Sex disparities in the risk of urgent dialysis following acute aortic dissections in Japan

The global outcome of acute aortic dissection (AD) remains poor, with a high risk of the need for urgent dialysis. This study aimed to clarify the association between sex and the requirement for urgent dialysis within 30 days after admission among patients with AD. This study included 79,998 cases who were hospitalized due to AD in Japan from 2010 to 2020 using an administrative claims database. The association between the risk of urgent dialysis and sex was investigated using the Fine and Gray model. Patients were classified into two groups based on the Stanford classification: type A AD (TAAD) and type B AD (TBAD). The lower subdistribution hazard ratio (SHR) in women was observed in both groups: TAAD (SHR: 0.58, 95% confidence interval [CI]: 0.54-0.62); TBAD (SHR: 0.49, 95% CI: 0.41-0.58). Our study revealed that women had a lower risk of requiring urgent dialysis than men in TAAD and TBAD.

Perioperative acute kidney injury: Current knowledge and the role of anaesthesiologists

Background

Among the different types of perioperative organ injury, acute kidney injury (AKI) occurs frequently and is consistently associated with increased rates of mortality and mortality. Despite development of many clinical trials to assess perioperative interventions, reliable means to prevent or reverse AKI are still lacking.

Objectives

This narrative review discusses recent literature on modifiable risk factors, current approaches to prevention and potential directions for future research.

Methods

A Pubmed search with the relevant keywords was done for articles published in the last 10 years.

Results

New insights into preoperative identification and optimisation, intraoperative strategies, including the choice of anaesthetic, haemodynamic and fluid management, have been made, with the aim of preventing perioperative AKI.

Conclusion

A patient-centric multidisciplinary approach is essential to protect kidney function of patients going for surgery. Much can be done by anaesthesiologists perioperatively, to reduce the risk of development of AKI, especially in susceptible patients. There is a need for further multicentred trials to enhance the currently generic perioperative recommendations.

Molecular hydrogen: prospective treatment strategy of kidney damage after cardiac surgery

Cardiac surgery-associated acute kidney injury is a common post-operative complication, mostly due to increasing oxidative stress. Recently, molecular hydrogen (H2 gas) has also been applied to cardiac surgery due to its ability to reduce oxidative stress. We evaluated the potential effect of H2 application on the kidney in an in vivo model of simulated heart transplantation. Pigs underwent cardiac surgery within 3 h while connected to extracorporeal circulation (ECC) and subsequent 60 min of spontaneous reperfusion of the heart. We used two experimental groups: T-pigs after transplantation and TH-pigs after transplantation treated with 4% H2 mixed with air during inhalation of anesthesia and throughout oxygenation of blood in ECC. The levels of creatinine, urea and phosphorus were measured in plasma. Renal tissue samples were analyzed by Western blot method for protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap-1), and superoxide dismutase (SOD1). After cardiac surgery, selected plasma biomarkers were elevated. However, H2 therapy was followed by the normalization of all these parameters. Our results suggest activation of Nrf2/Keap1 pathway as well as increased SOD1 protein expression in the group treated with H2. The administration of H2 had a protective effect on the kidneys of pigs after cardiac surgery, especially in terms of normalization of plasma biomarkers to control levels.

Kidney Injury after Cardiac Surgery: Prevention-Associated Cost Reduction

INTRODUCTION

Cardiac surgery may induce acute kidney injury and the need for renal replacement therapy. It is also associated with higher hospital costs, morbidity and mortality. The aims of this study were to investigate predictors of cardiac surgery associated acute kidney injury in our population and to determine the burden of acute kidney injury in elective cardiac surgery, evaluating the potential cost effectiveness of preventing it through the application of the Kidney Disease: Improving Global Outcomes bundle of care to high-risk patient groups identified by the [TIMP-2]x[IGFBP7] used as a screening test.

MATERIAL AND METHODS

In a University Hospital single-center retrospective cohort study we analyzed a consecutive sample of adults who underwent elective cardiac surgery between January and March 2015. A total of 276 patients were admitted during the study period. Data from all patients was analyzed until hospital discharge or the patient's death. The economic analysis was performed from the hospital costs' perspective.

RESULTS

Cardiac surgery associated acute kidney injury occurred in 86 patients (31%). After adjustment, higher preoperative serum creatinine (mg/L, ORadj = 1.09; 95% CI: 1.01 - 1.17), lower preoperative hemoglobin (g/dL, ORadj = 0.79; 95% CI: 0.67 - 0.94), chronic systemic hypertension (ORadj = 5.00; 95% CI: 1.67 - 15.02), an increase in cardiopulmonary bypass time (min, ORadj = 1.01; 95% CI: 1.00 - 1.01) and perioperative use of sodium nitroprusside (ORadj = 6.33; 95% CI: 1.80 - 22.28) remained significantly associated with cardiac surgery related acute kidney injury. The expected cumulative surplus cost for the hospital linked with cardiac surgery associated acute kidney injury (86 patients) was €120 695.84. Based on a median absolute risk reduction of 16.6%, by dosing kidney damage biomarkers in every patient and using preventive measures in high-risk patients, we would expect a break-even point upon screening 78 patients, which would translate, in our patient cohort, into an overall cost benefit of €7145.

CONCLUSION

Preoperative hemoglobin, serum creatinine, systemic hypertension, cardiopulmonary bypass time and perioperative use of sodium nitroprusside were independent predictors of cardiac surgery associated acute kidney injury. Our cost-effectiveness modelling suggests that the use of kidney structural damage biomarkers combined with an early prevention strategy could be associated with potential cost savings.

Expression and Significance of KIM-1, NGAL, and HO-1 in Patients with Acute Kidney Injury After Cardiac Valve Replacement

Objective

To investigate the changes and significance of perioperative expression levels of kidney injury molecule-1 (KIM-1), neutrophil gelatinase-related lipocalin (NGAL), and heme oxygenase-1 (HO-1) in patients with acute kidney injury (AKI) after cardiac valve replacement under cardiopulmonary bypass.

Methods

A total of 80 patients were divided into the AKI group and non-AKI group based on the postoperative occurrence of AKI. The expression levels of urinary KIM-1, NGAL, serum creatinine, urea nitrogen, and HO-1 were compared between the two groups before surgery and at 12 h, 24 h, and 48 h after surgery.

Results

There were 22 patients with postoperative AKI (AKI group), the incidence of postoperative AKI were 27.5%, and there were 58 patients without AKI (non-AKI group). There was no significant difference in general clinical data between the two groups (P > 0.05). Compared between AKI group and preoperative group, KIM-1, NGAL, HO-1, blood creatinine, and BUN levels were significantly increased, with significant differences (P < 0.05). Compared with non-AKI groups, KIM-1, NGAL, HO-1, blood creatinine, and blood urea nitrogen levels increased at all time points, but the difference was not significant (P > 0.05). Compared with AKI group and non-AKI group, KIM-1, NGAL, HO-1, blood creatinine, and BUN levels increased significantly, the differences were statistically significant (P < 0.05).

Conclusion

AKI can easily occur after cardiac valve replacement and postoperative expression levels of KIM-1, NGAL, and HO-1 can be early warning indicators of postoperative AKI.

Multicentre evaluation of renal impairment in thoracic surgery (MERITS): a retrospective cohort study

OBJECTIVES

To measure the unit-level variation in Acute Kidney Injury (AKI) incidence post-thoracic surgery over a contemporary 1-year period. Secondary aims include examining the associations with sex, age group, operation type, length of stay and mortality.

