality Improvement Project lowered the thresholds for acute kidney injury for the first time, so we assessed the impact of implementing the definition change on the rate of acute kidney injuries.

METHODS

For this interrupted time series analysis, we assembled 2 institutional National Surgical Quality Improvement Project files to identify adults undergoing inpatient noncardiac nonvascular surgery. The acute kidney injury definition changed on July 1, 2021, so patients were stratified by their operative date into 12-month pre and post groups. Weighted covariate propensity score matching and logistic regression were used to balance the periods and compare outcomes.

RESULTS

In total, 4,784 adults were eligible (55% pre and 45% post change). The overall rate of postoperative outcomes was similar, aside for acute kidney injury (pre 0.3%, post 5.6%, P < .0001). Regardless of the period, patients with acute kidney injuries had significantly longer lengths of stay and morbidity and mortality rates compared to those without an acute kidney injury. After the definition change, 81% of acute kidney injuries were stage I, and none were identified by urine output alone. After matching, surgery after the definition change was associated with an increased weighted odds of an acute kidney injury compared to surgery before the change (odds ratio 26.2; 95% confidence interval, 12.1-56.8).

CONCLUSION

In the year after the definition change, there was a 1,700% relative increase in the rate of reported acute kidney injuries. Newly identified acute kidney injuries are associated with high complication rates, and this definition change has implications for patient counseling, research, and quality reporting.

Association between intraoperative oliguria and postoperative acute kidney injury in non-cardiac surgical patients: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to evaluate the association between intraoperative oliguria and the risk of postoperative acute kidney injury (AKI) in patients undergoing non-cardiac surgery.

METHODS

The MEDLINE and EMBASE databases were searched up to August 2022 for studies in adult patients undergoing non-cardiac surgery, where the association between intraoperative urine output and the risk of postoperative AKI was assessed. Both randomised and non-randomised studies were eligible for inclusion. Study selection and risk of bias assessment were independently performed by two investigators. The risk of bias was evaluated using the Newcastle-Ottawa scale. We performed meta-analysis of the reported multivariate adjusted odds ratios for the association between intraoperative oliguria (defined as urine output < 0.5 mL/kg/hr) and the risk of postoperative AKI using the inverse-variance method with random effects models. We conducted sensitivity analyses using varying definitions of oliguria as well as by pooling unadjusted odds ratios to establish the robustness of the primary meta-analysis. We also conducted subgroup analyses according to surgery type and definition of AKI to explore potential sources of clinical or methodological heterogeneity.

RESULTS

Eleven studies (total 49,252 patients from 11 observational studies including a post hoc analysis of a randomised controlled trial) met the selection criteria. Seven of these studies contributed data from a total 17,148 patients to the primary meta-analysis. Intraoperative oliguria was associated with a significantly elevated risk of postoperative AKI (pooled adjusted odds ratio [OR] 1.74; 95% confidence interval [CI] 1.36-2.23, p < 0.0001, 8 studies). Sensitivity analyses supported the robustness of the primary meta-analysis. There was no evidence of any significant subgroup differences according to surgery type or definition of AKI.

CONCLUSIONS

This study demonstrated a significant association between intraoperative oliguria and the risk of postoperative AKI, regardless of the definitions of oliguria or AKI used. Further prospective and multi-centre studies using standardised definitions of intraoperative oliguria are required to define the thresholds of oliguria and establish strategies to minimise the risk of AKI.

Postoperative Acute Kidney Injury

Postoperative AKI is a common complication of major surgery and is associated with significant morbidity and mortality. The Kidney Disease Improving Global Outcomes AKI definition allows consensus classification and identification of postoperative AKI through changes in serum creatinine and/or urine output. However, such conventional diagnostic criteria may be inaccurate in the postoperative period, suggesting a potential to refine diagnosis by application of novel diagnostic biomarkers. Risk factors for the development of postoperative AKI can be thought of in terms of preoperative, intraoperative, and postoperative factors and, as such, represent areas that may be targeted perioperatively to minimize the risk of AKI. The treatment of postoperative AKI remains predominantly supportive, although application of management bundles may translate into improved outcomes.

Impact of early postoperative creatinine increase on mid-term renal function after cystectomy

OBJECTIVES

To determine whether early acute kidney injury affects mid-term renal function, to identify risk factors for impaired mid-term renal function, and to highlight the evolution of plasma creatinine and estimated glomerular filtration rate in the first 12 months after cystectomy and urinary diversion.

METHODS

We conducted a single-center retrospective observational cohort study from 2000 to 2019. We included 900 consecutive patients undergoing cystectomy and urinary diversion. Patients with incomplete data and preoperative hemodialysis were excluded. Early acute kidney injury was defined as an increase in plasma creatinine of >50% or >26.5 μmol/L within 24 h after surgery. Multiple linear regression analysis was performed to model the association between risk factors and change in plasma creatinine and estimated glomerular filtration rate at 12 months.

RESULTS

Early acute kidney injury was diagnosed in 183/900 patients (20.3%) and was associated with significant mid-term plasma creatinine increase compared to preoperative value (+10.0 μmol/L [95% confidence interval -1.5, 25.0] vs +4.0 μmol/L [-7.0, 13.0]; P < 0.001). Similarly, a significant estimated glomerular filtration rate change was found (-11.2 mL/min [95% confidence interval -19.8, 0.6] vs -4.9 mL/min [-15.6, 5.3]; P < 0.001). In the linear regression model, early acute kidney injury increased creatinine at 12 months by 9.8% (estimated glomerular filtration rate: decrease by 6.2 mL/min), male sex by 12.0%. Limitations include retrospective analysis from prospectively assessed data.

