Pilot cerebral oxygen status during air-to-air combat maneuvering.
BACKGROUND
Successful monitoring of in-flight cerebral oxygen status (COS; cerebral hemoglobin concentration changes and oxygenation changes under dynamic flight conditions) was recently achieved using near-infrared spectroscopy (NIRS). In this study, we examined the effects of air-to-air combat maneuvering on COS.


METHODS
Six F-15 fighter pilots performed 2-vs.-1 air-to-air combat one to three times in each of eight sorties. We took continuous measurements of the pilots' in-flight COS using a commercial NIRS system. We measured the direct effects of G-forces on COS as evidenced by relative concentrations of oxy- and deoxy-hemoglobin.


RESULTS
With respect to the G-levels reached during air combat maneuvering (Gz range of -0.4 to + 9.5), oxyhemoglobin concentration (O2Hb) and tissue oxygenation index (TOI, the ratio of oxygenated to total tissue hemoglobin) decreased with increasing G-forces during aerial combat maneuver (ACM). Maximum changes in relative O2Hb ranged from -4.2 to -26 micromol x L(-1). Subjects' experience as measured by total fighter time was an independent determinant of the magnitude of decrease in relative oxygenation.


CONCLUSIONS
1. Pilots' COS declined with dynamic G-forces experienced under aerial combat conditions. 2. Fighter pilots with more flying hours maintained a higher cerebral oxygen level at the same level of G-forces than pilots with less flying time. 3. NIRS technology in the form of the NIRO-300G has matured for continuous monitoring of in-flight cerebral oxygen status under vigorous field conditions.
Kobayashi
Asao
A
Aeromedical Laboratory, Japan Air Self Defense Force, Tokyo. nf5a-kbys@jcom.home.ne.jp
Tong
Andrew
A
Kikukawa
Azusa
A
D000328:Adult; D000337:Aerospace Medicine; D001921:Brain / Q000378:metabolism*; D006112:Gravitation; D006801:Humans; D007564:Japan; D008889:Military Personnel; D010100:Oxygen / Q000097:blood*; D019265:Spectroscopy, Near-Infrared
D010100:Oxygen