Association of the perfusion index with postoperative acute kidney injury: a retrospective study

Abstract

Backgrounds: Many studies have examined the risk factors for postoperative acute kidney injury (AKI), but few have focused on intraoperative peripheral perfusion index (PPI), which has recently been shown to be associated with postoperative morbidity and mortality. Therefore, this study aimed to evaluate the relationship between intraoperative PPI and postoperative AKI under the hypothesis that lower intraoperative PPI is associated with AKI occurrence. Methods:We retrospectively searched electronic medical records to identify patients who underwent surgery at the general surgery department from May 2021 to November 2021. Patient baseline characteristics, pre-and post-operative laboratory test results, comorbidities, intraoperative vital signs, and discharge profiles were obtained from the Institutional Clinical Data Warehouse and VitalDB.Intraoperative PPI was the primary exposure variable, and the primary outcome was postoperative AKI.Results: Overall, 2554 patients were identified and 1586 patients were included in our analysis.According to Kidney Disease Improving Global Outcomes criteria, postoperative AKI occurred in 123 (7.8%) patients. We found that risks of postoperative AKI increased (odds ratio 2.00, 95% confidence interval 1.16-3.44, p = 0.012) when PPI was < 0.5 for > 10% of surgery time. Other risk factors for AKI occurrence were male sex, older age, higher American Society of Anesthesiologists status, obesity, underlying renal disease, prolonged operation time, transfusion, and emergent operation. Conclusion:Low intraoperative PPI was independently associated with postoperative AKI.