Female exposure to high G: echocardiographic evaluation for chronic changes in cardiac function

Area of Science:

• Aerospace Medicine
• Cardiovascular Physiology
• Human Factors Engineering

Background:

• High-performance aircraft operations involve factors like high +Gz acceleration, positive pressure breathing, and anti-G straining maneuvers that alter cardiac preload and afterload.
• Centrifuge studies simulate these operational exposures, but the long-term cardiac effects on subjects remain unclear.

Purpose of the Study:

• To investigate the cumulative long-term effects of high +Gz exposure and G protection measures on cardiac function in centrifuge subjects.
• To determine if simulated flight conditions induce adverse cardiac changes.

Main Methods:

• A longitudinal study involved 18 new centrifuge panel members (7 males, 11 females) with no prior significant high +Gz exposure.
• Baseline echocardiographic studies were performed before any +Gz exposure on the Dynamic Environment Simulator (DES) centrifuge.
• Echocardiograms were repeated after subjects completed eight indoctrination sessions, totaling over 45 minutes of cumulative sustained acceleration >= 2 G, with each subject serving as their own control.

Main Results:

• No significant differences were observed in echocardiographic parameters between initial and follow-up studies.
• No significant differences were found in cardiac responses between male and female subjects.

Conclusions:

• Exposure to G forces greater than or equal to 2 G for a cumulative duration of 45 minutes did not result in significant changes in cardiac function in either men or women.
• Subjects will continue to be monitored in an ongoing longitudinal study throughout their careers as centrifuge subjects.