title: The protection against +Gz afforded by pressure breathing with different pressure schedules.
abstract: OBJECTIVE
  System of pressure breathing for +Gz (PBG) has been incorporated into service in the high performance fighter aircraft, but there were significant differences among PBG pressure schedules used in different countries. The purpose of this study was to define an optimal pressure schedule in PBG system.
  
  
  METHODS
  Five male subjects wearing GZ-2 anti-G suit and medium-sized bladder vest, plus PBG with 1.6, 2.4, and 3.2 kPa/G pressure schedules, respectively, were exposed to rapid onset (3.0 G/s) centrifuge +Gz runs. +Gz protection of PBG with each of the three pressure schedules were measured and the subjective ratings were collected.
  
  
  RESULTS
  The +Gz protection afforded by PBG with 1.60, 2.40, and 3.20 kPa/G pressure schedules were 2.00 +/- 0.31,  2.54 +/- 0.32, and 2.44 +/- 0.31 G, respectively. Subjective ratings showed that the PBG with 2.40 kPa/G pressure schedule was better than the other two.
  
  
  CONCLUSIONS
  Our data suggest that a PBG pressure schedule of 2.4 kPa/G in PBG system is optimal. It not only assures the anti-G performance of PBG, but also reduces its side effects.
authors.affiliation: Institute of Aviation Medicine, Air Force of China, Beijing.
authors.forename: X C
authors.initials: XC
authors.lastname: Geng
authors.forename: C L
authors.initials: CL
authors.lastname: Zhan
authors.forename: G D
authors.initials: GD
authors.lastname: Yan
authors.forename: X
authors.initials: X
authors.lastname: Chu
authors.forename: X
authors.initials: X
authors.lastname: Lu
mesh_terms: D000054:Acceleration; D000293:Adolescent; D000328:Adult; D000337:Aerospace Medicine / Q000592:standards*; D001359:Aviation; D003665:Decompression Sickness / Q000517:prevention & control*; D005676:Gravity Suits; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D018471:Hypergravity; D008297:Male; D011175:Positive-Pressure Respiration / Q000592:standards*