Blood Volume DeterminationCarmineCardiac VolumeStrokeStroke VolumeCardiac OutputBlood VolumeHemodynamicsBrain IschemiaBlood PressureHeart RateCerebrovascular DisordersFluid TherapyThermodilutionCardiography, ImpedanceTime FactorsVentricular Function, LeftVascular ResistanceReproducibility of ResultsHeartProspective StudiesHypovolemiaMagnetic Resonance ImagingVentricular Function, RightPlasma VolumeCardiovascular Physiological PhenomenaHeart VentriclesBlood Flow VelocityCerebral HemorrhageMyocardial ContractionRisk FactorsCerebral InfarctionSex Determination ProcessesCentral Venous PressureTreatment OutcomeEchocardiography, DopplerOxygen ConsumptionVentricular FunctionDogsSystoleMonitoring, PhysiologicHeart Function TestsIschemic Attack, TransientSupine PositionHead-Down TiltPhysical ExertionCerebral AqueductFollow-Up StudiesEchocardiographySensitivity and SpecificityMonitoring, IntraoperativeExercise TestDiastolePulmonary Wedge PressureLower Body Negative PressureAcute DiseasePredictive Value of Tests