CONCLUSIONS

Early acute kidney injury resulted in elevated plasma creatinine and decreased estimated glomerular filtration rate values 12 months postoperatively, albeit the clinical relevance remains questionable.

Renal Function Following Bariatric Surgery: a Literature Review of Potential Mechanisms

Obesity is a major and independent risk factor for onset and progression of many renal diseases. Bariatric surgery (BS) improves renal function by improving obesity-related metabolic disorders. However, the procedure is also accompanied by renal risks, including acute kidney injury (AKI) and oxalate nephropathy. Here, we briefly review the history and principle of frequently applied technique for BS and summarize the comprehensive BS effect on kidney function. Importantly, we highlight the possible molecular mechanisms associated with the recovery of renal function to provide novel ideas for future studies and clinical applications.

A low serum iron level is a potential predictor of poor renal function in patients following laparoscopic sleeve gastrectomy: a retrospective study

This study aimed to assess the association of serum iron level (Iron) with the estimated glomerular filtration rate (eGFR) after bariatric surgery (BS). We reviewed 210 patients with mean age of 39.1 ± 10.6 years (body mass index, 41.4 ± 5.5 kg/m²) undergoing BS. The primary outcome was the relationship between Iron and eGFR at 12-month after surgery. Multiple linear regression analyses were performed using postoperative eGFR as dependent variables and using Iron and other variables (i.e., age) as independent variables. At 12-month follow-up, 94 patients were analyzed. BMI significantly decreased, whereas serum iron level significantly increased. Although the percentage of patients with eGFR of < 90 mL/min/1.73 m² increased during the study period, no significant difference was found in postoperative 12-month eGFR. No correlations were noted between Iron and eGFR at baseline and postoperative 1 and 6 months, whereas a significant relationship was observed between Iron and postoperative 12-month eGFR. Multiple linear regression analyses revealed that Iron and presence of diabetes were the independent predictors of postoperative 12-month eGFR. This pilot study showed a positive association of postoperative serum iron level with renal function in this patient population. Further large-scale trials are needed to confirm the findings.

Obesity, Angiotensin-Blocking Drugs, and Acute Kidney Injury in Orthopedic Surgery

Postoperative acute kidney injury occurs in 7% to 11% of orthopedic surgeries. The effect of preoperative angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) on the development of postoperative acute kidney injury remains controversial. Adipose tissue has its own independently regulated angiotensin system. The primary aim of this study was to examine the effects of obesity and preoperative ACEIs and ARBs on postoperative acute kidney injury. Charts were reviewed of adult elective orthopedic surgery patients during a 2-year period when patients were instructed to take their ACEI or ARB on the morning of surgery. The patients were divided into an obese cohort (body mass index [BMI] ≥30 kg/m²) and a nonobese cohort (BMI <30 kg/m²). A multivariable model was created for the outcome of acute kidney injury, using obesity as a primary predictor and adjusting for demographics, medications, comorbidities, and intraoperative parameters in a logistic regression analysis. Obesity increased the likelihood of developing acute kidney injury after orthopedic surgery (odds ratio [OR], 1.86; 95% CI, 1.07-3.22; P=.028). For every 5-unit increase in BMI, the odds of acute kidney injury were 1.43 (95% CI, 1.26-1.62; P<.001). When receiving ACEIs or ARBs, only the nonobese patients had a statistically increased likelihood of postoperative acute kidney injury (OR, 3.30; 95% CI, 1.12-9.70; P=.030). Obesity is an independent risk factor for postoperative acute kidney injury. Obesity appears to influence the effect that preoperative ACEIs and ARBs have on postoperative acute kidney injury. [Orthopedics. 2021;44(2):e253-e258.].

Association of Serum Zinc Concentration with Preservation of Renal Function After Bariatric Surgery: a Retrospective Pilot Study

BACKGROUND

Although serum zinc level (Zn) is known to impact renal function in patients with diabetes, their correlation following bariatric surgery remains unknown. This study aimed at assessing the association of Zn with estimated glomerular filtration rate (eGFR) after laparoscopic sleeve gastrectomy (LSG).

METHODS

One hundred and twenty-nine patients in total (mean age, 38.1 ± 10.8; body mass index, 39.1 ± 5.1 kg/m²) with normal preoperative kidney function undergoing LSG at a single tertiary referral center were reviewed. The primary study endpoint was the relationship between Zn and post-LSG eGFR at 12-month follow-up. The secondary outcomes were the associations of percentage weight loss (%WL) with changes in Zn (△Zn) and eGFR (△eGFR).

RESULTS

The incidence of zinc deficiency was 8.5%, 8.1%, and 29.9% at baseline, post-LSG and one- and 12-month follow-up, respectively. At 12-month follow-up, Zn dropped from 104.1 ± 19.2 to 85.3 ± 38.9 μg/dL (p = 0.001), while eGFR levels decreased from 106.6 ± 10.3 to 102.1 ± 19.4 mL/min per 1.73 m² (p = 0.025). Zn correlated positively with eGFR at 6-month (r = 0.252, p = 0.037) and 12-month (r = 0.41, p = 0.001) follow-ups. Multiple linear regression analyses including baseline variables of age, sex, BMI, %WL, and diabetes identified Zn and %WL as independent predictors of eGFR at 12-month follow-up. There was no evidence of multicollinearity among these variables. Despite positive association between %WL and △eGFR (r = 0.222, p = 0.031), no correlation was noted between %WL and △Zn (r = - 0.129, p = 0.40).

