Risk Factors for Middle Ear Barotrauma in Patients with Carbon Monoxide Poisoning Undergoing Monoplace Hyperbaric Oxygen Therapy: A Retrospective Cohort Study

<b>Background</b>: Hyperbaric oxygen therapy (HBOT) is the standard treatment for moderate to severe carbon monoxide (CO) poisoning, but middle ear barotrauma (MEB) remains a common complication. This study identified risk factors associated with MEB in patients undergoing monoplace HBOT. <b>Methods</b>: This retrospective cohort study included patients treated for CO poisoning with monoplace HBOT at a tertiary academic hospital between May 2021 and December 2023. MEB severity was assessed before and after treatment using video otoscopy and graded according to the modified O'Neill Grading System. <b>Results</b>: MEB occurred predominantly at lower severity grades according to the O'Neill scale. In univariate analysis, significant risk factors for MEB included altered mental status at presentation (OR: 3.16, 95% CI: 1.35-7.40, <i>p</i> = 0.008), serum albumin > 4.3 g/dL (OR: 0.22, 95% CI: 0.10-0.65, <i>p</i> = 0.004), and magnesium levels (OR: 0.21, 95% CI: 0.05-0.98, <i>p</i> = 0.046). Multivariate analysis confirmed altered mental status (OR: 3.16, 95% CI: 1.05-9.52, <i>p</i> = 0.041), albumin > 4.3 g/dL (OR: 0.26, 95% CI: 0.10-0.65, <i>p</i> = 0.004), and magnesium level (OR: 0.21, 95% CI: 0.05-0.88, <i>p</i> = 0.033) as independent predictors of MEB. Patients with higher albumin and magnesium levels showed lower risk. <b>Conclusions</b>: Altered mental status, lower albumin, and lower magnesium levels predicted middle ear barotrauma in patients undergoing monoplace HBOT for CO poisoning. These findings highlight the importance of careful pre-treatment evaluation and close monitoring during therapy to reduce the incidence of MEB.