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

Journal of Critical Care October 2017 Volume 41, Pages 289–295

The Cerebral Oxygenation and Neurological Outcomes Following Critical Illness (CONFOCAL) Research Group on behalf of the Canadian Critical Care Trials Group,

Authors: Michael D. Wood, BA et al

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 a significant correlation (p = 0.168). However, critically ill patients who spent the majority of their ICU stay delirious had significantly lower mean BtO₂compared 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.