Serum lactate level as predictor of mortality and morbidity followlng coronary artery bypass grafting

Background / objective: Risk stratification for predicting mortality and morbidity is widely used in cardiac surgery. However, prediction of individual outcome shortly after cardiac surgery is difficult. Postoperative hyperiactemia has been related to an increased rate of postoperative complications and increased mortality following cardiac surgery. The aim of this study was to evaluate the frequency of intraoperative and postoperative hyperiactemia and to assess the value of serum lactate level in predicting mortality and morbidity following surgery. Patients and methods: 600 consecutive CABG from January 5, 2003 to December 30, 2003 at the Vilnius University Hospital Santariskiu Clinics were investigated. Serume lactate levels were measured before cardiopulmonary bypass, before declamping of the aorta, after heparin neutralization and at ICU admission. Morbidity was defined as the presence of one or more of the following categories of complications: cardiac, pulmonary, neurological and renal. Results: Lactate level greater than 5 mmol/l was found in 2.5% of patients during cardiopulmonary bypass, in 6.7% of patients shortly after weaning from CPB, and in 10.8% of patients on ICU admission. The mortality rate of patients with hyperiactemia at ICU admission was 19.3% and morbidity 59.6%. The mortality rate of patients without hyperiactemia was 3.2% and morbidity 10.3%. Conclusions: Hyperiactemia was quite frequent following cardiac surgery. Increased lactate levels (> 5 mmol/l) were found in more than 10% of patients following CABG surgery on ICU admission. Increased serum lactate levels following coronary artery bypass grafting identifies a group of patients with an increased risk of postoperative mortality and morbidity