Metabolic Acidosis Modifies Carboxyhemoglobin-serum Potassium Link in CO Poisoning: A Cross-sectional Study

Abstract

This study aimed to investigate whether metabolic acidosis modifies the association between carboxyhemoglobin (COHb) and serum potassium in acute carbon monoxide (CO) poisoning patients. A cross-sectional analysis was conducted on 124 patients. Serum potassium was the outcome, COHb saturation the exposure, and metabolic acidosis was defined as a standard base excess (SBE) < −3 mmol/L. The interaction was analyzed using multiple linear regression. The interaction between COHb and metabolic acidosis on serum potassium was significant (β = −0.0184, 95% CI: −0.0362 to −0.0005, P = 0.044). Subgroup analysis showed a stronger effect in patients with SBE < −4 mmol/L (β = −0.0269, P = 0.002). In conclusion, metabolic acidosis significantly enhances the negative association between COHb and serum potassium in acute CO poisoning, with the effect intensifying with acidosis severity. This highlights the need for integrated assessment of blood gas and electrolyte indicators, particularly in patients with moderate to severe acidosis, to mitigate the risk of a pronounced COHb-driven decrease in potassium.