DESIGN

A multicentre, observational, retrospective study in thoracic surgery.

SETTING

17 of 35 Society for Cardiothoracic Surgery of Great Britain and Ireland (SCTS) units participated. The student wing, known as SCTS STUDENTS, supported data collection.

PARTICIPANTS

Overall, 15 229 patients were collected of which 15 154 were included for analysis after exclusions. All patients (age≥18 years) undergoing any thoracic surgery from 1 April 2016 to 31 March 2017 were included. For analysis, we excluded patients with preoperative end-stage renal failure and those with incomplete data.

MAIN OUTCOME MEASURES

The primary outcome is the incidence of AKI within 7 days of the procedure or discharge date if earlier. Secondary outcomes include assessing associations with patient demographics (age, sex), type of procedure (open and minimally invasive), length of stay and mortality.

RESULTS

Out of 15 154 patients AKI was diagnosed in 1090 patients (7.2%) within 7 days of surgery with AKI stage 1 (4.8%), stage 2 (1.7%) and stage 3 (0.7%). There was a statistically significant variation in AKI incidence between units from 3.1 to 16.1% (p<0.05). Significant differences between AKI and non-AKI were found in post-operative length of stay (7 vs 3 days, p<0.001), 30-day mortality (9 vs 1.6%, p<0.001), 90-day mortality (14.7 vs 4.4%, p<0.001) and 1-year mortality (23.1 vs 12.2 %, p<0.001).

CONCLUSIONS

Following thoracic surgery, AKI incidence ranged from 3.1% to 16.1% between units (p<0.05) with associations between AKI and both length of stay and mortality. We propose AKI as a suitable comparative and absolute quality measure in thoracic surgery. Reducing rates of AKI may improve patient outcomes, length of stay and reduce costs.

Age, body mass index, and diabetes mellitus are associated with an increased risk of acute kidney injury after coronary surgery: Retrospective cohort study

Background/Aim: Cardiac surgery-associated acute kidney injury (CSA-AKI) is a significant complication of cardiac surgery and is associated with increased morbidity and mortality. Identifying risk factors can help clinicians alleviate the risk of developing CSA-AKI and associated complications. Therefore, this study aimed to identify pre-operative patient-related risk factors of CSA-AKI in patients undergoing coronary surgery. Methods: The current study was a single-center retrospective cohort study of adult patients undergoing coronary surgery with cardiopulmonary bypass (CPB) over an 8-month period. AKI was scored according to The Kidney Disease Improving Global Outcomes (KDIGO) scoring system. Patients’ age, gender, body mass index (BMI), comorbidities, KDIGO staging in AKI patients, and 30-day mortality rates were recorded. These variables were compared between AKI(−) and AKI (+) groups. Univariate binary regression analysis was performed between the variables that had statistically significant differences and AKI. Results: A total of 248 coronary surgery patients were analyzed. The overall incidence of CSA-AKI was 16.5%. Age, BMI, and the proportion of diabetic patients were significantly higher in the AKI (+) group (P = 0.04, P < 0.001, and P = 0.022, respectively). The proportion of gender, chronic obstructive pulmonary disease (COPD), hypertension (HT), baseline creatinine levels, aortic cross-clamping, cardiopulmonary bypass (CPB), total operation duration, and 30-day mortality were similar between the groups. Univariate analysis demonstrated that CSA-AKI was significantly associated with age ³ 65 years (odds ratio [OR] = 2.506; confidence interval [CI]: 1.265–4.967; P = 0.008), BMI of ³ 25 kg m-2 (OR = 8.994; CI: 1.199–67.980; P = 0.033), and diabetes mellitus (OR = 2.171; CI: 1.103–4.273; P = 0.025). Conclusion: The current study revealed that patients with increased age, BMI, and DM had a higher incidence of CSA-AKI. Therefore, even though these patient-related variables are known as non-modifiable parameters, more attention should be paid to preventing CSA-AKI during peri-operative management of these patients.

Intraoperative evaluation of renal resistive index with transesophageal echocardiography for the assessment of acute renal injury in patients undergoing coronary artery bypass grafting surgery: A prospective observational study

Background

Acute kidney injury (AKI) is a common complication after on pump coronary artery bypass grafting (CABG) surgery and is associated with a poor prognosis. Postoperative AKI is associated with morbidity, mortality, and increase in length of intensive care unit (ICU) stay and increases the financial burden. Identifying individuals at risk for developing AKI in postoperative period is extremely important to optimize outcomes. The aim of the study is to evaluate the association between the intraoperative transesophageal echocardiography (TEE) derived renal resistive index (RRI) and AKI in patients undergoing on-pump CABG surgery.

Methods

This prospective observational study was conducted in patients more than 18 years of age undergoing elective on pump CABG surgery between July 1, 2018, and December 31, 2019, at a tertiary care center. All preoperative, intraoperative, and postoperative parameters were recorded. TEE measurement was performed in hemodynamically stable patients before the sternum was opened. Postoperative AKI was diagnosed based on the serial measurement of serum creatinine and the monitoring of urine output.

Results

A total of 115 patients were included in our study. Thirty-nine (33.91%) patients had RRI >0.7 while remaining seventy-six (66.08%) patients had RRI <0.7. AKI was diagnosed in 26% (30/115) patients. AKI rates were significantly higher in patients with RRI values exceeding 0.7 with 46.15% (18/39) compared to 15.75% (12/76) in RRI values of less than 0.7. Multivariate analysis revealed that AKI was associated with an increase in RRI and diabetes mellitus. The RRI assessed by receiver operating characteristic (ROC) curve and the area under the curve (AUC) to distinguish between non-AKI and AKI groups were 0.705 (95% CI: 0.588-0.826) for preoperative RRI. The most accurate cut-off value to distinguish non-AKI and AKI groups was a preoperative RRI of 0.68 with a sensitivity of 70% and specificity of 67%.

Conclusions

An increased intraoperative RRI is an independent predictor of AKI in the postoperative period in patients undergoing CABG surgery. The cutoff value of TEE-derived RRI in the intraoperative period should be >0.68 to predict AKI in the postoperative period.

Perioperative renal protection

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a common but underestimated syndrome in the perioperative setting. AKI can be induced by different causes and is associated with increased morbidity and mortality. Unfortunately, no specific treatment options are available at the moment.

RECENT FINDINGS

AKI is now understood as being a continuum ranging from normal kidney function over AKI and acute kidney disease to ultimately chronic kidney disease. The KDIGO organization recommend in 2012 implementation of preventive bundles in patients at high risk for AKI. In the perioperative setting, relevant measures include hemodynamic optimization, with careful consideration of blood pressure targets, adequate fluid therapy to maintain organ perfusion and avoidance of hyperglycaemia. These measures are most effective if patients at risk are identified as soon as possible and measures are implemented accordingly. Although current point of care functional biomarkers can detect patients at risk earlier than the established damage biomarkers, some components of the preventive bundle are still under investigation.

SUMMARY

Good evidence exists for the use of biomarkers to identify individual patients at risk for AKI and for the implementation of haemodynamic optimization, abdication of nephrotoxins, adequate fluid administration using balanced crystalloid solutions and glycaemic control. The data for using colloids or the degree of nephrotoxicity of contrast media still remain inconclusive.

