Acute kidney injury, renal function, and the elderly obese surgical patient: a matched case-control study

Effect of potential risk factors on renal functions in simultaneous bilateral total knee arthroplasty

Objective

This retrospective study investigated the risk factors leading to a decrease in Renal glomerular filtration rate (eGFR) and the development of acute kidney injury (AKI) during the early postoperative period in patients undergoing simultaneous bilateral total knee arthroplasty (SBTKA).

Methods

SBTKA was performed on 862 patients between 2014 and 2021 in a single center, by a single surgeon. The risk factors affecting the development of AKI were analyzed by monitoring the changes in pre-and postoperative serum creatinine (Scr) levels and eGFR values. RIFLE criteria were used to evaluate the kidney functions of the patients, who were followed up for an average of 6 months.

Results

While there was no decrease in eGFR or AKI in 818 patients postoperatively, eGFR decreased and AKI of different stages developed in 44 patients, according to the RIFLE criteria. Of the 44 patients with AKI, 31 had Risk, 9 had Injury, 3 had Failure, and one had Loss of kidney function. Two patients with American Society of Anaesthesiologists (ASA) class IV died due to deepening of postoperative renal dysfunction.

Conclusion

We found that the direct risk factors in SBTKA in terms of eGFR decrease and AKI development include long operation time, increased need for blood transfusion, and diabetic nephropathy, while increased body mass index (BMI) is an indirect risk factor. When planning for a SBTKA, we presume that a thorough analysis of these factors will decrease AKI risk.

Incidence and predictors of acute kidney injury after elective surgery for lumbar degenerative disease: A 13-year analysis of the US Nationwide Inpatient Sample

BACKGROUND

Acute kidney injury (AKI) is a severe postoperative complication associated with poor clinical outcomes, including the development of chronic kidney disease (CKD) and death. This study aimed to investigate the incidence and determinants of AKI following elective surgeries for degenerative lumbar spine disease.

METHODS

All patient data were extracted from the US Nationwide Inpatient Sample database. After surgery, AKI's incidence and risk factors were identified for lumbar degenerative disease. ICD-9 and ICD-10 codes defined lumbar spine degenerative disease, fusion, decompression, and AKI. The study cohort was categorized by type of surgery, that is, decompression alone or spinal fusion. Regression analysis was used to identify associations between AKI and risk factors organized by surgery type.

RESULTS

The incidence of AKI after decompression or fusion was 1.1% and 1.8%, respectively. However, the incidence of AKI in the United States is rising. The strongest predictor of AKI was underlying CKD, which was associated with an 9.0- to 12.9-fold more significant risk of AKI than in subjects without comorbid CKD. In this setting, older age, congestive heart failure, anemia, obesity, coagulopathy and hospital-acquired infections were also strong predictors of AKI. In contrast, long-term aspirin/anticoagulant usage was associated with lowered AKI risk.

CONCLUSION

Findings of this study inform risk stratification for AKI and may help to optimize treatment decisions and care planning after elective surgery for lumbar degenerative disease.

Perioperative Pain Management for Thoracic Surgery: A Multi-Layered Approach

Cardiothoracic surgeries frequently pose unique challenges in the management of perioperative acute pain that require a multifaceted and personalized approach in order to optimize patient outcomes. This article discusses various analgesic strategies including regional anesthesia techniques such as thoracic epidurals, erector spinae plane blocks, and serratus anterior plane blocks and underscores the significance of perioperative multimodal medications, while providing nuanced recommendations for their use. This article further attempts to provide evidence for the efficacy of the different modalities and compares the effectiveness of the choice of analgesia. The roles of Acute Pain Services (APS) and Transitional Pain Services (TPS) in mitigating opioid dependence and chronic postsurgical pain are also discussed. Precision medicine is also presented as a potential way to offer a patient tailored analgesic strategy. Supported by various randomized controlled trials and meta-analyses, the article concludes that an integrated, patient-specific approach encompassing regional anesthesia and multimodal medications, while also utilizing the services of the Acute Pain Service can help to enhance pain management outcomes in cardiothoracic surgery.

The Effectiveness of Nutritional Strategies in the Treatment and Management of Obesity: A Systematic Review

Obesity, a condition primarily resulting from positive energy balance, has become a significant global health concern. Numerous studies have demonstrated that obesity is a major risk factor for various illnesses, including different types of cancer, coronary heart disease, sleep apnea, CV stroke, type II diabetes mellitus, etc. To effectively address this issue, prevention and treatment approaches to manage body weight are crucial. There are several evidence-based approaches available for the treatment and management of obesity, taking into account factors such as body mass index classification, individual weight history, and existing comorbidities. To facilitate successful obesity treatment and management, there are pragmatic approaches and tools available, including the reduction of energy density, portion control, and diet quality enhancement. These approaches encompass the use of medications, lifestyle interventions, bariatric surgery, and formula diets. Regardless of the specific method employed, behavior change, reduction of energy intake, and increased energy expenditure are integral components for successful treatment and management of obesity. These measures allow patients to personalize and customize their dietary patterns, leading to effective and sustainable weight reduction. Incorporating physical activities and self-monitoring of individual diets are effective techniques for promoting behavior change in obesity and weight management. The main objective of this systematic review is to evaluate the effectiveness of dietary/nutritional interventions in the treatment and management of obesity through provision of valuable insights into the effectiveness of such nutritional strategies. To attain this, a comprehensive analysis of various dietary approaches and their impacts on weight will be conducted.

Post-operative complications of total knee arthroplasty in patients with hypertension

BACKGROUND

Hypertension is one of the most common comorbidities among patients undergoing surgery. However, few studies have focused on patients undergoing knee arthroplasty, and most of them had small sample sizes. This study aimed to analyze post-operative complications associated with hypertension in patients who underwent knee replacement surgery.

METHODS

Data from the 2019 National Inpatient Sample (NIS) database were used. Patients who underwent primary total knee arthroplasty (pTKA) and those who underwent aseptic revision total knee arthroplasty (rTKA) were analyzed separately. Propensity score matching was performed to reduce the effects of demographic factors and comorbidities other than hypertension on post-operative complications. A multinomial logistic regression that included all significantly different demographics and comorbidities was performed to verify the results and evaluate the odds ratios.

RESULTS

A total of 107,981 patients who underwent pTKA and 6571 who underwent rTKA owing to mechanical complications were identified in the 2019 NIS database. Compared with the non-hypertension group, patients with hypertension had a higher risk of developing acute renal failure and electrolyte disorders after TKA. Further analysis revealed that hyponatraemia and hypokalaemia were associated with hypertension.

CONCLUSIONS

Hypertension was associated with the incidence of acute renal failure after TKA. It is important to identify patients with risk factors for acute renal failure (in addition to hypertension) and take careful measures to prevent acute renal failure in them.

