title: Cardiac and vascular responses to thigh cuffs and respiratory maneuvers on crewmembers of the International Space Station.
abstract: BACKGROUND
  The transition to microgravity eliminates the hydrostatic gradients in the vascular system. The resulting fluid redistribution commonly manifests as facial edema, engorgement of the external neck veins, nasal congestion, and headache. This experiment examined the responses to modified Valsalva and Mueller maneuvers measured by cardiac and vascular ultrasound (ECHO) in a baseline steady state and under the influence of thigh occlusion cuffs available as a countermeasure device (Braslet cuffs).
  
  
  METHODS
  Nine International Space Station crewmember subjects (expeditions 16-20) were examined in 15 experiment sessions 101 ± 46 days after launch (mean ± SD; 33-185). Twenty-seven cardiac and vascular parameters were obtained with/without respiratory maneuvers before and after tightening of the Braslet cuffs (162 parameter states/session). Quality of cardiac and vascular ultrasound examinations was assured through remote monitoring and guidance by investigators from the NASA Telescience Center in Houston, TX, and the Mission Control Center in Korolyov, Moscow region, Russia.
  
  
  RESULTS
  14 of 81 conditions (27 parameters measured at baseline, Valsalva, and Mueller maneuver) were significantly different when the Braslet was applied. Seven of 27 parameters were found to respond differently to respiratory maneuvers depending on the presence or absence of thigh compression.
  
  
  CONCLUSIONS
  Acute application of Braslet occlusion cuffs causes lower extremity fluid sequestration and exerts commensurate measurable effects on cardiac performance in microgravity. Ultrasound techniques to measure the hemodynamic effects of thigh cuffs in combination with respiratory maneuvers may serve as an effective tool in determining the volume status of a cardiac or hemodynamically compromised patient at the "microgravity bedside."
authors: Wyle Integrated Science and Engineering, Houston, Texas, USA. dhamilton@wylehou.com
authors: Douglas R
authors: DR
authors: Hamilton
authors: Ashot E
authors: AE
authors: Sargsyan
authors: Kathleen
authors: K
authors: Garcia
authors: Douglas J
authors: DJ
authors: Ebert
authors: Peggy A
authors: PA
authors: Whitson
authors: Alan H
authors: AH
authors: Feiveson
authors: Irina V
authors: IV
authors: Alferova
authors: Scott A
authors: SA
authors: Dulchavsky
authors: Vladimir P
authors: VP
authors: Matveev
authors: Valery V
authors: VV
authors: Bogomolov
authors: J Michael
authors: JM
authors: Duncan
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D002319:Cardiovascular System / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D012137:Respiratory System / Q000503:physiopathology*; D013026:Space Flight; D013848:Thigh / Q000098:blood supply*; D014463:Ultrasonography; D014893:Weightlessness; D018544:Weightlessness Countermeasures; D018474:Weightlessness Simulation / Q000379:methods