CONCLUSION

The results demonstrated a positive relationship between post-LSG serum zinc levels and preservation of renal function among patients with obesity in a surgical setting. Large-scale studies are warranted to support the findings.

Association of intraoperative hypotension with postoperative morbidity and mortality: systematic review and meta-analysis

Background

Intraoperative hypotension, with varying definitions in literature, may be associated with postoperative complications. The aim of this meta-analysis was to assess the association of intraoperative hypotension with postoperative morbidity and mortality.

Methods

MEDLINE, Embase and Cochrane databases were searched for studies published between January 1990 and August 2018. The primary endpoints were postoperative overall morbidity and mortality. Secondary endpoints were postoperative cardiac outcomes, acute kidney injury, stroke, delirium, surgical outcomes and combined outcomes. Subgroup analyses, sensitivity analyses and a meta-regression were performed to test the robustness of the results and to explore heterogeneity.

Results

The search identified 2931 studies, of which 29 were included in the meta-analysis, consisting of 130 862 patients. Intraoperative hypotension was associated with an increased risk of morbidity (odds ratio (OR) 2.08, 95 per cent confidence interval 1.56 to 2.77) and mortality (OR 1.94, 1.32 to 2.84). In the secondary analyses, intraoperative hypotension was associated with cardiac complications (OR 2.44, 1.52 to 3.93) and acute kidney injury (OR 2.69, 1.31 to 5.55). Overall heterogeneity was high, with an I² value of 88 per cent. When hypotension severity, outcome severity and study population variables were added to the meta-regression, heterogeneity was reduced to 50 per cent.

Conclusion

Intraoperative hypotension during non-cardiac surgery is associated with postoperative cardiac and renal morbidity, and mortality. A universally accepted standard definition of hypotension would facilitate further research into this topic.

Safety of bariatric surgery in patients with inflammatory bowel disease: A systematic review and meta-analysis

The efficacy of bariatric surgery in achieving weight loss and preventing long-term comorbidities such as cardiovascular diseases, diabetes mellitus and osteoarthritis is well established. Data regarding safety of bariatric surgery in patients with inflammatory bowel disease (IBD) is scarce. We attempted a systematic review and meta-analysis to evaluate the complications following bariatric surgery in patients with IBD. The primary outcomes evaluated were wound infection, Clavien-Dindo grade > II complications and IBD exacerbation (within 1 year). Secondary outcomes evaluated included overall mortality, stricture, small bowel obstruction, acute kidney injury (AKI) and thromboembolism. Pooled outcomes (event rate) with 95% confidence interval (CI) were calculated using random effects model. A total of 14 studies (all observational) with 2608 patients were included. The rates of primary outcomes were: wound infection (4.1%, 95% CI: 0.9-7.2), Clavien-Dindo grade > II complications (2.0%, 95%: CI 0.6-3.5) and IBD exacerbation (4.3%, 95% CI: 0.7-7.9). The pooled rate for other outcomes was: mortality 0.1%, stricture 6.5%, small bowel obstruction 6.7%, AKI 2.2% and thromboembolism 0.1%. Bariatric surgery is relatively safe in patients with IBD and should be pursued to reduce comorbidities associated with obesity. Future comparative studies are needed to further assess the safety of bariatric surgery in population with and without IBD.

Stratification of Readmission after Bariatric Surgery by Day of Post-Discharge Presentation

INTRODUCTION/PURPOSE

Reasons of postoperative readmissions may vary based on the timing of rehospitalization. This study characterizes predictors and causes for readmission after bariatric surgery on day-to-day basis after discharge.

MATERIALS AND METHODS

Using the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program data, patients who underwent Roux-en-Y gastric bypass or sleeve gastrectomy were identified. Perioperative factors of early readmissions (post-discharge days 0-9) were compared to those of late readmissions (post-discharge days 10-30). Multivariable analysis was conducted to identify predictors of early versus late readmissions. Reasons for readmissions were characterized on day-to-day basis.

RESULTS

Of 509,631 operations, 19,061 (3.7%) cases were readmitted. Of these, 9666 (50.7%) were early, while 9395 (49.3%) were late readmissions. White race (OR = 1.2, CI = [1.1-1.3]), revisional surgery (OR = 1.2, CI = [1.1-1.4]), Roux-en-Y gastric bypass (OR = 1.2, CI = [1.1-1.3]), pulmonary complication (OR = 1.8, CI = [1.5-2.3]), bleeding (OR = 2, CI = [1.6-2.6]), and post-acute care (OR = 1.8, CI = [1.2-2.6]) were predictors of early readmission. Late readmission was associated with body mass index ≥ 40 (CI = 0.83, OR = [0.77-0.89]), renal/urological complication (OR = 0.6, CI = [0.5-0.8]), and deep vein thrombosis (OR = 0.5, CI = [0.4-0.6]). PO intolerance or dehydration/electrolyte imbalance was the most common readmission reason, peaking on post-discharge days 19-30. Pain, medical complications, obstruction, and bleeding were causes of early readmissions. However, venous thromboembolism readmissions peaked after post-discharge day 9.

CONCLUSION

Complex bariatric operations and patients who require post-discharge extended care are associated with early readmissions. Such readmissions are due to early post-discharge complications. However, late readmissions are driven by interrelated risk factors and complications. These findings suggest that targeting patients at risk for delayed rehospitalization is the most efficient approach to minimize readmissions after bariatric surgery.

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.

