Transfer functions for arterial oxygen saturation during +Gz stress

Area of Science:

• Aerospace Medicine
• Physiological Modeling
• Biomedical Engineering

Background:

• Understanding the physiological effects of G-force exposure is critical for aviation and spaceflight safety.
• Arterial oxygen saturation (Sao2) is a key indicator of respiratory and circulatory function under stress.
• Developing predictive models for Sao2 response to G-stress can aid in protecting personnel.

Purpose of the Study:

• To investigate the relationship between G-force stress and arterial oxygen saturation (Sao2).
• To develop and evaluate transfer functions for predicting Sao2 responses to varying G-stress conditions.
• To explore the potential of synthetic transfer functions for improved physiological modeling.

Main Methods:

• Discrete, finite Fourier transforms were applied to G-force stress (input) and Sao2 (output) data.
• Transfer functions were derived from 12 subjects exposed to different G-stress profiles.
• Ensemble averaging was used to improve the reliability of transfer functions.
• A synthetic transfer function was created using an impulse response from mathematical functions.

Main Results:

• Transfer functions derived from variable G-stress responses reasonably predicted Sao2 during sustained 6-G stress.
• Predicting Sao2 responses to variable G-stress using transfer functions from sustained G-stress was unsuccessful.
• A synthetic transfer function demonstrated significant predictive ability and physiological interpretability.

Conclusions:

• Transfer function modeling shows promise for predicting Sao2 changes during G-force exposure.
• The success of prediction depends on the nature of the G-stress used for model derivation.
• Synthetic transfer functions offer a viable approach for creating physiologically relevant and predictive models of G-stress effects on Sao2.