The obesity paradox and orthopedic surgery

The Obesity Paradox describes the counterintuitive finding that although obesity contributes to the development of chronic conditions such as chronic kidney disease and cardiovascular disease, obesity seems to improve mortality in patients with these diseases. This paradox has also been sited in the critical care literature in regard to acute kidney injury, obesity and mortality. This study's objective is to examine the impact of obesity and post-surgical acute kidney injury on hospital length of stay and 2-year mortality after orthopedic surgery.We reviewed the electronic medical records of all adult elective orthopedic surgery patients over 2 years in a large academic hospital. The 1783 patients who met inclusion criteria were divided into obese (body mass index, BMI ≥ 30, n = 1123) and non-obese groups (BMI <30, n = 660). Demographics, medications, comorbidities, and perioperative variables were included in multivariable logistic regression analyses with acute kidney injury, length of hospital stay, and two-year mortality as primary outcomes. Outcomes were analyzed for the entire group, the obese cohort and the non-obese cohort.Acute kidney injury developed in 5% of the post-surgical orthopedic patients. Obesity increased the likelihood of developing acute kidney injury post orthopedic surgery (odds ratio [OR] = 1.82; 95% Confidence interval [CI] 1.05-3.15, P = .034). Acute kidney injury increased length of stay by 1.3 days and increased the odds of two-year mortality (OR = 2.08; 95% CI 1.03-4.22, P = .041). However, obese patients had a decreased likelihood of two-year mortality (OR = 0.53; 95% CI 0.33-0.84, P = .009).In adult orthopedic surgery patients, obesity increased the risk of acute kidney injury. Patients who developed an acute kidney injury had longer hospital stays and higher two-year mortality. Paradoxically, obesity decreased two-year mortality.

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.].

Intraoperative Monitoring of the Obese Patient Undergoing Surgery: A Narrative Review

With the increasing prevalence of obesity in the population, anaesthetists must confidently manage both the pathophysiological and technical challenges presented in bariatric and non-bariatric surgery. The intraoperative period represents an important opportunity to optimise and mitigate risk. However, there is little formal guidance on what intraoperative monitoring techniques should be used in this population. This narrative review collates the existing evidence for intraoperative monitoring devices in the obese patients. Although a number of non-invasive blood pressure monitors have been tested, an invasive arterial line remains the most reliable monitor if accurate, continuous monitoring is required. Goal-directed fluid therapy is recommended by clinical practice guidelines, but the methods tested to assess this had guarded applicability to the obese population. Transcutaneous carbon dioxide (CO₂) monitoring may offer additional benefit to standard capnography in this population. Individually titrated positive end expiratory pressure (PEEP) and recruitment manoeuvres improved intraoperative mechanics but yielded no benefit in the immediate postoperative period. Depth of anaesthesia monitoring appears to be beneficial in the perioperative period regarding recovery times and complications. Objective confirmation of reversal of neuromuscular blockade continues to be a central tenet of anaesthesia practice, particularly relevant to this group who have been characterised as an "at risk" extubation group. Where deep neuromuscular blockade is used, continuous neuromuscular blockade is suggested. Both obesity and the intraoperative context represent somewhat unstable search terms, as the clinical implications of the obesity phenotype are not uniform, and the type and urgency of surgery have significant impact on the intraoperative setting. This renders the generation of summary conclusions around what intraoperative monitoring techniques are suitable in this population highly challenging.

Tanshinone IIA Combined With Cyclosporine A Alleviates Lung Apoptosis Induced by Renal Ischemia-Reperfusion in Obese Rats

Acute lung injury (ALI), which is induced by renal ischemia-reperfusion (IR), is one of the leading causes of acute renal IR-related death. Obesity raises the frequency and severity of acute kidney injury (AKI) and ALI. Tanshinone IIA (TIIA) combined with cyclosporine A (CsA) was employed to lessen the lung apoptosis led by renal IR and to evaluate whether TIIA combined with CsA could alleviate lung apoptosis by regulating mitochondrial function through the PI3K/Akt/Bad pathway in obese rats. Hematoxylin-eosin (HE) staining was used to assess the histology of the lung injury. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) was used to assess apoptosis of the lung. Electron microscopy was used to assess mitochondrial morphology in lung cells. Arterial blood gas and pulmonary function were used to assess the external respiratory function. Mitochondrial function was used to assess the internal respiratory function and mitochondrial dynamics and biogenesis. Western blot (WB) was used to examine the PI3K/Akt/Bad pathway-related proteins. TIIA combined with CsA can alleviate lung apoptosis by regulating mitochondrial function through the PI3K/Akt/Bad pathway in obese rats.

Tanshinone IIA combined with CsA inhibit myocardial cell apoptosis induced by renal ischemia-reperfusion injury in obese rats

BACKGROUND

Acute myocardial injury (AMI), which is induced by renal ischemia-reperfusion (IR), is a significant cause of acute kidney injury (AKI)-related associated death. Obesity increases the severity and frequency of AMI and AKI. Tanshinone IIA (TIIA) combined with cyclosporine A (CsA) pretreatment was used to alleviate myocardial cell apoptosis induced by renal IR, and to determine whether TIIA combined with CsA would attenuate myocardial cell apoptosis by modulating mitochondrial function through the PI3K/Akt/Bad pathway in obese rats.

METHODS

Male rates were fed a high fat diet for 8 weeks to generate obesity. AKI was induced by 30 min of kidney ischemia followed 24 h of reperfusion. Obese rats were given TIIA (10 mg/kg·d) for 2 weeks and CsA (5 mg/kg) 30 min before renal IR. After 24 h of reperfusion, the rats were anaesthetized, the blood were fetched from the abdominal aorta and kidney were fetched from abdominal cavity, then related indicators were examined.

RESULTS

TIIA combined with CsA can alleviate the pathohistological injury and apoptosis induced by renal IR in myocardial cells. TIIA combined with CsA improved cardiac function after renal ischemia (30 min)-reperfusion (24 h) in obese rats. At the same time, TIIA combined with CsA improved mitochondrial function. Abnormal function of mitochondria was supported by decreases in respiration controlling rate (RCR), intracellular adenosine triphosphate (ATP), oxygen consumption rate, and mitochondrial membrane potential (MMP), and increases in mitochondrial reactive oxygen species (ROS), opening of the mitochondrial permeability transition pore (mPTP), mitochondrial DNA damage, and mitochondrial respiratory chain complex enzymes. The injury of mitochondrial dynamic function was assessed by decrease in dynamin-related protein 1 (Drp1), and increases in mitofusin1/2 (Mfn1/2), and mitochondrial biogenesis injury was assessed by decreases in PPARγ coactivator-1-α (PGC-1), nucleo respiratory factor1 (Nrf1), and transcription factor A of mitochondrial (TFam).

CONCLUSION

We used isolated mitochondria from rat myocardial tissues to demonstrate that myocardial mitochondrial dysfunction occurred along with renal IR to induce myocardial cell apoptosis; obesity aggravated apoptosis. TIIA combined with CsA attenuated myocardial cell apoptosis by modulating mitochondrial function through the PI3K/Akt/Bad pathway in obese rats.

Risk Factors and Effect of Acute Kidney Injury on Outcomes Following Total Hip and Knee Arthroplasty

BACKGROUND

Development of acute kidney injury (AKI) following primary total joint arthroplasty (TJA) is a potentially avoidable complication associated with negative outcomes including discharge to facilities and mortality. Few studies have identified modifiable risk factors or strategies that the surgeon may use to reduce this risk.

METHODS

We identified all patients undergoing primary TJA at a single hospital from 2005 to 2017, and collected patient demographics, comorbidities, short-term outcomes, as well as perioperative laboratory results. We defined AKI as an increase in creatinine levels by 50% or 0.3 points. We compared demographics, comorbidities, and outcomes between patients who developed AKI and those who did not. Multivariate regressions identified the independent effect of AKI on outcomes. A stochastic gradient boosting model was constructed to predict AKI.

RESULTS

In total, 814 (3.9%) of 20,800 patients developed AKI. AKI independently increased length of stay by 0.26 days (95% confidence interval [CI] 0.14-0.38, P < .001), in-hospital complication risk (odds ratio = 1.73, 95% CI 1.45-2.07, P < .001), and discharge to facility risk (odds ratio = 1.26, 95% CI 1.05-1.53, P = .012). Forty-one predictive variables were included in the predictive model, with important potentially modifiable variables including body mass index, perioperative hemoglobin levels, surgery duration, and operative fluids administered. The final predictive model demonstrated excellent performance with a c-statistic of 0.967.