Anemia following acute kidney injury after noncardiac surgery and long-term outcomes: the NARA-AKI cohort study

Background

This study was conducted to investigate whether acute kidney injury (AKI) is an independent predictor of anemia and whether anemia following AKI is a mediator of mortality after AKI.

Methods

This is a retrospective cohort study. Adults with noncardiac surgery from 2007 to 2011 were included. Obstetric or urological surgery, missing data or preoperative dialysis were excluded. Subjects were followed until the end of 2015 or lost to follow-up. Exposures of interest were postoperative AKI. Outcome variables were hematocrit values at 3, 6 and 12 months postoperatively and mortality. Associations between AKI and hematocrit or association between AKI and mortality were examined by multivariable linear regression or Cox regression, respectively.

Results

Among 6692 subjects, 445 (6.6%) developed AKI. Among those with postoperative data, AKI was independently associated with lower hematocrit at 3, 6 and 12 months postoperatively, with coefficients of −0.79 [95% confidence interval (CI) −1.47 to −0.11; n = 1750], −1.35 (−2.11 to −0.60; n = 1558) and −0.91 (−1.59 to −0.22; n = 2463), respectively. Higher stages or longer duration of AKI were associated with more severe anemia. AKI was associated with higher mortality after 3 months postoperatively with a hazard ratio of 1.54 (95% CI 1.12–2.12). Further adjustment with hematocrit at 3 months attenuated the association. The mediation effect was significant (P = 0.02) by mediation analysis.

Conclusions

AKI was an independent predictor of anemia following AKI. Higher mortality associated with AKI was at least partially mediated by anemia following AKI. Whether correction of anemia following AKI improves mortality requires further research.

Case Report: Acute kidney failure leading to permanent haemodialysis due to hyperoxaluria following one-anastomosis gastric bypass-related rapid weight loss

The one-anastomosis gastric bypass (OAGB) has been proven to provide good weight loss, comorbidity improvement, and quality of life with follow-up longer than five years. Although capable of improving many obesity-related diseases, OAGB is associated with post-operative medical complications mainly related to the induced malabsorption. A 52-year-old man affected by nephrotic syndrome due to a focal segmental glomerulosclerosis underwent OAGB uneventfully. At three months post-surgery, the patient had lost 40kg, reaching a BMI of 32. The patient was admitted to the nephrology unit for acute kidney injury with only mild improvement in renal function (SCr 9 mg/dl); proteinuria was still elevated (4g/24h), with microhaematuria. A renal biopsy was performed: oxalate deposits were demonstrated inside tubules, associated with acute and chronic tubular and interstitial damage and glomerulosclerosis (21/33 glomeruli). Urinary oxalate levels were found to be elevated (72mg/24h, range 13-40), providing the diagnosis of acute kidney injury due to hyperoxaluria, potentially associated to OAGB. No recovery in renal function was observed and the patient remained dialysis dependent. Early and rapid excessive weight loss in patients affected by chronic kidney insufficiency could be associated with the worsening of renal function. Increased calcium oxalate levels associated with OAGB-related malabsorption could be a key factor in kidney injury.

Strategies to Reduce Perioperative Nephrotoxicity

Postoperative acute kidney injury (AKI) is a common complication of surgery that is associated with significant adverse outcomes, including increased morbidity and mortality. The perioperative burden of AKI risk factors is complex and potentially large, including high-risk nephrotoxic medications, hypotension, hypovolemia, radiologic contrast, anemia, and surgery-specific factors. Understanding the pathogenesis, risk factors, and potential cumulative impact of perioperative nephrotoxic exposures is particularly important in the prevention and reduction of perioperative AKI. This review outlines the possible strategies to reduce perioperative nephrotoxicity and the development of postoperative AKI.

Impact of Preoperative Anemia on Postoperative Kidney Function Following Laparoscopic Bariatric Surgery

BACKGROUND

Preoperative anemia is a risk factor for acute kidney failure after high-risk surgeries. We assessed the impact of preoperative anemia on kidney function in an obese Asian population after laparoscopic bariatric surgery.

METHODS

Patient characteristics, comorbidities, type of surgery, perioperative profiles, eGFR, and micronutrition were retrospectively reviewed in 341 patients with obesity undergoing bariatric surgery. All patients, who had a preoperative estimated glomerular filtration rates (eGFR) ≥ 90 mL/min/1.73 m², were followed for 1 year and assigned to one of two groups: anemia or non-anemia group. Preoperative anemia was determined based on hemoglobin concentration.

RESULTS

The Pearson's correlation coefficient between preoperative body mass index (BMI) and preoperative eGFR of all patients was 0.169 (p = 0.005). Preoperatively, there were no significant differences in age, BMI, and eGFR between the anemia (n = 38) and non-anemia groups (n = 303). Patients in the anemia group had lower hemoglobin concentration at baseline, 1 month, and 12 months after surgery than those in the non-anemia group. Postoperative eGFR levels at 1 month (p = 0.993) and 1 year (p = 0.118) as well as hospital stay (p = 0.941) were comparable between the two groups. However, the percentage weight loss was significantly higher in the non-anemia group than that in the anemia group 1 year after bariatric surgery (30.0 ± 7.3% vs. 27.0 ± 8.1%; p = 0.041).

CONCLUSIONS

Preoperative anemia did not negatively impact kidney function following laparoscopic bariatric surgery during the 12-month follow-up. Considering the potential adverse impact of anemia on postoperative weight loss, preoperative correction of anemia may be recommended.

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.

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.

The Association Between Obesity and Risk of Acute Kidney Injury After Cardiac Surgery

OBJECTIVE

To determine the relationship between obesity and the risk of AKI after cardiac surgery (CS-AKI) in a cohort study.

