The Duration of Tolerance to Positive Acceleration
The Duration of Tolerance to Positive Acceleration

Author: Hugh Miller

Publisher:

Published: 1958

Total Pages: 24

ISBN-13:

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"Human tolerance to prolonged positive (headward) accelerations of sub-blackout magnitude has been investigated in this study. The data indicate that man is able to withstand the forces of positive g for durations much longer than previously supposed. Exposures as long as an hour at 3.0 g appear well tolerated by most subjects. Except for moderate tachycardia no pathologic abnormalities were observed in the electrocardiographic tracings recorded continuously on all subjects. Explored were the durations of tolerance at g levels varying from 3.0 to 6.0 g. The effects of anti-g suits upon tolerance are also reported."--Abstract.

Respiratory Mechanics During Forward Acceleration
Respiratory Mechanics During Forward Acceleration

Author: John F. Watson

Publisher:

Published: 1961

Total Pages: 26

ISBN-13:

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"Static relaxation pressure volume curves of the thorax and lung were obtained on 4 trained subjects while in the supine position on the human centrifuge at 1, 2, 3, and 4 g. As acceleration increased, the intrapulmonic pressure increased for a constant volume shifting the pressure volume curve downward and to the right. Compliance of the thorax and lung decreases from 1 to 4 g as the result of the fall in pulmonary mid-position. Inspiration during 4 g acceleration, regardless of the end expiratory position was always active. Elastic work of breathing approximately doubles from 1 to 4 g while non-elastic work does not change. Absolute lung volumes during acceleration decrease proportionately with the exception of residual volume which did not change. Since these changes are similar to those described during negative pressure breathing, positive pressure breathing is suggested as a means by which respiration during forward acceleration may be improved and toleration increased."--Abstract.