CONCLUSION

Our results confirm that AKI has adverse effects on outcome metrics including length of stay, discharge, and complications. Although many risk factors are nonmodifiable, maintaining adequate renal perfusion through optimizing preoperative hemoglobin, sufficient fluid resuscitation, and reducing blood loss, such as through the use of tranexamic acid, may aid in mitigating this risk.

Incidence and Predictors of Acute Kidney Injury in Patients Undergoing Elective Hepatic Resection for Malignant Tumors: A 3-year Prospective Observational Study

Background

Acute kidney injury (AKI) is common in patients undergoing major surgeries, and leads to the need for renal replacement therapy and increased morbidity, intensive care unit (ICU) and hospital length of stay (LOS), cost, and mortality. We evaluated the incidence and predictors of postoperative AKI in patients undergoing hepatic resections and their short-term outcomes.

Materials and methods

This prospective observational study was conducted over a 3-year period in 180 patients undergoing elective hepatic resections for a variety of indications. We used the Acute Kidney Injury Network criteria to determine the incidence of AKI at 72 hours. Perioperative variables contributing to the development of AKI and the short-term postoperative outcomes of patients were evaluated.

Results

Postoperative AKI occurred in 29.4% of patients. Persistent renal dysfunction was seen in five patients. Development of AKI was associated with hepatic failure (18.5 vs 5.5%, p < 0.005), prolonged ICU (2 vs 1 days, p < 0.001) and hospital LOS (11 vs 8 days, p < 0.004), and increased ICU and hospital mortality (9.6 vs 1.4%, p < 0.02). Age [OR (odds ratio) 1.033, 95% CI (confidence interval) 1.003–1.065, p = 0.03], BMI (body mass index) (OR 1.131, 95% CI 1.043–1.227, p = 0.003), and need for postoperative ventilation (OR 3.456, 95% CI 1.593–7.495, p = 0.002) were independent predictors of AKI.

Conclusion

AKI after elective hepatic resection occurred in nearly one-third of our patients. Persistent renal dysfunction was seen in five patients. Age, BMI, and need for postoperative ventilation were independent predictors of postoperative AKI. (CTRI reg. No.: CTRI/2016/06/007044).

How to cite this article

Joshi M, Milmile R, Dhakane P, Bhosale SJ, Kulkarni AP. Incidence and Predictors of Acute Kidney Injury in Patients Undergoing Elective Hepatic Resection for Malignant Tumors: A 3-year Prospective Observational Study. Indian J Crit Care Med 2021;25(4):398–404.

Relationship of body mass index, serum creatine kinase, and acute kidney injury after severe trauma

OBJECTIVES

Body mass index (BMI) is associated with acute kidney injury (AKI) after trauma, but underlying mechanisms are unclear. Body mass index correlates with both excess adiposity and increased muscle mass. Since the latter could predispose to severe rhabdomyolysis after trauma, we hypothesized that the BMI-AKI association may be partially explained by a direct relationship of BMI with serum creatine kinase (CK).

METHODS

Prospective cohort study of 463 critically ill patients admitted to a level I trauma center from 2005 to 2015 with Injury Severity Score of >15 and serum CK measured in the first 7 days. We defined AKI by AKI Network creatinine criteria. We used simple linear regression to determine the association of BMI with peak CK and multivariable logistic regression to adjust the BMI-AKI association for peak CK and confounders.

RESULTS

Median age was 43 years, 350 (76%) were male, 366 (79%) had blunt mechanism, and median Injury Severity Score was 24. Body mass index was associated with peak CK (R = 0.05, p < 0.001). Acute kidney injury developed in 148 patients (32%), and median time to peak CK was 29 hours (interquartile range, 15-56 hours) after presentation. Body mass index was significantly associated with AKI in multivariable models adjusted for age, race, sex, diabetes, injury mechanism and severity, and red blood cell transfusions (odds ratio [OR], 1.31 per 5 kg/m; 95% confidence interval [CI], 1.09-1.58; p = 0.004). Adding peak CK to the model partially attenuated the association of BMI with AKI (OR, 1.26 per 5 kg/m; 95% CI, 1.04-1.52; p = 0.018), and peak CK was also associated with AKI (OR, 1.19 per natural log; 95% CI, 1.00-1.41; p = 0.049). Peak CK remained associated with AKI when restricted to patients with values of <5,000 U/L (OR, 1.31 per natural log; 95% CI, 1.01-1.69; p = 0.043).

CONCLUSION

Serum CK correlated with BMI and partially attenuated the association of BMI with AKI after major trauma, suggesting that excess muscle injury may contribute to the BMI-AKI association.

LEVEL OF EVIDENCE

Epidemiologic study, level III.

Abdominal adiposity assessed using CT angiography associates with acute kidney injury after trans-catheter aortic valve replacement

AIM

To determine if there is an association between area-based visceral abdominal adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAT), and abdominal circumference measured on computed tomography (CT) angiography before trans-catheter aortic valve replacement (TAVR) and post-TAVR acute kidney injury (AKI).

MATERIALS AND METHODS

In this retrospective cohort study of 106 TAVR patients, SAT and VAT areas and abdominal circumference was measured on a single CT section at L4 vertebral level. Univariate comparisons between patients who did and did not develop AKI were undertaken for radiological measurements. Multivariable logistic regression was used to assess association between CT measurements and the development of post-TAVR AKI.

RESULTS

Post-TAVR AKI occurred in 20 of 106 patients (19%). In univariate comparisons, body mass index (BMI) did not differ significantly between patients who did and did not develop AKI (p=0.14); however, VAT+SAT (443.2±163.7 versus 351±168.7 cm²; p=0.03), VAT (213.9±110.6 versus 153.9±96.1 cm²; p=0.03), and outer abdominal circumference (100.2±14.4 cm versus 91.8±13.3 cm; p=0.02) were significantly higher in the patients who did not develop post-TAVR AKI. These three measures on pre-TAVR CT angiogram remained significantly associated with reduced post-TAVR AKI with a lower incidence of post-TAVR AKI after multivariable adjustment for pre-TAVR estimated glomerular filtration rate and patient height (p<0.05).

CONCLUSION

This study found that increased abdominal obesity as assessed by measures on pre-TAVR CT angiogram is associated with a significantly lower incidence of AKI.

Artificial Intelligence in Acute Kidney Injury Risk Prediction

Acute kidney injury (AKI) is a frequent complication in hospitalized patients, which is associated with worse short and long-term outcomes. It is crucial to develop methods to identify patients at risk for AKI and to diagnose subclinical AKI in order to improve patient outcomes. The advances in clinical informatics and the increasing availability of electronic medical records have allowed for the development of artificial intelligence predictive models of risk estimation in AKI. In this review, we discussed the progress of AKI risk prediction from risk scores to electronic alerts to machine learning methods.

