A103-23 Association of Cerebral Hypoxia Measured by the Jugular Bulb Venous-Arterial Co₂ to Arterial-Venous O₂ Content Difference Ratio With Mortality in Acute Brain Injury

Abstract

RationaleAcute brain injury (ABI) is largely driven by impaired cerebral oxygen delivery that compromises oxidative metabolism. Although advanced neuromonitoring techniques can identify cerebral hypoxia, their limited availability restricts widespread implementation. Jugular bulb arteriovenous blood gas analysis offers a pragmatic, global assessment of cerebral metabolism at the bedside. The ratio of the venoarterial carbon dioxide tension difference to the arteriovenous oxygen content difference (P(v-a)CO₂/C(a-v)O₂) reflects the balance between cerebral oxygen extraction and carbon dioxide production and may serve as a surrogate of tissue hypoxia. However, the prognostic value of this index, specifically when derived from jugular bulb arteriovenous blood gases, has not been previously evaluated in patients with ABI. We aimed to evaluate the association between early cerebral hypoxia defined by this ratio and in-hospital mortality in mechanically ventilated patients with ABI.MethodsWe conducted a retrospective cohort study including adult patients with ABI admitted to a neurocritical care unit who required invasive mechanical ventilation and jugular bulb catheterization, with paired arterial and jugular venous blood gases obtained at ICU admission and 12 hours. Early cerebral hypoxia was defined using the P(v-a)CO₂/C(a-v)O₂ ratio, with the optimal threshold for mortality discrimination identified through receiver operating characteristic (ROC) analysis. The primary outcome was in-hospital mortality. Survival was analyzed using Kaplan-Meier curves and Cox proportional hazards models. Multivariate models were adjusted for age, Sequential Organ Failure Assessment (SOFA) Score and Glasgow Coma Scale at admission.ResultsA total of 115 patients were included; median age was 56 years (IQR 41.0-67.0), and in-hospital mortality was 43.5%. ROC analysis identified a P(v-a)CO₂/C(a-v)O₂ ratio ≥1.9 as the optimal threshold to define cerebral hypoxia (AUC-ROC 0.59), which was present in 43.5% of patients. In the 30-day truncated Cox model, early cerebral hypoxia was associated with a significantly increased hazard of death (hazard ratio [HR] 1.75; 95% CI 1.05-2.93; p = 0.03). Logistic regression models evaluating early mortality demonstrated a consistent direction of association. Findings remained similar after adjustment for age, SOFA and Glasgow Coma Scale at admission.ConclusionsEarly cerebral hypoxia identified by a P(v-a)CO₂/C(a-v)O₂ ratio ≥1.9 is associated with increased in-hospital mortality risk in mechanically ventilated patients with acute brain injury. Jugular bulb-derived metabolic monitoring may represent an accessible approach for early physiological risk stratification in neurocritical care. Prospective studies are needed to determine whether targeted interventions guided by P(v-a)CO₂/C(a-v)O₂ ratio can improve outcomes.

This abstract is funded by: None