Brain Tissue Oxygenation in the Contralateral Hemisphere of Critically Ill Patients with Spontaneous Intracerebral Hemorrhage: A Prospective Observational Study

Background Brain tissue oxygen pressure (PbtO₂) monitoring is increasingly used in neurocritical care, but whether PbtO₂ provides complementary information beyond conventional parameters such as intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in spontaneous intracerebral hemorrhage (ICH) is unclear. Methods We conducted a prospective, single-centre observational cohort study in a dedicated Neurocritical Care Unit between January 2021 and March 2023. Adult patients with spontaneous ICH requiring invasive multimodal brain monitoring were consecutively enrolled. Continuous monitoring included ICP, CPP, pressure reactivity index (PRx), bedside optimal CPP (CPPopt) and PbtO₂. Neuromonitoring data were analyzed during the first 48 hours and between days 3–7. Paired comparisons were used to assess temporal changes. Linear regression models were used to explore the relationship between PbtO₂, CPP, and PRx. Results Thirty-one patients were included, of whom 18 underwent PbtO₂ monitoring. ICP remained within normal ranges, while CPP increased significantly from the first 48 hours to days 3–7. PRx improved over time, suggesting better cerebrovascular autoregulation. In contrast, PbtO₂ values remained close to hypoxic thresholds and did not significantly differ between periods. During the first 48 hours, median PbtO₂ was 21.72 mmHg (IQR 18.67–27.04) despite preserved systemic oxygenation. No significant correlation was found between PbtO₂ and paO₂/FiO₂ ratio. In linear regression models the association between PbtO₂ and cerebral perfusion was more evident during the first 48 hours although visual inspection suggested a non-linear relationship, with higher PbtO₂ values clustering around a relatively narrow CPP range. Conclusions In critically ill patients with spontaneous ICH, brain tissue oxygenation, evaluated with PbtO₂, remains suboptimal despite controlled ICP, elevated CPP, and adequate systemic oxygenation. However, PbtO₂ may be closely related to cerebral perfusion dynamics, supporting its potential role as a complementary tool for individualized neurocritical care management.