Acute kidney injury in patients with acute coronary syndrome after percutaneous coronary intervention: pathophysiologies, risk factors and preventive measures

Background: Percutaneous coronary intervention (PCI) has been an effective treatment for acute coronary syndrome (ACS) patients. Acute kidney injury (AKI) is one of the common complications after PCI, which seriously affects the living quality and survival time of patients. The approach followed for the patient with AKI after PCI depends on the clinical context and may vary by resource availability. Summary: This review focuses on the pathophysiologies, influencing factors, and preventive measures of AKI in patients with ACS after PCI. The knowledge may better serve the patients and improve their outcomes. Key Messages: Many studies have been carried out for the definition and standard of AKI in the past few years. Etiologies of AKI after PCI included renal damage of contrast medium and atherosclerotic embolism, cardiac insufficiency and surgical factors on renal function. Basic conditions, treatment modalities, and perioperative changes are major risk factors of AKI. Studies have reported that the prevention of contrast-induced nephropathy, modulating the volume overload, some pharmaceuticals and blood purification treatment are helpful to prevent the occurrence of AKI.

Rationale and Design of Assessing the Effectiveness of Short-Term Low-Dose Lithium Therapy in Averting Cardiac Surgery-Associated Acute Kidney Injury: A Randomized, Double Blinded, Placebo Controlled Pilot Trial

Background: Burgeoning pre-clinical evidence suggests that therapeutic targeting of glycogen synthase kinase 3β (GSK3β), a convergence point of multiple cellular protective signaling pathways, confers a beneficial effect on acute kidney injury (AKI) in experimental models. However, it remains unknown if GSK3β inhibition likewise mitigates AKI in humans. Cardiac surgery associated acute kidney injury (CSA-AKI) poses a significant challenge for clinicians and currently the only treatment available is general supportive measures. Lithium, an FDA approved mood stabilizer, is the best-known GSK3β inhibitor and has been safely used for over half a century as the first line regimen to treat bipolar affective disorders. This study attempts to examine the effectiveness of short term low dose lithium on CSA-AKI in human patients.

Methods/Design: This is a single center, prospective, randomized, double blinded, placebo controlled pilot study on patients undergoing cardiac surgery with cardiopulmonary bypass. Patients will be randomized to receive a small dose of lithium or placebo treatment for three consecutive days. Renal function will be measured via creatinine as well as novel AKI biomarkers. The primary outcome is incidence of AKI according to Acute Kidney Injury Network (AKIN) criteria, and secondary outcomes include receipt of new dialysis, days on dialysis, days on mechanical ventilation, infections within 1 month of surgery, and death within 90 days of surgery.

Discussion: As a standard selective inhibitor of GSK3β, lithium has been shown to exert a beneficial effect on tissue repair and regeneration upon acute injury in multiple organ systems, including the central nervous system and hematopoietic system. In experimental AKI, lithium at small doses is able to ameliorate AKI and promote kidney repair. Successful completion of this study will help to assess the effectiveness of lithium in CSA-AKI and could potentially pave the way for large-scale randomized trials to thoroughly evaluate the efficacy of this novel regimen for preventing AKI after cardiac surgery.

Trial Registration: This study was registered prospectively on the 17th February 2017 at ClinicalTrials.gov (NCT03056248, https://clinicaltrials.gov/ct2/show/NCT03056248?term=NCT03056248&draw=2&rank=1).

How new biomarkers aid the anesthetist to detect and prevent perioperative acute kidney injury

PURPOSE OF REVIEW

Acute kidney injury (AKI) is underestimated but common in the perioperative setting. Although the association of this syndrome with an increased morbidity and mortality has been well established, little progress has been made in the diagnosis or prevention of AKI in recent years. This is partly due to the late detection of AKI by conventional criteria based of functional biomarkers, serum creatinine, and urine output. In addition, conceptually AKI is now recognized as being part of a continuum, in which preventive intervention is time critical. This review will summarize the current best available evidence and explain why timely perioperative management does have impact on the development of AKI and overall outcomes for patients.

RECENT FINDINGS

Damage biomarkers can reliably identify AKI earlier than conventional functional biomarkers, facilitating more timely preventive intervention. Although the interventions published in the Kidney Disease: Improving Global Outcomes guideline are all important, the most relevant preventive options perioperatively include maintenance of adequate volume status and perfusion pressure, and the focus on balanced crystalloid solutions as maintenance fluid.

SUMMARY

AKI is a time critical syndrome that requires timely detection and damage biomarkers can help to adjust the perioperative management to prevent further injury.

Total arch replacement in patients with chronic kidney disease

BACKGROUND

We investigated the effect of preoperative renal dysfunction on postoperative outcomes in patients undergoing elective isolated total arch replacement (TAR) with mild hypothermic lower body circulatory arrest with antegrade selective cerebral perfusion (SCP).

METHODS

One hundred and forty-four patients who had undergone elective isolated TAR between January 2002 and December 2019 were retrospectively analyzed. Patients were divided into two groups according to whether their preoperative estimated glomerular filtration rate (eGFR) was lower than or higher than 60 ml/min/1.73 m² . We compared perioperative data and mid-term outcomes after adjusting for patients' baseline characteristics using weighted logistic regression analysis and inverse probability of treatment weighting.

RESULTS

More patients underwent postoperative stroke in the chronic kidney disease group compared with the normal group (2.8% vs. 0%, respectively; p = .049). Overall 30-day mortality and hospital mortality were 0% in both groups, and there was no significant difference in overall survival between the two groups (log-rank test, p = .129). Multivariate Cox proportional hazard analysis showed that eGFR < 60 ml/min/1.73 m² was not an independent predictor (hazard ratio: 1.636, 95% confidence interval 0.829-3.231; p = .156).

CONCLUSIONS

Preoperative eGFR <60 ml/min/1.73 m² was not associated with worse outcomes after elective isolated TAR with mild hypothermic lower body circulatory arrest with antegrade SCP.

Renal Impairment After Cardiac Surgery: Risk Factors, Outcome and Cost Effectiveness

Introduction Acute kidney injury (AKI) is considered one of the serious complications in the medical field. It has a large impact on patients' life medically, socially and economically. It also has a financial burden on governments and hospitals regardless of which part of the world is considered. On the other hand, AKI is a common complication of cardiac surgery, which alone has a tremendous burden and implications on patients and governments. In this study, we will discuss the various risk factors, outcomes and financial burden of renal impairment associated with cardiac surgery. Methods This is a retrospective case-control study, which included 144 adult patients who underwent open cardiac surgical procedures at King Fahad University Hospital in the Eastern Province of Saudi Arabia over a period of five years from January 2015 till the end of December 2019. We included all types of cardiac surgeries performed such as coronary artery bypass grafting (CABG), valve surgery and aortic dissection repair and excluded patients with end-stage renal disease (ESRD) requiring dialysis preoperatively and pediatric patients. Two control groups were defined, those who developed renal impairment (group A) and those who did not develop it (group B). Results The mean age of the patients was 58.59 ± 12.6 years (range: 42 to 77 years). Mean serum creatinine level in the postoperative period was 1.95 ± 1.5 mg/dL in group A compared to group B of 1.0 ± 0.32 mg/dL (P-value<0.01). Mean serum blood urea nitrogen (BUN) in group A was 26.45 ± 19.9 mg/dL compared to group B of 16.79 ± 16.2 mg/dL in group B (P-value < 0.01). Diabetic were more likely to develop renal impairment than non-diabetic (P-value = 0.049, OR 2.73; 95% CI: 0.97-7.66). Obese patients were two times more likely to develop renal impairment than non-obese (P-value = 0.056, OR 2.6; 95% CI: 0.94-7.1). The average cost for each patient with renal impairment who required dialysis was 110,000 Saudi Riyal (~ 29,000 $) compared to other patients. Conclusion Serum creatinine, BUN, diabetes and obesity are strong indicators in developing AKI in cardiac surgery. In addition, the financial burden was almost doubled in patients developing AKI.