Black Race and Body Mass Index Are Risk Factors for Rhabdomyolysis and Acute Kidney Injury in Trauma

Purpose: Obesity has been shown in a single-center study to be a risk factor for rhabdomyolysis. More recently, sickle cell trait, known to be more prevalent in blacks, has been shown to be a risk factor for rhabdomyolysis. We hypothesized that in trauma patients, black race and a higher body mass index (BMI) are associated with risk for rhabdomyolysis and acute kidney injury (AKI). Materials and Methods: The National Trauma Data Bank (NTDB) was queried (2013-2015) to identify patients age ≥18 years and grouped by BMI: normal (18.5-24.99 kg/m2), underweight (16.5-18.49 kg/m2), overweight (25-29.99 kg/m2), obese (30-34.99 kg/m2), severely obese (35-39.99 kg/m2), and morbidly obese (≥40 kg/m2). A multivariable logistic regression model was used to assess whether a higher BMI or black race was associated with rhabdomyolysis or AKI. Results: After adjusting for covariates, severe obesity (odds ratio (OR) = 1.42, confidence interval (CI) = 1.01-1.99, p < .001), morbid obesity (OR = 1.46, CI = 1.04-2.06, p < .001), and black race (OR = 1.52, CI = 1.24-1.88, p < .001) were associated with higher risk for rhabdomyolysis. Patients that were overweight (OR = 1.17, CI = 1.11-1.24, p < .001), obese (OR = 1.32, CI = 1.24-1.41, p < .001), severely obese (OR = 1.72, CI = 1.59-1.86, p < .001), morbidly obese (OR = 1.77, CI = 1.64-1.92, p < .001), or black (OR = 1.31, CI = 1.24-1.38, p < .001) were associated with higher risk for AKI. Conclusions: Black race was associated with an increased risk of rhabdomyolysis as well as AKI in trauma. BMI ≥25 kg/m2 was associated with increased risk for AKI with the morbidly obese having the highest risk. BMI ≥35 kg/m2 was found to be associated with increased risk of rhabdomyolysis. Future studies should investigate the role for routine screening of these high-risk populations and other potential associated factors such as adherence to weight-based fluid resuscitation.

Preoperative proteinuria is associated with increased rates of acute kidney injury after partial nephrectomy

Purpose

We investigated the association between preoperative proteinuria and early postoperative renal function after robotic partial nephrectomy (RPN).

Patients and Methods

We retrospectively reviewed 1121 consecutive RPN cases at a single academic center from 2006 to 2016. Patients without pre-existing CKD (eGFR≥60 mL/min/1.73m²) who had a urinalysis within 1-month prior to RPN were included. The cohort was categorized by the presence or absence of preoperative proteinuria (trace or greater (≥1+) urine dipstick), and groups were compared in terms of clinical and functional outcomes. The incidence of acute kidney injury (AKI) was assessed using RIFLE criteria. Univariate and multivariable models were used to identify factors associated with postoperative AKI.

Results

Of 947 patients, 97 (10.5%) had preoperative proteinuria. Characteristics associated with preoperative proteinuria included non-white race (p<0.01), preoperative diabetes (p<0.01) and hypertension (HTN) (p<0.01), higher ASA (p<0.01), higher BMI (p<0.01), and higher Charlson score (p<0.01). The incidence of AKI was higher in patients with preoperative proteinuria (10.3% vs. 4.6%, p=0.01). The median eGFR preservation measured within one month after surgery was lower (83.6% vs. 91%, p=0.04) in those with proteinuria; however, there were no significant differences by 3 months after surgery or last follow-up visit. Independent predictors of AKI were high BMI (p<0.01), longer ischemia time (p<0.01), and preoperative proteinuria (p=0.04).

Conclusion

Preoperative proteinuria by urine dipstick is an independent predictor of postoperative AKI after RPN. This test may be used to identify patients, especially those without overt CKD, who are at increased risk for developing AKI after RPN.

Acute Kidney Injury in Subjects With Chronic Kidney Disease Undergoing Total Joint Arthroplasty

BACKGROUND

Chronic kidney disease (CKD) has been associated with higher incidence of complications after total joint arthroplasty (TJA) but the incidence, risk factors and outcomes of acute kidney injury (AKI) in this setting remains insufficiently understood.

METHODS

We assessed the impact of baseline CKD on the risk of developing AKI after TJA performed between 1/2012 and 12/2016 in a single-center, retrospective cohort study. CKD was defined by estimated glomerular filtration rate <60 mL/min/1.73 m² on 2 separate occasions within 3 months prior TJA. AKI was defined using a modified Kidney Disease: Improving Global Outcomes criteria based on serum creatinine (sCr) only to assess the severity of AKI. Complete AKI recovery was defined as the lowest post-AKI sCr within 20% of pre-AKI sCr values and partial recovery if within 30%, all within 90 days after TJA.

RESULTS

Twenty-four percent of the 1,212 subjects undergoing TJA had pre-existing CKD. The overall incidence of AKI in the CKD subjects was 30%; of these, 55% had stage-1 AKI, 1% had stage-2 AKI and 44% had stage-3 AKI. AKI was more common in African Americans, those with diabetes or heart failure, requiring perioperative transfusions or receiving diuretics before surgery. While 82% of the AKI subjects achieved complete recovery of kidney function, 4% had only partial recovery and 14% did not reach a post-AKI sCr level within 30% of pre-AKI values. The incidence (P < 0.001) but not the severity (P = 0.202) of AKI correlated with stages of baseline CKD.

CONCLUSIONS

The presence of CKD was associated with a high incidence of AKI after TJA. In these subjects, more than half the cases of AKI were of mild degree and had a favorable outcome. However, 18% of them did not have complete recovery of kidney function. Stages of baseline CKD were associated with increased incidence but not severity of AKI after TJA.

Survival and Risk Factors Among Dialytic Acute Kidney Injury Patients After Cardiovascular Surgery

OBJECTIVE

Acute kidney injury (AKI) is a frequent postoperative complication after cardiovascular surgery. It has been described as a predictor of decreased survival rates, but how dialysis decreases survival when initiated on the postoperative period has yet to be determined. To analyze the survival of patients who presented postoperative AKI requiring dialysis up to 30 days after cardiovascular surgery and its risk factors is the aim of this study.

METHODS

Of the 5,189 cardiovascular surgeries performed in a 4-year period, 157 patients developed AKI requiring dialysis in the postoperative period. The Kaplan-Meier survival curve and log-rank test were used in the statistical analysis to compare the curves of categorical variables. P-value< 0.05 was considered significant.

RESULTS

Patient average survival was 546 days and mortality was 70.7%. The need for dialysis on the postoperative period decreased late survival. Risk factors for decreased survival included age (P<0.001) and postoperative complications (P<0.0003).

CONCLUSION

The average survival was approximately one year among dialytic patients. Age and postoperative complications were risk factors that determined decreased survival.

Surgical Technical Evidence Review for Elective Total Joint Replacement Conducted for the AHRQ Safety Program for Improving Surgical Care and Recovery

Background:

Use of enhanced recovery pathways (ERPs) can improve patient outcomes, yet national implementation of these pathways remains low. The Agency for Healthcare Research and Quality (AHRQ; funder), the American College of Surgeons, and the Johns Hopkins Medicine Armstrong Institute for Patent Safety and Quality have developed the Safety Program for Improving Surgical Care and Recovery—a national effort to catalyze implementation of practices to improve perioperative care and enhance recovery of surgical patients. This review synthesizes evidence that can be used to develop a protocol for elective total knee arthroplasty (TKA) and total hip arthroplasty (THA).

Study Design:

This review focuses on potential components of the protocol relevant to surgeons; anesthesia components are reported separately. Components were identified through review of existing pathways and from consultation with technical experts. For each, a structured review of MEDLINE identified systematic reviews, randomized trials, and observational studies that reported on these components in patients undergoing elective TKA/THA. This primary evidence review was combined with existing clinical guidelines in a narrative format.

