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Gender Differences in Cardiovascular Tolerance to Short Arm CentrifugationIn preparation for the NASA Artificial Gravity (AG) pilot study, the tolerability of the proposed AG parameters was tested in 11 ambulatory human subjects (6m, 5w) by exposing each to a short arm centrifuge trial. Subjects were oriented in the supine position (but inclined 6deg head down) on one arm of the centrifuge, and the rotation rate (30.6-33.4 rpm) and radial position of the feet were set to produce 2.5G of equivalent gravitational load at the force plate directly beneath the feet, 1G at the level of the mediastinum, and approximately 0.55G at the labyrinth. Amongst the 6 men participating in this preliminary study, 5 completed at least 60 minutes of the trial successfully with no adverse sequelae. However, amongst the female cohort the test was stopped by the medical monitor before 60 min in all but one case, with pre-syncope listed as the reason for termination in all cases. Mean time before abort of the centrifuge run amongst the women was 33.2 +/- 20.97 min. It is known that women have a greater predisposition to syncope during orthostatic stress, under normal tilt table conditions, during LBNP, and following space flight. The reasons for this difference are the subject of some debate, but anthropometric factors, the vasoactive effects of sex hormones, gender differences in susceptibility to motion sickness, catecholamine levels, ability to augment total peripheral resistance in response to orthostatic stress, and structural differences in cardiac anatomy and physiology have all been suggested. This finding led to the exclusion of women from the AG pilot study. Clearly if AG is to be employed as a multi-system countermeasure it must provide physiological protection at rotation rates within the tolerance limits of all potential astronauts. Further investigation of the responses of women to centrifugation will be necessary to determine how to adjust AG parameters for tolerance by female subjects before a more detailed investigation of the appropriate dose in terms of G load, rotation rate, exposure duration and frequency can be performed.
Document ID
20070016629
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Fong, Kevin J.
(University Coll. London, United Kingdom)
Arya, Maneesh
(Wyle Labs., Inc. Houston, TX, United States)
Paloski, William H.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 23, 2013
Publication Date
April 12, 2007
Subject Category
Aerospace Medicine
Meeting Information
Meeting: 28th Annual International Gravitational Physiology
Location: San Antonio, TX
Country: United States
Start Date: April 8, 2007
End Date: April 13, 2007
Funding Number(s)
CONTRACT_GRANT: NIH-MOI-RR-0073
Distribution Limits
Public
Copyright
Other

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