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

We have found that pulse wave delay increases linearly with +Gz experienced by conscious subjects and that G-tolerance limits, as measured using conventional light bars, occur repeatedly at the same pulse wave delays or delta delay. When protective modalities such as anti-G suits or supinating seats are used, the delta delays increase at a slower rate as a function of +Gz. G-tolerance thresholds occur at higher +Gz levels with protection but the delta pulse wave delays reach the same value for all tolerance levels. This parameter can be used to warn expert systems of the approach of G-LOC during actual flight and/or provides an objective measure of G protection provided by new or modified anti-G equipment. Therefore, this tool can be used in the research setting to evaluate the efficacy of G-protective equipment in an objective manner.