[Surgical treatment of infective endocarditis: Surgical indications, complications, intrahospital and long-term mortality]

BACKGROUND

In addition to medical treatment, half of the patients with infective endocarditis (IE) receive surgical treatment. Despite clear recommendations on the indications and the operating delays, the decision remains difficult and must take into consideration several factors.

METHODS

A retrospective study was performed at Foch Hospital. All patients operated for IE between 2005 and 2018 were included. Patient characteristics, indications and operating delays, as well as intrahospital mortality, were noted. Patient follow-up was provided by phone calls.

RESULTS

Fifty-two patients were operated on for IE between 2005 and 2018. The most frequent surgical indications were the presence of a massive symptomatic regurgitation, an uncontrolled infection and large vegetations with embolism. The average operative delay was 13.2 days with 56.5% of patients operated within the first 10 days. The most common postoperative complications were acute kidney injury (AKI) in 57.7% of cases, with 9.6% of dialysis, shock in 50% of cases, rhythm disorders in 40.4% of cases, infectious complications in 19.2% of cases, conductive disorders in 25% of cases, of which 17.3% require a definitive pacemaker implementation. The intrahospital mortality was 7.7% and the average length of hospital stay was 35 days. Survival at one year and 5 years was 95% and 85%, respectively.

CONCLUSION

The indications and the operating delays were conformed to international recommendations. Intrahospital and long-term mortality rate was low.

A Novel Patient-Specific Model for Predicting Severe Oliguria; Development and Comparison With Kidney Disease: Improving Global Outcomes Acute Kidney Injury Classification

OBJECTIVES

The Kidney Disease: Improving Global Outcomes urine output criteria for acute kidney injury lack specificity for identifying patients at risk of adverse renal outcomes. The objective was to develop a model that analyses hourly urine output values in real time to identify those at risk of developing severe oliguria.

DESIGN

This was a retrospective cohort study utilizing prospectively collected data.

SETTING

A cardiac ICU in the United Kingdom.

PATIENTS

Patients undergoing cardiac surgery between January 2013 and November 2017.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Patients were randomly assigned to development (n = 981) and validation (n = 2,389) datasets. A patient-specific, dynamic Bayesian model was developed to predict future urine output on an hourly basis. Model discrimination and calibration for predicting severe oliguria (< 0.3 mL/kg/hr for 6 hr) occurring within the next 12 hours were tested in the validation dataset at multiple time points. Patients with a high risk of severe oliguria (p > 0.8) were identified and their outcomes were compared with those for low-risk patients and for patients who met the Kidney Disease: Improving Global Outcomes urine output criterion for acute kidney injury. Model discrimination was excellent at all time points (area under the curve > 0.9 for all). Calibration of the model's predictions was also excellent. After adjustment using multivariable logistic regression, patients in the high-risk group were more likely to require renal replacement therapy (odds ratio, 10.4; 95% CI, 5.9-18.1), suffer prolonged hospital stay (odds ratio, 4.4; 95% CI, 3.0-6.4), and die in hospital (odds ratio, 6.4; 95% CI, 2.8-14.0) (p < 0.001 for all). Outcomes for those identified as high risk by the model were significantly worse than for patients who met the Kidney Disease: Improving Global Outcomes urine output criterion.

CONCLUSIONS

This novel, patient-specific model identifies patients at increased risk of severe oliguria. Classification according to model predictions outperformed the Kidney Disease: Improving Global Outcomes urine output criterion. As the new model identifies patients at risk before severe oliguria develops it could potentially facilitate intervention to improve patient outcomes.

Risk factor for acute kidney injury in patients with chronic kidney disease receiving valve surgery with cardiopulmonary bypass

INTRODUCTION

Acute kidney injury (AKI) after cardiopulmonary bypass (CPB) in patients with pre-existing impaired renal function carries deleterious outcomes but is not frequently evaluated. The optimal CPB strategy for preventing AKI in this vulnerable patient group is still controversial.

METHODS

A total of 156 patients with preoperative estimated glomerular filtration rate (e-GFR) <30 ml/min but not on chronic dialysis receiving valve operation under CPB were included in the present study. Postoperative AKI was defined as KDIGO (Kidney Disease Improving Global Outcomes) stage 3. Hospital mortality and two-year renal function evolution were compared between patients with postoperative AKI and those without AKI. Risk factors for the development of postoperative AKI were also studied.

RESULTS

The incidence of postoperative KDIGO-3 was high (44.2%). Hospital mortality was higher in the AKI group (30.4%) than in the non-AKI group (8.0%). Among the hospital survivors, renal function deterioration to permanent dialysis at two years was also more common in AKI group (14.5%) than in non-AKI group (4.6%). Univariate logistic regression for postoperative AKI revealed male gender, increased age, height, weight, BSA, and BMI, high preoperative serum creatinine, prolonged CPB duration, and decreased CPB target temperature as risk factors. However, multivariate analysis revealed only high preoperative serum creatinine and decreased CPB target temperature as significant risk factors for postoperative AKI.

CONCLUSION

To prevent postoperative AKI in CKD patients, low CPB target temperature is avoided, especially for those with high preoperative serum creatinine levels.

Predicting Acute Kidney Injury After Cardiac Surgery Using a Simpler Model

OBJECTIVE

To develop a simple model for the prediction of acute kidney injury (AKI) and renal replacement therapy (RRT) that could be used in clinical or research risk stratification.

DESIGN

Retrospective analysis.

SETTING

Multi-institutional.

PARTICIPANTS

All cardiac surgery patients from September 2016 to December 2018.

INTERVENTIONS

Observational.

MEASUREMENTS AND MAIN RESULTS

The study cohort was divided into a development set (75%) and validation set (25%). The following 2 data epochs were used: preoperative data and immediate postoperative data (within 4 h of intensive care unit admission). Univariate statistics were used to identify variables associated with AKI or RRT. Stepwise logistic regression was used to develop a parsimonious model. Model discrimination and calibration were evaluated in the test set. Models were compared with previously published models and with a more comprehensive model developed using the least absolute shrinkage and selection operator. The study included 22,731 patients at 33 hospitals. The incidences of AKI (any stage) and RRT for the present analysis were 5,829 patients (25.6%) and 488 patients (2.1%), respectively. Models were developed for AKI, with an area under the receiver operating curve (AU-ROC) of 0.67 and 0.69 preoperatively and postoperatively, respectively. Models for RRT had an AU-ROC of 0.77 and 0.80 preoperatively and postoperatively, respectively. These models contained between 3 and 5 variables. Comparatively, comprehensive least absolute shrinkage and selection operator models contained between 21 and 26 variables, with an AU-ROC of 0.71 and 0.72 for AKI and 0.84 and 0.87 for RRT respectively.

CONCLUSION

In the present study, simple, clinically applicable models for predicting AKI and RRT preoperatively and immediate postoperatively were developed. Even though AKI prediction remained poor, RRT prediction was good with a parsimonious model.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Transesophageal Echocardiography, Acute Kidney Injury, and Length of Hospitalization Among Adults Undergoing Coronary Artery Bypass Graft Surgery

OBJECTIVE

To test the association between transesophageal echocardiography (TEE) and incidence of acute kidney injury and length of hospitalization among United States adults undergoing isolated coronary artery bypass graft (CABG) surgery.

