Sequential L-lactate concentration in hospitalized equine neonates: a prospective multicenter study

Reasons for performing the study: Evaluation of serial blood lactate concentrations [LAC] are of prognostic value for morbidity and mortality in critically ill human patients and neonatal foals but have not been prospectively evaluated in a large multi-center study of critically ill neonatal foals. Objectives: To prospectively evaluate the prognostic value of sequential [LAC] analysis in critically ill neonatal foals with risk of mortality. Study design: Prospective, observational study Methods: Thirteen university and private equine referral hospitals enrolled 643 foals over the 2008 foaling season. [LAC] was measured at admission and 24, 48, 72 and 120 after admission. [LAC] changes over time ([LAC]∆) were calculated between sampling points. Results: Non-survivors had significantly greater [LAC]ADMIT, [LAC]24, and [LAC]48 compared to surviving foals (p < 0.001). [LAC]∆ in non-surviving foal did not decrease over time while survivors showed significant positive [LAC]∆ between [LAC]ADM-24 and all other time periods (p < 0.001). Logistic regression analysis showed that the odds of survival decreased for each 1 mmol/L [LAC] increase at all time points for all sick foals, independent of major final diagnoses as potential confounders. Septic foals showed significantly greater [LAC] at all time points compared with non-septic foals (p < 0.001). [LAC]D in septic foals was significantly more positive (suggesting better clearance) at [LAC]ADM-24 and [LAC]72-96 (p < 0.01), while in non-septic foals [LAC]D was significantly positive between [LAC]ADM-24 compared to all other time periods (p < 0.001). Conclusions: [LAC] is a strong, independent biomarker to predict mortality in critically ill foals. Lactate metabolism is impaired in non-surviving and septic foals and [LAC]D can be utilized to identify patients that are at high risk for mortality. Potential relevance: Sequential [LAC] analysis identifies impaired lactate metabolism in critically ill foals and helps to identify foals that are at risk of dying