Dissociation between the bispectral index and central hemodynamics during cardiopulmonary bypass and hypothermia in children with congenital heart defects

Heart rate (HR) and arterial pressure remain the most widely used clinical guides to the depth of anesthesia. In pediatric cardiac surgery, however, their informative value is limited: during cardiopulmonary bypass, hemodynamic variables are determined mainly by the perfusion regimen (pump flow, circuit pressure, perfusate temperature and vasomotor tone controlled by the perfusionist) rather than by the autonomic response to anesthetic depth. The extent to which the relationship between the Bispectral Index (BIS) and central hemodynamics is preserved at different stages of surgery in children has not been sufficiently quantified, although this determines whether hemodynamic variables can serve as surrogate markers of anesthetic depth.