Abstract
OBJECTIVE
To generate, on a multi-axial centrifuge, a negative to positive acceleration profile that reproduces the physiological reaction and subjective symptoms experienced by agile aircraft pilots. Previous research will be summarized and current status of research described.
METHODS
Experiments have been accomplished with the Dynamic Environment Simulator (DES) using different profile generating techniques. The DES was programmed with a set of open-loop profiles that provided five second duration baseline exposures ranging from +1.4 Gz down to -2 Gz followed by rapid transition to positive G levels up 2 to 8 +Gz. Volunteer subjects were instrumented and trained to report visual symptoms.
RESULTS
Both profile generation approaches produce the reduced cardiovascular and subjective tolerance in a subset of subjects tested. Accumulated stress and motion sickness are factors in quantitative measures. Use of the anti-G straining maneuver may only temporarily alleviate the symptoms with a second period of visual symptoms even as the G load is removed. Positive pressure breathing for G (PBG) does not appear to exacerbate the effect, but the advantages gained from PBG may be lost when a sustained G pull is preceded by a negative G push.
CONCLUSIONS
The utility and limitations of using a multi-axial centrifuge for the study of negative to positive G transitions have been described. Greater study is necessary on multiple factors affecting the effect and large numbers of volunteer subjects are needed.
TY - JOUR
T1 - The effect of brief headward acceleration on human G tolerance.
AU - Chelette,T L,
AU - Allnutt,R,
AU - Albery,W B,
AU - Tripp,L D,
PY - 2001/9/7/pubmed
PY - 2001/9/11/medline
PY - 2001/9/7/entrez
SP - P55
EP - 8
JF - Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology
JO - J Gravit Physiol
VL - 5
IS - 1
N2 - OBJECTIVE: To generate, on a multi-axial centrifuge, a negative to positive acceleration profile that reproduces the physiological reaction and subjective symptoms experienced by agile aircraft pilots. Previous research will be summarized and current status of research described. METHODS: Experiments have been accomplished with the Dynamic Environment Simulator (DES) using different profile generating techniques. The DES was programmed with a set of open-loop profiles that provided five second duration baseline exposures ranging from +1.4 Gz down to -2 Gz followed by rapid transition to positive G levels up 2 to 8 +Gz. Volunteer subjects were instrumented and trained to report visual symptoms. RESULTS: Both profile generation approaches produce the reduced cardiovascular and subjective tolerance in a subset of subjects tested. Accumulated stress and motion sickness are factors in quantitative measures. Use of the anti-G straining maneuver may only temporarily alleviate the symptoms with a second period of visual symptoms even as the G load is removed. Positive pressure breathing for G (PBG) does not appear to exacerbate the effect, but the advantages gained from PBG may be lost when a sustained G pull is preceded by a negative G push. CONCLUSIONS: The utility and limitations of using a multi-axial centrifuge for the study of negative to positive G transitions have been described. Greater study is necessary on multiple factors affecting the effect and large numbers of volunteer subjects are needed.
SN - 1077-9248
UR - https://www.unboundmedicine.com/medline/citation/11542365/The_effect_of_brief_headward_acceleration_on_human_G_tolerance_
DB - PRIME
DP - Unbound Medicine
ER -
