Blood Flow VelocityQuantum DotsRegional Blood FlowQuantum TheoryUltrasonography, Doppler, TranscranialCerebrovascular CirculationMiddle Cerebral ArteryUltrasonography, DopplerOphthalmic ArteryCerebral ArteriesPulsatile FlowUltrasonography, Doppler, ColorUltrasonography, Doppler, PulsedCoronary CirculationBlood PressureVascular ResistanceLaser-Doppler FlowmetryHemodynamicsHypocapniaCiliary ArteriesRetinal ArteryEchocardiography, DopplerEchoencephalographyRheologyUmbilical ArteriesHyperventilationCarbon DioxideMicrocirculationDiastoleUltrasonography, PrenatalAnterior Cerebral ArteryHyperemiaCadmium CompoundsHeart RateUltrasonographyModels, CardiovascularArteriesReference ValuesIntracranial PressureSystoleHeart Rate, FetalCeliac ArteryCoronary VesselsHomeostasisVasodilationTime FactorsAcetazolamideGestational AgeOxygenVasodilator AgentsDogsDoppler EffectPregnancyMesenteric Artery, SuperiorBrainReproducibility of ResultsFetal Growth RetardationSelenium CompoundsCircle of WillisEchocardiography, Doppler, ColorCarotid Artery, InternalPlacental CirculationProspective StudiesCollateral CirculationHemorheologyTilt-Table TestFetal HeartFlow CytometryPosterior Cerebral ArteryVasomotor SystemHypotension, OrthostaticEchocardiographySplanchnic CirculationHypercapniaBlood ViscosityPulmonary CirculationBlood Circulation TimePostureSemiconductorsBlood VolumePartial PressurePapaverineRetinal VesselsAdenosineUterusEchocardiography, TransesophagealVasoconstrictionEchocardiography, Doppler, PulsedCardiac OutputMicrospheresRenal CirculationCarotid ArteriesOxygen ConsumptionSensitivity and SpecificityMitral ValveVentricular Function, LeftOrthostatic IntoleranceInfant, NewbornAnalysis of VarianceFetus