DESIGN

This was an observational, retrospective cohort analysis.

SETTING

This study used a multicenter claims dataset from a commercially insured population undergoing CABG surgery in the United States between 2004 and 2016.

PARTICIPANTS

Adults aged 18 years or older with continuous insurance enrollment and an absence of renal-related diagnoses before the index CABG surgery.

INTERVENTIONS

Receipt of TEE within 1 calendar day of the index CABG surgery date.

MEASUREMENTS AND MAIN RESULTS

Of 51,487 CABG surgeries, 5,361 (10.4%; [95% confidence interval [CI]: 10.1-10.7%]) developed acute kidney injury and the mean length of hospitalization was 8.8 days (95% CI: 8.7-8.8). The TEE group demonstrated a greater absolute risk difference (RD) for acute kidney injury by multiple linear regression, overall, (RD=+1.0; [95% CI: 0.4-1.5%]; p < 0.001) and among a low-risk subgroup (RD=+1.0; [95% CI: 0.4-1.6; p = 0.002), but not by instrumental variable analysis (RD=+0.9 [95% CI: -1.1 to 2.9%]; p = 0.362). The TEE group demonstrated a longer length of hospitalization by multiple linear regression, overall (+2.0%; [95% CI: 1.1-2.9%]; p < 0.001), among a low-risk subgroup (+2.2%; [95% CI: 1.2-3.2%]; p < 0.001), and by instrumental variable analysis (+10.3%; [95% CI: 7.0-13.7%]; p < 0.001).

CONCLUSIONS

TEE monitoring in CABG surgery was not associated with a lower incidence of acute kidney injury or decreased length of hospitalization. These findings highlight the importance of additional work to study the clinical effectiveness of TEE in CABG surgery.

Secular Trends in Incidence, Modality and Mortality with Dialysis Receiving AKI in Children in Ontario: A Population-Based Cohort Study

BACKGROUND AND OBJECTIVES

There is a limited appreciation of the epidemiology of dialysis-receiving AKI in children. The primary objective of the study was to evaluate changes in the incidence of dialysis-receiving AKI among children over a period of 20 years in Ontario, Canada. The secondary objectives were to assess temporal trends in the utilization of various dialysis modalities and 30-day mortality among children with dialysis-receiving AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All children (29 days to 18 years) who received their first dialysis for AKI between 1996 and 2015 were identified from healthcare administrative databases. Those who received dialysis for ESKD, inborn errors of metabolism, and poisonings were excluded. The incidence rates of dialysis-receiving AKI were reported annually. The Cochran-Armitage test was used to assess trends in the incidence and short-term mortality after dialysis-receiving AKI.

RESULTS

We identified 1394 children treated with dialysis for AKI during a hospital stay. There was a significant increase in the incidence of dialysis-receiving AKI among hospitalized children from 1996 (0.58 per 1000 person-years) to 2015 (0.65 per 1000 person-years) (P=0.01). The use of continuous kidney replacement therapy and intermittent hemodialysis increased whereas the relative use of peritoneal dialysis declined over time. Thirty-day mortality rates after dialysis-receiving AKI increased from 14% to 25% between 1996 and 2009 and reduced to 19% in the more recent years (P=0.03).

CONCLUSIONS

In Ontario, the incidence of dialysis-receiving AKI among children has increased between 1996 and 2015. The use of peritoneal dialysis for AKI has declined and the short-term mortality after dialysis-receiving AKI has increased.

Valvular Heart Disease in Patients ≥80 Years of Age

In the United States, the octogenarian population is projected to triple by 2050. With this aging population, the prevalence of valvular heart disease (VHD) is on the rise. The etiology, approach to treatment, and expected outcomes of VHD are different in the elderly compared with younger patients. Both stenotic and regurgitant lesions are associated with unfavorable outcomes if left untreated. Surgical mortality remains high due to multiple co-morbidities, and long-term survival benefit is dependent on many variables including valvular pathology. Quality of life is an important consideration in treatment decisions in this age group. Increasingly, octogenarian patients are receiving transcatheter therapies, with transcatheter aortic valve replacement having the greatest momentum. Numerous transcatheter devices for management of other valve lesions are currently in early clinical trials. This review will describe the epidemiology, etiology, diagnosis, and therapeutic options for VHD in the oldest old, with a focus on transcatheter technologies.

The correlation of post-operative acute kidney injury and perioperative anaemia in patients undergoing cardiac surgery with cardiopulmonary bypass

Background and objective

Acute kidney injury (AKI) following cardiac surgery with cardiopulmonary bypass (CPB) is polyethiological clinical syndrome. During CPB haemodilution develops, which is useful in reducing the risk of thrombosis; however, haemodilutional anaemia decreases oxygen transfer and provokes tissue hypoxia, which can lead to acute organ damage. The aim of the study was to find out the impact of perioperative anaemia on AKI after cardiac surgery with CPB.

Materials and methods

This prospective study included 58 adult patients undergoing elective cardiac surgery with CPB, without any preoperative chronic renal disease or any systemic autoimmune disease. Serum concentrations of NGAL had been tested before the surgery, 2 hours, 6 hours, and one day after the surgery. Perioperative anaemia was assessed according to the Ht value before the surgery, the Ht value during CPB, and immediately after the surgery.

Results

The rate of haemodilutional anaemia is 77.59% in this study. The average of serum NGAL concentration before CPB was 63.95 ± 33.25 ng/mL and it was significantly lower than the average concentration 2 hours after the surgery, 6 hours after the surgery and one day after the surgery (respectively 148.51 ± 62.39, 119.44 ± 55, 128.70 ± 59.04 ng/mL, p < 0.05). AKI developed in 46.55% of the patients. A significant positive reasonable correlation between the development of perioperative anaemia and AKI was determined (r = 0.50, p < 0.05).

Conclusions

Post-operative AKI after cardiac surgery with CPB has a moderate positive correlation with perioperative haemodilutional anaemia. A longer CPB time and aortic cross-clamping time were found to be the risk factors for the development of AKI.

Meta-Analysis Comparing Renal Outcomes after Transcatheter versus Surgical Aortic Valve Replacement

Background

Acute kidney injury (AKI) is a common complication of aortic valve replacement. However, comparative on the incidence of (AKI) following transcatheter (TAVR) versus surgical valve replacement (SAVR) is sparse.

Methods

We performed a meta-analysis of the randomized controlled trials (RCT) and propensity-matched observational studies comparing (A) incidence of AKI and (B) incidence of dialysis-requiring AKI at 30 days after TAVR and SAVR.

Results

Twenty-six studies (20 propensity-matched studies; 6 RCTs) including 19,954 patients were analyzed. The incidence of AKI was lower after TAVR than after SAVR (7.1% vs. 12.1%, OR 0.52; 95%CI, 0.39-0.68; p<0.001, I²=57%), but the incidence of dialysis-requiring AKI was similar (2.8% vs. 4.1%, OR 0.78; 95%CI, 0.49-1.25; p=0.31, I²=70%). Similar results were observed in a sensitivity analysis including RCTs only for both AKI ([5 RCTs; 5,418 patients], 2.0% vs. 5.0%, OR 0.39; 95%CI, 0.28-0.53; p<0.001, I²=0%), and dialysis-requiring AKI ([2 RCTs; 769 patients]; 2.9% vs. 2.6%, OR 1.1; 95%CI, 0.47-2.58; p=0.83, I²=0%). However, in studies including low-intermediate risk patients only, TAVR was associated with lower incidence of AKI ([10 studies; 6,510 patients], 7.6% vs. 12.4%, OR 0.55, 95%CI 0.39-0.77, p<0.001, I²=57%), and dialysis-requiring AKI, ([10 studies; 12,034 patients], 2.0% vs. 3.6%, OR 0.57, 95%CI 0.38-0.85, p=0.005, I²=23%).

