Association between Early Phase Serum Lactate Levels and Occurrence of Delayed Neuropsychiatric Sequelae in Adult Patients with Acute Carbon Monoxide Poisoning: A Systematic Review and Meta-Analysis

Abstract

The primary goal of treating carbon monoxide (CO) poisoning is preventing or minimizing the development of delayed neuropsychiatric sequelae (DNS). Therefore, screening patients with a high probability for the occurrence of DNS at the earliest is essential. However, prognostic tools for predicting DNS are insufficient, and the usefulness of the lactate level as a predictor is unclear. This systematic review and meta-analysis investigated the association between early phase serum lactate levels and the occurrence of DNS in adult patients with acute CO poisoning. Observational studies that included adult patients with CO poisoning and reported initial lactate concentrations were retrieved from the Embase, MEDLINE, Google Scholar and six domestic databases (KoreaMED, KMBASE, KISS, NDSL, KISTi and RISS) in January 2022. Lactate values were collected as continuous variables and analyzed using standardized mean differences (SMD) using a random-effect model. The risk of bias was evaluated using the Quality in Prognosis Studies (QUIPS) tool, and subgroup, sensitivity and meta regression analyses were performed. Eight studies involving a total of 1350 patients were included. The early phase serum lactate concentration was significantly higher in the DNS group than in the non-DNS group in adult patients with acute CO poisoning (8 studies; SMD, 0.31; 95% CI, 0.11–0.50; I2 = 44%; p = 0.002). The heterogeneity decreased to I2 = 8% in sensitivity analysis (omitting Han2021; 7 studies; SMD, 0.38; 95% CI, 0.23–0.53; I2 = 8%; p < 0.001). The risk of bias was assessed as high in five studies. The DNS group was associated with significantly higher lactate concentration than that in the non-DNS group.

Predictive Value of Complete Blood Count, Venous Blood Gas Measurements, and Glucose/Potassium Ratio for Delayed Neuropsychiatric Syndrome in Children with Acute Carbon Monoxide Poisoning Due to Coal-Burning Stove

“…Considering that the definition of high lactate level is 2 mmol/L or more, the median lactate values of the patients in the DNS (+) and DNS (−) groups were <2 mmol/L. 17 The reason for this result may be that patients admit to the emergency department in a short time after the poisoning occurs and they are not exposed to CO for a long time.…”

“… 16 The DNS group was associated with significantly higher lactate concentration than that in the non-DNS group in studies in adult patients. 17 However, the results of the studies on the relationship between lactate level and clinical severity in acute CO poisoning in children are not clear. 10 , 18 In some studies, lactate levels in CO poisonings were not statistically significant for the severe course in the acute phase in pediatric population.…”