clinicaltrials.gov NCT00769691 and NCT00981474.

Decline in cognition 1 month after shoulder surgery is associated with brain cellular injury as demonstrated by elevated plasma GFAP concentrations.

Background Individualizing blood pressure targets could improve organ perfusion compared to current practices. In this study we assess whether hypotension defined by cerebral autoregulation monitoring versus standard definitions is associated with elevation in the brain specific injury biomarker glial fibrillary acidic protein plasma levels (GFAP). Methods Plasma GFAP levels were measured in 121 patients undergoing cardiac surgery after anesthesia induction, at the conclusion of surgery, and on post-operative day 1 (POD1). Cerebral autoregulation was monitored during surgery with the cerebral oximetry index (COx), which correlates low frequency changes in mean arterial pressure (MAP) and regional cerebral oxygen saturation. Blood pressure was recorded every 15 minutes in the ICU. Hypotension was defined based on autoregulation data as MAP < optimal MAP (MAP at lowest COx), and based on standard definitions (systolic blood pressure decrement > 20%, > 30% from baseline, and/or < 100mmHg). Results MAP (mean±SD) in the ICU was 74±7.3 mmHg; optimal MAP was 78±12.8 mmHg (p=0.008). The incidence of hypotension varied from 22% to 37% based on standard definitions, but it occurred in 54% of patients based on COx (p<0.001). There was no relationship between standard definitions of hypotentions and plasma GFAP levels, but MAP < optimal was positively related with POD1 GFAP levels (Coef, 1.77; 95%CI, 1.27-2.48; p=0.001) after adjusting for GFAP levels at the conclusion of surgery and low cardiac output syndrome. Conclusions Individualizing blood pressure management using cerebral autoregulation monitoring may better ensure brain perfusion than current practice.