Can initial lactate levels predict the severity of unintentional carbon monoxide poisoning?

Introduction: Accidental carbon monoxide (CO) intoxication is a major cause of unintentional poisoning. This study aimed to determine the value of initial lactate levels in patients with CO poisoning and to evaluate its utilization in the emergency department (ED). Methods: A retrospective cross-sectional study was carried out among patients with CO intoxication, who were admitted to the ED between April 1, 2011 and April 1, 2012. The study data were extracted from a hospital database system using International Classification of Diseases-10 diagnosis codes. The patients were analyzed according to lactate levels, carboxyhemoglobin (COHb) levels, electrocardiographic manifestations, and clinical features at admission to the ED. Results: A total of 74 patients with CO poisoning were enrolled in this study. The average COHb value of the patients was 21.5 +/- 13.9%. A total of 50 patients (67.6%) received normobaric oxygen treatment and 24 patients (32.4%) received hyperbaric oxygen (HBO) treatment. The patients who received HBO treatment had increased lactate levels compared with patients receiving normobaric oxygen treatment (2.3 mmol/L vs. 1.0 mmol/L, p < 0.001). The lactate levels were positively correlated with COHb values (r = 0.738, p < 0.001). We determined that a lactate level of 1.85 mmol/L has a sensitivity of 70.8% and a specificity of 78.0% to predict the HBO treatment needed in CO poisoning. Conclusion: In evaluating patients with CO poisoning, an initial lactate level could be taken into consideration as an adjunctive parameter of severity, together with the clinical criteria and levels of COHb.