The correlation between lactate levels and the length of stay in the intensive care unit in post-operative patients of rheumatic valvular heart disease surgery

Background: Valvular heart surgery with cardiopulmonary bypass (CPB) may be accompanied by increased serum lactate levels. Serum lactate levels can predict postoperative outcomes. This study aimed to correlate serum lactate levels to the length of stay (LOS) in the intensive care unit (ICU) in patients with rheumatic valvular heart surgery (RVHS). Method: This was a prospective cohort study of thirty (30) patients with post-cardiac surgery of RVHS from February 2016 to June 2019 in Dr. Kariadi Hospital Semarang, Indonesia. Subjects were selected by consecutive sampling. Serum lactate levels were examined in one hour after RVHS. Patients were divided into 2 groups, i.e. group with lactate levels <3.0 mmol/L and with ≥3.0 mmol/L. Patients were followed up during hospitalization. The differences in LOS in the ICU were analyzed using the Mann-Whitney test. The correlation between serum lactate levels and the LOS in the ICU was analyzed by the Spearman correlative test. Results: The average lactate level in the ICU was 3.9 ± 1.06 mmol/L. The average CPB time was 68.7 ± 8.55 minutes. The median of LOS in ICU was 3 days (range 2–6 days). There were no differences in baseline characteristics, echocardiographic, and laboratory data between both groups, except height (p=0.036), heart rate (p=0.025), and CPB time (57.40 ± 4.93 vs 71.00 ± 7.22, p=0.001). There were no significant differences in LOS in total in-hospital stay (p=0.813) and LOS in ICU stay ( p=0.132) between both groups. There was a significant positive moderate correlation between serum lactate levels and the LOS in the ICU (Spearman r=0.522, p=0.003). Conclusion: There was a moderate positive correlation between serum lactate levels and the LOS in ICU patients with RVHS. If confirmed by further studies, lactate levels may be a predictor for the outcome of RVHS.