METHODS

A total of 1,601 patients undergoing cardiac surgery were collected and their incidence of CS-AKI was recorded. They were divided into underweight, normal weight, overweight, and obese groups. Logistic regression was used to estimate the association between BMI (body mass index) and CS-AKI risk. Then, a meta-analysis of published cohort studies was conducted to confirm this result using PubMed and Embase databases.

RESULTS

A significant association was observed in this independent cohort after adjusting age, gender, hypertension and New York Heart Association classification (NYHA) class. Compared with normal BMI group (18.5 ≤ BMI < 24.0), the individuals with aberrant BMI level had an increased AKI risk (OR: 1.68, 95% CI: 1.01-2.78) for BMI < 18.5 group and (OR: 1.43, 95% CI: 0.96-2.15) for BMI ≥ 28.0. Interestingly, the U-shape curve showed the CS-AKI risk reduced with the increasing of BMI when BMI ≤ 24.0. As BMI increases with BMI > 24.0, the risk of developing CS-AKI increased significantly. In the confirmed meta-analysis, compared with normal weight, overweight group with cardiac surgery had higher AKI risk (OR: 1.28, 95% CI: 1.16-1.41, P_{heterogeneity} = 0.49). The similar association was found in obesity subgroup (OR: 1.79, 95% CI: 1.57-2.03, P_{heterogeneity} = 0.42).

CONCLUSION

In conclusion, the results suggested that abnormal BMI was a risk factor for CS-AKI independently.

Acute kidney injury after thoracic surgery: a proposal for a multicentre evaluation (MERITS)

OBJECTIVES

Because the mortality rate is very low in thoracic surgery, its use as a quality discriminator is limited. Acute kidney injury (AKI) is a candidate measure because it is associated with increased rates of morbidity and mortality and is partly preventable. The incidence of AKI after thoracic surgery is not well documented. We conducted an audit to determine the incidence and outcomes of AKI. This audit became a pilot project, and the results indicate the feasibility of a larger study.

METHODS

Retrospective data on renal function post-thoracic surgery were collected at a tertiary cardiothoracic unit over 12 months. Renal impairment was classified according to the Kidney Disease Improving Global Outcomes criteria.

RESULTS

Of 568 patients (mean = 59  ±  SD 18; 38% women), AKI was diagnosed in 86 (15.1%) within 72 h post-thoracic surgery based on the Kidney Disease Improving Global Outcomes staging system (stage 1, n = 55; stage 2, n = 25; stage 3, n = 6). Significant differences were found in postoperative length of stay (3 vs 5 days; P < 0.001) of patients with and without AKI. There was a significant difference between the age groups of patients with and without AKI (P < 0.05) in the open surgical group but not in the group having video-assisted thoracoscopic surgery (VATS). There was no significant difference in the mortality rates between patients with and without AKI.

CONCLUSIONS

The incidence of AKI after thoracic surgery was 15.1%. AKI was associated with longer hospital stays and was more likely in ≥60-year-old patients after open surgery than after VATS. Reducing AKI could improve patient outcomes. We propose that AKI may be a useful quality measure in thoracic surgery. We are developing a multicentre audit based on this approach.

Impact of serum uric acid on renal function after bariatric surgery: a retrospective study

BACKGROUND

Despite a known negative association between serum uric acid level (SUA) and renal function, this correlation in patients after bariatric surgery remains unknown.

OBJECTIVE

To assess correlation between postoperative SUA and estimated glomerular filtration rate (eGFR) at 12 months after bariatric surgery.

SETTING

A single tertiary referral center.

METHODS

A total of 252 patients (age = 40.5 ± 11.2; body mass index = 39.0 ± 5.5 kg/m²) undergoing bariatric surgery divided into 2 groups (i.e., normal renal function [90 ≤ eGFR < 125 mL/min/1.73 m², n = 176] versus renal function impairment [eGFR < 90 mL/min/1.73 m², n = 76]) were assessed for relationships between SUA and eGFR in both groups (primary endpoint) and associations of percentage weight loss with changes in SUA (△SUA) and eGFR (△eGFR) for all patients (secondary endpoint) at 12 months.

RESULTS

Overall, prevalence of hyperuricemia was 40.4% and 22.2% (baseline and postoperative 12 mo, respectively). Reverse relationship was observed between SUA and eGFR (r = -.152, P = .007) for all patients with no association noted between baseline SUA and eGFR in each group as well as between SUA and eGFR at 12 months in the normal group (r = -.076, P = .437). The reverse relationship was found (r = -.417, P = .005) in renal function impairment group for whom SUA was identified as a predictor of eGFR at 12 months. There was no association of percentage weight loss with △SUA (r = .089, P = .601) and △eGFR (r = -.046, P = .785).

CONCLUSION

The results demonstrated a negative relationship between postoperative SUA and renal function in patients with preexisting renal dysfunction undergoing bariatric surgery. Clinical significance of our findings warrants further investigation.

Impact of intra-operative fluid and noradrenaline administration on early postoperative renal function after cystectomy and urinary diversion: A retrospective observational cohort study

BACKGROUND

The use of noradrenaline to enable a restrictive approach to intra-operative fluid therapy to avoid salt and water overload has gained increasing acceptance. However, concerns have been raised about the impact of this approach on renal function.

OBJECTIVES

To identify risk factors for acute kidney injury (AKI) in patients undergoing cystectomy with urinary diversion and determine whether administration of noradrenaline and intra-operative hydration regimens affect early postoperative renal function.

