Cerebral Blood Flow During Acceleration in Flight Measured with SPECT

Siitonen SL, Kauppinen T, Leino TK, Vanninen E, Kuronen P, Länsimies E. Cerebral blood flow during acceleration in flight measured with SPECT. Aviat Space Environ Med 2003; 74:201–6.

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). Results: 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.