Acute kidney injury following bariatric surgery

Association Between Preoperative Anemia and Postoperative Acute Kidney Injury in Patients Undergoing Metabolic and Bariatric Surgery: a Multi-institute Study

BACKGROUND

This multi-institute retrospective cohort study investigated the association between preoperative anemia and postoperative acute kidney injury (AKI) in patients undergoing metabolic and bariatric surgery (MBS).

METHODS

Using the TriNetX research network, we identified adult patients who underwent MBS between January 2010 and December 2024. Patients were categorized as anemic or non-anemic based on preoperative hemoglobin levels (hemoglobin < 12 g/dL for females and < 13 g/dL for males). Propensity score matching was performed to balance the baseline characteristics. The primary outcome was AKI within 30 days of MBS. The secondary outcomes included infections, intensive care unit admission, surgical complications, and deep vein thrombosis. Analyses were conducted separately for female and male patients, with additional sensitivity analyses for the female subgroups.

RESULTS

After propensity score matching, preoperative anemia was significantly associated with an increased risk of postoperative AKI in females (1.51% vs. 0.71%, odds ratio (OR) 2.14, 95% confidence interval (CI) 1.53-2.98, p < 0.0001) (n = 7144 pairs). This association persisted in all sensitivity analyses. Even mild anemia (hemoglobin 10-12 g/dL) was associated with a higher AKI risk (OR 1.62, p = 0.004) in female patients. In males (n = 971 pairs), anemia similarly increased the AKI risk (4.94% vs. 2.68%, OR 1.89, 95% CI 1.16-3.07, p = 0.009). No significant differences were observed in secondary outcomes for either sex.

CONCLUSION

Preoperative anemia is independently associated with an increased risk of postoperative AKI in both female and male patients undergoing MBS, suggesting that preoperative anemia screening and management could be important for reducing postoperative kidney complications in this population.

Assessment of predictors of acute kidney injury and progression to chronic kidney disease following bariatric surgery

BACKGROUND

Despite the overall safety of metabolic and bariatric surgery (MBS), the potential for postoperative complications such as acute kidney injury (AKI) remains a critical concern. Decade-old studies from our institution reported rates of AKI following MBS between 5.8% and 8.6%, with factors such as higher body mass index (BMI), diabetes, and hypertension identified as potential contributors. However, the incidence and factors associated with AKI following MBS have remained underexplored in contemporary literature.

OBJECTIVES

To investigate the incidence and risk factors associated with postoperative AKI, as well as the potential for progression to CKD and renal failure.

SETTING

Quaternary academic medical center with a high-volume MBS practice.

METHODS

A retrospective review of adult patients undergoing primary laparoscopic MBS between 2008 and 2022 to identify patients who developed AKI, defined as postoperative increase in serum creatinine (sCr) by .3 mg/dL within 72 hours. A multivariable logistic regression was constructed to identify potential AKI risk factors.

RESULTS

Among 1697 patients, the incidence of AKI was 3.0% (n = 51). The distribution of AKI was not significantly different between procedure types. There was no significant correlation between anesthesia medications given and the occurrence of AKI. Male gender was the most significant predictor of AKI (adjusted odds ratio [aOR] = 3.87, 95% confidence interval {CI} [2.14-6.99]), followed by hypertension (aOR = 2.12, 95% CI [1.03-4.83]) and longer surgical duration (aOR = 1.19, 95% CI [1.05-1.35]) per 30 minutes. Of those who developed AKI, 7 (13.7%) required dialysis acutely for management, while 3 patients (5.9%) progressed to chronic renal failure and required transplant.

CONCLUSIONS

AKI is a rare but serious complication following MBS that occurs in approximately 3% of cases. AKI incidence is higher in male patients, those with hypertension, insulin-requiring diabetes, renal insufficiency, and longer procedure durations. Heightened awareness of the identified risk factors should help guide patient selection, and additional efforts should be directed towards refining postoperative follow-up.

Enhanced efficacy of aprepitant-based triple prophylaxis in preventing postoperative nausea and vomiting following metabolic bariatric surgery: a single-center, retrospective cohort study

Background

Metabolic bariatric surgery (MBS) is associated with high risk of postoperative nausea and vomiting (PONV). We aimed to investigate the impact of aprepitant-based triple prophylaxis on PONV after MBS.

Methods

We reviewed a retrospective cohort of patients who underwent primary MBS between December 28, 2023 and May 31, 2024. The eligible patients were divided into two groups based on whether receiving additional oral single 125 mg dose of aprepitant preoperatively to the dual prophylaxis (ondansetron 8 mg and dexamethasone 10 mg). Multivariable and propensity score-adjusted analyses were performed to compare the composite PONV endpoints between the groups.

