Temporal trends in jugular bulb-to-arterial CO₂ difference as a prognostic biomarker in severe traumatic brain injury

Introduction Monitoring cerebral perfusion and metabolism is critical for mitigating secondary injury in Traumatic Brain Injury (TBI). The jugular bulb-to-arterial CO₂ difference (CO₂ gap) offers insights into regional cerebral perfusion and oxygen utilization, potentially serving as a prognostic biomarker in TBI. This study evaluates the prognostic significance of the CO₂ gap in predicting mortality in severe TBI. Methods Adult severe TBI patients post decompressive surgery requiring post-surgical ICU care were included. Jugular bulb and arterial blood gases were analyzed at 12, 24, and 48 h post-surgery to calculate the CO₂ gap. Primary outcomes included temporal trends in CO₂ gap values, and secondary outcomes included mortality at 14 and 28 days. Statistical analysis utilized a linear mixed-effects model and survival analysis. Results Eleven patients were included, with 18.2% surviving to day 14 and 9.1% surviving to day 28. Non-survivors demonstrated a lower CO₂ gap initially, followed by raising CO₂ gap. Survivors had a higher CO₂ gap initially, followed by decreasing but maintained CO₂ gap. Conclusion In this small, high-acuity cohort of severe traumatic brain injury patients requiring decompressive surgery, temporal trends in the jugular bulb-to-arterial CO₂ difference differed between survivors and non-survivors. The CO₂ gap demonstrates potential as a dynamic marker of early prognosis in severe TBI. These findings are preliminary and hypothesis-generating and require validation in larger, representative cohorts before prognostic application.