DESIGN

Retrospective observational cohort study.

SETTING

University hospital, from 2007 to 2016.

PATIENTS

A total of 769 consecutive patients scheduled for cystectomy and urinary diversion. Those with incomplete data and having pre-operative haemodialysis were excluded.

MAIN OUTCOME MEASURES

AKI was defined as a serum creatinine increase of more than 50% over 72 postoperative hours. Multiple logistic regression analysis was performed to model the association between risk factors and AKI.

RESULTS

Postoperative AKI was diagnosed in 86/769 patients (11.1%). Independent predictors for AKI were the amount of crystalloid administered (odds ratio (OR) 0.79 [95% confidence interval (CI), 0.68 to 0.91], P = 0.002), antihypertensive medication (OR 2.07 [95% CI, 1.25 to 3.43], P = 0.005), pre-operative haemoglobin value (OR 1.02 [95% CI, 1.01 to 1.03], P = 0.010), duration of surgery (OR 1.01 [95% CI, 1.00 to 1.01], P = 0.002), age (OR 1.32 [95% CI, 1.44 to 1.79], P = 0.002) but not the administration of noradrenaline (OR 1.09 [95% CI, 0.94 to 1.21], P = 0.097). Postoperative AKI was associated with longer hospital stay (18 [15 to 22] vs. 16 [15 to 19] days; P = 0.035) and a higher 90-day major postoperative complication rate (41.9 vs. 27.5%; P = 0.002).

CONCLUSION

Noradrenaline administration did not increase the risk for AKI. A too restrictive approach to administration of crystalloids was associated with an increased risk for AKI, particularly in older patients, those receiving antihypertensive medication, and those whose surgery was prolonged. As AKI was associated with longer hospital stay and increased postoperative morbidity, these observations should be taken into account to improve outcome when addressing peri-operative fluid management.

TRIAL REGISTRATION

Not applicable.

The impact of chronic kidney disease on bariatric perioperative outcome: a MBSAQIP matched analysis

BACKGROUND

Morbid obesity is considered a strong independent risk factor for chronic kidney disease (CKD), and bariatric surgery remains the most effective treatment for obesity-related co-morbidities. Previous large database analyses have suggested that CKD does not independently increase the risk of adverse outcomes after bariatric surgery. The safety of elective bariatric surgery in this patient population remains unclear. To this end, we compared 30-day outcomes in this patient population after laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass.

OBJECTIVES

To compare 30-day outcomes in CKD patients after laparoscopic sleeve gastrectomy or gastric bypass.

SETTING

University Hospital, United States.

METHODS

Using the Metabolic and Bariatric Surgery Accreditation Quality Improvement Program database, we identified patients with CKD who underwent laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass in 2015 or 2016. An unmatched cohort analysis, a propensity-matched analysis, and a case-control, matched-cohort analysis was performed of patients with and without CKD.

RESULTS

Of the 302,092 patients included in this study, 2362 (.7%) had CKD, of whom 837 (35.4%) required dialysis. CKD patients were older with significantly higher rates of co-morbid conditions. Hospital length of stay, intensive care unit admission, reoperation, readmission, bleeding, cardiopulmonary, infectious complications, and total morbidity were significantly higher in CKD patients. In propensity-matched and case-control matched analyses of 4006 patients and 2264 patients, respectively, poorer outcomes in CKD patients highlight it an independent risk factor for morbidity.

CONCLUSIONS

In contrast to previously reported large database analysis, CKD and dependence on dialysis independently increases the risk of 30-day adverse outcomes after primary bariatric surgery. The benefits conferred by bariatric surgery should be carefully weighed against the increased risk of complications in this challenging population.

Development and validation of quick Acute Kidney Injury-score (q-AKI) to predict acute kidney injury at admission to a multidisciplinary intensive care unit

AKI is associated with increased risk of death, prolonged length of stay and development of de-novo chronic kidney disease. The aim of our study is the development and validation of prediction models to identify the risk of AKI in ICU patients up to 7 days. We retrospectively recruited 692 consecutive patients admitted to the ICU at San Bortolo Hospital (Vicenza, Italy) from 1 June 2016 to 31 March 2017: 455 patients were treated as the derivation group and 237 as the validation group. Candidate variables were selected based on a literature review and expert opinion. Admission eGFR< 90 ml/min /1.73 mq (OR 2.78; 95% CI 1.78–4.35; p<0.001); SOFAcv ≥ 2 (OR 2.23; 95% CI 1.48–3.37; p<0.001); lactate ≥ 2 mmol/L (OR 1.81; 95% CI 1.19–2.74; p = 0.005) and (TIMP-2)•(IGFBP7) ≥ 0.3 (OR 1.65; 95% CI 1.08–2.52; p = 0.019) were significantly associated with AKI. For the q-AKI score, we stratified patients into different AKI Risk score levels: 0–2; 3–4; 5–6; 7–8 and 9–10. In both cohorts, we observed that the proportion of AKI patients was higher in the higher score levels.

Greater Rates of Acute Kidney Injury in African American Total Knee Arthroplasty Patients

BACKGROUND

This retrospective study compared the change in serum creatinine between African American and Caucasian total knee arthroplasty (TKA) patients. The authors hypothesized that African Americans would demonstrate significantly greater change, and that a significantly greater proportion would demonstrate creatinine changes consistent with acute kidney injury (AKI).