Results:

Sixteen components were reviewed. Of the 10 preoperative components, most were focused on risk factor assessment including anemia, diabetes mellitus, tobacco use, obesity, nutrition, immune-modulating therapy, and opiates. Preoperative education, venous thromboembolism (VTE) prophylaxis, and bathing/Staphylococcus aureus decolonization were also included. The routine use of drains was the only intraoperative component evaluated. The 5 postoperative components included early mobilization, continuous passive motion, extended duration VTE prophylaxis, early oral alimentation, and discharge planning.

Conclusion:

This review synthesizes the evidence supporting potential surgical components of an ERP for elective TKA/THA. The AHRQ Safety Program for Improving Surgical Care and Recovery aims to guide hospitals and surgeons in identifying the best practices to implement in the surgical care of TKA and THA patients.

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.

The Rate of Acute Kidney Injury After Total Hip Arthroplasty Is Low but Increases Significantly in Patients with Specific Comorbidities

BACKGROUND

The purpose of this study was to investigate the rate and risk factors associated with the development of acute kidney injury after total hip arthroplasty, including the perioperative use of nonsteroidal anti-inflammatory drugs (NSAIDs).

METHODS

We retrospectively collected the demographic and comorbidity data of all patients who underwent total hip arthroplasty between 2004 and 2014 at our institution (n = 8,949). We conducted analyses of the entire cohort and a nested case-control subset. Subjects who developed acute kidney injury were matched by age, sex, and year of surgical procedure to subjects without acute kidney injury. Variables associated with acute kidney injury were determined using univariate and multivariate logistic regressions.

RESULTS

The mean patient age (and standard deviation) was 64.6 ± 13.8 years, 48.6% of patients were male, and 114 cases (1.1%) developed acute kidney injury, mostly stage 1 (79%). Variables associated with acute kidney injury included older age (odds ratio [OR], 1.4 per decade; p < 0.001), male sex (OR, 1.78; p = 0.005), chronic kidney disease (OR, 4.6; p < 0.001), heart failure (OR, 4.5; p < 0.001), diabetes (OR, 2.1; p < 0.001), and hypertension (OR, 2.1; p = 0.007). The results were consistent in the case-control analysis. NSAIDs were not associated with acute kidney injury (OR, 1.26; p = 0.36), but were avoided in subjects at risk, making any interpretation difficult because of confounding. A risk model for acute kidney injury after total hip arthroplasty was developed for clinical use and had good discrimination (area under the curve, 0.82; p < 0.001).

CONCLUSIONS

The rate of acute kidney injury after total hip arthroplasty is low, but increases significantly, from <1% to >20%, in those with several independent risk factors present preoperatively. Increasing awareness of these risk factors may help to decrease the risk of acute kidney injury after total hip arthroplasty.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Acute Kidney Disease After Total Hip and Knee Arthroplasty: Incidence and Associated Factors

BACKGROUND

The development of acute kidney disease (AKD) following total joint arthroplasty has not been well characterized in the literature. We sought to calculate the incidence and identify risk factors associated with postoperative AKD for patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA).

METHODS

A total of 1000 consecutive cases (860 unique patients, including revisions) of TKA or THA performed between January 2010 and May 2016 were identified. Seventy-nine cases were excluded due to pre-existing kidney dysfunction and 23 additional cases were excluded due to incomplete data, resulting in 898 cases included in the study. There were 492 females and 406 males with a mean age of 58.1 years (range, 14-93 years). The Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease criteria and serum creatinine values were used to determine AKD status. Multiple logistic regression modeling was used to identify postoperative AKD risk factors.

RESULTS

Overall incidence of postoperative AKD was 6.8% (n = 61). Use of perioperative angiotensin receptor blocker (ARBs) or angiotensin-converting enzyme inhibitors (ACEi) (odds ratio [OR] = 2.09; P = .030), increasing body mass index (BMI) (OR = 1.58 per 10 kg/m²; P = .014), and use of vancomycin perioperatively (OR = 1.91; P = .021) were associated with increased odds of development of postoperative AKD.

CONCLUSION

A 6.8% incidence rate of postoperative AKD was noted in patients undergoing TKA or THA. Perioperative use of ARBs/ACEi, perioperative vancomycin use, and increased BMI were associated with increased odds of postoperative AKD.

Are There Modifiable Risk Factors to Improve AKI?

Acute kidney injury (AKI) is a common critical syndrome, with high morbidity and mortality. Patients with AKI typically have an adverse prognosis, from incident chronic kidney disease (CKD), progression to end-stage renal disease (ESRD), subsequent cardiovascular disease, and ultimately death. However, there is currently no effective therapy for AKI. Early detection of risk factors for AKI may offer a good approach to prevention or early intervention. Traditional risk factors include extreme age, many common comorbid diseases, such as preexisting CKD, some specific exposures, such as sepsis, and exposure to some nephrotoxic agents. Recently, several novel risk factors for AKI, such as hyperuricemia, hypoalbuminemia, obesity, anemia, and hyperglycemia, have been identified. The underlying mechanisms between these nontraditional risk factors and AKI and whether their correction can reduce AKI occurrence remain to be clarified. This review describes the current epidemiology of AKI, summarizes its outcome, outlines the traditional risk profile, and finally highlights some recently identified novel risk factors.

Acute kidney injury following primary hip and knee arthroplasty surgery

Acute kidney injury (AKI) is a recognised postoperative complication following primary hip/knee arthroplasty surgery. The aim of this study was to determine causative and potentially modifiable risk factors associated with postoperative AKI. Standard data were collected for 413 consecutive arthroplasty patients, both retrospectively and prospectively. Univariate and multivariate analyses were performed to identify any potential causative factors. Eight percent of patients developed postoperative AKI. Univariate analysis found increasing age, history of previous chronic kidney disease and requirement for postoperative intravenous fluids to be risk factors for AKI. The multivariate regression analysis model identified age and volume of postoperative fluid prescription as predictive of postoperative AKI. Antibiotic regime and prescription of non-steroidal anti-inflammatory drugs had no significant effect on the risk of AKI. No patients required dialysis but length of stay increased by 50% in the AKI group. Postoperative AKI may result in significant postoperative morbidity and increased length of stay, and may necessitate invasive therapies such as dialysis. Episodes of AKI could also predispose to future similar episodes and are associated with a long-term decrease in baseline renal function. This study has demonstrated that the identified risk factors are generally non-modifiable. Further work is suggested to determine whether targeted interventions in high risk patients would reduce the incidence of AKI.

Renoprotection: focus on TRPV1, TRPV4, TRPC6 and TRPM2

Members of the transient receptor potential (TRP) cation channel receptor family have unique sites of regulatory function in the kidney which enables them to promote regional vasodilatation and controlled Ca²⁺ influx into podocytes and tubular cells. Activated TRP vanilloid 1 receptor channels (TRPV1) have been found to elicit renoprotection in rodent models of acute kidney injury following ischaemia/reperfusion. Transient receptor potential cation channel, subfamily C, member 6 (TRPC6) in podocytes is involved in chronic proteinuric kidney disease, particularly in focal segmental glomerulosclerosis (FSGS). TRP vanilloid 4 receptor channels (TRPV4) are highly expressed in the kidney, where they induce Ca²⁺ influx into endothelial and tubular cells. TRP melastatin (TRPM2) non-selective cation channels are expressed in the cytoplasm and intracellular organelles, where their inhibition ameliorates ischaemic renal pathology. Although some of their basic properties have been recently identified, the renovascular role of TRPV1, TRPV4, TRPC6 and TRPM2 channels in disease states such as obesity, hypertension and diabetes is largely unknown. In this review, we discuss recent evidence for TRPV1, TRPV4, TRPC6 and TRPM2 serving as potential targets for acute and chronic renoprotection in chronic vascular and metabolic disease.