Conclusions

TAVR is associated with better renal outcomes at 30 days in comparison with SAVR, especially in patients at low-intermediate surgical risk. Further studies are needed to assess the impact of AKI on long-term outcomes of patients undergoing TAVR and SAVR.

Arterial stiffness is a predictor for acute kidney injury following coronary artery bypass graft surgery

Background

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a serious postoperative complication of cardiac surgery, an episode of which impacts on patient morbidity and mortality. Pulse wave velocity (PWV; a non-invasive measurement tool to assess arterial stiffness) has been shown to predict kidney disease progression, and cardiovascular and all-cause mortality in patients with chronic kidney disease. We hypothesised that PWV would also predict acute kidney injury in subjects who have undergone non-valve repair elective coronary artery bypass graft (CABG) surgery .

Methods

This was a prospective, observational, exploratory study. PWV was determined with a Vicorder device, together with standard clinical and biochemical parameters. AKI staging was defined according to the Kidney Disease Improving Global Outcomes (KDIGO) Clinical Practice Guidelines.

Results

137 patients were included in the study. 85% were male, and mean age was 66.3 years (SD = 9.7 years). There were 40 episodes (29%) of CSA-AKI. Each 1 unit increase in PWV score was associated with a 1.5 fold greater odds of a CSA-AKI event (p = 0.006(odds ratio = 1.5; confidence interval:1.13–2.10). A 1 unit increase in estimated glomerular filtration rate resulted in an estimated 85% decrease in the odds of developing AKI, each year, men have an odds reduction of 15% of developing AKI compared with females and each 1 year increase in age lowered the odds of developing AKI by 87%.

Conclusions

This pilot exploratory study revealed that PWV, assessed prior to non-valve repair elective CABG surgery, independently predicts CSA-AKI events. PWV is a simple, non-invasive technique that could potentially be used to risk stratify for CSA- AKI following elective cardiac surgery.

Trial registration

ClinTrial.Gov NCT02364427. Registered 18 February 2015.

Renal complications of anaesthesia

Peri-operative acute kidney injury is common, accounting for 30-40% of all in-hospital cases of acute kidney injury. It is associated with clinically significant morbidity and mortality even with what was hitherto regarded as relatively trivial increases in serum creatinine, and carries over a 12-fold relative risk of death following major abdominal surgery. Comorbid conditions such as diabetes, hypertension, liver disease and particularly pre-existing chronic kidney disease, as well as the type and urgency of surgery, are major risk factors for the development of postoperative acute kidney injury. As yet, there are no specific treatment options for the injured kidney, although there are several modifiable risk factors of which the anaesthetist should be aware. As well as the avoidance of potential nephrotoxins and appropriate volume balance, optimal anaesthetic management should aim to reduce the risk of postoperative renal complications. This may include careful ventilatory management and blood pressure control, as well as appropriate analgesic strategies. The choice of anaesthetic agent may also influence renal outcomes. Rather than concentrate on the classical management of acute kidney injury, this review focuses on the potential development of acute kidney injury peri-operatively, and the means by which this may be ameliorated.

Transient acute kidney injury after cardiac surgery does not independently affect postoperative outcomes

BACKGROUND

The objective of this study was to assess the incidence of in-hospital acute kidney injury (AKI) after cardiac surgery by comparing preoperative baseline renal function with renal function during the postoperative period and at discharge, and to relate these indices with in-hospital postoperative outcomes.

METHODS

A retrospective analysis was performed over a 4-year period from a series of 426 adult patients. Kidney function was based on serum creatinine (SCr), Cockroft-Gault estimated creatinine clearance (eCrCl), and glomerular filtration rate estimated with the Modification of Diet in Renal Disease formula (eGFR). Baseline values were compared with "peak" values of altered kidney function postoperatively, and "discharge" values. In-hospital mortality and complication rates were compared between patients with transient and persistent AKI, and those without postoperative AKI.

RESULTS

After surgery, AKI (Risk-Injury-Failure-Loss-Endstage [RIFLE] classes Injury and Failure) was diagnosed in 14.6-17.5% of patients based on peak values. AKI diagnosis was reduced to 3.6-4.5% when SCr, eCrCl, and eGFR were measured at discharge. In-hospital mortality of patients with transient AKI was 4% versus 26% in patients with AKI at discharge (odds ratio = 0.11, 95% confidence interval 0.02-0.62, P = 0.011).

CONCLUSIONS

A diagnosis of AKI based on measurements of eGFR during the postoperative period was nearly four times more frequent than the same diagnosis at discharge. Transient AKI was the predominate presentation of postoperative kidney dysfunction in this study. Transient AKI did not affect in-hospital outcomes compared with patients without AKI. Patients with persistent AKI at discharge had the highest mortality.

Update on perioperative acute kidney injury

PURPOSE OF REVIEW

In this review, we discuss the latest updates on perioperative acute kidney injury (AKI) and the specific considerations that are relevant to different surgeries and patient populations.

RECENT FINDINGS

AKI diagnosis is constantly evolving. New biomarkers detect AKI early and shed a light on the possible cause of AKI. Hypotension, even for a short duration, is associated with perioperative AKI. The debate on the deleterious effects of chloride-rich solutions is still far from conclusion. Remote ischemic preconditioning is showing promising results in the possible prevention of perioperative AKI. No definite data show a beneficiary effect of statins, fenoldepam, or sodium bicarbonate in preventing AKI.

SUMMARY

Perioperative AKI is prevalent and associated with significant morbidity and mortality. Considering the lack of effective preventive or therapeutic interventions, this review focuses on perioperative AKI: measures for early diagnosis, defining risks and possible mechanisms, and summarizing current knowledge for intraoperative fluid and hemodynamic management to reduce risk of AKI.

Biomarker enhanced risk prediction for development of AKI after cardiac surgery

Background

Acute kidney injury (AKI) is a common post-cardiac surgery complication and influences patient morbidity and prognosis. This study was designed to identify preoperative candidate urine biomarkers in patients undergoing cardiac surgery.

Methods

A prospective cohort study of adults undergoing cardiac surgery at increased risk for AKI at a single hospital between July 2010 and September 2012 was performed. The primary outcome was the development of AKI, defined as an absolute serum creatinine (SCr) level increase ≥ 0.5 mg/dL or a ≥ 50% relative increase within 72 h of surgery. A secondary outcome was development of AKI defined by Kidney Disease Improving Global Outcomes (KDIGO). Urine collected by voiding within 4 h prior to surgery was used for proteomic analysis and confirmatory enzyme linked immunosorbent assays (ELISAs) studies. Biomarkers were tested for AKI-prediction using Cox and Snell R², area under the receiver operating curve (AUROC), and percent of corrected classifications. To evaluate the added effect of each candidate biomarker on AKI discrimination, receiver operator characteristic (ROC) curves, integrated discrimination improvement (IDI), and net reclassification improvement (NRI) were calculated.

