Mathematical modeling of the push-pull effect for various acceleration profiles and countermeasures

Area of Science:

• Aerospace Medicine
• Cardiovascular Physiology
• Computational Modeling

Background:

• The push-pull maneuver (PPM) poses a risk of G-induced loss of consciousness (G-LOC) for pilots in high-performance aircraft.
• Developing effective countermeasures requires a comprehensive understanding of the underlying physiological responses.

Purpose of the Study:

• To develop and utilize a mechanistic computer model to predict cardiovascular responses during the PPM.
• To evaluate the protective effects of extended coverage anti-G suits (ECGS) and neck pressure on +Gz tolerance.

Main Methods:

• A computer model was created incorporating dynamic carotid baroreflex responses and detailed anatomical vessel segment modeling.
• The model simulated the effects of various PPM acceleration profiles on cardiovascular responses.
• Model predictions were validated against experimental data from centrifuge and tilt-table studies.

Main Results:

• +Gz tolerance during the PPM was reduced by higher preceding +Gz levels, greater -Gz during the push phase, and prolonged push phase duration.
• ECGS with minimal inflation delay and a multilevel pressure schedule (higher leg bladder pressure) showed potential for improved protection.
• Neck pressure during the push phase partially inhibited the carotid baroreflex, yielding only a minor increase in tolerance.

Conclusions:

• Mathematical modeling indicates that enhancing ECGS design and inflation timing can significantly improve +Gz tolerance during the PPM.
• These findings suggest avenues for developing more effective G-protection strategies for aviators.