Serum Lactate and Second ED Visits for Children With Bronchiolitis

Source: Kim G, Han S, Bae SP, et al. Lactate levels as a predictor of emergency department revisits in infants with acute bronchiolitis. Pediatr Emerg Care. 2024;40(9):p 660-664; doi: 10.1097/PEC.0000000000003220.Investigators from Soonchunhyang University, Asan, South Korea, conducted a retrospective study to identify biomarkers that predicted emergency department (ED) revisits within 24 hours after an index ED encounter among infants diagnosed with acute bronchiolitis. Study participants were infants with a clinical diagnosis of bronchiolitis who were seen at 1 of 3 EDs in South Korea between 2020 and 2022. Only patients who were not admitted at the time of the index ED visit, and on whom laboratory tests, including white blood cell count (WBC), C-reactive protein (CRP), lactate level, and arterial blood gases, were performed, were enrolled. Data including laboratory results, demographics, and vital signs (systolic and diastolic blood pressure [BP], pulse, and respiratory rate) were obtained from the medical records of participants. The primary outcome was a revisit for acute bronchiolitis within 24 hours of the index encounter. Univariate analysis was used to identify laboratory or vital signs associated with a revisit. For the identified variables, receiver operating characteristic (ROC) curve analysis was used to identify the cutoff value that maximized sensitivity and specificity. Multivariate regression was then used to identify independent predictors of a revisit.Data were analyzed on 172 patients with acute bronchiolitis, including 100 with a revisit within 24 hours (revisit group) and 72 with no revisit (discharge group). Children in the revisit group were significantly younger than those in the discharge group (median age 3.5 and 7.0 months, respectively; P = 0.02). The admission rate was 80% for those with a revisit within 24 hours. Among the assessed biomarkers, systolic BP, pulse rate, respiratory rate, lactate level, pH, and pCO2 all were statistically associated with a revisit (P <0.10). On multivariate analysis, only a lactate level >2.15 mmol/L was independently associated with a revisit. The sensitivity and specificity for a high lactate level in predicting a revisit were 83.3% (95% confidence interval [CI], 74.0, 90.4) and 79.4% (95% CI, 67.9, 88.3), respectively, and the positive and negative predictive values were 84.3% (95% CI, 75.0, 91.1) and 78.3% (95% CI, 66.7, 87.3), respectively.The authors conclude that high lactate levels were predictive of an ED revisit within 24 hours following an initial ED evaluation in infants with acute bronchiolitis.Dr Bechtel has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.Bronchiolitis is a source of considerable morbidity and mortality for young children. (See AAP Grand Rounds. 2024;51[6]:67.)1 It is estimated that worldwide, bronchiolitis causes 3.2 million pediatric hospitalizations and 59,000 deaths annually.2 Predicting which children will have severe disease requiring hospitalization would be helpful to pediatric providers. Additionally, reducing revisits can lead to decreased health care costs and alleviate ED overcrowding.Several authors have looked at clinical history and physical examination findings to predict which factors, such as age, age-adjusted respiratory rate, initial oxygen saturation, “ill or toxic” appearance, and adequate oral intake indicate children will have a second ED visit or severe disease requiring hospitalization.3,4 However, these clinical indicators are somewhat subjective, thus necessitating objective measures to determine the severity of bronchiolitis.In the current study, serum lactate levels were a significant independent predictor of unscheduled ED revisits for infants with acute bronchiolitis, offering the ability to objectively determine patient disposition and outcome at the initial ED visit. However, there are multiple study limitations that must be addressed before serum lactate is used as a prognostic factor in children with bronchiolitis.First, there may have been selection bias due to several factors: the retrospective nature of the study; a high proportion of patients without laboratory testing; and that the decision to obtain serum lactate was at the discretion of the attending emergency physicians. Second, there was the potential for patients revisiting other hospitals, which could not be excluded. Third, the authors did not stratify their analysis on differences in age groups within the first 12 months of life, as morbidity from bronchiolitis has been shown to be greater in younger infants.3,4 Fourth, the study investigators excluded infants with comorbidities, such as congenital diseases and prematurity, limiting the generalizability of their findings. Finally, the reasons for admission—whether the child needed positive pressure support, oxygen or parenteral fluid therapy—are not addressed in the revisit data. It would be helpful to know illness severity at the revisit, as only 2 patients required ICU admission.Serum lactate levels may be predictive of second ED visits in young children with bronchiolitis.Previous investigators who have examined laboratory data to assess severity and prognosis of bronchiolitis in infants have focused on inflammatory biomarkers (eg, procalcitonin, CRP).5 The current investigators also sought objective indicators, but solely of unscheduled ED revisits. The results, however, clearly require prospective validation.