Association of cerebral tissue oxygen saturation with the development of delirium in circulatory shock – a prospective observational cohort study

Delirium is a frequent neuropsychiatric complication in critical illness associated with increased risk of long-term cognitive impairment and mortality. We hypothesized that lower cerebral tissue oxygen saturation (cStO2) levels measured with near infrared spectroscopy (NIRS) associate with worse outcome, including mortality, and the risk for developing delirium in circulatory shock. We conducted the prospective, observational, multi-center study (ASSESS-SHOCK, ClinicalTrials.gov: NCT03814564), from April 2019 to May 2023. We enrolled adult circulatory shock patients within 24 hours of intensive care unit (ICU) admission. We registered cStO2 continuously for 48 hours using INVOS™ NIRS devices. We calculated the time-weighted mean cStO2 values and areas under the predefined thresholds of 60%, 50%, and 40% respectively. The primary objective was the association of time-weighted mean cStO2 during 0-48 hours with development of delirium during days 1-7. Secondary endpoints were ICU- and 90-day mortality. We included 256 patients, of whom 87 (34%) developed delirium. The 0-48 h mean cStO2 values did not differ between patients with and without delirium: 61.6% (interquartile range [IQR] 57.3 to 67.7) vs 63.1% (IQR 57.7 to 68.1, p=0.716), respectively. Lower time-weighted mean cStO2 during 48 hours was, however, associated with higher 90-day mortality: in non-survivors cStO2 was 60.0% (IQR 52.8 to 64.7) compared to 63.9% (IQR 58.1 to 68.9) in survivors (p<0.001). Conclusions: In circulatory shock, lower mean cStO2 values were not associated with delirium but they were associated with 90-d mortality. NIRS monitoring could serve as an adjunct method for identifying patients at risk for developing adverse outcomes, including mortality. Trial registration: ClinicalTrials.gov Identifier: NCT03814564, registered 15 January 2019. The ASSESS-SHOCK study: Assessment of peripheral perfusion, tissue oxygen saturation, endothelial function, and coagulation disorder in circulatory shock.