The Effect of Red Blood Cell Transfusion on Cerebral Autoregulation in Patients with Severe Traumatic Brain Injury

Background: Red blood cell (RBC) transfusion is associated with inconsistent changes in brain tissue oxygenation (PbO2). Previous studies have failed to consider alterations in cerebral autoregulation. Our objective was to investigate the effect of RBC transfusion on cerebral autoregulation, as measured by pressure reactivity index (PRx). Methods: Retrospective analysis of 28 severe traumatic brain injury (TBI) patients from a prospective registry between 2007 and 2014. We recorded hemoglobin (Hb) concentration, intracranial pressure, PbO2, cerebral perfusion pressure, PRx, and cerebral lactate/pyruvate ratio for 6\ua0h before and after RBC transfusion. We also recorded body temperature, PaO2, PCO2, pH, and fraction of inspired oxygen. Subgroups of normoxia (PbO2 >20\ua0mmHg) and hypoxia (PbO2 2 increased [23.5\ua0mmHg (SD 8) to 25.0\ua0mmHg (SD 9), p\ua0=\ua00.033] following transfusion. PRx increased post-transfusion [0.028 (SD 0.29) to 0.11 (SD 0.24), p\ua0=\ua00.034], indicating worsening cerebrovascular pressure reactivity. In patients with mean PbO2 >20\ua0mmHg pre-transfusion (n\ua0=\ua020), the PRx increased significantly [ 120.052 (SD 0.24) to 0.079 (SD 0.22), p\ua0=\ua00.007] but did not change in patients with PbO2