Regional cerebral oxygen saturation during initial mobilization of critically ill patients is associated with clinical outcomes: a prospective observational study.

Background: Vital signs help determine the safety of early mobilization in critically ill patients in intensive care units. However, none of these variables directly assess cerebral circulation. Therefore, we aimed to investigate the relationship of regional cerebral oxygen saturation (rSO₂) and vital signs with in-hospital death in critically ill patients.

Methods: This prospective study included critically ill patients admitted to the Uonuma Kikan Hospital Emergency Center who received physical therapy between June 2020 and December 2022. We continuously measured rSO₂ during the initial mobilization using a wearable brain near-infrared spectroscopy device. With in-hospital death as the primary endpoint, the association between rSO₂ and in-hospital death was assessed in Analysis 1 to determine the rSO₂ cut-off value that predicts in-hospital death. In Analysis 2, patients were categorised into survival and non-survival groups to examine the temporal changes in vital signs and rSO₂ associated with postural changes during mobilization.

Results: Of the 132 eligible patients, 98 were included in Analysis 1, and 70 were included in Analysis 2. Analysis 1 demonstrated that lower premobilization rSO₂ was independently associated with in-hospital death (odds ratio 0.835, 95% confidence interval 0.724-0.961, p = 0.012). Receiver operating characteristic curve analysis identified an optimal rSO₂ cut-off value of 57% for predicting in-hospital death (area under the curve 0.818, sensitivity 73%, specificity 83%). Analysis 2 showed that rSO₂ changes during mobilization were unrelated to changes in vital signs, suggesting rSO₂ as an independent prognostic marker.

Conclusions: The results suggest that rSO₂ measured during initial mobilization is associated with in-hospital death in critically ill patients.