The Relationship Between Carboxyhemoglobin Level and Red Cell Distribution Width and Inflammatory Indices in Cases of Carbon Monoxide Poisoning

Aim: Carbon monoxide (CO) poisoning is an important cause of morbidity and mortality among emergency department admissions. Although carboxyhemoglobin (COHb) level is a widely used marker, it may not always reflect clinical severity and biological response. This study aimed to evaluate the relationship between COHb levels, red cell distribution width (RDW), and hemogram-derived inflammatory indices in patients presenting with CO poisoning.Material and Methods: This retrospective, descriptive, and cross-sectional study included 216 patients diagnosed with CO poisoning between January 1, 2020, and December 31, 2024. Demographic data, complete blood count parameters, biochemical parameters, and arterial blood gas results were recorded. The relationships between COHb and RDW, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), multiple inflammation indices (MII-1, MII-2, MII-3), pan-immune-inflammation value (PIV), and lactate were analyzed using Spearman correlation analysis.Results: In patients who were followed without hospitalization, COHb levels showed significant positive correlations with NLR, PLR, SII, MII-1, MII-2, MII-3, and lactate. In patients receiving hyperbaric oxygen therapy, COHb was positively correlated with NLR, SII, PIV, and lactate. In patients who did not receive hyperbaric oxygen therapy, a significant negative correlation was observed between COHb and RDW. No significant inflammatory associations were found in ward or intensive care patients.Conclusion: Inflammatory indices derived from routine hemogram parameters, when evaluated together with COHb and lactate, may contribute to understanding the early systemic inflammatory and metabolic response in CO poisoning. RDW appears to show variability depending on clinical subgroups.