Results

A total of 207 patients were included in the study. Of these, 129 patients received dual prophylaxis, while the remaining 78 patients received additional single 125 mg dose of aprepitant. Similar to multivariable logistic regression analysis, propensity-adjusted logistic regression analysis revealed that the aprepitant-based triple prophylaxis group had a significantly higher complete response rate (82.1% vs. 24.0%, adjusted OR 10.312, 95% CI 4.186-25.399, p < 0.001), a lower incidence of PONV (59.0% vs. 85.3%, adjusted OR 0.287, 95% CI 0.125-0.663, p = 0.004), and required fewer rescue antiemetics (7.7% vs. 37.2%, adjusted OR 0.155, 95% CI 0.052-0.457, p < 0.001) compared to the dual prophylaxis group. Propensity score-adjusted analysis demonstrated that the addition of aprepitant to dual prophylaxis significantly reduced the incidence of PONV, vomiting frequency, and both the Nausea VAS and Nausea Subscale scores (all p < 0.05).

Conclusion

Our findings indicate that the addition of a single preoperative dose of aprepitant to a dual antiemetic prophylaxis of dexamethasone and ondansetron might be associated with a further improve outcomes related to composite PONV endpoints in patients undergoing metabolic bariatric surgery.

Metabolic/bariatric surgery optimization: a position statement by Arabic association for the study of diabetes and metabolism (AASD)

For patients considering bariatric surgery, it is essential to have clear answers to common questions to ensure the success of the procedure. Patients should understand that surgery is not a quick fix but a tool that must be complemented by lifestyle changes, including dietary adjustments and regular physical activity. The procedure carries potential risks that should be weighed against the potential benefits. Health authorities play a critical role in ensuring that bariatric surgery is performed under the highest standards of care. Recommendations are provided to determine who is an appropriate candidate for surgery, what preoperative evaluations are necessary, and how to monitor patients postoperatively to maximize outcomes and minimize risks. Additionally, authorities are responsible for ensuring access to follow-up care, including nutritional support and psychological counseling, which are vital for the long-term success of bariatric surgery.Understanding these aspects by both patients and decision-makers is critical before proceeding with bariatric surgery. The following questions guide patients and healthcare professionals in making informed decisions about the procedure and managing the expectations and outcomes associated with bariatric surgery.

Bariatric surgery and changes in metformin distribution: About a fatal case

A 65 year-old woman, suffering from mellitus type 2 diabetes and obesity, died at home, three days after bariatric surgery (Roux-en-Y gastric by-pass: RYGB). Her treatment, including metformin and dapagliflozin, was stopped before surgery and not postoperatively reinstalled. A forensic autopsy, toxicological and histological analyses were performed. No macroscopic or microscopic evidence of digestive perforation or peritonitis was identified, excluding an early surgery complication as the cause of death. Toxicological analysis revealed the presence of Metformin in all matrices tested, with a potentially fatal blood concentration. Death was attributed to lactic acidosis caused by a metformin overdose. With no evidence for suicide by ingestion of metformin, the authors supposed that the bariatric surgery might have caused changes in the absorption of metformin, leading to a rapid overdose and death. The only study in the literature on this subject, demonstrated a significant increase in the bioavailability of metformin following oral administration in gastric bypass patients. Thus, it can be anticipated that a therapeutic dose can become toxic when administrated to a subject who recently modified her digestive equipment. As this represents the first case of metformin overdose following bariatric surgery, further cases will be needed to confirm our initial observations.

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.

Pre-bariatric surgery acute kidney injury: Can this be prevented?

Key Clinical Message

Pre-bariatric surgery dietary recommendations should take into account daily protein intake and other risk factors for kidney injury. This is important because a high protein intake can potentially lead to kidney injury.

Abstract

Bariatric surgery has been shown to be a highly effective intervention for achieving weight loss and reducing obesity related-comorbidities. Acute kidney injury (AKI) is considered one of the common complications in perioperative and post-bariatric surgery. However, pre-bariatric surgery AKI has never been reported. Several studies demonstrated that pre-bariatric surgery weight loss improved surgical outcomes and decrease postoperative complications. Some diet regimens have been introduced including low-caloric diet (LCD), very-low caloric diet (VLCD), and very-low caloric ketogenic diet (VLCKD). We present a patient who develops AKI after 10 days of having a high-protein diet from a pre-bariatric weight loss strategy.

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).

