Correlation of Peripheral Tissue Oxygen Saturation with Blood Lactate during Post-operative Period in Patients Undergoing Off-Pump Coronary Artery Bypass Graft Surgery

Objectives: The objectives of the study are to evaluate the relationship between peripheral StO2 and arterial lactate levels during the early post-operative period in OPCAB patients and to assess their association with intensive care unit (ICU) length of stay. Material and Methods: In this prospective observational study, 73 adult patients undergoing elective OPCAB were included. Peripheral StO2 (near-infrared spectroscopy) and arterial lactate levels were recorded at ICU admission and at 1, 3, 6, and 10 h postoperatively. Correlation analyses were performed between StO2, lactate, and ICU stay duration. Results: Lactate levels peaked at 1 h postoperatively and gradually declined, whereas StO2 reached its lowest value at 3 h, then recovered. A progressively stronger inverse correlation between StO2 and lactate was observed over time, most pronounced at 6 h (r = −0.57, p < 0.001) and 10 h (r = −0.50, p < 0.001). Lactate at 6 h showed a strong positive correlation with ICU stay (r = 0.66), while StO2 at 6 h demonstrated a moderate negative correlation (r = −0.40). Conclusion: Peripheral StO2 shows a significant inverse relationship with blood lactate during the early postoperative period following OPCAB. Both parameters are associated with ICU stay duration, with StO2 offering the advantage of continuous bedside monitoring. Combined assessment may improve early detection of microcirculatory dysfunction and post-operative risk stratification.