title: Venoconstrictive thigh cuffs impede fluid shifts during simulated microgravity.
abstract: BACKGROUND
  This study determined the efficacy of venoconstrictive thigh cuffs, inflated to 50 mmHg, on impeding fluid redistributions during simulated microgravity.
  
  
  METHODS
  There were 10 healthy male subjects who were exposed to a 2-h tilt protocol which started in the standing position, and was followed by 30 min supine, 30 min standing, 30 min supine, 30 min of -12 degrees head down tilt (HDT, to simulate microgravity), 15 min of HDT with venoconstrictive thigh cuffs inflated, a further 10 min of HDT, 5 min supine, and 10 min standing. To increase the sensitivity of the techniques in an Earth-based model, 12 degrees HDT was used to simulate microgravity effects on body fluid shifts. Volume changes were measured with anthropometric sleeve plethysmography.
  
  
  RESULTS
  Transition to the various tilt positions resulted in concomitant decrements in leg volume (Stand [STD] to Supine [SUP], -3.0%; SUP to HDT, -2.0%). Inflation of the venoconstrictive thigh cuffs to 50 mmHg, during simulated microgravity, resulted in a significant 3.0% increase in leg volume from that seen in HDT (p < 0.01). No significant changes in systemic cardiovascular parameters were noted during cuff inflation.
  
  
  CONCLUSIONS
  We conclude that venoconstrictive thigh cuffs, inflated to 50 mmHg for 15 min during 12 degrees HDT, can create a more Earth-like fluid distribution. Cuffs could potentially be used to ameliorate the symptoms of cephalad edema seen with space adaptation syndrome and to potentiate existing fluid volume countermeasure protocols.
authors.affiliation: Space Physiology Laboratory, NASA Ames Research Center, Moffett Field, CA, USA.
authors.forename: K N
authors.initials: KN
authors.lastname: Lindgren
authors.forename: D
authors.initials: D
authors.lastname: Kraft
authors.forename: R E
authors.initials: RE
authors.lastname: Ballard
authors.forename: A
authors.initials: A
authors.lastname: Tucker
authors.forename: A R
authors.initials: AR
authors.lastname: Hargens
mesh_terms: D000328:Adult; D001810:Blood Volume / Q000502:physiology; D018495:Fluid Shifts / Q000502:physiology*; D005676:Gravity Suits; D018475:Head-Down Tilt / Q000009:adverse effects / Q000502:physiology; D006801:Humans; D008297:Male; D010991:Plethysmography; D011187:Posture; D012680:Sensitivity and Specificity; D018489:Space Motion Sickness / Q000503:physiopathology / Q000517:prevention & control; D013848:Thigh / Q000098:blood supply*; D013997:Time Factors; D018474:Weightlessness Simulation / Q000009:adverse effects*