To the Editor Brown et al1 took a thought-provoking approach to deriving individualized mean arterial pressure (MAP) goals based on autoregulation parameters in an effort to reduce the incidence of delirium after cardiopulmonary bypass (CPB). We wonder about the reproducibility of this complex derivation of the MAP corresponding to the lower limit of autoregulation and whether this value derived from pre-CPB hemodynamic data are applicable to the cerebral blood flow state while on CPB.