Pv-aCO2/ΔAVO2 ratio and lactate define high-risk hemodynamic profiles in cardiac surgery

Introduction Cardiac surgery with cardiopulmonary bypass (CPB) induces physiological stress that often results in hemodynamic mismatch. Assessment of macro- and microcirculatory variables is crucial for adequate tissue oxygenation. Conventional markers like lactate and ScvO 2 are limited, while CO 2 -derived indices, including Pv-aCO 2 and the Pv-aCO 2 /ΔAVO 2 ratio, may provide earlier detection of anaerobic metabolism. This study aimed to determine critical oxygen delivery (DO 2 crit) and its association with hemodynamic profiles and outcomes. Methods A retrospective study analyzed 508 adults undergoing cardiac surgery with CPB at the Instituto Nacional de Cardiología “Ignacio Chávez” (June 2022–June 2024). Patients were stratified into Profile 1 (lactate 1), and Profile 3 (lactate ≥ 2 mmol/L and Pv-aCO 2 /ΔAVO 2 ≤ 1). Clinical, surgical, and hemodynamic data were collected, and outcomes assessed using logistic regression adjusted for age and sex. Results Of 508 patients, 165 were Profile 1, 295 Profile 2, and 48 Profile 3. Profile 2 showed higher central venous pressure, elevated Pv-aCO 2 , greater vasoactive support, and longer CPB and cross-clamp times. This group had higher risks of cerebrovascular events (OR 4.3), pneumonia (OR 2.0), and acute kidney injury (OR 1.8). DO 2 crit ≤ 7.3 ml/min/kg was linked to Profile 2 and adverse outcomes. Conclusions Integration of macro- and microcirculatory variables identifies prognostically relevant subgroups. Profile 2, defined by lactate ≥ 2 mmol/L and Pv-aCO 2 /ΔAVO 2 > 1, was associated with increased morbidity and DO 2 crit ≤ 7.3 ml/min/kg. Early profiling may improve risk stratification and guide targeted interventions.