Admission and Sequentially Measured Plasma Lactate Concentrations as Prognostic Indicators in Adult Equine Emergencies
Blood lactate concentration [LAC] may be a useful indicator of disease severity and outcome in equine patients. We hypothesized that prognosis for survival decreases in the face of persistently increased [LAC].
Adult emergency admissions (excepting ophthalmologic, superficial wound, and septic synovitis) were included. Admission [LAC] was measured on a commercial blood gas analyzer. Subsequent [LAC] were determined at 6, 12, 24, 48, and 72 hours after admission with a lactate monitor validated for use in the horse. Animals euthanized for financial reasons were not included. Logistic regression was used to evaluate risk, as captured in the odds ratio of death with increased [LAC].
249 horses were enrolled. All 6 samples were obtained in 108 cases. Overall survival was ~82%. All colic patients treated medically survived, survival in surgically-managed colic patients was ~83%. All gastrointestinal ruptures were non-survivors. Overall, risk of non-survival was significantly (P<0.05) increased 7.3-fold for each mmol/L increase in [LAC] at admission, ~4-fold at 12 hours, ~5-fold at 24 hours, ~4 fold at 48 hours and ~50-fold at 72 hours. A diagnosis of 'Small Intestinal Strangulating' colic had an ~37-fold increased risk of death for each 1 mmol/l increase in [LAC] at admission, followed by 'Colitis' (~20-fold), 'Other" (~19-fold), and 'Reproductive' (~11-fold).
Increased [LAC] appears to have utility as a prognostic indicator at admission and subsequent time periods. Further evaluation of its use, particularly by specific diagnosis category, and utilizing survival analysis techniques, is forthcoming.