Hyperlactatemia and low central venous saturation can predict prognosis after cardiac surgery

Introduction

Hyperlactatemia and low central venous saturation are commonly encountered in critically ill patients and carry a prognostic significance in those with sepsis. Few reports, however, have examined the relationship between these parameters immediately after cardiac surgery and clinical outcome. We examined the ability of the arterial plasma lactate concentration and central venous saturation to predict patient outcome after cardiac surgery.

Methods

We performed a consecutive observational study in a university hospital. A total of 125 patients undergoing cardiac surgery were studied. Demographic data were analyzed. Samples of arterial lactate, arterial gases, and central venous saturation were collected at the time of admission in the ICU, 12 and 24 hours later. Univariate and multivariate analyses were performed.

Results

Of the 125 patients in this study, 115 (92%) patients survived and 10 (8%) died. The lactate level was higher in nonsurvivors than in survivors (P < 0.001). A higher lactate level (>3.3 mmol/l) was an independent predictor of death (OR = 23, 95% CI = 3.9–136), of occurrence of arrhythmias (OR = 5.36, 95% CI = 1.9–15), renal dysfunction (OR = 9.93, 95% CI = 2.9–34), and shock (OR = 67.2, 95% CI = 6.4–710). There were no relationships of higher level of lactate and longer time of stay in the ICU, cardiac dysfunction or myocardial ischemia. Low central venous saturation (<60%) was an independent predictor of arrhythmias (OR = 12.74, 95% CI = 3.45–47), infection (OR = 6.61, 95% CI = 2.2–19.6), shock (OR = 16.7, 95% CI = 1.8–156), and need for transfusion (OR = 3.68, 95% CI = 1.25–10.8). There were no relations of low central venous saturation with cardiac dysfunction, renal dysfunction or myocardial ischemia.

Conclusion

In this observational study, the postoperative plasma arterial lactate and central venous saturation concentration strongly and independently predicted the outcome after cardiac surgery. These findings suggest that these parameters may be markers of prognosis after cardiac surgery and support the role of hemodynamic optimization in reducing complications.