Postoperative acute kidney injury in high-risk patients undergoing major abdominal surgery

Purpose Acute kidney injury (AKI) is a frequent complication in high-risk patients undergoing major surgery and is associated with longer hospital stay, increased risk for nosocomial infection and significantly higher costs. Materials and methods A prospective observational study exploring the incidence of AKI (AKIN classification at any stage) in high-risk patients within 48 hours after major abdominal surgery was conducted. Patients' preoperative characteristics, intraoperative management, and outcome were evaluated for associations with AKI using a logistic regression model. Results Data from 258 patients were analyzed. Thirty-one patients (12%) developed AKI, reaching the AKIN stage 1. No patient reached an AKIN stage higher than 1. AKI patients were older (75.2 vs 70.2 years; P = 0.0113) and had a higher body mass index (26.5 vs 25.1 kg/m²). In addition, AKI patients had a significantly longer ICU length of stay (3.4 vs 2.4 days; P= .0017). Creatinine levels of AKI patients increased significantly compared to the preoperative levels at 24 (P= .0486), 48 (P= .0011) and 72 hours (P= .0055), while after 72 hours it showed a downwards trend. At ICU discharge, 28 out of 31 patients (90.3%) recovered preoperative levels. Multivariate analysis identified age (OR 1.088; P= .002) and BMI (OR 1.124; P= .022) as risk factors for AKI development. Moreover, AKI development was an independent risk factor for ICU stays longer than 48 hours (OR 2.561; P= .019). Conclusions Mild AKI is a not rare complication in high-risk patients undergoing major abdominal surgery. Although in almost the totality of cases, the indicators of renal function recovered to preoperative levels, post-operative AKI represents a primary risk factor for a prolonged ICU stay.