Abstract
The incidence of presyncopal events is high soon after a long-duration spaceflight;>60% of returning astronauts could not complete a 10-min 80° head-up tilt test on landing day (R+0) after ~6 months of spaceflight. The objective of this study was to demonstrate the ability of a lower body gradient compression garment (GCG) to protect against an excessive increase in heart rate and a decrease in blood pressure during standing after long-duration spaceflight. Methods: Eleven astronauts (9 M, 2 F) volunteered to participate. The stand test protocol consisted of 2 min of prone rest followed by 3.5 min of standing. Subjects completed one familiarization session, two preflight data collection sessions in standard clothing, and three tests on landing day while wearing GCG. Postflight tests were conducted 1–4 h (R+0A), ~12 h (R+0B), and ~28 h after landing (R+0C). Results: All astronauts completed the stand test preflight. Three astronauts were unable to attempt the stand test at R+0A, and one of these was unable to start the test at R+0B. One astronaut was unable to complete 3.5 min of standing at R+0B (test ended at 3.3 min). Review of the individual’s blood pressure data revealed no hypotension but the astronaut reported significant motion sickness. Of the astronauts who participated in testing on landing day, the heart rate and mean arterial pressure responses to standing (stand-prone) were not different than preflight at any of the postflight sessions. Conclusion: Wearing the GCG after spaceflight prevented the tachycardia that normally occurs while standing after spaceflight without compression garments and protected against a decrease in blood pressure during a short stand test.
Highlights
We have previously reported that 60–80% of astronauts experienced orthostatic intolerance during 10 min of 80° head-up tilt conducted in the controlled conditions of the laboratory 4–6 h after landing from long-duration spaceflight (Meck et al, 2001; Lee et al, 2015)
In collaboration with the manufacturer of JOBST medical compression garments (Essity, Stockholm, Sweden), we developed an elastic three-piece gradient compression garment (GCG) consisting of two thigh-high stockings and shorts that extend to the bottom of the rib cage that provides a continuous gradient of compression from the feet to the top of the garment
Data from one subject at R+0A and R+0B were not analyzed because the astronaut was provided the wrong size GCG for those tests, but this individual did wear the correct GCG at R+0C so those data are included in the analyses
Summary
We have previously reported that 60–80% of astronauts experienced orthostatic intolerance during 10 min of 80° head-up tilt conducted in the controlled conditions of the laboratory 4–6 h after landing from long-duration spaceflight (Meck et al, 2001; Lee et al, 2015). We have previously demonstrated the efficacy of a next-generation lower body GCG after 2 weeks of bed rest as a spaceflight analog (Stenger et al, 2014) and during the first few hours after Space Shuttle missions (Stenger et al, 2013), but it was unclear as to whether these garments would provide sufficient protection from orthostatic intolerance immediately after landing from longer missions. Heart rate and blood pressure measurements during preflight stand tests without the GCG were compared to those obtained when astronauts completed the same testing protocol three times in the first 24 h after landing while wearing the GCG
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