Obesity-Related Kidney Disease: Current Understanding and Future Perspectives

Obesity is a serious chronic disease and an independent risk factor for the new onset and progression of chronic kidney disease (CKD). CKD prevalence is expected to increase, at least partly due to the continuous rise in the prevalence of obesity. The concept of obesity-related kidney disease (OKD) has been introduced to describe the still incompletely understood interplay between obesity, CKD, and other cardiometabolic conditions, including risk factors for OKD and cardiovascular disease, such as diabetes and hypertension. Current therapeutics target obesity and CKD individually. Non-pharmacological interventions play a major part, but the efficacy and clinical applicability of lifestyle changes and metabolic surgery remain debatable, because the strategies do not benefit everyone, and it remains questionable whether lifestyle changes can be sustained in the long term. Pharmacological interventions, such as sodium-glucose co-transporter 2 inhibitors and the non-steroidal mineralocorticoid receptor antagonist finerenone, provide kidney protection but have limited or no impact on body weight. Medicines based on glucagon-like peptide-1 (GLP-1) induce clinically relevant weight loss and may also offer kidney benefits. An urgent medical need remains for investigations to better understand the intertwined pathophysiologies in OKD, paving the way for the best possible therapeutic strategies in this increasingly prevalent disease complex.

Association of the perfusion index with postoperative acute kidney injury: a retrospective study

BACKGROUND

Many studies have examined the risk factors for postoperative acute kidney injury (AKI), but few have focused on intraoperative peripheral perfusion index (PPI) that has recently been shown to be associated with postoperative morbidity and mortality. Therefore, this study aimed to evaluate the relationship between intraoperative PPI and postoperative AKI under the hypothesis that lower intraoperative PPI is associated with AKI occurrence.

METHODS

We retrospectively searched electronic medical records to identify patients who underwent surgery at the general surgery department from May 2021 to November 2021. Patient baseline characteristics, pre- and post-operative laboratory test results, comorbidities, intraoperative vital signs, and discharge profiles were obtained from the Institutional Clinical Data Warehouse and VitalDB. Intraoperative PPI was the primary exposure variable, and the primary outcome was postoperative AKI.

RESULTS

Overall, 2,554 patients were identified and 1,586 patients were included in our analysis. According to Kidney Disease Improving Global Outcomes (KDIGO) criteria, postoperative AKI occurred in 123 (7.8%) patients. We found that risks of postoperative AKI increased (odds ratio: 2.00, 95% CI [1.16, 3.44], P = 0.012) when PPI was less than 0.5 for more than 10% of surgery time. Other risk factors for AKI occurrence were male sex, older age, higher American Society of Anesthesiologists physical status, obesity, underlying renal disease, prolonged operation time, transfusion, and emergent operation.

CONCLUSIONS

Low intraoperative PPI was independently associated with postoperative AKI.

Acute post sleeve surgery bleeding as rare cause of acute renal failure: a case report

BACKGROUND

Bariatric surgeries have been considered as one of the most important treatment procedures in recent years. Being aware of the side effects of this surgery will lead to better results after the surgery.

CASE PRESENTATION

A 37-year-old Iranian male patient presented one day after sleeve surgery with symptoms of weakness, lethargy, and shortness of breath, which hospitalization and workup to were done to rule out pulmonary embolism. Because of the high creatinine and anuria, we couldn't perform computed tomography angiography. A bedside ultrasound was done for the patient and showed a mild to moderate amount of fluid around the spleen and some blood clots. Due to the progressive clinical findings and suspected internal bleeding, the patient was a candidate for laparoscopic revision procedure. Gradually, after performing the surgery, removing the blood clot and reducing the compressive effect of that on the inferior verna cava which was the main reason of renal failure, the patient was able to urinate afterwards and was discharged in good general condition.

CONCLUSION

Surgeons should be aware of the management of rare surgical complications after bariatric surgeries. To be best of our knowledge, this was the first case report of a patient with acute renal failure after bariatric surgery and the rare cause of clot compression on inferior vena cava and raised abdominal compartment pressure.

Determination of Risk Factors for Postoperative Acute Kidney Injury in Patients With Gynecologic Malignancies

Background Postoperative acute kidney injury (AKI) is an important cause of mortality and morbidity among surgical patients. There is little information on the occurrence of AKI after operations for gynecologic malignancies. This study aimed to determine the incidence of AKI in patients who underwent surgery for gynecological malignancies and determine the risk factors in those who developed postoperative AKI. Methodology A total of 1,000 patients were enrolled retrospectively from January 2007 to March 2013. AKI was defined according to the Kidney Disease Improving Global Outcomes 2012 Clinical Practice Guideline for Acute Kidney Injury. Perioperative variables of patients were collected from medical charts. Results The incidence of postoperative AKI was 8.8%, with stage 1 occurring in 5.9%, stage 2 in 2.4%, and stage 3 in 0.5% of the patients. Patients who had AKI were significantly older, had higher body mass index (BMI) higher preoperative C-reactive protein (CRP) levels, and more frequently had a history of distant organ metastasis when compared with those who did not have AKI. When compared with patients who did not develop AKI postoperatively, longer operation times and intraoperative usage of higher amounts of erythrocyte suspension and fresh frozen plasma were seen in those who developed AKI. Conclusions Patients who had AKI were older, had higher BMI with higher preoperative CRP levels, more frequent distant organ metastasis, longer operation times, and higher amounts of blood transfused intraoperatively. Defining preoperative, intraoperative, and postoperative risk factors for postoperative AKI and taking necessary precautions are important for the early detection and intervention of AKI.

