Low brain tissue oxygenation contributes to the development of delirium in critically ill patients: A prospective observational study

Abstract Purpose To test the hypothesis that poor brain tissue oxygenation (BtO2 ) during the first 24 h of critical illness correlates with the proportion of time spent delirious. We also sought to define the physiological determinants of BtO2. Materials and methods Adult patients admitted to the ICU within the previous 24 h were considered eligible for enrollment if they required mechanical ventilation, and/or vasopressor support. BtO2 was measured using near-infrared spectroscopy, for 24 h after enrollment. Hourly vital signs and clinically ordered arterial and central venous blood gases were collected throughout BtO2 monitoring. Patients were screened daily for delirium with the confusion assessment method for the intensive care unit (CAM-ICU). Results BtO2 and the proportion of time spent delirious did not result in significant correlation (p = 0.168). However, critically ill patients who spent the majority of their ICU stay delirious had significantly lower mean BtO2 compared to non-delirious patients, (p = 0.017). BtO2 correlated positively with central venous pO2 (p = 0.00003) and hemoglobin concentration (p = 0.001). Logistic regression indicated that lower BtO2 , higher narcotic doses and a history of alcohol abuse were independent risk factors for delirium. Conclusions Poor cerebral oxygenation during the first 24 hours of critical illness contributes to the development of delirium. Trial registration This trial is registered on clinicaltrials.gov (Identifier: NCT02344043), retrospectively registered January 8, 2015.