Isolated High Lactate or Low Central Venous Oxygen Saturation AfterCardiac Surgery and Association with Outcome

Abstract

Objective

To determine if isolated abnormally low central venous oxygen saturation (ScvO₂) 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.

Methods

Retrospective, observational. Academic tertiary care hospital. Six hundred twenty-nine adult, on-pump cardiac surgery patients with ScvO₂ and arterial lactate obtained on admission to the ICU. 

Results

Comparing outcomes across the isolated low ScvO₂ 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 ScvO₂<70% and lactate<2 mmol/L or in those with lactate 2-3.9 mmol/L and ScvO₂≥70%. However, patients with lactate≥4 mmol/L and ScvO₂≥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).  

Conclusion

Low ScvO₂ with normal lactate or moderately elevated lactate with normal ScvO₂ 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 ScvO₂was 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.

J Card Vasc Anest 9 Set 2013 (Online First) (Abstract)