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.

METHOD

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.