NIRS Monitoring of Pilots Subjected to +Gz Acceleration and G-Induced Loss of Consciousness (G-LOC)

Abstract

With the increasing maneuverability of modern aircraft, there is an increased frequency of pilots losing consciousness due to high +Gz acceleration. This phenomena is defined as “G-induced loss of consciousness” (G-LOC). We used an NIRS system of our design to monitor cerebral oxygenation changes of pilots subjected to high +Gz acceleration and G-LOC. During the +Gz pulse, ∆HbO₂, and ∆TotalHb decreased, with lesser changes of ∆Hb. The maximum decrease of ∆HbO₂ and ∆TotalHb usually occurred at the onset of G-LOC. After GLOC, ∆HbO₂ and ∆TotalHb increased rapidly for the first few seconds, beginning the reactive hyperemic recovery phase. ∆HbO₂ and ∆TotalHb peaked, and then began to decrease towards baseline. The subjects were unconscious for 3#x2013;#x2013;10 seconds after the onset of G-LOC. Upon returning to consciousness, the subjects were disoriented for another 4–#x2013;11 seconds. NIRS provides an additional means of studying physiological mechanisms leading to and recovery from G-LOC.