METHODS

Primary TKAs performed at a single institution between July 2011 and June 2016 were identified: 1035 primary TKAs met inclusion and exclusion criteria (110 African American, 925 Caucasian, excluding Hispanic and Asian patients). None were excluded based on gender, age, body mass index, preoperative diagnosis, or comorbidities. All patients had preoperative and postoperative creatinine levels available in the electronic medical records. Each patient received the same preop and postop protocol for nonsteroidal anti-inflammatory drug use along with other drugs administered including anesthesia. All patients received 1 g of intravenous vancomycin with some patients additionally receiving 1 g of vancomycin powder administered locally at the end of surgery. All patients were controlled for fluid intake and blood loss, along with no patient receiving a transfusion or intravenous contrast. Patient demographics and preoperative/postoperative serum creatinine were recorded and then analyzed for presence of AKI (≥0.3 mg/dL). Preoperative/postoperative serum creatinine concentrations were compared between African American and Caucasian patients using 2 × 2 repeated measures analysis of variance. Prevalence of patients in each group demonstrating AKI was calculated using Fisher's exact test.

RESULTS

African American patients had significantly greater serum creatinine preoperatively (1.00 ± 0.26 vs 0.90 ± 0.22, P < .001) and a significantly greater increase postoperatively (0.10 vs 0.03, P < .001). A significantly greater number of African American patients demonstrated AKI (10.9% vs 5.1%, P = .03). Furthermore, a significantly greater number of African American patients stayed in the hospital an additional 2 or more days for renal issues (2.7% vs 0.4%, P = .03).

CONCLUSION

Altered renal function was significantly more common in African American TKA patients. Future studies are necessary to determine if tailoring anti-inflammatories, perioperative medications, and preoperative comorbidities reduce the risk of renal injury and/or a longer hospital stay for this subset of patients.

Periprocedural Concerns in the Patient with Renal Disease

Treating patients with kidney disease can be both a difficult and a complex process. Understanding how to care for patients who have kidney disease is essential for lowering perioperative as well as periprocedural morbidity and mortality. The primary aim in renal evaluation and care is to control and mitigate factors that may result in acute kidney injury (AKI) and/or cause further decline in renal function. It is essential for the foot and ankle specialist to recognize patients who are predisposed to developing or already have impairment of renal function.

The Japanese clinical practice guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention is necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

Obesity, acute kidney injury and mortality in patients with sepsis: a cohort analysis

Although the prognostic effect of obesity has been studied in critically ill patients its impact on outcomes of septic patients and its role as a risk factor for acute kidney injury (AKI) is not consensual. We aimed to analyze the impact of obesity on the occurrence of AKI and on in-hospital mortality in a cohort of critically ill septic patients. This study is retrospective including 456 adult patients with sepsis admitted to the Division of Intensive Medicine of the Centro Hospitalar Lisboa Norte (Lisbon, Portugal) between January 2008 and December 2014. Obesity was defined as a body mass index of 30 kg/m² or higher. The Kidney Disease Improving Global Outcomes classification was used to diagnose and classify patients developing AKI. AKI occurred in 87.5% of patients (19.5% with stage 1, 22.6% with stage 2 and 45.4% with stage 3). Obese patients developed AKI more frequently than non-obese patients (92.8% versus 85.5%, p = .035; unadjusted OR 2.2 (95% CI: 1.04–4.6), p = .039; adjusted OR 2.31 (95% CI: 1.07–5.02), p = .034). The percentage of obese patients, however, did not differ between AKI stages (stage 1, 25.1%; stage 2, 28.6%; stage 3, 15.4%; p = .145). There was no association between obesity and mortality (p = .739). Of note, when comparing AKI patients with or without obesity in terms of in-hospital mortality there were also no significant differences between those groups (38.4% versus 38.4%, p = .998). Obesity was associated with the occurrence of AKI in critically ill patients with sepsis; however, it was not associated with in-hospital mortality.

The Japanese Clinical Practice Guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention are necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

Awareness, incidence and clinical significance of acute kidney injury after non-general anesthesia: A retrospective cohort study

Postoperative acute kidney injury is associated with high mortality and poor prognosis. Additional investigations into the risk factors for this condition and the outcomes of patients who undergo surgeries under non-general anesthesia (GA) are necessary.This retrospective cohort study included data on all surgeries performed in adult patients from January 2006 to December 2015 at a tertiary hospital in Korea. Patients were divided into those undergoing surgeries with non-GA and those undergoing surgeries with GA. We analyzed the nephrological evaluation patterns, the risk factors for acute kidney injury, and prognoses after acute kidney injury by reviewing mortality, progression to end-stage renal disease, and serum creatinine doubling/estimated glomerular filtration rate halving from baseline.Of 74,524 patients, 20,332 underwent surgery with non-GA. These patients had baseline (adjusted odds ratio [OR], .68, 95% confidence interval [CI], .63-.72; P < .01] and follow-up serum creatinine levels (adjusted OR, .34; 95% CI, .33-.36; P < .01) less frequently measured than those undergoing GA. However, the incidence of acute kidney injury did not differ significantly between the 2 groups. Moreover, postoperative acute kidney injury after non-GA surgery showed a worse clinical prognosis which was similar with that of GA operations.Patients undergoing surgeries under non-GA did not receive sufficient evaluation for their risks of acute kidney injury. As an acute kidney injury in non-GA was associated a worse prognosis as in GA surgeries, more clinical attention should be considered.

Intraoperative hypotension and the risk of postoperative adverse outcomes: a systematic review

BACKGROUND

Intraoperative hypotension is a common side effect of general anaesthesia and might lead to inadequate organ perfusion. It is unclear to what extent hypotension during noncardiac surgery is associated with unfavourable outcomes.