Optimization of central venous pressure during the perioperative period is associated with improved prognosis of high-risk operation patients

Background

While central venous pressure (CVP) measurement is used to guide fluid management for high-risk surgical patients during the perioperative period, its relationship to patient prognosis is unknown.

Methods

This single-center, retrospective observational study enrolled patients undergoing high-risk surgery from February 1, 2014 to November 31, 2020, who were admitted to the surgical intensive care unit (ICU) directly after surgery. Patients were divided into the following three groups according to the first CVP measurement (CVP1) after admission to the ICU: low, CVP1 <8 mmHg; moderate, 8 mmHg≤ CVP1 ≤ 12 mmHg; and high, CVP1 >12 mmHg. Perioperative fluid balance, 28-day mortality, length of stay in the ICU, and hospitalization and surgical complications were compared across groups.

Results

Of the 775 high-risk surgical patients enrolled in the study, 228 were included in the analysis. Median (interquartile range) positive fluid balance during surgery was lowest in the low CVP1 group and highest in the high CVP1 group (low CVP1: 770 [410, 1205] mL; moderate CVP1: 1070 [685, 1500] mL; high CVP1: 1570 [1008, 2000] mL; all P <0.001). The volume of positive fluid balance during the perioperative period was correlated with CVP1 (r=0.336, P <0.001). The partial arterial pressure of oxygen(PaO₂)/fraction of inspired oxygen(FiO₂) ratio was significantly lower in the high CVP1 group than in the low and moderate CVP1 groups (low CVP1: 400.0 [299.5, 443.3] mmHg; moderate CVP1: 362.5 [330.0, 434.9] mmHg; high CVP1: 335.3 [254.0, 363.5] mmHg; all P <0.001). The incidence of postoperative acute kidney injury (AKI) was lowest in the moderate CVP1 group (low CVP1: 9.2%; moderate CVP1: 2.7%; high CVP1: 16.0%; P=0.007). The proportion of patients receiving renal replacement therapy was highest in the high CVP1 group (low CVP1: 1.5%; moderate CVP1: 0.9%; high CVP1: 10.0%; P=0.014). Logistic regression analysis showed that intraoperative hypotension and CVP1 >12 mmHg were risk factors for AKI within 72 h after surgery (adjusted odds ratio[aOR]=3.875, 95% confidence interval[CI]: 1.378-10.900, P=0.010 and aOR=1.147, 95%CI: 1.006-1.309, P=0.041).

Conclusions

CVP that is either too high or too low increases the incidence of postoperative AKI. Sequential fluid therapy based on CVP after patients are transferred to the ICU post-surgery does not reduce the risk of organ dysfunction caused by an excessive amount of intraoperative fluid. However, CVP can be used as a safety limit indicator for perioperative fluid management in high-risk surgical patients.

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.

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

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

Roux-en-Y gastric bypass surgery induced oxalosis and acute kidney injury: A case report

Introduction and importance

Diabetes mellitus and hypertension are two conditions that can coexist in obese individuals. Roux-en-Y gastric bypass (RYGB) surgery, are used to control obesity. Complications such as steatorrhea, hyperoxaluria, and decreased bone mineral density, may occur after RYGB.

Case presentation

A 58-year-old woman referred to the emergency department complaining of pain on the right side of her lower abdomen. Her past medical history was RYGB surgery, COVID-19 with 40% pulmonary involvement, and Chronic Kidney Disease (CKD). Rapid progressive glomerulonephritis (RPGN) was predicted based on extensive laboratory test results. A kidney biopsy demonstrated oxalate nephropathy. Along with the findings from the kidney biopsy, acute tubulointerstitial nephritis with tubular injury secondary oxalosis was diagnosed.

Clinical discussion

RYGB surgery and chronic kidney disease, can increase the risk of secondary oxalosis. Recent studies introduce enteric hyperoxaluria as an important marker for diagnosing end-stage kidney disease. Renal biopsy is often prescribed for absolute recognition of oxalosis. On the other hand, our patient has a recent history of COVID-19 infection. The use of anti-Covid-19 drugs in patients with renal insufficiency should be considered with caution.

Conclusion

It is important to monitor kidney function following RYGB surgery, particularly in patients with underlying diseases such as diabetes or hypertension.