Results

Forty-seven of 755 patients met screening criteria including 15 with AKI. Proteomic analysis identified 29 proteins with a significant ≥2-fold change. Confirmatory ELISA measurements of five candidate markers showed urinary complement factor B (CFB) and histidine rich glycoprotein (HRG) concentrations were significantly increased in patients with AKI. By multivariate analysis, NRI, and IDI the addition of CFB and HRG to the standard clinical assessment significantly improved risk prediction for the primary outcome. Only HRG was a significant predictor in the 21 patients with AKI defined by KDIGO criteria.

Conclusions

Pre-operative urine measurement of CFB or HRG significantly enhanced the current post-surgery AKI risk stratification for more restrictive definition of AKI. HRG, but not CFB or clinical risk stratification, predicted AKI defined by KDIGO. The ability of these biomarkers to predict risk for dialysis-requiring AKI or death could not be reliably assessed in our study due to a small number of patients with either outcome.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-0902-9) contains supplementary material, which is available to authorized users.

Preoperative serum ST2 level predicts acute kidney injury after adult cardiac surgery

OBJECTIVE

The purpose of this study was to evaluate the relationship between preoperative levels of serum soluble ST2 (ST2) and acute kidney injury (AKI) after cardiac surgery. Previous research has shown that biomarkers facilitate the prediction of AKI and other complications after cardiac surgery.

METHODS

Preoperative ST2 proteins were measured in 1498 patients undergoing isolated coronary artery bypass graft surgery at 8 hospitals participating in the Northern New England Biomarker Study from 2004 to 2007. AKI severity was defined using the Acute Kidney Injury Network (AKIN) definition. Preoperative ST2 levels were measured using multiplex assays. Ordered logistic regression was used to examine the relationship between ST2 levels and levels of AKI severity.

RESULTS

Participants in this study showed a significant association between elevated preoperative ST2 levels and acute kidney risk. Before adjustment, the odds of patients developing AKIN stage 2 or 3, compared with AKIN stage 1, are 2.43 times higher (95% confidence interval, 1.86-3.16; P < .001) for patients in the highest tercile of preoperative ST2. After adjustment, patients in the highest tercile of preoperative ST2 had significantly greater odds of developing AKIN stage 2 or 3 AKI (odds ratio, 1.99; 95% confidence interval, 1.50-2.65; P < .001) compared with patients with AKIN stage 1.

CONCLUSIONS

Preoperative ST2 levels are associated with postoperative AKI risk and can be used to identify patients at higher risk of developing AKI after cardiac surgery.

Risk of de novo dialysis after elective cardiac surgery according to preoperative renal dysfunction

OBJECTIVES

The aim was to estimate the risk of dialysis postoperative de novo dialysis in patients undergoing elective cardiac surgery, according to varying degrees of pre-existing renal dysfunction, and to compare the outcomes with the expected prevalence of dialysis based on several risk scores.

METHODS

A retrospective analysis was performed over a 5-year period (2012-16) from a series of 1332 adult patients who underwent elective cardiac surgery. Patients were divided into 3 estimated creatinine clearance (eCrCl) groups: eCrCl >60 ml/min, eCrCl from 50 ml/min to 60 ml/min and eCrCl ≤49 ml/min. The primary outcome was any renal failure requiring first-time dialysis during the postoperative hospital stay. The expected risk for postoperative dialysis was calculated with 3 predictive scores: the Society of Thoracic Surgeons Bedside Risk Tool, the Cleveland Clinic Score and the Simplified Renal Index. The global accuracy of eCrCl and the different scores was evaluated in terms of calibration and discrimination.

RESULTS

In the overall population, 26.6% of patients presented moderate or severe pre-existing renal dysfunction, and the need for de novo dialysis varied from 0.6% to 5.0% depending on the degree of preoperative eCrCl (P < 0.0001). Preoperative renal dysfunction with eCrCl <50 ml/min was associated with nearly 8-fold increase of risk for postoperative dialysis; eCrCl between 50 ml/min and 60 ml/min showed a 2-fold increase, though this last difference did not reach statistical significance.

CONCLUSIONS

In elective cardiac surgery, isolated preoperative eCrCl seemed to be an accurate indicator of risk for postoperative de novo dialysis. More complex models did not provide additional information to stratify that risk.

Evaluation of the Effect of Aminophylline in Reducing the Incidence of Acute Kidney Injury After Cardiac Surgery

Objectives

Acute renal failure is a common complication of major cardiovascular surgeries (One-third of patients). Adenosine release as a vascular vasodilator increases after cardiac surgery, which reduces renal and glomerular blood flow and subsequently causes kidney ischemic damage. The present study aimed at evaluating the impact of aminophylline as an adenosine receptor antagonist on renal function after cardiac surgery hoping to find an appropriate method to reduce acute kidney injury.

Methods

The patients in the intervention group received 5 mg/kg aminophylline bolus after induction of anesthesia; then, 0.25 mg/kg/hr of the drug was administered intraoperatively and up to 48 hours after surgery in the ICU cardiac surgery. Similar volume of normal saline was injected to the patients of the second group. Serum BUN, Cr, and GFR were measured pre- and postoperatively and 3 days postsurgery. Patients’ 24- hour urine output and RIFLE were also calculated.

Results

Those patients who received medication were extubated earlier (P = 0.018) and received lower amount of inotropic drugs (P < 0001). According to the RIFLE criteria, most of the patients experienced no change or even improved GFR and Cr amounts compared to the control group (p < 0.05). GFR and Cr value of all the patients with Cleveland score, less and more than 6, showed a significant difference between the 2 groups (P = 0.001 and P = 0.01, respectively). According to the RIFLE criteria, most of the patients experienced no change or even improved GFR.

Conclusions

Aminophylline in cardiac surgery can reduce the frequency of acute kidney injury according to RIFLE criteria and could be used in the prevention of AKI as a safe and efficient modality in high-risk patients. Also, the use of this drug may reduce the need for inotropic medication at the time of surgery, intensive care unit stay length, and extubation time.

Evaluation of acute kidney injury (AKI) with RIFLE, AKIN, CK, and KDIGO in critically ill trauma patients

PURPOSE

The aim of our study was to evaluate the effects of AKI development on mortality with four different classification systems (RIFLE, AKIN, CK, KDIGO) in critically ill trauma patients followed in the intensive care unit.

METHODS

A retrospective review of 2034 patients in our intensive care unit was conducted between July 2010 and August 2013. A total of 198 patients with primary trauma were included in the study to evaluate the development of AKI.

RESULTS

When the presence of AKI was investigated according to the four criteria (RIFLE, AKIN, CK, and KDIGO), the highest incidence of AKI was found according to the KDIGO classification (74.2%), followed by AKIN (72.2%), RIFLE (69.7%), and CK (59.1%). It was observed that more AKI developed according to KDIGO in patients with multiple trauma and thoracic trauma (p = 0.031, p = 0.029). Sixty-two (31%) of the 198 trauma patients monitored in the intensive care unit died; mortality was frequently found high in AKI stage 2 and 3 patients. According to the CK classification, there was a significant increase in mortality in patients with AKI on the first day (p = 0.045). AKI classifications by RIFLE, AKIN, CK, and KDIGO were independently associated with the risk of in-hospital death.

CONCLUSION

In this study, the presence of AKI was found to be an independent risk factor in the development of in-hospital mortality according to all classification systems (RIFLE, AKIN, CK, and KDIGO) in critically traumatic patients followed in ICU, and the compatibility between RIFLE, AKIN, and KDIGO was the highest among the classification systems.

