Acute Kidney Injury After Open Heart Surgery

Introduction: Acute kidney injury (AKI) is a term used to describe when the kidney loses its function rapidly. And it’s associated with an increase in the level of serum creatinine by 0.5 to 1mg/dL. It can be diagnosed by a plethora of criteria such as the Kidney Disease Improving Global Outcomes (KDIGO) and the Risk, Injury, Failure, Loss, End-stage (RIFLE) criteria. Cardiac surgery-associated AKI (CSA-AKI) is the most prevalent complication in patients following cardiac surgery and is also linked to increased mortality and morbidity rates. In addition, exogenous and endogenous toxins, ischemia and reperfusion, inflammation, oxidative stress, metabolic factors, and neurohormonal activation may all play a role in the development of CSA-AKI. All these factors may be active at varying time intervals and with different degrees of intensity, or may function simultaneously. 

Methods: In late 2019, a retrospective study was conducted by reviewing the health data of patients who underwent coronary artery bypass graft (CABG), valvular repairs, and other open cardiac surgeries at the King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia, between November 2014 and June 2019. Information was obtained from the Hospital information system, Jeddah, Saudi Arabia. Of the 159 patients who underwent open-heart surgery at KAUH, 126 (79.2%) were male and 33 (20.8%) were female. Patients below 15 years of age and those with poor renal function prior to open cardiac surgery were excluded. The KDIGO criteria were used to diagnose AKI for our patients.

Results: In this study, 34% of the patients experienced AKI after open cardiac surgery, and the most frequent risk factor encountered was diabetes mellitus (DM), which was present in 97 (61%) patients, followed by angina pectoris in 93 (58.5%) patients. Hypertension was identified in 85 (53.5%) and acute myocardial infarction in 82 (51.6%) patients. There were only two (1.3%) patients with known cases of chronic obstructive lung disease (COPD). Of the surgeries, 131 (82.4%) were classified as elective and 28 (17.6%) were urgent.

Conclusion: The most common risk factor associated with AKI following open-heart surgery is DM, followed by angina pectoris. However, further studies are required to investigate all the cardiac procedures.

Hemodilution is associated with underestimation of serum creatinine in cardiac surgery patients: a retrospective analysis

Background

Fluid overload is related to the development and prognosis of cardiac surgery-associated acute kidney injury (CSA-AKI). The study is to investigate the influence of serum creatinine (SCr) corrected by fluid balance on the prognosis of patients with cardiac surgery.

Methods

A retrospective study was conducted in 1334 patients who underwent elective cardiac surgery from January 1 to December 31, 2015. Kidney Disease: Improving Global Outcomes (KDIGO) criteria for AKI were applied to identify CSA-AKI. SCr was measured every 24 h during ICU period and was accordingly adjusted for cumulative fluid balance. Changes in SCr, defined as ∆Crea, were determined by difference between before and after adjustment for cumulative fluid balance. All patients were then divided into three groups: underestimation group (∆Crea ≥ P₇₅), normal group (P₂₅ < ∆Crea < P₇₅) and overestimation group (∆Crea ≤ P₂₅).

Results

The incidence of AKI increased from 29.5% to 31.8% after adjustment for fluid balance. Patients in underestimation group showed prolonged length of ICU stay compared with normal group and overestimation group (3.2 [1.0–4.0] vs 2.1 [1.0–3.0] d, P < 0.001; 3.2  [1.0–4.0] vs 2.3 [1.0–3.0] d, P < 0.001). Length of hospital stay and mechanical ventilation dependent days in underestimation group were significantly longer than normal group (P < 0.001). Multivariate analysis showed age, baseline SCr and left ventricular ejection fraction were independently associated with underestimation of creatinine.

Conclusions

Cumulative fluid balance after cardiac surgery disturbs accurate measurement of serum creatinine. Patients with underestimation of SCr were associated with poor prognosis.

Acute Kidney Injury after Cardiac Surgery: Risk Factors and Novel Biomarkers

Acute kidney injury (AKI) is a common and severe complication after cardiac surgery. Currently, a series of novel biomarkers have favored the assessment of AKI after cardiac surgery in addition to the conventional indicators. The biomartkers, such as urinary liver fatty acid binding protein (L-FABP), urinary neutrophil gelatinase-associated lipocalin (NGAL), serum L-FABP, heart-type FABP, kidney injury molecule 1 (KIM-1), and interleukin-18 were found to be significantly higher in patients who developed AKI after cardiac surgery than those who did not. Apart from urinary interleukin-18, the novel biomarkers have been recognized as reliable indicators for predicting the diagnosis, adverse outcome, and even mortality of AKI after cardiac surgery. The timing of the renal replacement therapy is a significant predictor relating to patients’ prognoses. In patients with AKI after cardiac surgery, renal replacement therapy should be performed as early as possible in order to achieve promising outcomes. In children, AKI after cardiac surgery can be managed with peritoneal dialysis. AKI after cardiac surgery has received extensive attention as it may increase early mortality and impact long-term survival of patients as well. The purpose of this article was to analyze the changes of the pertinent biomarkers, to explore the related risk factors leading to the occurrence of AKI after cardiac surgery, and to provide a basis for the clinical prevention and reduction of AKI.

