Blood Flow VelocityMiddle Cerebral ArteryCerebral ArteriesUltrasonography, Doppler, TranscranialCerebrovascular CirculationHypocapniaRegional Blood FlowHomeostasisCarbon DioxideBlood PressurePulsatile FlowUltrasonography, DopplerMephentermineUterusEphedrineArteriesOphthalmic ArteryEchoencephalographyFetal Growth RetardationUltrasonography, Doppler, ColorInfarction, Middle Cerebral ArteryUltrasonography, Doppler, PulsedHemodynamicsHypotension, OrthostaticUmbilical ArteriesPregnancyVascular ResistanceMesenteric Artery, SuperiorAnterior Cerebral ArteryFemoral ArteryHeart RateLaser-Doppler FlowmetryCoronary CirculationPosterior Cerebral ArteryBrainOxygenSpectroscopy, Near-InfraredCarotid ArteriesCircle of WillisCerebral InfarctionUltrasonographyUltrasonography, PrenatalCarotid Artery, InternalRheologyRetinal ArteryBrain IschemiaPulmonary ArteryBasilar ArteryBronchial ArteriesVasodilationCerebral AngiographyGestational AgeMicrocirculationSplanchnic CirculationDogsPlacental CirculationHyperemiaVasodilator AgentsCoronary VesselsTime FactorsVasoconstrictionReference ValuesExerciseCerebral Arterial DiseasesHeart Rate, FetalBrachial ArteryCerebrovascular DisordersArterial Occlusive DiseasesUterine ArteryCiliary ArteriesEchocardiography, DopplerCarotid Artery, ExternalMesenteric ArteriesProspective StudiesCardiac OutputHyperventilationRenal ArteryVertebral ArteryOxygen ConsumptionIschemic Attack, TransientCeliac ArteryRadial ArteryIntracranial PressureCarotid Artery, CommonNitroglycerinAnalysis of VarianceDiastoleUltrasonography, Doppler, DuplexModels, CardiovascularSubarachnoid HemorrhageAcetazolamideMagnetic Resonance AngiographyCerebral VeinsAltitudeFetusPostureLegHypercapniaCerebral PalsyVasomotor System