Popliteal VeinVeinsFemoral VeinVenous InsufficiencyUltrasonography, Doppler, DuplexSaphenous VeinPhlebographySkin Diseases, VascularVaricose VeinsVenous PressureTransducers, PressureLegVenous ValvesVenous ThrombosisIntermittent Pneumatic Compression DevicesThrombophlebitisPopliteal CystPostphlebitic SyndromeCatheterization, PeripheralPortal VeinAneurysmConstriction, PathologicUltrasonography, Doppler, ColorPulmonary VeinsPlethysmographyVascular Surgical ProceduresJugular VeinsPulmonary EmbolismSupine PositionDermatitisMesenteric VeinsRenal VeinsUmbilical VeinsIliac VeinBlood Flow VelocityRegional Blood FlowHepatic VeinsHemodynamicsSubclavian Vein