Early Prediction of Acute Kidney Injury in High Risk Patients After Non-cardiac Surgery

Study Overview
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Brief Summary
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Acute kidney injury (AKI) is a common complication after non-cardiac surgery with adverse short and long term morbidity and mortality. So far there have been no effective therapy for AKI treatment developed, possibly due to the heterogenicity of this syndrome. Therefore, prevention of AKI in high risk patients undergoing non-cardiac surgery, as emphasized by Kidney Disease Improving Global Outcomes (KDIGO), becomes the first priority. However, early prediction of AKI is the first step before taking preventive measures, which really make a great challenge to clinical practitioners because of such a limited time window and complex clinical scenarios. Recently, cumulative evidence have shown that biomarkers and renal ultrasound may play an important role in AKI prediction after non-cardiac surgery. The purpose of this study is to investigate the combination of biomarkers, urine sedimentation and renal resistive index for early prediction of AKI in high risk patients undergoing non-cardiac surgery.

Detailed Description
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Early prediction of AKI have long been a study hotspot. Various clinical prediction models, biomarkers, urine sedimentation scores and imaging tools are developed and validated in different clinical settings mainly focusing on contrast associated AKI, durg induced AKI and cardiac surgery associated AKI. Due to the heterogenicity of this syndrome, one parameter which fits all patients for prediction of AKI dose not possibly exist. As a result, searching for combination parameters that can well predict AKI after non-cardiac surgery become the first priority for prevention of AKI. Evidence in non-cardiac surgery population have been gradually accumulated in recent years. Biomarkers for G1 cell cycle arrest, e.g. tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin like growth factor binding protein-7 (IGFBP-7), have demonstrated robust predictive performance in high risk surgical patients. Renal resistive index as calculated by ultrasound have also showed its validity in AKI prediction in patients following orthopedic surgery. Hence, the investigators make an assumption that combination of biomarkers, urine sedimentation and renal resistive index may improve the predictive value of AKI after non-cardiac surgery. The purpose of this study is to investigate the combination of biomarkers, urine sedimentation and renal resistive index for early prediction of AKI in high risk patients undergoing non-cardiac surgery. Adult patients undergoing non-cardiac surgery and then admitting to surgical intensive care unit (SICU) will be immediately screened for this study. After enrollment, blood and urine samples, in addition to clinical routine tests, will be collected for the tests of biomarkers and urine sedimentation, such as serum creatinine, TIMP-2, IGFBP-7, α-1 microglobulin, microalbumin, transferrin, granular cast and so on. Meanwhile, central venous pressure (CVP) will be measured by primary nurse. If the patients were enrolled at daytime between 8:00-16:00, experienced intensivists will also calculate the renal resistive index (RI) by ultrasound. Urine samples will be collected again for storage after 6 and 12 hours admitting to SICU, at which time urine sedimentation and CVP will be repeatedly measured at the discretion of physician in-charge. AKI is monitored by serum creatinine daily in SICU and on demand in general wards, and by urine output (UO) every 3 hours in SICU. Patients will be followed up for postoperative complications, renal recovery, survival, SICU/in hospital stay and total cost until the first thing that happens: discharge/death, 30d after operation or withdrawing the study. Perioperative data will be recorded by specialized researchers.

Official Title
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Combination of Biomarkers, Urine Sedimentation and Renal Resistive Index for Early Prediction of Acute Kidney Injury in High Risk Patients After Non-cardiac Surgery: a Prospective Observational Cohort Study

Conditions
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Acute Kidney Injury

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥ 18 years; Undergoing non-cardiac surgery; Admitted to SICU immediately after surgery Exclusion Criteria: Chronic kidney disease stage 5 (CKD-5) or requiring long-term dialysis; Undergoing kidney-related surgery; AKI before admission to SICU; Without Foley catheter placement ;Written informed consent not obtained

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of acute kidney injury within 7 days after surgery | AKI is diagnosed according to KDIGO criteria | within 7 days after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Severity of acute kidney injury within 7 days after surgery | AKI is classified according to KDIGO criteria | within 7 days after surgery | 
| Incidence of postoperative complications | Defined as newly onset medical conditions that are harmful to patients' recovery and required therapeutic intervention, including pulmonary infection, pleural effusion, atelectasis, respiratory failure, surgical bleeding, new onset arrhythmia, acute myocardial infarction, congestive heart failure, stroke, ileus, liver injury, digestive tract bleeding, wound infection, urinary tract infection, severe sepsis, acute kidney injury, pulmonary embolism and deep venous thrombosis. | 30 days after operation or withdrawing the study ( the first thing that happens: discharge/death) | 
| Rate of ICU or in-hospital mortality | ICU/In-hospital mortality | 30 days after operation or withdrawing the study ( the first thing that happens: discharge/death) | 
| Rate of dialysis dependent at discharge | Defined as requiring any modality of renal replacement therapy at discharge | Until the first thing that happens: discharge/death, 30 days after operation or withdrawing the study. | 
| Rate of continuous decreased kidney function at discharge | Estimated glomerular filtration rate (eGFR) decreased more than 25% of baseline value at discharge | 30 days after operation or withdrawing the study ( the first thing that happens: discharge/death) | 
| Rate of major adverse kidney events (MAKE) | Defined as a composite of death, dialysis dependent or continuous decreased kidney function | 30 days after operation or withdrawing the study ( the first thing that happens: discharge/death) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Acute Kidney Injury, Early prediction, Non cardiac surgery, Biomarker, Urine sedimentation, Renal resistive index