Visualizing the burden of brain tissue hypoxia and metabolic dysfunction assessed by multimodal neuromonitoring in subarachnoid hemorrhage patients: the TITAN study

Abstract

Purpose: Brain tissue hypoxia and metabolic dysfunction are common in patients with subarachnoid hemorrhage (SAH) and may worsen prognosis. We aimed to assess the impact of episodes of low brain tissue partial pressure of oxygen (PbtO₂) and metabolic dysfunction (elevated lactate pyruvate ratio-LPR measured by cerebral microdialysis, CMD) on neurological outcome at 6 months.

Methods: This is a multicentric retrospective cohort study of SAH patients admitted to 5 neurocritical care units who required invasive multimodal neuromonitoring. The relationship between episodes of low PbtO₂ combined with elevated LPR and 6-month Glasgow Outcome Scale (GOS) was visualized in a color-coded plot. We performed a multivariate analysis of the association between the percentage of time spent with the low PbtO₂ and/or high LPR and neurological outcome and mortality at 6 months.

Results: We included 232 SAH patients with a median of 117 (IQR 77-154) h of monitoring per patient. The color-coded plot illustrated that combined episodes of low PbtO₂ and elevated LPR were prevalent in patients with unfavorable neurological outcome (e.g., GOS 1-3). This association was less evident in patients with isolated low PbtO₂ or isolated elevated LPR_. In a multivariate model, the cumulative PbtO₂/LPR burden was independently associated with unfavorable neurological outcome.

Conclusions: In this study, low PbtO₂ and metabolic insults were more prevalent among SAH patients with unfavorable long-term neurological outcome at 6 months. The role of multimodal neuromonitoring in guiding therapies and potentially influencing the outcome of these patients warrants further studies.

Keywords: Brain metabolism; Brain oxygenation; Invasive multimodal monitoring; Stroke.