Specific Aim I: To determine whether subjects wearing breast-high, graded compression garments developed symptoms of orthostatic intolerance after 14 days of head-down tilt bed rest (Groups 1 and 2).
Specific Aim II: To determine the time course of cardiovascular readaptation during the first three days of post-bed rest recovery after using compression garments for a short period of time on BR+0 (Group 1).
Specific Aim III: To determine the effect of wearing graded compression garments on BR+0, with reduced compression on subsequent days, on the time course of cardiovascular readaptation during the first three days of post-bed rest recovery (Group 2).
The subjects were fitted with Jobst custom compression garments and a series of measurements were taken along the legs and torso. The circumference of each leg and of the torso was measured every 1.5 inches beginning at the foot and ending just below the breast-line. These measurements were used to construct the custom-made garments worn on BR+0. Approximately two weeks for construction of the garments were required between the time that these measurements were made and their delivery to the investigator. These procedures are the same as those employed for the Space Shuttle experiment “Evaluation of Commercial Compression Garments to Prevent Post-Spaceflight Orthostatic Intolerance” (Alternative Compression Garments) (ACG) (DSO 641). Additionally, measurements of the ankle, calf, thigh, and waist circumference were taken before and after bed rest (BR–5, BR+0, BR+1, BR+2, and BR+3) to track anthropometric changes as a result of and during recovery from bed rest. These measurements were not previously conducted during bed rest studies and mirrored the measurements made during the Space Shuttle investigation (DSO 641).
Data collected was used:
Group 1 donned the full compression, breast-high garment ensemble (shorts and thigh-high garments) upon waking and doffed the garment after BR+0 cardiovascular and orthostatic tolerance testing. This group did not wear any compression garment for the remainder of the study.
Group 2 donned the full compression, breast-high garment ensemble upon waking and doffed the garment at the end of the day on BR+0. On BR+1, this group wore an off-the-shelf, thigh-high garment that provided 30-40 mmHg of compression at the ankle, and decreased up the leg following the Jobst gradient to approximately 10 mmHg at the top of the leg. On BR+2, this group wore an off-the-shelf, thigh-high garment that provided 10-20 mmHg of compression at the ankle, and decreased up the leg following the Jobst gradient to approximately 5 mmHg at the top of the leg. No group wore compression garments on BR+3.
Plasma volume measurements were made on test days BR–5, BR+0, BR+1, BR+2, and BR+3 using the carbon monoxide rebreathing technique. Blood samples were analyzed for hemoglobin, carboxyhemoglobin, and hematocrit. Total blood volume, red blood cell volume, and plasma volume was calculated. Cardiac Function of the heart was also imaged using two- and three-dimensional echocardiography. Hemodynamic assessment was accomplished by the use of continuous, pulsed wave, and color flow doppler.
The tilt test was performed as a standard measures tilt as previously described, but for up to 15 minutes only and without blood draws, on BR–5, BR+0, BR+1, and BR+3. Briefly, continuous finger blood pressure and electrocardiography (ECG) was acquired with a laboratory system. Images from at least three cardiac cycles were independently analyzed. Aortic annulus area, stroke volume, and cardiac output (stroke volume multiplied by heart rate) was calculated. Subjects were supine for five minutes for baseline data collection, followed by 15 space bar minutes of 80 degree head-up tilt or until symptoms of presyncope.
This experiment has concluded in ground-based studies sponsored by the National Aeronautics and Space Administration's Human Adaptation and Countermeasures Division.
These gradient compression garment's (GCG) prevented the orthostatic intolerance that is normally present after two weeks of head-down tilt bed rest. There were minimal differences between the control and treatment groups on BR+1, but both groups recovered to the same level by BR+3. Overall, these garments are effective in preventing immediate post-bed rest orthostatic intolerance, and the use of lower compression garments (thigh-high only) in the recovery period can provide additional protection without significantly impeding the recovery process. These results suggest that the GCG will be beneficial to protect long-duration astronauts and in commercial space flight applications during the immediate post-flight and recovery periods during re-adaptation to Earth gravity.
|Mission||Launch/Start Date||Landing/End Date||Duration|
|Campaign 17||05/11/2011||02/12/2012||278 days|