Supplementary Material for: Clinical and Operative Determinants of Acute Kidney Injury after Cardiac Surgery

<b><i>Introduction:</i></b> Cardiac surgery-associated acute kidney injury (CSA-AKI) is associated with increased morbidity and mortality. <b><i>Objectives:</i></b> We aimed to identify potentially modifiable risk factors for CSA-AKI. <b><i>Methods:</i></b> This was a<b><i></i></b>single-center retrospective cohort study of 495 adult patients undergoing cardiac surgery. AKI was diagnosed and staged using full KDIGO criteria incorporating baseline serum creatinine (SC) levels and correction of postoperative SC levels for fluid balance. We examined the association of routinely available clinical and laboratory data with AKI using multivariate logistic regression modeling. <b><i>Results:</i></b> A total of 103 (20.8%) patients developed AKI: 16 (15.5%) patients were diagnosed with AKI upon hospital admission, and 87 (84.5%) patients were diagnosed with CSA-AKI. Correction of SC levels for fluid balance increased the number of AKI cases to 104 (21.0%), with 6 patients categorized to different AKI stages. Univariate logistic regression analysis identified five preoperative (age, sex, diabetes mellitus, preoperative systolic pulmonary arterial pressure [PSPAP], acute decompensated heart failure) and five intraoperative predictors of AKI (age, sex, red blood cell [RBC] volume transfused, use of minimally invasive surgery, duration of cardiopulmonary bypass). When all preoperative and intraoperative variables were incorporated into one model, six predictors remained significant (age, sex, use of minimally invasive surgery, RBC volume transfused, PSPAP, duration of cardiopulmonary bypass). Model discrimination performance showed an area under the curve of 0.69 for the model including only preoperative variables, 0.76 for the model including only intraoperative variables, and 0.77 for the model including all preoperative and intraoperative variables. <b><i>Conclusions:</i></b> Use of minimally invasive surgery and therapies mitigating PSPAP and intraoperative blood loss may offer protection against CSA-AKI.

引言：心脏手术相关急性肾损伤（cardiac surgery-associated acute kidney injury, CSA-AKI）与更高的发病率及死亡率密切相关。
研究目的：本研究旨在明确心脏手术相关急性肾损伤（cardiac surgery-associated acute kidney injury, CSA-AKI）潜在可干预的危险因素。
研究方法：本研究为单中心回顾性队列研究，纳入了495例行心脏手术的成年患者。急性肾损伤（acute kidney injury, AKI）的诊断与分期采用完整的改善全球肾脏病预后组织（Kidney Disease: Improving Global Outcomes, KDIGO）标准，结合基线血清肌酐（serum creatinine, SC）水平，并根据液体平衡情况对术后血清肌酐水平进行校正。本研究采用多因素logistic回归模型，分析常规采集的临床及实验室数据与AKI的相关性。
研究结果：共计103例（20.8%）患者发生AKI，其中16例（15.5%）于入院时即被诊断为AKI，87例（84.5%）为心脏手术相关急性肾损伤（CSA-AKI）。根据液体平衡情况校正血清肌酐水平后，AKI病例数增至104例（21.0%），其中6例患者的AKI分期发生变更。单因素logistic回归分析筛选出5项术前危险因素（年龄、性别、糖尿病、术前收缩肺动脉压（preoperative systolic pulmonary arterial pressure, PSPAP）、急性失代偿性心力衰竭）以及5项术中危险因素（年龄、性别、输注红细胞（red blood cell, RBC）体积、微创手术应用情况、体外循环（cardiopulmonary bypass）时长）。将所有术前及术中变量纳入单模型后，仍有6项危险因素具有统计学意义：年龄、性别、微创手术应用情况、输注红细胞体积、术前收缩肺动脉压及体外循环时长。模型区分度分析结果显示：仅纳入术前变量的模型的曲线下面积（area under the curve, AUC）为0.69，仅纳入术中变量的模型曲线下面积为0.76，同时纳入术前及术中变量的模型曲线下面积为0.77。
结论：微创手术应用以及可降低术前收缩肺动脉压、减少术中失血量的治疗手段，或许可对心脏手术相关急性肾损伤（CSA-AKI）起到保护作用。