Early Postoperative Serum Creatinine Adjusted for Fluid Balance Precisely Predicts Subsequent Acute Kidney Injury After Cardiac Surgery

OBJECTIVES

Cumulative fluid overload may influence acute kidney injury (AKI) diagnosis due to the dilution effect. The authors hypothesized a small increase of early postoperative serum creatinine (SCr) adjusted for fluid balance might have superior discrimination ability in subsequent AKI prediction.

DESIGN

Retrospective analyses.

SETTING

A single-center study in a university hospital.

PARTICIPANTS

The study comprised 1,016 adult patients who underwent elective isolated or combined valve surgery in 2015.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Baseline characteristics, intraoperative parameters, and intraoperative and postoperative fluid balance were collected through a retrospective chart review. Early postoperative SCr level was drawn within 12 hours of surgical completion and then measured daily. Early relative changes of SCr were categorized as a cutoff value of 10% with or without adjustment for cumulative fluid balance. Kidney Disease: Improving Global Outcomes criteria were used to detect AKI. Logistic analyses were performed to determine risk factors for subsequent AKI with the inclusion of measured or fluid-adjusted early relative changes of SCr, respectively. In this study, 355 patients (34.9%) developed AKI. Multivariate logistic analyses showed age, weight, European System for Cardiac Operative Risk Evaluation II, and cardiopulmonary bypass duration were associated independently with the development of AKI. Model discrimination for AKI prediction was improved significantly when the addition of measured (area under the receiver operating characteristic curve [AUROC] 0.830) and fluid-adjusted early changes of SCr to the basic model (AUROC 0.850).

CONCLUSIONS

Early fluid-adjusted relative changes of SCr could improve the predictive ability for subsequent development of AKI in valve surgery patients.

Acute kidney injury after non-cardiovascular surgery: risk factors and impact on development of chronic kidney disease and long-term mortality

OBJECTIVE

To identify factors associated with acute kidney injury (AKI) and its progression to chronic kidney disease (CKD) in a non-cardiac/non-vascular surgery setting.

METHODS

This study examined the Veterans Affairs Surgical Quality database for surgical entries between 2000-2014. Demographics, comorbidities, laboratory findings and hospital outcomes were assessed. The primary end-point was the occurrence of AKI, defined as an increase of ≥0.3 mg/dL, 48 h post-operatively. Major adverse cardiac event (MACE) was defined as the composite first occurrence of myocardial infarction, cardiac arrest, and death in 30 days (secondary end-point) and was compared between two groups. Rates of progression to CKD in 1 year and long-term survival were examined.

MAIN OUTCOME MEASURES

Occurrence of AKI 48 h post-operatively.

RESULTS

AKI was documented in 8.5% of patients. Age, diabetes, and chronic obstructive pulmonary disease, chronic kidney disease, platelet count, serum albumin level, and duration of surgery were identified as independent predictors of AKI. In total, 6.4% patients developed MACE, which was more frequent in patients with AKI (p < .001). Age and pre-operative hematocrit <30% were independent predictors of progression to CKD. Pre-operative hematocrit with a cut-off value of 30% was the only modifiable factor to predict the long-term survival.

CONCLUSION

Development of AKI is associated with increased odds of various post-operative complications and long-term renal insufficiency and mortality.

The utility of the additive EuroSCORE, RIFLE and AKIN staging scores in the prediction and diagnosis of acute kidney injury after cardiac surgery

BACKGROUND/AIMS

Acute kidney injury (AKI) following cardiac surgery is a complication associated with high rates of morbidity and mortality. We compared staging systems for the diagnosis of AKI after cardiac surgery, and assessed pre-operative factors predictive of post-operative AKI.

METHODS

Clinical data, surgical risk scores, procedure and clinical outcome were obtained on all 4,651 patients undergoing cardiac surgery to the Royal Infirmary of Edinburgh between April 2006 and March 2011, of whom 4,572 had sufficient measurements of creatinine before and after surgery to permit inclusion and analysis. The presence of AKI was assessed using the AKIN and RIFLE criteria.

RESULTS

By AKIN criteria, 12.4% of the studied population developed AKI versus 6.5% by RIFLE criteria. Any post-operation AKI was associated with increased mortality from 2.2 to 13.5% (relative risk 7.0, p < 0.001), and increased inpatient stay from a median of 7 (IQR 4) to 9 (IQR 11) days (p < 0.05). Patients identified by AKIN, but not RIFLE, had a mean peak creatinine rise of 34% from baseline and had a significantly lower mortality compared to RIFLE-'Risk' AKI (mortality 6.1 vs. 9.7%; p < 0.05). Pre-operative creatinine, diabetes, NYHA Class IV dyspnoea and EuroSCORE-1 (a surgical risk score) all predicted subsequent AKI on multivariate analysis. EuroSCORE-1 outperformed any single demographic factor in predicting post-operative AKI risk, equating to an 8% increase in relative risk for each additional point.

CONCLUSION

AKI after cardiac surgery is associated with delayed discharge and high mortality rates. The AKIN and RIFLE criteria identify patients at a range of AKI severity levels suitable for trial recruitment. The utility of EuroSCORE as a risk stratification tool to identify high AKI-risk subjects for prospective intervention merits further study.