OBJECTIVES: Lactate has in some pediatric emergency departments (PEDs) gained acceptance as a screening tool for critical illness, with cut-off values of 2.0 to 2.5 mmol/L. We aimed to investigate if lactate could predict the need of acute resuscitation in patients in a PED.

PATIENTS AND METHODS: This retrospective observational cohort study included patients aged 0 to 17 years admitted to the PED at Copenhagen University Hospital in Denmark from January 1, 2019 to January 1, 2021. Patients were included if they had lactate measured as part of their routine blood sampling because of acute PED evaluation. Area under the receiver operating characteristic (ROC) curve (AUC) was calculated to assess the ability of lactate to predict the need of acute resuscitation. In patients without need of acute resuscitation, we calculated the lactate upper limit as the 95th percentile, and significant predictors were included in a multiple linear regression model.

RESULTS: A total of 1355 children were included. Fourteen (1%) children with a need of acute resuscitation had a median lactate of 1.7 mmol/L (interquartile range, 1.4-2.3) versus 1.6 mmol/L (interquartile range, 1.3-2.1) in children without need of resuscitation (P > 0.05). The AUC for lactate to predict acute resuscitation was 0.56 (95% confidence interval, 0.54-0.59). In children without need of acute resuscitation, the 95th percentile of lactate was 3.2 mmol/L, and 392 (29.8%) had lactate greater than 2.0 mmol/L. Increasing age and venous sampling were associated with lower lactate. Lactate was not associated with sex, pediatric early warning score, or duration of hospital admission. The 95th percentile of lactate after inhaled beta-2-agonists was 5.0 mmol/L.

CONCLUSIONS: In children evaluated in a PED, lactate achieved a low AUC, suggesting a poor ability of predicting acute resuscitation. In children without need of acute resuscitation, the 95th percentile for lactate was 3.2 mmol/L, higher than the generally accepted cut-off values. This is important to recognize to avoid concern in otherwise clinically stable children. Our data did not support the use of lactate as a screening tool for early recognition of critical illness in a PED.