Computer modeling of acceleration effects on cerebral oxygen saturation.
BACKGROUND
Failure to effectively regulate BP and cerebral perfusion during high-G aircraft maneuvering may contribute to reduced performance in pilots due to the fact that perfusion to the peripheral cerebral tissues may not be adequate to support the mental demands of flight. Therefore, a critical area of investigation is the study of cortical tissue oxygenation responses to +Gz acceleration.


METHODS
Two experiments were used to build two sections of a cerebral oxygen saturation (rSo2) model. Experiment 1: Six subjects participated in the study. A cerebral oximeter (gold standard) provided rSo2. Acceleration profiles (subjects relaxed) included a 0.1 G x s(-1) G onset to central light loss (CLL) and a 3 G x s(-1) onset to a G level that was 1 Gz above CLL to an endpoint of G-LOC. Experiment 2: There were 12 subjects (with G protection) who participated in this study. The rSo2 data were collected during five different simulated aerial combat maneuvers. A model was created that read the Gz profile as input and calculated changes in rSo2. The correlation coefficient, linear best-fit slope, and mean percent error were calculated to determine agreement.


RESULTS
The average value for the correlation coefficients, linear best-fit slopes, and mean percent errors for the unprotected subjects were 0.79, 0.87, and 6.08, respectively. These values for the protected subjects were 5 G (0.994, 1.011, 0.384), 6 G (0.994, 0.909, 0.811), 7 G (0.986, 1.061, 0.692), 8 G (0.969, 1.016, 1.300), and 9 G (0.994, 0.979, 0.558), respectively.


CONCLUSIONS
The model is a good predictor of rSo2 values for protected and unprotected subjects under +Gz stress.
McKinley
Richard A
RA
Aircrew Performance and Protection Branch, Air Force Research Laboratory, 2215 First St., Bldg. 33, Wright-Patterson AFB, OH 45433-7947, USA. Richard.McKinley2@wpafb.af.mil
Tripp
Lloyd D
LD
Bolia
Steve D
SD
Roark
Marvin R
MR
D000328:Adult; D000401:Aircraft; D001921:Brain / Q000098:blood supply*; D003198:Computer Simulation; D005260:Female; D005544:Forecasting; D005676:Gravity Suits; D006801:Humans; D018471:Hypergravity; D008297:Male; D010092:Oximetry; D010100:Oxygen / Q000032:analysis*; D012039:Regional Blood Flow
D010100:Oxygen