Obesity-Related Glomerulopathy: Clinical Management

Obesity-related glomerulopathy (ORG) and other obesity-associated kidney diseases pose a major challenge to the treating nephrologist. We review the benefits of weight loss and optimal management of ORG and kidney disease in the setting of obesity. Therapeutic strategies in ORG were limited mainly in the past to weight loss through lifestyle interventions and bariatric surgery, antihypertensive treatment, and renin-angiotensin-aldosterone system blockade. Current approaches to obtain the desired weight loss include novel pharmacologic therapies that have been approved for the treatment of diabetes while offering kidney protection, such as sodium-glucose cotransporter-2 inhibitors and glucagon-like peptide-1-receptor agonists. This review focuses on the nephroprotective role of the renin-angiotensin-aldosterone system blockade and of these new pharmacologic agents, and on the renal effects of bariatric surgery in chronic kidney disease.

Perioperative Risks of Sleeve Gastrectomy Versus Roux-en-Y Gastric Bypass Among Patients With Chronic Kidney Disease: A Review of the MBSAQIP Database

OBJECTIVE

To determine whether patients with CKD experience higher rates of perioperative complications after RYGB compared to sleeve gastrectomy.

SUMMARY OF BACKGROUND DATA

For obese CKD patients who qualify for bariatric surgery, sleeve gastrectomy is often preferred to RYGB based on perceptions of prohibitively-high perioperative risks surrounding RYGB. However, some patients with CKD are not candidates for sleeve gastrectomy and the incremental increased-risk from RYGB has never been rigorously tested in this population.

METHODS

CKD patients who underwent RYGB or sleeve gastrectomy between 2015 and 2017 were identified from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program Participant Use File. RYGB patients were 1:1 propensity-score matched with sleeve gastrectomy patients based on preoperative factors that influence operative choice. Primary outcomes included 30-day readmissions, surgical complications, medical complications, and death. Secondary outcomes included the individual complications used to create the composite surgical/medical complications. Univariate logistic regression was used to compare outcomes. E-value statistic was used to test the strength of outcome point estimates against possible unmeasured confounding.

RESULTS

Demographics were similar between RYGB (n = 673) and sleeve gastrectomy (n = 673) cohorts. There were no statistically significant differences in primary outcomes. Among secondary outcomes, only acute kidney injury was statistically-significantly higher among RYGB patients (4.9% vs 2.7%, P = 0.035, E-value 1.27).

CONCLUSIONS

Among well-matched cohorts of RYGB and sleeve gastrectomy patients, incidence of primary outcomes were similar. Among secondary outcomes, only acute kidney injury was statistically-significantly higher among RYGB patients; however, the E-value for this difference was small and relatively weak confounder(s) could abrogate the statistical difference. The perception that RYGB has prohibitively-high perioperative risks among CKD patients is disputable and operative selection should be weighed on patient candidacy and anticipated long-term benefit.

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.].

The Impact of Bariatric Surgery on Renal Function: a Retrospective Analysis of Short-Term Outcomes

PURPOSE

Obesity and diabetes mellitus are now leading causes of chronic kidney disease. Our study investigated the effects of bariatric surgery on estimated glomerular filtration (eGFR) and urinary microalbumin/creatinine ratio (ACR) in morbidly obese patients.

MATERIALS AND METHODS

The clinical materials for patients who underwent bariatric surgery were retrospectively analyzed with a 6-month follow-up period between January 1, 2018, and June 1, 2020. The eGFR (ml/min) was calculated using the Cockcroft-Gault formula equation. The urinary ACR was measured during the follow-up. Body mass index (BMI, kg/m²), percent weight loss (%WL), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were recorded during the follow-up.

RESULTS

Sixty-one patients who underwent bariatric surgery-laparoscopic Roux-en-Y gastric bypass (LRYGB; n = 22) and laparoscopic sleeve gastrectomy (LSG; n = 39)-were included in this study. The eGFR of both groups decreased at the follow-up outpatient visits (p < 0.001), although eGFR did not differ between the two groups. Unexpectedly, the ACR increased in the first month after LSG (p < 0.01) but decreased with a descending trend with no significant difference (p > 0.05) throughout the remaining follow-up period. Interestingly, ACR showed a descending trend with no significant difference during the follow-up in the LRYGB group (p > 0.05). The SBP and DBP decreased after bariatric surgery, with no significant difference between the two groups (p > 0.05).

CONCLUSION

Bariatric surgery is associated with improvements in postoperative renal function 6 months following surgery. The different alterations in ACR following LSG and LRYGB procedures demonstrate the underlying mechanism.

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.

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.

The Short-Term Renal Effects of Bariatric Surgery: A Comparative Study Between Sleeve Gastrectomy and One Anastomosis Gastric Bypass Operations Among Egyptian Patients With Severe Obesity

PURPOSE

Obesity is a major health problem with many renal sequelae. Bariatric surgery (BS) has become the treatment of choice for severe obesity. This study was conducted to assess the short-term renal effects of BS and to compare such effects between two distinct forms of BS.

