Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common and serious complication, significantly increasing postoperative morbidity and mortality. We aimed to evaluate whether intraoperative peripheral perfusion index (PPI) was associated with the risk of major adverse kidney events, as defined by MAKE30, as well as CSA-AKI and 30-day mortality.

In this retrospective observational cohort, we studied patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Hemodynamic data were extracted from intraoperative monitors at 1-minute intervals. Multivariable logistic regression was used, adjusting for acute kidney injury risk factors and intraoperative MAP and central venous pressure (CVP). Sensitivity analyses included post-CPB periods and LASSO-based variable selection.

We analyzed 446 adult patients. Lower intraoperative PPI values were significantly associated with an increased risk of MAKE30. For every 15 min spent with a PPI < 0.5, the odds of MAKE30 increased by 49% (OR 1.49; 95% CI 1.27–1.76; p < 0.001). Similarly, for every 15 min with a PPI <1.5, the odds increased by 18% (OR 1.18; 95% CI 1.08–1.28; p < 0.001). The duration of time with PPI values below 0.5 and 1.5 was also significantly associated with CSA-AKI and mortality. Sensitivity analyses confirmed that these associations were robust.

Low intraoperative PPI is independently associated with an increased risk of MAKE30, CSA-AKI, and 30-day mortality following cardiac surgery with CPB. Future prospective studies should investigate whether interventions aimed at optimizing PPI through goal-directed therapy can improve postoperative outcomes.