Arterial Stiffness as a Predictor of Postoperative Intensive Care Unit (ICU) Mortality: An Observational Study

Background Arterial stiffness has emerged as a key determinant of cardiovascular risk, yet its prognostic impact in postoperative intensive care unit (ICU) patients remains unclear. This study evaluated the association of arterial stiffness indices (augmentation index (AIX@75), pulse pressure (PP)) with ICU mortality in postoperative surgical patients. Methods This was a prospective observational study including 117 postoperative ICU patients. Demographics, comorbidities, Acute Physiology and Chronic Health Evaluation II (APACHE II), Sequential Organ Failure Assessment (SOFA), laboratory values, hemodynamics, central pressures, AIX, AIX@75, and PP were recorded. Mortality was the primary endpoint. Statistical analyses included Mann-Whitney U tests, receiver operating characteristic (ROC) curve analysis, logistic regression, and Kaplan-Meier survival curves. Results Overall mortality was 38.5% (45/117). Non-survivors had significantly higher APACHE II scores (p = 0.001) and PP (p = 0.005). ROC curves identified AIX@75 as a strong mortality predictor (area under the curve (AUC) = 0.78), with an optimal cut-off of ≥23.5 (sensitivity = 82%; specificity = 68%). PP had modest discriminatory ability (AUC = 0.62) with a cut-off of ≥42.5 (sensitivity = 84.4%; specificity = 36.1%). Logistic regression showed AIX@75 significantly predicted mortality (OR = 1.037 per unit; p = 0.006), while PP showed a borderline association (p = 0.062). Kaplan-Meier curves demonstrated significantly reduced survival in high-AIX@75 patients (p < 0.001) and a trend for PP (p = 0.069). Conclusions AIX@75 is a robust independent predictor of postoperative mortality in ICU patients, outperforming PP. Arterial stiffness assessment may provide valuable early risk stratification in postoperative critical care.