Impact of body mass index on risk of acute kidney injury and mortality in elderly patients undergoing hip fracture surgery

The literature is limited regarding risk factors for acute kidney injury (AKI) and mortality in hip fracture patients, although AKI is common in these patients. While obese patients were at increased risk of AKI, underweight patients with and without AKI had elevated mortality for up to 1 year after hip fracture surgery, compared with normal-weight patients.

INTRODUCTION

This study aimed to examine risk of postoperative AKI and subsequent mortality, by body mass index (BMI) level, in hip fracture surgery patients aged 65 and over.

METHODS

A regional cohort study using medical databases was used. We included all patients who underwent surgery to repair a hip fracture during the years 2005-2011 (n = 13,529) at hospitals in Northern Denmark. We calculated cumulative risk of AKI by BMI level during 5 days postsurgery and subsequent short-term (6-30 days postsurgery) and long-term (31-365 days post-surgery) mortality. We calculated crude and adjusted hazard ratios (aHRs) for AKI and death with 95% confidence intervals (CIs), comparing underweight, overweight, and obese patients with normal-weight patients.

RESULTS

Risks of AKI within five postoperative days were 11.9, 10.1, 12.5, and 17.9% for normal-weight, underweight, overweight, and obese patients, respectively. Among those who developed AKI, short-term mortality was 14.1% for normal-weight patients compared to 23.1% for underweight (aHR 1.7 (95% CI 1.2-2.4)), 10.7% for overweight (aHR 0.9 (95% CI 0.6-1.1)), and 15.2% for obese (aHR 0.9 (95% CI 0.6-1.4)) patients. Long-term mortality was 24.5% for normal-weight, 43.8% for underweight (aHR 1.6 (95% CI 1.0-2.6)), 20.5% for overweight (aHR 0.8 (95% CI 0.6-1.2)), and 21.4% for obese (aHR 1.1 (95% CI 0.7-1.8) AKI patients. Similar associations between BMI and mortality were observed among patients without postoperative AKI, although the absolute mortality risk estimates by BMI were considerably lower in patients without than in those with AKI.

CONCLUSIONS

Obese patients were at increased risk of AKI compared with normal-weight patients. Among patients with and without postoperative AKI, overweight and obesity were not associated with mortality. Compared to normal-weight patients, underweight patients had elevated mortality for up to 1 year after hip fracture surgery irrespective of the presence of AKI. The absolute mortality risks were higher in all BMI groups with the presence of AKI.

Surgical Risks and Costs of Care are Greater in Patients Who Are Super Obese and Undergoing THA

BACKGROUND

Patients with morbid obesity, defined as a BMI greater than 40 kg/m², and super obesity, defined as a BMI greater than 50 kg/m², increasingly present for total hip replacement. There is disagreement in the literature whether these individuals have greater surgical risks and costs for the episode of care, and the magnitude of those risks and costs. There also is no established threshold for obesity as defined by BMI in identifying increased complications, risks, and costs of care. Until recently, analysis of higher BMI data was limited to small cohorts from hospital-based data banks, based on BMI or height and weight only, often as part of a multivariate analysis. On October 1, 2010 the Centers for Medicare & Medicaid Services added a fifth digit to the BMI data, V85.xx, in the Medicare data bank, which allowed data mining of cases of patients with higher BMI. To our knowledge, our study is the first large retrospective Medicare data mining study, which allows us to examine BMI levels greater than 40 and 50 kg/m² to delineate risks, complications, and costs for these patients.

QUESTIONS/PURPOSES

We sought to quantify (1) the surgical risk, and (2) the costs associated with complications after THA in patients who were morbidly obesity (BMI ≥ 40 kg/m²) or super obese (BMI ≥ 50 kg/m²).

METHODS

This is a retrospective study of patients, using Medicare hospital claims data, who underwent THA. The ICD-9 Clinical Modification (CM) diagnosis code V85.4x was used to identify patients with morbid obesity and with super obesity from October 1, 2010 through December 31, 2014. Patients without any BMI-related diagnosis codes were used as the control group. Twelve complications occurring during the 90 days after THA were analyzed using multivariate Cox models adjusting for patient demographic, comorbidities, and institutional factors. In addition, hospital charges and payments were compared from primary surgery through the subsequent 90 days.

RESULTS

Patients with morbid obesity had increased postoperative complications including prosthetic joint infection (hazard ratio [HR], 3.71; 95% CI, 3.2-4.31; p < 0.001), revision (HR, 1.91; 95% CI, 1.69-2.16; p < 0.001), and wound dehiscence (HR, 3.91; 95% CI, 3.14-4.86; p < 0.001). In addition, patients with morbid obesity had increased risk of deep vein thrombosis (HR, 1.43; 95% CI, 1.14-1.79; p < 0.002), pulmonary embolism (HR, 1.57; 95% CI, 1.25-1.99; p < 0.001), implant failure (HR, 1.48; 95% CI, 1.3-1.68; p < 0.001), acute renal failure (HR, 1.68; 95% CI, 1.56-1.80; p < 0.001), and all-cause readmission (HR, 1.48; 95% CI, 1.40-1.56; p < 0.001). However, death (HR, 0.94 95% CI, 0.73-1.19 p < 0.592), acute myocardial infarction (HR, 0.94; 95% CI, 0.74-1.2 p < 0.631), and dislocation (HR 1.07; 95% CI, 0.85-1.34; p < 0.585) were not different between patients in the control and morbidly obese groups. Super obese patients had an increased risk of infection (HR, 6.48; 95% CI, 4.54-9.25; p < 0.001), wound dehiscence (HR, 9.81; 95% CI, 6.31-15.24; p < 0.001), and readmission (HR, 2.16; 95% CI, 1.84-2.54; p < 0.001) compared with patients with normal BMI. Controlling for patient and institutional factors, each THA had mean total hospital charges of USD 88,419 among patients who were super obese compared with USD 73,827 for the control group, a difference of USD 14,591. Medicare payment for the patients who were super obese also was higher, but only by USD 3631.

CONCLUSIONS

Patients who are super obese are at increased risk for serious complications compared with patients with morbid obesity, whose risks are elevated relative to patients whose BMI is less than 40 kg/m². Costs of care for patients who were super obese, likewise, were increased. We present BMI outcomes to allow an objective basis for patient counseling, risk stratification, maintaining access to orthopaedic surgical care, and maintaining hospital operating margins.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Risk and Cost of 90-Day Complications in Morbidly and Superobese Patients After Total Knee Arthroplasty

BACKGROUND

This study investigated the risk and cost of postoperative complications associated with morbid and super obesity after total knee arthroplasty (TKA).

METHODS

A retrospective cohort study was conducted of patients who underwent TKA using Medicare hospital claims data. The International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code V85.4x was used to identify morbidly obese patients (body mass index [BMI] ≥40 kg/m(2)) and superobese patients (BMI ≥50 kg/m(2)) in 2011-2013. Patients without any BMI-related diagnosis codes were used as controls. Twelve complications occurred in the 90-day period after TKA were analyzed using multivariate Cox models, adjusting for patient demographic, morbidity, and institutional factors. In addition, hospital charges and payments were compared from primary surgery through subsequent 90 days.

