Risk Factors Associated with 30-day Mortality in Patients with Postoperative Acute Kidney Injury Who Underwent Continuous Renal Replacement Therapy in the Intensive Care Unit

Purpose: To evaluate the risk factors associated with 30-day mortality in patients with postoperative acute kidney injury who underwent continuous renal replacement therapy (CRRT).Methods: Retrospective analysis of the medical charts of patients with postoperative acute kidney injury who underwent CRRT in the intensive care unit between April 2012 and May 2019 was conducted.Results: There were 71 patients whose average age was 64.8 years, and average Acute Physiology and Chronic Health Evaluation 2 score was 26.2. There were 37 patients who had non-trauma emergency surgery, 16 who required trauma surgery, and 18 who had elective major surgery. In most patients, CRRT was started based on Stage 3 Acute Kidney Injury Network criteria, and the mean creatinine level at the time of CRRT initiation (3.62 mg/dL). The median period from surgery to CRRT was 3 days, and the median CRRT application was 4 days. Forty-seven patients died within 30 days of receiving CRRT. Age, elective major surgery, creatinine level on initiation of CRRT, use of norepinephrine upon the initiation of CRRT, and average daily fluid balance/body weight for 3 days following the initiation of CRRT were associated with increasing 30-day mortality in univariate analysis. In multivariate analysis, age, major elective surgery, and norepinephrine use upon initiation of CRRT were identified as independent risk factors for 30-day mortality.Conclusion: Surgical patients who underwent CRRT postoperatively had a poor prognosis. The risk of death in elderly patients who have undergone major elective surgery, or are receiving norepinephrine upon initiation of CRRT should be considered.