Isolated High Lactate or Low Central Venous Oxygen Saturation After Cardiac Surgery and Association With Outcome

Objective To determine if isolated abnormally low central venous oxygen saturation (ScvO 2 ) or elevated lactate levels on admission to an intensive care unit (ICU) are associated with increased morbidity and length of stay (LOS) after cardiac surgery. Design Retrospective, observational. Setting Academic tertiary care hospital. Participants Six hundred twenty-nine adult, on-pump cardiac surgery patients with ScvO 2 and arterial lactate obtained on admission to the ICU. Interventions None. Measurements and Main Results Comparing outcomes across the isolated low ScvO 2 and high lactate categories, no significant differences in ICU/hospital LOS, ICU readmission rate, length of mechanical ventilation, or incidence of major complications were observed in patients with ScvO 2 2 ≥70%. However, patients with lactate≥4 mmol/L and ScvO 2 ≥70% exhibited significantly longer median ICU LOS (p = 0.018), hospital LOS (p = 0.032), length of mechanical ventilation (p = 0.0001), and higher incidence of major complications (p = 0.008). Multivariate analysis identified isolated elevated lactate levels≥4 mmol/L as an independent predictor for major complications (OR 4.29, p = 0.0008). Conclusions Low ScvO 2 with normal lactate or moderately elevated lactate with normal ScvO 2 upon ICU admission after cardiac surgery was not associated with increased morbidity or length of stay. Markedly elevated lactate levels in the setting of a normal ScvO 2 was associated with significantly higher incidence of major complications and prolonged length of stay. Additionally, a lactate level≥4 mmol/L was an independent predictor of major complications.