MATERIALS AND METHODS

A single-center non-randomized prospective observational study was conducted on 57 patients with severe obesity. Two distinct forms of BS have been performed; laparoscopic sleeve gastrectomy (LSG) and laparoscopic one anastomosis gastric bypass (OAGB). Anthropometric measurements, 24-h urinary creatinine clearance (CL_Cr), protein and oxalate excretion, and abdominal fat tissue analysis by computerized tomography were performed prior to surgery and 6 months later.

RESULTS

LSG and OAGB were performed in 47 and 10 participants, respectively. BS resulted in pronounced reduction of body mass index (- 27.1% ± 7.11), with no substantial weight loss discrepancy between LSG and OAGB. The median percent change in 24-h urinary CL_Cr and protein and oxalate excretion were - 35.7, - 42.2, and - 5.8, respectively. The median (IQR) percent change of urinary oxalate excretion was - 11.1 (- 22.6, - 1.4) and 113.08 (82.5, 179.7) for LSG and OAGB, respectively (p < 0.001). The subcutaneous abdominal fat surface area has been found to be the significant predictor of the persistence of glomerular hyperfiltration after BS.

CONCLUSION

Both LSG and OAGB can alleviate many of the obesity-related pathological renal changes. However, postoperative hyperoxaluria remains a serious issue particularly in OAGB. Detailed radiological abdominal fat tissue analysis by CT may aid in predicting the renal outcome following BS.

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.

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.

Preventing Perioperative Acute Kidney Injury

How to cite this article: Bhosale SJ, Kulkarni AP. Preventing Perioperative Acute Kidney Injury. Indian J Crit Care Med 2020;24(Suppl 3):S126–S128.

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.

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.

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.

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.

Nephrological aspects of surgical weight correction in morbid obesity

Obesity, including morbid obesity, is a growing worldwide problem. The adverse effect of obesity on the kidneys is associated with the development of comorbid conditions, such as insulin resistance (IR), metabolic syndrome (MS), diabetes mellitus (DM), arterial hypertension (AH), which are the recognized risk factors of chronic kidney disease (СKD). Obesity also causes direct kidney damage with the development of non-immune focal segmental glomerulosclerosis. The leading pathophysiological mechanisms of kidney damage in obesity are intrarenal hemodynamic disorders with the formation of hyperfiltration and damaging effects of adipokines produced by adipose tissue. Bariatric surgery (BS) has taken a leading position in the treatment of morbid obesity, demonstrating its effectiveness not only in long-term weight loss, but also in the correction of IR, MS, DM, AH. Nephroprotective effect of significant and persistent weight loss is caused by the elimination of hyperfiltration and damaging effect of adipokines. Results of the observational studies of the immediate and long-term effects of BS have demonstrated positive renal outcomes, in particular, the decrease in albuminuria/proteinuria, the improvement or stabilization of glomerular filtration rate, the delay of end-stage renal failure development; surgical correction of body weight in dialysis patients with morbid obesity lets them realize subsequent kidney transplantation. Large, randomized prospective studies with a longer follow-up are needed; analysis of the long-term renal consequences of BS in obesity patients with pre-existing renal impairment, including dialysis patients, is required; stratification of the BS risk of renal complications (acute kidney damage, nephrolithiasis, nephrocalcinosis) and effective strategy for managing these risks need to be developed.

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.

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.

Low, rather than High, Body Mass Index Is a Risk Factor for Acute Kidney Injury in Multiethnic Asian Patients: A Retrospective Observational Study

Background

Acute kidney injury (AKI) is common in hospitalised patients. The relationship between body mass index (BMI) and the risk of having AKI for patients in the acute hospital setting is not known, particularly in the Asian population.

Methods

This was a retrospective, single-centre, observational study conducted in Singapore, a multiethnic population. All patients aged ≥21 years and hospitalised from January to December 2013 were recruited.

Results

A total of 12,555 patients were eligible for the analysis. A BMI of <18.5 kg/m² was independently associated with the development of AKI in hospitalised patients (odds ratio (OR): 1.23 [95% confidence interval [CI]: 1.04–1.44, P = 0.01]) but not for overweight and obesity. Subgroup analysis further revealed that underweight patients aged ≥75 and repeated hospitalisation posed a higher risk of AKI (OR: 1.25 [CI: 1.01–1.56], P = 0.04; OR: 1.23 [CI: 1.04–1.44], P = 0.01, resp.). Analyses by interactions between different age groups and BMI using continuous or categorised variables did not affect the overall probability of developing AKI.

Conclusions

Underweight Asian patients are susceptible to AKI in acute hospital settings. Identification of this novel risk factor for AKI allows us to optimise patient care by prevention, early detection, and timely intervention.

