Blood Flow VelocityRegional Blood FlowUltrasonography, Doppler, TranscranialCerebrovascular CirculationLiver CirculationUltrasonography, Doppler, ColorArteriesVascular ResistanceUltrasonography, Doppler, PulsedUltrasonography, DopplerPulsatile FlowBlood PressureHepatic ArteryHemodynamicsMiddle Cerebral ArteryRheologyCerebral ArteriesOphthalmic ArterySplanchnic CirculationUmbilical ArteriesHeart RateDogsHyperemiaBlood CirculationCoronary CirculationUterusMesenteric Artery, SuperiorBronchial ArteriesLaser-Doppler FlowmetryHypocapniaFemoral ArteryPortal VeinCarbon DioxideCardiac OutputRetinal ArterySplenic ArteryCiliary ArteriesVeinsEchocardiography, DopplerMicrospheresEchoencephalographyHyperventilationPregnancyAnesthesiaMicrocirculationTime FactorsDiastoleUltrasonography, PrenatalOxygenAnterior Cerebral ArteryBlood Gas AnalysisUltrasonographyModels, CardiovascularIntracranial PressureLegReference ValuesHeart Rate, FetalHomeostasisPartial PressureSystoleVasodilationCoronary VesselsHypercapniaCeliac ArteryVasodilator AgentsSwineGestational AgeBrainAcetazolamideProspective StudiesDoppler EffectCircle of WillisVasomotor SystemReproducibility of ResultsTilt-Table TestFetal Growth RetardationCarotid Artery, InternalPulmonary CirculationBlood VolumeHypotension, OrthostaticCollateral CirculationEchocardiography, Doppler, ColorPlacental CirculationHemorheologyOxygen ConsumptionFetal HeartEchocardiographyBlood ViscosityRenal CirculationHypotensionVasoconstrictionPosturePosterior Cerebral ArteryHematocritRespirationFlow CytometryCarotid ArteriesAnalysis of VarianceLiverRetinal Vessels