Introduction: Intraoperative hemodynamic and metabolic optimization of both the high-risk surgical patients and critically ill patients remains challenging. Reductions in oxygen delivery or increases in oxygen consumption can initiate complex cellular processes precipitating oxygen debt (OXD). Methods: This study tested the hypothesis that intraoperative changes in sublingual microcirculatory flow may reflect clinically relevant transitions from aerobic to anaerobic metabolism (TRANAM). We included patients undergoing elective major and emergency non-cardiac surgery. Macro- and microcirculatory variables, oxygen extraction, and transitions of metabolism were assessed in both cohorts. Results: In the elective group, OXD was progressively increased over time, with an estimated 2.24 unit increase every 30 min (adjusted p < 0.001). Also, OXD was negatively correlated with central venous pressure (ρ = −0.247, adjusted p = 0.006) and positively correlated with stroke volume variation (ρ = 0.185, adjusted p = 0.041). However, it was not significantly correlated with sublingual microcirculation variables. In the emergency surgery group, OXD increased during the first two intraoperative hours and then gradually decreased until the end of surgery. In that cohort, OXD was positively correlated with diastolic arterial pressure (ρ = 0.338, adjusted p = 0.005), mean arterial pressure (ρ = 0.278, adjusted p = 0.023), and systemic vascular resistance (ρ = 0.296, adjusted p = 0.015). Also, OXD was negatively correlated with the cardiac index (ρ = −0.352, adjusted p = 0.003), consensus proportion of perfused vessels (PPV) (ρ = −0.438, adjusted p < 0.001), and Consensus PPV (small) (ρ = −0.434, adjusted p < 0.001). Conclusions: TRANAM were evident in both the elective major and emergency non-cardiac surgery cohorts independent of underlying alterations in the sublingual microcirculation.
