Relationship between serum lactate levels and morbidity outcomes in cardiovascular patients after CABG

ABSTRACT

To evaluate the relationship between postoperative serum lactate levels and outcome in patients undergoing open heart surgery and verify the clinical impact of hyperlactatemia[HL] and low lactemia[LL] during CABG in terms of postoperative morbidity and mortality rate. Descriptive study. Sina Heart Centre [non-university hospital in Isphan, Iran] from fall 2005 to fall 2006. Hundred consecutive patients undergoing cardiac surgery with cardiopulmonary bypass were admitted in the study. Post operative lactate concentration and other metabolic parameters were determined. Evaluation of lactate concentrations, pH values and base excess during the first 24 post operative hours were assessed. Hyperlactatemia was defined as a peak arterial blood lactate concentration exceeding 3 mmol/l. Pre- and intraoperative factors were tested for independent association with the peak arterial lactate concentration and HL. The postoperative outcome of patients with or without hyperlactatemia was compared. We found positive effect of time on lactate and pH levels. On day 1, HL and LL patients had comparable lactate concentrations, which remained significantly higher than those of HL patients. HL is frequent after cardiac surgery. Based on our analyses, postoperative measurement of lactate level appears to be clinically useful. A threshold of 3 mmol/L at ICU admission was able to identify a subpopulation of patients at higher postoperative risk. Sequential determinations identified patients at higher risk for major complication and thus the need for closer surveillance of their therapeutic responses and their metabolic consequences