Sequential L-lactate concentration in hospitalised equine neonates: A prospective multicentre study

Reasons for performing studyEvaluation 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 multicentre study of critically ill neonatal foals. ObjectivesTo prospectively evaluate the prognostic value of sequential [LAC] analysis in critically ill neonatal foals with risk of mortality. Study designProspective, observational study. MethodsThirteen university and private equine referral hospitals enrolled 643 foals over the 2008 foaling season and [LAC] was measured at admission ([LAC](ADMIT)) and 24 ([LAC](24)), 48 ([LAC](48)), 72 ([LAC](72)), 96 ([LAC](96)) and 120h ([LAC](120)) after admission. [LAC] changes over time ([LAC]) were calculated between sampling points. ResultsNonsurvivors had significantly greater [LAC](ADMIT), [LAC](24) and [LAC](48) compared with surviving foals (P<0.001). In nonsurviving foals [LAC] 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 1mmol/l [LAC] increase at all time points for all critically ill foals, independent of major final diagnoses as potential confounders. Septic foals had significantly greater [LAC] at all time points compared with nonseptic foals (P<0.001) and [LAC] in septic foals was significantly more positive (suggesting better clearance of lactate from the blood) only at [LAC](ADM-24) and [LAC](72-96) (P<0.01), while in nonseptic foals [LAC] was significantly positive between [LAC](ADM-24) compared with all other time periods (P<0.001). ConclusionsBlood lactate concentration is a strong, independent biomarker used to predict mortality in critically ill foals. Lactate metabolism is impaired in nonsurviving and septic foals and [LAC] can be utilised to identify patients at high risk for mortality.