Advanced Metabolic-Guided Perfusion Concepts in an Obese Patient Undergoing Cardiac Surgery: A Case Report

Obesity increases metabolic oxygen demand, impairs microvascular reserve, and reduces tolerance to hemodilution during cardiopulmonary bypass (CPB), making adequate indexed oxygen delivery (DO₂i) especially important. Evidence on DO₂i-guided perfusion in obese patients undergoing redo cardiac surgery remains limited. We report the case of a 61-year-old obese woman (125 kg; BSA 2.23 m²) undergoing redo mitral valve replacement and tricuspid repair. Her elevated oxygen requirements and prolonged CPB time placed her at high risk for oxygen-delivery instability. Continuous metabolic monitoring integrated DO₂i, indexed carbon-dioxide production (VCO₂i), oxygen consumption index (VO₂i), mixed venous oxygen saturation (SvO₂), temperature-corrected oxygen-extraction ratio (O₂Eri), and the DO₂/VCO₂ ratio. Because the procedure was performed at 30°C, DO₂i was adjusted using a Q₁₀-based correction to reflect reduced metabolic demand under moderate hypothermia. A goal-directed perfusion strategy targeting a temperature-corrected DO₂i ≥ 300 mL/min/m² enabled early detection and correction of transient DO₂i declines (nadir 260 mL/min/m²). Cumulative AUC-DO₂ remained <1,000 mL/min/m²/min, with minimal exposure to DO₂i <280 mL/min/m². Aerobic metabolism was preserved throughout CPB, postoperative lactate stayed low, no acute kidney injury developed, and recovery was uncomplicated. This case shows that integrating DO₂i with advanced metabolic indices and temperature-adjusted analysis can enhance predictive perfusion management in obese high-risk patients. Further research is needed to define optimal DO₂i thresholds and temperature-specific GDP strategies for this population.