The relationship between intraoperative hypotension and acute kidney injury in elderly and super elderly patients undergoing noncardiac surgery: a retrospective cohort analysis.

BACKGROUND: Intraoperative hypotension has been identified as a significant factor associated with postoperative renal dysfunction. While numerous studies have reported on the relationship between incidence of postoperative acute kidney injury (AKI) and intraoperative hypotension, limited research has specifically focused on elderly and super elderly patients. METHODS: This retrospective cohort study comprised subjects aged 60 years and older who underwent elective non-cardiac surgery under general anesthesia. AKI was defined in accordance with established clinical criteria based on changes in serum creatinine concentration. We explored potential harm thresholds for the lowest intraoperative mean arterial pressure (MAP) and the largest MAP reduction from baseline. Logistic regression with restricted cubic splines was conducted to assess the relationships between AKI and both the lowest intraoperative MAP or the largest MAP reduction from baseline across elderly patient subgroups aged 60–69, 70–79, 80–89, and 90 + years. RESULTS: A total of 10,859 patients were included in the final analysis. The overall incidence of AKI in this population was 2.77% (301 out of 10,859). Specifically, the incidence rates among patients aged 60–69, 70–79, and 80–89 years were 2.10%, 3.13%, and 4.68%, respectively. The lowest MAP and the incidence of postoperative AKI exhibited a non-linear relationship, both univariably and multivariably (p = 0.0005 and p = 0.0215, respectively), suggesting that the absolute MAP was associated with the risk of AKI. The predicted minimum incidence of AKI (probability = 2.31%) occurred at a lowest MAP of 86 mmHg. Within the MAP range from 74 to 102 mmHg, the incidence of AKI was below the population average. The largest reduction in MAP from baseline was not significantly associated with the probability of AKI. CONCLUSIONS: This study shows that the risk of postoperative AKI was strongly correlated with absolute intraoperative hypotension in both the elderly and super elderly populations. In older adults, maintaining a stable absolute intraoperative MAP should be considered to prevent intraoperative renal injury. TRIAL REGISTRATION: This study was registered in Chinese Clinical Trial Registry with the registration number ChiCTR2400094990 on December 31, 2024.