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Hemodynamic responses and G Protection Afforded by Three Different Anti-G Systems

Research output: Contribution to journalArticle

Ross Daniel Pollock, Rachel Firth, Jessica Storey, Katherine Phillips, Desmond Connolly, Nicholas D.C. Green, Alec Thomas Stevenson

Original languageEnglish
Pages (from-to)925-933
Number of pages9
JournalAerospace medicine and human performance
Volume90
Issue number11
DOIs
Accepted/In press9 Aug 2019
Published1 Nov 2019

King's Authors

Abstract

BACKGROUND: UK Royal Air Force fast jet aircrew use three different anti-G systems, however, little objective comparison of the G protection they provide exists. The G-protection afforded by each system and associated hemodynamic responses were investigated. METHODS: Ten subjects performed centrifuge acceleration exposures using Mk-10 (S1) and Mk-4 (S2) five-bladder anti-G trousers (AGT) and full coverage AGT plus pressure breathing for G-protection (PBG; S3). Measurements of relaxed G tolerance (RGT), eye-level blood pressure (BP eye), lower body blood volume (LBV), stroke volume (SV) and total peripheral resistance (TPR) were made during gradual onset runs (GOR) and rapid onset runs (ROR). The subjective effort required to maintain clear vision at +7 and +8 G z provided an indication of the protection provided by the system. RESULTS: All systems moderated decreases in SV and BP eye and increases in LBV under increased +G z. S3 provided the greatest mean RGT during GOR (+6.2 G z) and ROR (+6 G z), reduced the effort required to maintain clear vision at up to +8 G z, prevented venous pooling and afforded the greatest rise in TPR. The majority of indices revealed no difference between S1 and S2 although RGT during the ROR was greater with S2 (+0.25 G z). DISCUSSION: S3 effectively prevented pooling of blood in the lower limbs under +G z, despite the use of PBG, and offers an advantage over five-bladder AGT. Given the similarities of S1 and S2, it was unsurprising that the majority of indices measured were similar. The objective measurement of hemodynamic parameters provides useful information for comparing the G-protection provided by anti-G systems.

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