Rapid changes in PPR occurring during monitoring can be explained by a change in MABP/ABP-AMP relationship, regardless whether ABP changes influence intracranial elastance or not.    ///    "Rapid changes in PPR occurring during monitoring can be explained by a change in MABP/ABP-AMP relationship, regardless whether ABP changes influence intracranial elastance or not. "    ///    In accordance with the theoretical assumptions the quotient MABP/ABP-AMP was found to be suitable to express these opposite effects on PPR. 