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Cerebral blood flow during acceleration in flight measured with SPECT
Simo L Siitonen1, Tomi Kauppinen, Tuomo K Leino
1Department of Aviation Medicine, Research Institute of Military Medicine, Helsinki, Finland. simo.siitonen@fimnet.fi
Introduction:
Positive pressure breathing for G-protection (PBG) reduces the need for fighter pilots to use the fatiguing anti-G straining maneuver (AGSM) so that they can better endure high acceleration (+Gz). The aim of the study was to determine the differences in cerebral blood flow during flight with an extended-coverage anti-G suit (ECGS) with AGSM or with PBG.
Methods:
Subjects were eight male members of the Finnish Air Force. Each was studied in the laboratory at +1 Gz and then during two identical flights in the back seat of the BAe Hawk Mk 51 jet trainer at +6 Gz, first with AGSM and second with PBG (24 mmHg). Regional cerebral blood flow (rCBF) was measured by injecting (99 m) Tc-ECD for deposition at +6 Gz, then scanning the subject in the laboratory an hour later using single photon emission computed tomography (SPECT).
Result:
The rCBF was 30% below baseline for both the AGSM and PBG.
Conclusions:
PBG maintained CBF at +6 Gz without the need for the fatiguing AGSM.