Association of blood lactate concentration and outcome in foals

Background: Lactate concentration in blood or plasma ([LAC]) and change in [LAC] are associated with survival in sick foals. Hypothesis: [LAC] and change in [LAC] over time are associated with survival at 96 hours and discharge in neonatal foals. Furthermore [LAC] and change in [LAC] over time correlate with blood culture results and blood pressure at admission. Animals: Two hundred and twenty-five foals consecutively admitted to a Neonatal Intensive Care Unit. Methods: Retrospective case review. Foals ≤30 days of age with [LAC] from arterial (190) or umbilical (35) blood gas analysis ([LAC] _BG) at admission, 24, and 48 hours. [LAC] _BG, blood pressure, blood culture status, and outcome (survival versus nonsurvival at 96 hours and discharge) were recorded. Change in [LAC] _BG over time ([LAC] _BGδ) was calculated. Results: [LAC] _BG was lower in survivors (96 hours and discharge) at all times. [LAC] _BGδ was larger for survivors (96 hours). Odds of survival (96 hours and discharge) decreased 18, 39, 53 and 22, 38, and 47%, respectively, at each sample time for every 1 mmol/L increment in [LAC] _BG and increased 156% for each 1.0/day increment in [LAC] _BGδ from admission to 24 hours at 96 hours. Blood pressure and [LAC] _BG were not correlated (P =.196) until removal of selected foals (mean arterial pressure <60mmHg, admission [LAC] _BG <5.5mmol/L) (P <.001). Bacteremia was not associated with [LAC] _BG. Proposed admission [LAC] _BG cut-points for future studies were 6.5mmol/L (96 hours) and 5.5mmol/L (discharge). Conclusions and Clinical Importance: Prospective studies evaluating [LAC], [LAC] _BGδ, and cut-points in sick foals are warranted.