Hybrid diffuse optical appraisal of peripheral and cerebral changes in critically ill patients receiving red blood...

Significance: Red blood cell transfusions (RBCTs) to restore hemoglobin concentration and hematocrit values in anemic patients are debated in critical illness. Aim: We used non-invasive hybrid diffuse optics (DO) to study RBCT's effect on the brain and peripheral muscle evaluated in critically ill patients. Approach: Critically ill patients admitted to the neurotrauma intensive care unit of the Vall d'Hebron University Hospital that required blood transfusion were included in the study and continuously monitored by DO methods alongside time-specific blood gas samples. Results: In 14 patients, blood-derived hemoglobin, hematocrit, and DO-derived metabolic rate of oxygen, oxy- and total hemoglobin significantly increased after RBCT. Oxygen extraction fraction significantly decreased. Blood flow significantly increased only in muscles. Deoxy-hemoglobin concentration remained unchanged. No significant differences were found between cerebral and peripheral signals post-RBCT, except for the metabolic rate of oxygen (higher in muscle). Conclusion: Hybrid DO monitoring quantifies cerebral and peripheral microvascular changes during red blood cell transfusion, enabling insights into oxygen metabolism and advancing critical care management.