Incidence and risk factors of postoperative acute kidney injury in geriatric patients after abdominal surgery

Background. The elderly are vulnerable to postoperative complications. Often acute kidney injury (AKI) is often an underestimated threatening complication of the postoperative period. To date, there is a large gap in the study of acute kidney injury after emergency abdominal surgery, especially among the elderly as a group at increased risk of postoperative complications. The aim of our research is to assess the incidence and risk factors for AKI after emergency abdominal surgery among geriatric patients. Materials and methods. The retrospective study included 70 people: 41 (56 %) females and 29 (44 %) males aged 61 to 93 years with ASA class III–IV who underwent emergency abdominal surgery. Postoperative acute kidney injury was determined according to the KDIGO criteria. Results. 60 % of participants developed acute kidney injury in the postoperative period according to the KDIGO criteria. Intra-operatively, patients with AKI required a significantly higher volume of infusion therapy (2600 (1300; 3600) vs. 1440 (800; 2400), p = 0.023) and more frequent use of colloid fluids (28 (66.7 %) vs. 6 (21.4 %), p < 0.01). Periods of intraoperative hypotension were significantly more frequent in those with AKI in the postoperative period: 18 (42.9 %) vs. 3 (10.7 %), p = 0.004. Patients who subsequently developed acute kidney injury were more likely to receive vasopressor support intraoperatively: 9 (21.4 %) vs. 1 (3.6 %), p = 0.038. The leukocyte count was significantly higher in participants with AKI in the first two days of the postoperative period: day 1 — 13.2 (7.25; 16.85) vs. 9.25 (7; 11), p = 0.043; day 2 — 12.1 (9.6; 15.75) vs. 8.80 (7; 11), p = 0.044. On the first day after surgery, patients with AKI had a significantly lower level of proteinemia: 52.1 (44.7; 57.4) vs. 58.8 (55.8; 67), p = 0.002. AKI in the postoperative period increased the frequency of admission to the intensive care unit (39 (92.9 %) vs. 18 (64.3 %), p = 0.002), the frequency of relaparotomy (9 (21.4 %) vs. 1 (3.6 %), p = 0.038), re-admission to the intensive care unit (11 (26.2 %) vs. 1 (3.6 %), p = 0.014) and postoperative hospital mortality (24 (57.1 %) vs. 3 (10.7 %), p < 0.001). Conclusions. AKI is a frequent complication among geriatric patients after emergency abdominal surgery, which leads to increased mortality. The main risk factors for postoperative AKI after emergency abdominal surgery among elderly people are episodes of intraoperative hypotension, intraoperative use of colloid fluids, intraoperative need for vasopressor support, as well as leukocytosis and hypoproteinemia after surgery.