title: Cerebral blood flow during acceleration in flight measured with SPECT.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Aviation Medicine, Research Institute of Military Medicine, Helsinki, Finland. simo.siitonen@fimnet.fi
authors.forename: Simo L
authors.initials: SL
authors.lastname: Siitonen
authors.forename: Tomi
authors.initials: T
authors.lastname: Kauppinen
authors.forename: Tuomo K
authors.initials: TK
authors.lastname: Leino
authors.forename: Esko
authors.initials: E
authors.lastname: Vanninen
authors.forename: Pentti
authors.initials: P
authors.lastname: Kuronen
authors.forename: Esko
authors.initials: E
authors.lastname: Länsimies
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging; D005676:Gravity Suits; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D015899:Tomography, Emission-Computed, Single-Photon