Objective
Carbon monoxide (CO) poisoning causes brain injury by hypoxia and inflammatory mechanisms. Hypoxic conditions result in increased serum phosphate concentration due to loss of polarity of the cell membrane, changes in membrane fluidity, and consequent destruction of phospholipids in the cell membrane. This study aimed to evaluate whether serum phosphate measured in the emergency department (ED) can serve as an early predictor of neurocognitive sequelae 1 month after acute CO poisoning.
Methods
We included patients ≥16 years with acute CO poisoning from a cohort who were treated at a single tertiary academic hospital in Wonju, Korea, between January 2006 and May 2021. Neurocognitive outcome was assessed using the Global Deterioration Scale score; patients were classified into favorable (1–3 points) or poor (4–7 points) neurocognitive outcome groups based on this score. These two groups were compared before and after propensity score matching.
Results
Data from 888 patients were analyzed. Seven hundred seventy-one patients (86.8%) were assigned to the favorable outcome group and 117 patients (13.2%) to the poor outcome group. Patients with a poor outcome had a higher mean serum phosphate level than those with a favorable outcome (3.9 mg/dL vs. 3.5 mg/dL, P=0.001). Propensity score matching yielded 85 matched patient pairs. After matching, serum phosphate level in the ED was not significantly different between the favorable and poor outcome groups (3.9 vs. 3.7 mg/dL, P=0.349).
Conclusion
Serum phosphate level measured in the ED did not predict poor neurocognitive outcomes 1 month after CO poisoning.

Objective
Carbon monoxide (CO) activates intravascular neutrophils through platelet-neutrophil aggregates, which cause neutrophil degranulation. This process causes the release of myeloperoxidase (MPO), proteases, and reactive oxygen species. The MPO index (MPXI) is a newly reported inflammatory marker that reflects the MPO level within neutrophils. The MPXI in conditions associated with neutrophil activation depends on the net effect of azurophil degranulation. This study aimed to determine whether the MPXI can predict neurocognitive prognosis 1 month after acute CO poisoning.
Methods
We included patients aged ≥16 years with acute CO poisoning from a cohort at a single tertiary academic hospital in Wonju, Korea, between January 2010 and May 2021. Data from 699 patients were analyzed. The neurocognitive outcome was assessed using Global Deterioration Scale scores and classified as favorable (score, 1–3 points) or poor (score, 4–7 points). The MPXI was determined within 1 hour of arrival to the emergency department.
Results
Among the 699 patients, 52 (7.4%) showed poor outcomes. The median MPXI of the patients in the poor outcome group was higher than that of the favorable outcome group (0.85 vs. 0.2, P=0.189). However, a significant difference was not found between the favorable and poor outcome groups, and MPXI was not a significant variable in multivariate logistic regression.
Conclusion
The MPXI evaluated in the emergency department did not differ based on neurocognitive outcome at 1 month after acute CO poisoning.