Debenham MIB, Grantham TDA, Smirl JD, Foster GE, Dalton BH. The effects of acute normobaric hypoxia on vestibular-evoked balance responses in humans.
J Vestib Res 2023;
33:31-49. [PMID:
36530112 DOI:
10.3233/ves-220075]
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Abstract
BACKGROUND
Hypoxia influences standing balance and vestibular function.
OBJECTIVE
The purpose here was to investigate the effect of hypoxia on the vestibular control of balance.
METHODS
Twenty participants (10 males; 10 females) were tested over two days (normobaric hypoxia and normoxia). Participants stood on a force plate (head rotated leftward) and experienced random, continuous electrical vestibular stimulation (EVS) during trials of eyes open (EO) and closed (EC) at baseline (BL), after 5 (H1), 30 (H2) and 55-min (H3) of hypoxia, and 10-min into normoxic recovery (NR). Vestibular-evoked balance responses were quantified using cumulant density, coherence, and gain functions between EVS and anteroposterior forces.
RESULTS
Oxyhemoglobin saturation, end-tidal oxygen and carbon dioxide decreased for H1-3 compared to BL; however, end-tidal carbon dioxide remained reduced at NR with EC (p≤0.003). EVS-AP force peak-to-peak amplitude was lower at H3 and NR than at BL (p≤0.01). At multiple frequencies, EVS-AP force coherence and gain estimates were lower at H3 and NR than BL for females; however, this was only observed for coherence for males.
CONCLUSIONS
Overall, vestibular-evoked balance responses are blunted following normobaric hypoxia >30 min, which persists into NR and may contribute to the reported increases in postural sway.
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