Serum phosphate is not an early predictor of neurocognitive outcomes in acute carbon monoxide poisoning patients

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.