Abdulkadir Bilgiç, Burak Toprak, Rahime Akın
Objective Systemic inflammation triggered by cardiopulmonary bypass (CPB) plays a critical role in postoperative complications and mortality. The Delta Neutrophil Index (DNI), which quantifies circulating immature neutrophils, is increasingly recognized as a marker of systemic inflammation. While its utility has been demonstrated in sepsis and non-cardiac surgeries, its role in cardiac procedures remains underexplored. This study aimed to evaluate the relationship between intraoperative DNI levels and postoperative mortality in patients undergoing open-heart surgery with CPB. Methods This retrospective observational study included 245 patients who underwent CPB between January 2022 and July 2023. DNI was measured at five predefined time points: induction, 5, 45, and 90 min after CPB initiation, and immediately postoperatively. Patients were categorized into two groups based on in-hospital mortality: those who experienced mortality (“Ex” group, n = 67) and those who survived (“Non-Ex” group, n = 178). Logistic regression was used to assess the association between DNI values and mortality. Results DNI levels were significantly higher in the Ex group at induction (1.22 ± 0.96 vs 0.47 ± 0.39; p = 0.002), 5 min (2.04 ± 1.07 vs 1.08 ± 0.58; p < 0.001), 90 min (1.76 ± 0.84 vs 1.07 ± 0.81; p = 0.004), and postoperatively (2.14 ± 1.38 vs 0.58 ± 0.32; p < 0.001). Each unit increase in postoperative DNI was associated with a 21.78-fold increase in mortality risk (95% CI: 6.12–67.92; p < 0.001). CPB and cross-clamp durations were also significantly longer in Ex patients. Conclusions Elevated intraoperative and postoperative DNI levels are strongly associated with increased in-hospital mortality following CPB. DNI may serve as a dynamic and practical biomarker to aid perioperative risk stratification, pending further validation. Incorporating DNI into routine intraoperative monitoring may enhance early identification of high-risk patients and improve postoperative outcomes.