Factors associated with favorable response to hyperbaric oxygen therapy among patients presenting with iatrogenic cerebral arterial gas embolism

Background: Iatrogenic cerebral arterial gas embolism (CAGE) is an uncommon but potentially a fatal condition. Hyperbaric oxygen (HBO₂) therapy is the only definitive treatment for patients with CAGE presenting with acute neurologic deficits. Methods: We reviewed medical records and neuroimaging of consecutive CAGE patients treated with HBO₂ at a state referral hyperbaric facility over a 22-year period. We analyzed the effect of demographics, source of intra-arterial gas, signs and symptoms, results of imaging studies, time between event and HBO₂ treatment, and response to HBO₂ treatment in 36 consecutive patients. Favorable outcome was defined by complete resolution or improvement of CAGE signs and symptoms at 24 h after HBO₂ treatment. Unfavorable outcome was defined by unchanged or worsened neurologic signs and symptoms or in hospital death. Results: A total of 26 (72%) of the 36 patients had favorable outcome. Patients with favorable outcome were younger compared to those with unfavorable outcome (mean age [years, SD] 44.7 ± 17.8 vs. 58.1 ± 24.1, p = 0.08). Cardiopulmonary symptoms were significantly more common in CAGE related to venous source of gas compared to arterial source (p = 0.024) but did not influence the rate of favorable outcomes. Adjusted multivariate analysis demonstrated that time from event to HBO₂ ≤6 h (positively) and the presence of infarct/edema on head computerized tomography (CT)/magnetic resonance imaging (MRI) before HBO₂ (negatively) were independent predictors of favorable outcome at 24 h after HBO₂ treatment [odds ratio (OR) 9.08 confidence interval (CI) (1.13-72.69), p = 0.0376, and (OR) 0.034 (CI) (0.002-0.58), p = 0.0200, respectively]. Two of the 36 patients were treated with thrombolytics because of acute focal deficits and suspected ischemia - one with intravenous and the second with intra-arterial thrombolysis. The latter patient developed fatal intracerebral hemorrhage. Conclusions: A high proportion of CAGE patients treated with HBO₂ had favorable outcomes. Time-to-HBO₂ ≤6 h increased the odds of favorable outcome, whereas the presence of infarct/edema on CT/MRI scan before HBO ₂ reduced the odds of a favorable outcome. Timely diagnosis and differentiation from thrombo-embolic ischemic events appears to be an important determinant of successful HBO₂ treatment.