Intraoperative tranexamic acid is associated with postoperative stroke in patients undergoing cardiac surgery

BACKGROUND

Stroke is a devastating and potentially preventable complication of cardiac surgery. Tranexamic acid (TXA) is a commonly antifibrinolytic agent in cardiac surgeries with cardiopulmonary bypass (CPB), however, there is concern that it might increase incidence of stroke after cardiac surgery. In this retrospective study, we investigated whether TXA usage could increase postoperative stroke in cardiac surgery.

METHODS

A retrospective study was conducted from January 1, 2010, to December 31, 2015, in 2,016 patients undergoing cardiac surgery, 664 patients received intravenous TXA infusion and 1,352 patients did not receive any antifibrinolytic agent. Univariate and propensity-weighted multivariate regression analysis were applied for data analysis.

RESULTS

Intraoperative TXA administration was associated with postoperative stroke (1.7% vs. 0.5%; adjusted OR, 4.11; 95% CI, 1.33 to 12.71; p = 0.014) and coma (adjusted OR, 2.77; 95% CI, 1.06 to 7.26; p = 0.038) in cardiac surgery. As subtype analysis was performed, TXA administration was still associated with postoperative stroke (1.7% vs. 0.3%; adjusted OR, 5.78; 95% CI, 1.34 to 27.89; p = 0.018) in patients undergoing valve surgery or multi-valve surgery only, but was not associated with postoperative stroke (1.7% vs. 1.3%; adjusted OR, 5.21; 95% CI, 0.27 to 101.17; p = 0.276) in patients undergoing CABG surgery only. However, TXA administration was not associated with postoperative mortality (adjusted OR, 1.31; 95% CI, 0.56 to 3.71; p = 0.451), seizure (adjusted OR, 1.13; 95% CI, 0.42 to 3.04; p = 0.816), continuous renal replacement therapy (adjusted OR, 1.36; 95% CI, 0.56 to 3.28; p = 0.495) and resternotomy for postoperative bleeding (adjusted OR, 1.55; 95% CI, 0.55 to 4.30; p = 0.405). No difference was found in postoperative ventilation time (adjusted B, -1.45; SE, 2.33; p = 0.535), length of intensive care unit stay (adjusted B, -0.12; SE, 0.25; p = 0.633) and length of hospital stay (adjusted B, 0.48; SE, 0.58; p = 0.408).

CONCLUSIONS

Based on the 5-year experience of TXA administration in cardiac surgery with CPB, we found that postoperative stroke was associated with intraoperative TXA administration in patients undergoing cardiac surgery, especially in those undergoing valve surgeries only. This study may suggest that TXA should be administrated according to clear indications after evaluating the bleeding risk in patients undergoing cardiac surgery, especially in those with high stroke risk.

Postoperative acute kidney injury

Acute kidney injury (AKI) after cardiac surgery is a common and serious complication. Several definitions of AKI have been proposed recently, and include both increases in serum creatinine levels and decreases in urine output as diagnostic criteria. The pathophysiology of postoperative AKI is complex and involves both ischemic injury and systemic inflammation. Identifying risk factors, such as old age, underlying diabetes, heart failure, and obesity, may aid in the application of preventative methods for postoperative AKI. Additionally, recognizing different risks after different types of surgical procedures would be valuable. Novel biomarkers that could detect AKI more precisely at an earlier time point are being investigated. Several new biomarkers have been assessed in large multi-center studies and are believed to accommodate conventional clinical findings in diagnosing postoperative AKI. In high-risk patients, preventative measures, such as the maintenance of adequate hemodynamics and sufficient fluid resuscitation, could lower the incidence of postoperative AKI. Avoiding nephrotoxic agents and optimizing preoperative hemoglobin levels to avoid excessive transfusions would also be beneficial. In situations in which medical management fails to maintain sufficient urine output and acid-base and electrolyte homeostasis, early initiation of renal replacement therapy should be considered.

Incidence and progression of cardiac surgery-associated acute kidney injury and its relationship with bypass and cross clamp time

INTRODUCTION

Cardiac surgery-associated kidney injury (CSA-AKI) is common but relatively less is known about its progression. The present study is aimed at evaluating the incidence and course of CSA-AKI and its relationship with the different durations of cardiopulmonary bypass (CPB) and cross clamp times.

MATERIALS AND METHODS

Occurrences of CSA-AKI are evaluated as per the Akin Kidney Injury Network (AKIN) criteria over the course of 5 postoperative day (POD) in 100 patients. The relationship of different durations of CPB and aortic cross clamp time with CSA-AKI is analyzed by Chi-squared test for trend and other appropriate tests using INSTAT software.

RESULTS

One hundred (43 male, 57 female; mean age of 37.01 ± 12.28 years, and baseline mean serum creatinine 0.99 ± 0.20 mg %) patients undergone mostly valve replacement, and congenital heart disease correction was evaluated. Nearly 49% suffered CSA-AKI (81.63% AKIN Class I) with maximum numbers on 2 nd POD. Serum creatinine followed a falling trend 3 rd POD onward except in 8.16% cases of CSA-AKI. Oliguria was absent even in AKIN Class II. The CPB time >70 min and cross clamp time >60 min increase CSA-AKI risk by an OR of 4.76 and 2.84, respectively (P < 0.05).

CONCLUSION

CSA-AKI is very prevalent; mostly of AKIN Class I and increases with increasing CPB and cross clamp time. Urine output is not a reliable indicator of CSA-AKI. The AKIN Class II on the very 1 st POD or increasing trend of serum creatinine beyond 3 rd POD should alert for early intervention.

Sex and the Risk of AKI Following Cardio-thoracic Surgery: A Meta-Analysis

BACKGROUND AND OBJECTIVES

Being a woman is a well established risk factor for the development of cardiothoracic surgery-associated AKI. In striking contrast, women are less likely to develop AKI associated with noncardiac surgical procedures than men. In an attempt to ascertain why being a woman might be protective for ischemic AKI after general surgery but deleterious in patients undergoing cardiothoracic surgery, we examined cardiothoracic surgery-associated AKI in greater detail.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a systematic review and meta-analysis of cardiothoracic surgery-associated AKI studies published between January of 1978 and December of 2015 to further explore the relationship between sex and cardiothoracic surgery-associated AKI.

RESULTS

Sixty-four studies were identified that provided sex-specific data regarding the incidence of cardiothoracic surgery-associated AKI among 1,057,412 subjects. Using univariate analysis, women were more likely than men to develop AKI postoperatively (odds ratio, 1.21; 95% confidence interval, 1.09 to 1.33; P<0.001). However, when the analysis was restricted to the 120,464 subjects reported in 29 studies that used the Acute Kidney Injury Network criteria, the RIFLE criteria, or the Kidney Disease Improving Global Outcomes criteria to define AKI, there was no significant sex-related difference in risk. Seventeen studies used multivariate analysis to assess risk factors for cardiothoracic surgery-associated AKI and provided sex-specific odd ratios. Among the 1,587,181 individuals included in these studies, the risk of developing cardiothoracic surgery-associated AKI was not significantly associated with sex (odds ratio, 1.04; 95% confidence interval, 0.92 to 1.19; P=0.51). However, when the analysis was restricted to the 5106 subjects reported in four studies that used the Acute Kidney Injury Network criteria to define AKI, the risk of developing AKI was significantly lower in women compared with in men (odds ratio, 0.75; 95% confidence interval, 0.65 to 0.87; P<0.001).

CONCLUSIONS

Our systematic review and meta-analysis contradict the generally held consensus that being a woman is an independent risk factor for the development of cardiothoracic surgery-associated AKI.