Predictors of Perioperative Acute Kidney Injury in Obese Patients Undergoing Laparoscopic Bariatric Surgery: a Single-Centre Retrospective Cohort Study

BACKGROUND

Obesity has been associated with increased risk of perioperative acute kidney injury (AKI). We aim to establish the incidence of AKI among patients undergoing laparoscopic bariatric surgery and identify potential risk factors.

METHODS

Records of 1230 patients who underwent laparoscopic bariatric surgery in a tertiary centre from 1 December 2009 to 31 January 2014 were retrospectively studied. AKI diagnosis was made by comparing the baseline and post-operative serum creatinine to determine the presence of predefined significant change based on the Kidney Disease: Improving Global Outcomes (KDIGO) definition. Univariate analyses were performed to determine significant clinical factors, and multiple logistic regression analysis was subsequently done to determine independent predictors of AKI.

RESULTS

Thirty-five (2.9 %) patients developed AKI during the first 72 h post-surgery. Multivariate logistic regression analysis revealed impaired renal function (OR 10.429, 95 % CI 3.560 to 30.552), use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers (OR 3.038, 95 % CI 1.352 to 6.824), and body mass index (OR 1.048, 95 % CI 1.005 to 1.093) as independent predictors of perioperative acute kidney injury in the obese patients who underwent laparoscopic bariatric surgery.

CONCLUSIONS

We found that the incidence of perioperative AKI among patients who underwent laparoscopic bariatric surgery is at 2.9 %. Impaired renal function, use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers and raised body mass index were found to be independent predictors of AKI. Patients with these risk factors could be considered at risk for developing perioperative AKI, and extra perioperative vigilance should be undertaken.

Hypertension in Obesity and the Impact of Weight Loss

PURPOSE OF REVIEW

Several interrelated mechanisms promote the development of hypertension in obesity, often contributing to end organ damage including cardiovascular disease and chronic kidney disease.

RECENT FINDINGS

The treatment of hypertension in obesity is complicated by a high prevalence of resistant hypertension, as well as unpredictable hemodynamic effects of many medications. Weight loss stabilizes neurohormonal activity and causes clinically significant reductions in blood pressure. While lifestyle interventions can improve blood pressure, they fail to consistently yield sustained weight loss and have not demonstrated long-term benefits. Bariatric surgery provides more permanent weight reduction, corresponding with dramatic declines in blood pressure and attenuation of long-term cardiovascular risk. Hypertension is closely linked to the prevalence, pathophysiology, and morbidity of obesity. There are multiple barriers to managing hypertension in obesity. Surgical weight loss offers the most promise in reducing blood pressure and decreasing end organ damage in this patient population.

Bariatric Surgery and Kidney-Related Outcomes

The prevalence of severe obesity in both the general and the chronic kidney disease (CKD) populations continues to rise, with more than one-fifth of CKD patients in the United States having a body mass index of ≥35 kg/m². Severe obesity has significant renal consequences, including increased risk of end-stage renal disease (ESRD) and nephrolithiasis. Bariatric surgery represents an effective method for achieving sustained weight loss, and evidence from randomized controlled trials suggests that bariatric surgery is also effective in improving blood pressure, reducing hyperglycemia, and even inducing diabetes remission. There is also observational evidence suggesting that bariatric surgery may diminish the long-term risk of kidney function decline and ESRD. Bariatric surgery appears to be relatively safe in patients with CKD, with postoperative complications only slightly higher than in the general bariatric surgery population. The use of bariatric surgery in patients with CKD might help prevent progression to ESRD or enable selected ESRD patients with severe obesity to become candidates for kidney transplantation. However, there are also renal risks in bariatric surgery, namely, acute kidney injury, nephrolithiasis, and, in rare cases, oxalate nephropathy, particularly in types of surgery involving higher degrees of malabsorption. Although bariatric surgery may improve long-term kidney outcomes, this potential benefit remains unproved and must be balanced with potential adverse events.

Lithium Toxicity Following Vertical Sleeve Gastrectomy: A Case Report

We are presenting the first documented case of lithium toxicity after vertical sleeve gastrectomy surgery in an 18 year-old female with psychiatric history of bipolar disorder who was treated with lithium. This case illustrates the need for closer monitoring of lithium levels following bariatric surgery. Both psychiatrists and surgeons should be aware of the potential risk of lithium toxicity following bariatric surgery, as well as the need to judiciously monitor lithium level and possibly adjust the dose of some medications.

