Retrospective evaluation of the prognostic utility of plasma lactate concentration, base deficit, pH, and anion gap in canine and feline emergency patients

Abstract

Objective: To determine the association of plasma lactate concentration, pH, base deficit (BD), and anion gap (AG) in dogs and cats on presentation to an emergency room with outcome, and to compare the prognostic significance of hyperlactatemia with a concurrent metabolic acidosis with that of hyperlactatemia and a normal metabolic acid–base balance. Design: Retrospective study. Setting: University teaching hospital. Animals: Five hundred sixty-six dogs and 185 cats that had venous blood gas analysis performed. Interventions: None. Measurements and Main Results: Medical records were reviewed for plasma lactate concentrations, electrolyte concentrations, and acid–base parameters obtained on emergency room admission, clinical diagnosis, and in-hospital mortality. The primary outcome measure was all-cause mortality for the hospitalized visit. Median plasma lactate concentration and AG were higher, BD was more negative, and pH was lower, in non-survivor dogs and cats. The prevalence of hyperlactatemia was 53% in dogs and 30% in cats. Lactic acidosis was present in 42% and 80% of hyperlactatemic dogs and cats, respectively. Multivariate regression analyses revealed that plasma lactate concentration, BD, and pH, but not AG, were independent predictors of mortality in dogs, and that only plasma lactate concentration was an independent predictor of mortality in cats. Mortality was highest for animals with lactic acidosis, at 59.8% in dogs and 49% in cats. Mortality in dogs with lactic acidosis was significantly higher than dogs with hyperlactatemia and a normal acid–base status (P < 0.0001). Conclusions: The presence and magnitude of hyperlactatemia on presentation to the emergency room may help identify dogs and cats with high likelihood of in-hospital mortality, and the presence of lactic acidosis specifically may help identify dogs with yet higher risk of in-hospital mortality.