Current and emerging technology in G-LOC detection: pulse wave delay for +Gz tolerance assessment

Area of Science:

• Aerospace Medicine
• Human Physiology
• Cardiovascular Research

Background:

• Understanding physiological responses to high G-forces is critical for aviation safety.
• G-force induced Loss of Consciousness (G-LOC) is a significant risk for pilots.
• Current methods for assessing G-tolerance and protective equipment efficacy require objective measures.

Purpose of the Study:

• To investigate the relationship between pulse wave delay and +Gz exposure in conscious subjects.
• To determine if pulse wave delay can serve as a predictor for G-tolerance limits and G-LOC.
• To evaluate the utility of pulse wave delay in assessing the effectiveness of anti-G protective measures.

Main Methods:

• Monitoring pulse wave delay in conscious subjects under varying levels of +Gz acceleration.
• Comparing pulse wave delay measurements with conventional G-tolerance limits (light bars).
• Analyzing the effect of protective modalities (anti-G suits, supinating seats) on pulse wave delay response to +Gz.

Main Results:

• Pulse wave delay demonstrates a linear increase with increasing +Gz levels.
• Consistent pulse wave delay values were observed at G-tolerance limits, irrespective of protection.
• Protective equipment reduced the rate of delta delay increase with +Gz, but the final delta delay at tolerance remained consistent.
• +Gz tolerance thresholds were elevated with protective measures.

Conclusions:

• Pulse wave delay is a reliable, objective physiological parameter that correlates with +Gz exposure and G-tolerance.
• This parameter can potentially be integrated into expert systems to provide early warnings of impending G-LOC.
• Pulse wave delay offers a valuable tool for the objective evaluation of anti-G protective equipment in research and development.