Valsalva ManeuverVagus NerveSinus of ValsalvaVagus Nerve StimulationVagus Nerve DiseasesAutonomic Nervous SystemVagus Nerve InjuriesVagotomyAutonomic Nervous System DiseasesHeart Septal Defects, AtrialHeart RateBlood PressurePelvic FloorEmbolism, ParadoxicalPure Autonomic FailurePostureReflexUltrasonography, Doppler, TranscranialBaroreflexHypotension, OrthostaticHeadache Disorders, PrimarySupine PositionRespirationSciatic NerveForamen Ovale, PatentMaximal Voluntary VentilationPneumocephalusNerve FibersButylscopolammonium BromideUterine ProlapseKinetocardiographyHypovolemiaAortic AneurysmParasympathetic Nervous SystemPatient PositioningPeripheral NervesSympathetic Nervous SystemTilt-Table TestVaricocelePressoreceptorsEchocardiography, TransesophagealPerineumOptic NerveCentral Venous PressureElectric StimulationThoraxPressureHead-Down TiltHemodynamicsHemostasis, SurgicalMicroscopy, AcousticGlossopharyngeal NerveCoughHeartElectric Stimulation TherapyBlood Flow Velocity