METHODS

We conducted a systematic search in PubMed, Embase, Web of Science, and CINAHL, and classified the quality of retrieved articles according to predefined adapted STROBE and CONSORT criteria. Reported strengths of associations from high-quality studies were classified into end-organ specific injury risks, such as acute kidney injury, myocardial injury, and stroke, and overall organ injury risks for various arterial blood pressure thresholds.

RESULTS

We present an overview of 42 articles on reported associations between various absolute and relative intraoperative hypotension definitions and their associations with postoperative adverse outcomes after noncardiac surgery. Elevated risks of end-organ injury were reported for prolonged exposure (≥10 min) to mean arterial pressures <80 mm Hg and for shorter durations <70 mm Hg. Reported risks increase with increased durations for mean arterial pressures <65-60 mm Hg or for any exposure <55-50 mm Hg.

CONCLUSIONS

The reported associations suggest that organ injury might occur when mean arterial pressure decreases <80 mm Hg for ≥10 min, and that this risk increases with blood pressures becoming progressively lower. Given the retrospective observational design of the studies reviewed, reflected by large variability in patient characteristics, hypotension definitions and outcomes, solid conclusions on which blood pressures under which circumstances are truly too low cannot be drawn. We provide recommendations for the design of future studies. CLINICAL REGISTRATION NUMBER: (PROSPERO ID). CRD42013005171.

Body Mass Index as a Predictor of Acute Kidney Injury in Critically Ill Patients: A Retrospective Single-Center Study

Background

The aim of this study was to examine the influence of body mass index (BMI) on the development of acute kidney injury (AKI) in critically ill patients in intensive care unit (ICU).

Methods

Data of patients admitted to medical ICU from December 2011 to May 2014 were retrospectively analyzed. Patients were classified into three groups according to their BMI: underweight (<18.5 kg/m²), normal (18.5–24.9 kg/m²), and overweight (≥25 kg/m²). The incidence of AKI was compared among these groups and factors associated with the development of AKI were analyzed. AKI was defined according to the Risk, Injury, Failure, Loss of kidney function, and End-stage (RIFLE) kidney disease criteria.

Results

A total of 468 patients were analyzed. Their mean BMI was 21.5±3.9 kg/m², including 102 (21.8%) underweight, 286 (61.1%) normal-weight, and 80 (17.1%) overweight patients. Overall, AKI occurred in 82 (17.5%) patients. The overweight group had significantly (p<0.001) higher incidence of AKI (36.3%) than the underweight (9.8%) or normal group (15.0%). In addition, BMI was significantly higher in patients with AKI than that in those without AKI (23.4±4.2 vs. 21.1±3.7, p<0.001). Multivariate analysis showed that BMI was significantly associated with the development of AKI (odds ratio, 1.893; 95% confidence interval, 1.224–2.927).

Conclusion

BMI may be associated with the development of AKI in critically ill patients.

Long-term effects of bariatric surgery on acute kidney injury: a propensity-matched cohort in the UK Clinical Practice Research Datalink

OBJECTIVE

Bariatric surgery is an effective method of weight reduction and has been associated with acute kidney injury (AKI) as a perioperative event. However, the long-term effects of the weight reduction after surgery on AKI are unknown. The objective of this study is to quantify the association of bariatric surgery with later risk of AKI.

DESIGN

This study uses a propensity score-matched cohort of patients from the UK Clinical Practice Research Datalink database with and without bariatric surgery to compare rates of AKI episodes derived from linkage to the Hospital Episode Statistics.

SETTING

England, UK.

PARTICIPANTS

We included 2643 patients with bariatric surgery and 2595 patients without.

RESULTS

Results were compatible with an increased risk of AKI in the first 30 days following surgery compared with patients without surgery, but AKI incidence was substantially decreased in patients with bariatric surgery during long-term follow-up (rate ratio 0.37, 95% CI 0.23 to 0.61) even after accounting for chronic kidney disease status at baseline. Over the whole period of follow-up, bariatric surgery had a net protective effect on risk of AKI (rate ratio 0.45, 95% CI 0.28 to 0.72).

CONCLUSIONS

Bariatric surgery was associated with protective effects on AKI incidence during long-term follow-up. While the risk of AKI may be increased within the first 30 days, the net effect seen was beneficial.

Renal protection in the 21st century

PURPOSE OF REVIEW

Among critically ill patients, acute kidney injury (AKI) is still a common and serious complication with a tremendous impact on short-term and long-term outcomes. The objective of this review is to discuss strategies for renal protection and prevention of AKI in ICU patients.

RECENT FINDINGS

It is fundamental to identify patients at risk for AKI as soon as possible and as accurately as possible. In order to achieve these goals, translational approaches implementing new biomarkers have shown promising results. Focusing on the role of potential preventive strategies, hemodynamic stabilization is the most important intervention with proven efficacy. Recent published data undermined any hope that high-dose statin therapy in statin-naïve patients could exert renoprotective effects. However, preliminary data revealed the renoprotective activity of dexmedetomidine when used as a sedative agent. Moreover, several studies demonstrated the protective effects of remote ischemic preconditioning in various organs including the kidneys. The use of balanced crystalloid instead of hyperchloremic solutions also contributes to the reduction of AKI in critically ill patients.

SUMMARY

To prevent AKI, it is crucial to identify patients at risk as early as possible. Establishing hemodynamic stability and an adequate intravascular volume state to ensure a sufficient perfusion pressure is the only effective therapeutic intervention. It is self-evident that nephrotoxic agents should be avoided whenever it is possible.

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.