Objective: To study and quantify the relationship between dynamic lactic acid monitoring indexes and prognosis of critically ill patients in intensive care unit (ICU).
Methods: One hundred and one critically ill patients with elevated blood lactic acid level were included in this study and divided into death group (n=50) and survival group (n=51). Differences in their lactic acid indexes (including: lactic acid level, duration of lacticemia, lactic clearance), acute physiology and chronic health evaluation II (APACHEII) score, and other clinical indicators which reflected organ/system status were compared, and prognostic significant lacticemia indexes were formulated by multi-variable logistic analysis. Subsequently, patients were grouped by significant lactic indexes separately and compared with incidence of shock/multiple organ dysfunction syndrome (MODS), APACHE II score and mortality.
Results: Differences in lactic acid level, peak lactic acid level, 12-hour and 24-hour lactic acid clearance between death group and survival group showed statistically significant difference (P<0.05 or P<0.01). Peak lactic acid level, 12-hour lactic clearance, APACHE II score and blood pH had significant correlation with prognosis, odds ratios (OR) were 1.466, 0.922, 1.208, 0.032, respectively. Patients with peak lactic acid value> or =10 mmol/L or 12-hour lactic clearance< or =10% had significantly higher mortality: 77.8% and 70.6%, respectively (P<0.05 and P<0.01). Although patients with lacticemia>24 hours had higher mortality, there was no statistically significant difference.
Conclusion: Peak lactic acid level, 12-hour lactic clearance, APACHE II score and blood pH are good indicators to evaluate patients' prognosis. Peak lactic acid value> or =10 mmol/L or 12-hour lactic clearance< or =10% is an alert of extremely bad prognosis. Prognosis value of duration of lacticemia is limited.