Hemodilution Combined With Hypercapnia Impairs Cerebral Autoregulation During Normothermic Cardiopulmonary Bypass

Objective To investigate the influence of hemodilution and arterial pCO2 on cerebral autoregulation and cerebral vascular CO2 reactivity. Design Prospective interventional study. Setting University hospital-based single-center study. Participants Forty adult patients undergoing elective cardiac surgery using normothermic cardiopulmonary bypass. Interventions Blood pressure variations induced by 6/minute metronome-triggered breathing (baseline) and cyclic 6/min changes of indexed pump flow at 3 levels of arterial pCO2. Measurements and Main Results Based on median hematocrit on bypass, patients were assigned to either a group of a hematocrit≥28% or