RESULTS

Morbidly obese patients showed a significantly elevated risk in most complications examined, with a 2-fold or higher risk in dislocation and wound dehiscence. In addition, death, periprosthetic joint infection, acute renal failure, and knee revision had significant hazard ratios between 1.5 and 2.0. However, risk of deep vein thrombosis and acute myocardial infarction did not increase for the morbidly obese patients. Superobese patients had significant increase in risk of infection, wound dehiscence, acute renal failures, revisions, death, and readmission compared with patients with BMI 40-49 kg/m(2). Significant dose-response trend was found between the level of BMI and risk for death, dislocation, implant failure, infection, readmission, revision, wound dehiscence, and acute renal failure. Controlling for patient and institutional factors, each TKA had an average total hospital charges of $75,884 among superobese patients, compared to $65,118 for the control group, a difference of $10,767. Medicare payment for the superobese patients was also higher, but only by $2703.

CONCLUSION

Morbidly obese patients pose a significantly higher risk profile than normal-weight patients in a broad range of complications after TKA. Superobese patients add another layer of risk compared with less obese patients and are considerably more expensive to treat by health care systems. Technical difficulties and the high demand on resources present a severe challenge for providing treatment for such patients.

Renoprotective effect of a combination of garlic and telmisartan against ischemia/reperfusion-induced kidney injury in obese rats

Obesity enhances the frequency and severity of acute kidney injury (AKI). Telmisartan pre-treatment was used experimentally in the amelioration of ischemia/reperfusion (IR)-induced AKI. However, there is a lack of evidence regarding its beneficial effects on AKI in obese animals. The present study, therefore, aimed to explore the protective effects of garlic and/or telmisartan against renal damage induced by unilateral IR in obese rats. Meloxicam was used as a standard anti-inflammatory agent. Prophylactic oral administration of meloxicam (3 mg kg(-1)), garlic (500 mg kg(-1)) and/or telmisartan (5 and 10 mg kg(-1)) for 4 wk protected against renal function deterioration induced by IR in obese rats. Both doses of telmisartan significantly reduced serum total cholesterol and triacyglycerol levels as well as peri-renal adipocytes size and renal fibrosis. Renal nuclear factor-kappa B immunoreactivity, tumor necrosis factor-alpha content as well as interleukin-10, adiponectin receptor 1 and macrophages (M1, M2) polarization markers (CD11c, CD206) mRNA expressions were down-regulated in ischemic kidney tissues and white adipose tissues around them by all treatments. Moreover, garlic, telmisartan and their combinations significantly suppressed oxidative stress in renal ischemic tissues. Histological picture was also improved by these treatments. Interestingly, the combinations provided a greater protection than their monotherapy in a dose-dependent manner. We suppose that this combination may be a promising prophylactic regimen for managing AKI in case of obesity. Thus, future experimental and clinical large-scale studies are necessary.

Risk Stratification for Acute Kidney Injury: Are Biomarkers Enough?

Acute kidney injury (AKI) is a common and serious complication that is associated with several adverse outcomes in hospitalized patients. AKI significantly increases the risk of mortality, need for renal replacement therapy, and intensive care admission, and it also has serious economic ramifications. Effective risk stratification to identify patients at risk for severe AKI is essential for targeting our health care and research resources to tackle this important public health issue. The overwhelming majority of research in earlier diagnosis and risk stratification of AKI over the past 10 years has focused on novel biomarker development. The purpose of this review is to provide an update on other novel risk stratification tools than can be used in the prognostication of AKI. We discuss the utility of the furosemide stress test in predicting the severity of AKI and the renal angina index in predicting the occurrence of AKI. We also discuss NephroCheck, a prognostic test that measures tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 for the early detection of severe AKI.

The Impact of Obesity on Health Care Utilization and Expenditures in a Medicare Supplement Population

Objective: Obesity is a contributor to increased chronic conditions resulting in higher utilization of medical services among broad populations of older adults. The objective of this study was to evaluate the magnitude of the impact of weight on health care use patterns among Medicare Supplement insureds. Method: We estimated the impact of weight as a function of body mass index (BMI) on health care utilization and expenditures using propensity weighted multivariate regression models. The outcomes were controlled initially for demographics and socioeconomics and then additionally for chronic conditions and health status. Results: Among the 9,484 survey respondents, 22.9% were obese. Those categorized as obese were significantly more likely to incur inpatient admissions and orthopedic procedures. Annualized health care expenditures were US$1,496 higher for obese compared with normal weight. The excess utilization and expenditures associated with obesity were explained by chronic conditions and poor health status. Conclusion: Obesity-related expenditures associated with medical management are largely preventable and may benefit from interventions that target lifestyle behaviors and weight management among older adults.

The impact of hyperglycemia and obesity on hospitalization costs and clinical outcome in general surgery patients

BACKGROUND

The impact of obesity on clinical outcomes and hospitalization costs in general surgery patients with and without diabetes (DM) is unknown.

MATERIALS AND METHODS

We reviewed medical records of 2451 patients who underwent gastrointestinal surgery at two university hospitals. Hyperglycemia was defined as BG ≥140 mg/dl. Overweight was defined by body mass index (BMI) between 25-29.9 kg/m(2) and obesity as a BMI ≥30 kg/m(2). Hospital cost was calculated using cost-charge ratios from Centers for Medicare and Medicaid Services. Hospital complications included a composite of major cardiovascular events, pneumonia, bacteremia, acute kidney injury (AKI), respiratory failure, and death.

RESULTS

Hyperglycemia was present in 1575 patients (74.8%). Compared to patients with normoglycemia, those with DM and non-DM with hyperglycemia had higher number of complications (8.9% vs. 35.8% vs. 30.0%, p<0.0001), longer hospital stay (5 days vs. 9 days vs. 9 days, p<0.0001), more readmissions within 30 days (9.3% vs. 18.8% vs. 17.2%, p<0.0001), and higher hospitalization costs ($20,273 vs. $79,545 vs. $72,675, p<0.0001). In contrast, compared to normal-weight subjects, overweight and obesity were not associated with increased hospitalization costs ($58,313 vs. $58,173 vs. $66,633, p=0.74) or risk of complications, except for AKI (11.9% vs. 14.8% vs. 20.5%, p<0.0001). Multivariate analysis revealed that DM (OR=4.4, 95% CI=2.8,7.0) or perioperative hyperglycemia (OR=4.1, 95% CI=2.7-6.2) were independently associated with increased risk of complications.

CONCLUSION

Hyperglycemia but not increasing BMI, in patients with and without diabetes undergoing gastrointestinal surgery was associated with a higher number of complications and hospitalization costs.

Risk factors for renal dysfunction after total hip joint replacement; a retrospective cohort study

Background and purpose of the study

Renal injury and dysfunction are serious complications after major surgery, which may lead to increased morbidity and mortality. The objective of our study was to identify the possible risk factors for renal dysfunction after total hip joint replacement surgery.

Methods

A retrospective study was conducted among 599 consecutive primary hip joint replacements performed between January 2011 and December 2013. According to the RIFLE criteria, increased postoperative serum creatinine was considered indicative of postoperative renal injury. The Welch two-sample test, chi-square test, and Fisher exact test were used for statistical analysis.

Results

Eighty-one patients (13.8 %) had significant moderate or severe postoperative renal dysfunction in which 10 patients (1.7 %) acquired severe and permanent renal impairment.

Conclusion

We identified advanced age, hypertension, general anesthesia, high ASA scores, low intra-operative systolic BP, and prophylactic dicloxacillin as significant risk factors. Low baseline systolic BP, low baseline diastolic blood pressure, and hip fracture diagnosis were independent risk factors for postoperative increase in serum creatinine. Smoking, diabetes mellitus, high BMI, gender, and duration of surgery were not identified as significant risk factors.

