Arterial lactate concentration, hospital survival, sepsis and SIRS in critically ill neonatal foals

Summary Reasons for performing study: Blood lactate concentration has been shown to be a useful clinical indicator in human patients, but has not been formally investigated in critically ill foals. Objective: To investigate the association of blood lactate with hospital survival, markers of cardiovascular status, metabolic acid base status, sepsis and systemic inflammatory response syndrome (SIRS). Methods: A database containing clinical, haematological, plasma biochemical and hospital outcome data on neonatal foals referred to an intensive care unit in 2000-2001 was analysed. Seventy-two foals for which arterial lactate was measured at admission were included in the study. Results: Sixty-one foals had an admission lactate concentration >2.5 mmol/1. Admission lactate was statistically associated with hospital survival, mean arterial pressure, blood creatinine concentration, bacteraemia, anion gap, lactate concentration at 18-36 h after admission and evidence of SIRS, but not with packed cell volume or heart rate. Lactate at 18-36 h was also associated with survival and evidence of SIRS. Anion gap, base excess, base excess due to unidentified anions (BEua), simplified strong ion gap or bicarbonate correctly classified foals for presence of hyperlactaemia (>5 mmol/1) in 80% of animals. Conclusions: Admission blood lactate gives important prognostic information. Lactate should be measured rather than assumed from the anion gap, base excess, BEua, simplified strong ion gap or bicarbonate. Potential relevance: Blood lactate concentrations at admission are clinically relevant in neonatal foals and warrant further investigation. This should include the clinical value of measuring changes in lactate in response to treatment.