Cardiovascular and renal effects of weight reduction in obesity and the metabolic syndrome

Obesity is a critical public health issue worldwide. Patients with obesity have markedly increased morbidity and mortality compared to the general population. The increased health risks of obesity in part are due to its close association with each of the other components of the metabolic syndrome, including hypertension, dyslipidemia, and insulin resistance. Accordingly, obese individuals are at particularly increased risk of cardiovascular disease and chronic kidney disease. Modest weight loss results in improvements in serum cholesterol levels, blood pressure, and glycemic profiles. Lifestyle interventions for weight loss have long been the mainstay of treatment in obesity. However, the existing literature demonstrates limited weight loss sustainability and inconsistent cardiovascular and renal benefits using these modalities. In addition to improvements in intermediate risk factors, surgical interventions provide a more lasting impact on long-term cardiovascular and renal outcomes, though carry higher short-term risks due to perioperative complications.

Is Bariatric Surgery an Effective Treatment for Type II Diabetic Kidney Disease?

Type II diabetic kidney disease is devastating to patients and society alike. This review will evaluate bariatric surgery as a treatment for diabetic kidney disease primarily through its ability to induce and maintain regression of type II diabetes. The review begins by outlining the global challenge of diabetic kidney disease, its link to obesity, and the comparative benefits of bariatric surgery on weight and type II diabetes. It then surveys comprehensively the relevant literature, which reports that although bariatric surgery is associated with reductions in albuminuria, its effect on harder clinical end points like progression of diabetic kidney disease is not known. The review also includes a critical assessment of the risks and costs of bariatric surgery and concludes by acknowledging the major knowledge gaps in the field and providing research strategies to overcome them. Until these knowledge gaps are filled, clinicians will be forced to rely on their own subjective judgment in determining the benefit-risk ratio of bariatric surgery for patients with diabetic kidney disease.

Preexisting Diabetes and Risks of Morbidity and Mortality After Gastrectomy for Gastric Cancer: A Nationwide Database Study

The purpose of this study was to determine the risk of surgical mortality and morbidity in patients with diabetes mellitus (DM) undergoing a gastrectomy for gastric cancer (GC). Using the Taiwan National Health Insurance Research Database, we identified 6284 patients who underwent gastrectomy for GC from 1999 to 2010. In addition, we created a non-DM control cohort consisting of 6268 patients who received gastrectomy during the same period. Compared with the non-DM cohort, the DM cohort exhibited a higher prevalence of preoperative coexisting medical conditions, namely hypertension, hyperlipidemia, coronary artery disease, chronic kidney disease, chronic pulmonary disease, stroke, and cirrhosis. The odds ratio (OR) of 30-day postoperative mortality after gastrectomy in the DM cohort was 1.04 (95% confidence interval 0.78-1.40) after we adjusted for covariates. The DM cohort did not exhibit a significantly higher risk of 30-day postoperative morbidities. Further analysis revealed that only patients with a history of a DM-related coma exhibited a higher risk of 30-day postoperative mortality (adjusted OR 2.46, 95% confidence interval 1.10 - 5.54). Moreover, the risk of 90-day postoperative mortality was significantly higher in patients with DM-related eye involvement, coma, peripheral circulatory disease, and renal manifestations, in comparison with the non-DM cohort. The risk of 90-day mortality after gastrectomy for GC is higher in patients with DM-related manifestations than those without DM.

Perioperative risk factors for acute kidney injury after liver resection surgery: an historical cohort study

PURPOSE

This study aimed to identify the incidence and risk factors for acute kidney injury (AKI) after liver resection surgery and to clarify the relationship between postoperative AKI and outcome.

METHODS

We conducted a historical cohort study of patients who underwent liver resection surgery with sevoflurane anesthesia from January 2004 to October 2011. Acute kidney injury was diagnosed based on the Acute Kidney Injury Network classification within 72 hr after the surgery. Patient data, surgical and anesthetic data, and laboratory data were extracted manually from the patients' electronic charts. Multivariable logistic regression analysis was used to identify perioperative risk factors for postoperative AKI.

RESULTS

Acute kidney injury was diagnosed in 78 of 642 patients (12.1%; 95% confidence interval [CI]: 9.7 to 14.9). Multivariable analysis showed an independent association between postoperative AKI and preoperative estimated glomerular filtration rate (adjusted odds ratio [aOR] 0.74; 95% CI: 0.64 to 0.85), preoperative hypertension (aOR 2.10; 95% CI: 1.11 to 3.97), and intraoperative red blood cell transfusion (aOR 1.04; 95% CI: 1.01 to 1.07). Development of AKI within 72 hr after liver resection surgery was associated with increased hospital mortality, prolonged length of stay, and increased rates of mechanical ventilation, reintubation, and renal replacement therapy.

CONCLUSION

Perioperative risk factors for AKI after liver resection surgery are similar to those established for other surgical procedures. Further studies are needed to establish causality and to determine whether interventions on modifiable risk factors can reduce the incidence of postoperative AKI and improve patient outcome. This study was registered at the University Hospital Medical Information Network (UMIN) Center (UMIN 000008089).