Obesity Is Associated With Increased Complications After Operative Management of End-Stage Ankle Arthritis

BACKGROUND

Total ankle arthroplasty (TAA) and ankle arthrodesis (AA) are two operative options for the management of end-stage ankle arthritis that has failed conservative interventions. Obesity is associated with a greater incidence of musculoskeletal disease, particularly osteoarthritis of the weight-bearing joints, including the ankle. The objective of the present study was to use a national database to examine the association between obesity and postoperative complications after TAA and AA.

METHODS

The PearlDiver database was queried for patients undergoing AA and TAA using International Classification of Diseases, 9th Revision (ICD-9) procedure codes. Patients were divided into obese (body mass index ≥30 kg/m(2)) and nonobese (body mass index <30 kg/m(2)) cohorts using ICD-9 codes for body mass index and obesity. Complications within 90 days postoperatively were assessed using ICD-9 and Current Procedural Terminology (CPT) codes.

RESULTS

23,029 patients were identified from 2005 to 2011, including 5361 with TAA and 17,668 with AA. Obese TAA patients had a significantly increased risk of 90-day major, minor, local, systemic, venous thromboembolic, infectious, and medical complications compared with nonobese patients. The incidence of revision TAA was also significantly higher in obese patients compared with nonobese patients. Findings were similar for AA, as all types of complications were significantly higher in obese patients compared with nonobese patients.

CONCLUSION

Obesity was associated with significantly increased rates of all complications after both TAA and AA. The cause of this association was likely multifactorial, including increased rates of medical comorbidities, intraoperative factors, and larger soft tissue envelopes.

LEVEL OF EVIDENCE

Level III, comparative series.

Acute kidney injury after open ventral hernia repair: an analysis of the 2005-2012 ACS-NSQIP datasets

PURPOSE

Acute kidney injury (AKI) is a serious postoperative complication, negatively impacting mortality rates, extending length of stay, and raising hospital costs. The purpose of this study was to examine AKI following open ventral hernia repair (OVHR) using a large, heterogeneous database to determine the incidence and identify risk factors for this complication.

METHODS

Using the 2005-2012 ACS-NSQIP database, patients undergoing open ventral hernia repair were identified by CPT codes. Patients with acute kidney injury within 30 days of surgery were compared to controls by multivariate logistic regression across preoperative and intraoperative characteristics.

RESULTS

Of 48,629 open ventral hernia repair patients identified in the dataset, AKI developed in 1.4% (681 patients). Multivariate logistic regression determined a number of factors associated with AKI. These include WHO Class III obesity (OR = 2.57, p < 0.001), history of cardiovascular disease (OR = 1.81, p < 0.001), diabetes (OR = 1.29, p = 0.028), hypoalbuminemia (OR = 1.42, p = 0.004), and chronic kidney disease (for a baseline GFR of 60-89 mL/min/1.73 m2, OR = 1.62, p = 0.001; for 30-59 mL/min/1.73 m2, OR = 2.25, p < 0.001; for 15-29 mL/min/1.73 m2, OR = 4.96, p < 0.001). Intraoperative factors include prolonged operative time (for ≥1 SD above the mean, OR = 1.68, p = 0.002; for ≥2SD above the mean, OR = 2.76, p < 0.001) and intraoperative transfusion (OR = 2.44, p < 0.001).

CONCLUSIONS

Patients with a history of obesity, chronic kidney disease, cardiovascular history, diabetes, and hypoalbuminemia are at increased risk for AKI when undergoing OVHR. Intraoperative variables such as prolonged operative times and blood transfusions may also suggest increased risk. Preoperative identification of patients with these characteristics and perioperative hemodynamic stabilization are important first steps to minimize this complication.

Risk factors for acute kidney injury in older adults with critical illness: a retrospective cohort study

BACKGROUND

Risk for acute kidney injury (AKI) in older adults has not been evaluated systematically. We sought to delineate the determinants of risk for AKI in older compared with younger adults.

STUDY DESIGN

Retrospective analysis of patients hospitalized in July 2000 to September 2008.

SETTING & PARTICIPANTS

We identified all adult patients admitted to an intensive care unit (n=45,655) in a large tertiary-care university hospital system. We excluded patients receiving dialysis or a kidney transplant prior to hospital admission and patients with baseline creatinine levels ≥ 4mg/dL, liver transplantation, indeterminate AKI status, or unknown age, leaving 39,938 patients.

PREDICTOR

We collected data for multiple susceptibilities and exposures, including age, sex, race, body mass, comorbid conditions, severity of illness, baseline kidney function, sepsis, and shock.

OUTCOMES

We defined AKI according to KDIGO (Kidney Disease: Improving Global Outcomes) criteria. We examined susceptibilities and exposures across age strata for impact on the development of AKI.

MEASUREMENTS

We calculated area under the receiver operating characteristic curve (AUC) for prediction of AKI across age groups.

RESULTS

25,230 (63.2%) patients were 55 years or older. Overall, 25,120 (62.9%) patients developed AKI (69.2% aged ≥55 years). Examples of risk factors for AKI in the oldest age category (≥75 years) were drugs (vancomycin, aminoglycosides, and nonsteroidal anti-inflammatories), history of hypertension (OR, 1.13; 95% CI, 1.02-1.25), and sepsis (OR, 2.12; 95% CI, 1.68-2.67). Fewer variables remained predictive of AKI as age increased and the model for older patients was less predictive (P<0.001). For the age categories 18 to 54, 55 to 64, 65 to 74, and 75 years or older, AUCs were 0.744 (95% CI, 0.735-0.752), 0.714 (95% CI, 0.702-0.726), 0.706 (95% CI, 0.693-0.718), and 0.673 (95% CI, 0.661-0.685), respectively.

LIMITATIONS

Analysis may not apply to non-intensive care unit patients.

CONCLUSIONS

The likelihood of developing AKI increases with age; however, the same variables are less predictive for AKI as age increases. Efforts to quantify risk for AKI may be more difficult in older adults.

Incidence of acute kidney injury following total joint arthroplasty: a retrospective review by RIFLE criteria

Background

Total joint arthroplasty (TJA) is a common procedure with demand for arthroplasties expected to increase exponentially. Incidence of acute kidney injury (AKI) following TJA is reportedly low, with most studies finding an incidence of <2%, increasing to 9% when emergency orthopaedic patients are included.

Methods

Retrospective medical record review of consecutive primary, elective TJA procedures was undertaken at a large tertiary hospital (Alfred). Demographic, peri-operative and post-operative data were recorded. Factors associated with AKI (based on RIFLE criteria) were determined using multiple logistic regression.

Results

Between January 2011 and June 2013, 425 patients underwent TJA; 252 total knee replacements (TKR) and 173 total hip replacements (THR). Sixty-seven patients (14.8%) developed AKI, including 51 TKR. Factors associated with AKI (adjusting for known confounders) include increasing body mass index [adjusted odds ratio (AOR) 1.14; 95% CI: 1.07, 1.21], older age (AOR 1.07; 95% CI 1.02, 1.13) and lower pre-operative glomerular filtration rate (AOR 0.97; 95% CI 0.96, 0.99) and taking angiotensin-converting enzyme inhibitors (AOR 2.70; 95% CI 1.12, 6.48) and angiotensin-II receptor blockers (AOR 2.64; 95% CI 1.18, 5.93). In most patients, AKI resolved by discharge, however, only 62% of patients had renal function tests after discharge.

Conclusions

This study showed a rate of AKI of nearly 15% in our TJA population, substantially higher than previously reported. Given that AKI and long-term complications are associated, prospective research is needed to further understand the associated factors and predict those at risk of AKI. There may be opportunities to maximize the pre-operative medical management and mitigate risk.