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KMID : 1024120130600010055
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Journal of Aerospace Medical Center, ROKAF
2013 Volume.60 No. 1 p.55 ~ p.65
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Role of Hepatic Vein to Maintain Venous Return During Valsalva Maneuver
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Bang Dong-Ho
Lim Dae-Keon
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Abstract
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Introduction : Gravity-induced loss of consciousness(G-LOC) is caused by loss of cerebral blood flow during high +Gzforce (cranio-caudaldirection).Theanti-gravity straining maneuver (AGSM)is known to be the method to preventG-LOC.The AGSM is composed ofrepeated Valsalva maneuvers (VM)with closed glottis and uick breathing. Recently,ultrasonography (US) of the internal jugular vein was used to assess the change of supra-cardiac hemodynamics during the AGSM.The purpose of ourstudy was to determinechangeofliverhemodynamicsduring VM in healthy volunteers.
Materials and Methods : Ten healthy volunteers who experienced the human centrifugeeducationprogram were enrolled.They wer emen, and their mean age was 30.6± 1.43(range29-33) years. Using conventional US, the diameter of intrahepatic inferiorvena cava (IVC),rightmain portalvein (RMPV),and middle hepatic vein (MHV)were measured during both restand VM.Using spectralDoppler US,the peak velocity of the RMPV and that of the MHV were measured,and those waveformswererecordedduring both restand VM.Changesin vesseldiameterand peakvelocitywerethencomparedusingWilcoxonsignedrank-test.
Results: The mean diameterofther in trahepatic IVC was 2.18± 0.42 cm at rest and 0.27± 0.45cm duringVM (P =0.005),that of the RMPV was1.00± 0.10 cm at rest and 0.99± 0.13 cm during VM (P =0.261),and that of the MHV was 0.76± 0.05 cm at rest and 0.61± 0.12 cm during VM (P = 0.005).The peak velocity of the RMPV was 30.6± 6.38 cm/s at rest and 29.0± 8.47 cm/s during VM (P =0.398) and that of the MHV was 27.2± 3.90 cm/s at rest and 35.3± 6.64 cm/s during VM (P =0.007). The waveform of the RMPV was changed in 9 (90%) subjects and that of the MHV was changed in all subjects (100%).
Conclusion : During VM,intrahepatic IVC and hepatic vein decreased in diameter, and there was no change in portal venous flow.
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KEYWORD
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Liver, Ultrasonography, G-tolerance, Valsalvamaneuver
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