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Autonomic and cognitive function response to normobaric hyperoxia exposure in healthy subjects. Preliminary study

Lookup NU author(s): Emerita Professor Julia Newton



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2020, MDPI AG. All rights reserved.Background and objective: This is the first study to investigate the effect of high-flow oxygen therapy, using a normobaric chamber on cognitive, biochemical (oxidative stress parameters and the level of neurotrophins), cardiovascular and autonomic functioning. Materials and methods: 17 healthy volunteers, eight males and nine females, with a mean age of 37.5 years, were examined. The experimental study involved ten two-hour exposures in a normobaric chamber with a total pressure of 1500 hPa, in air adjusted to 37% oxygen, 1.079% carbon dioxide and 0.44% hydrogen. Cognitive function was assessed by using Trail Making Test parts A, B and difference in results of these tests (TMT A, TMT B and TMT B-A); California Verbal Learning Test (CVLT); Digit symbol substitution test (DSST); and Digit Span (DS). Fatigue (Fatigue Severity Scale (FSS)), cardiovascular, autonomic and baroreceptor functioning (Task Force Monitor) and biochemical parameters were measured before and after intervention. Results: After 10 sessions in the normobaric chamber, significant decreases in weight, caused mainly by body fat % decrease (24.86 vs. 23.93%, p = 0.04 were observed. TMT part A and B results improved (p = 0.0007 and p = 0.001, respectively). In contrast, there was no statistically significant influence on TMT B-A. Moreover, decrease in the number of symbols left after a one-minute test in DSST was noted (p = 0.0001). The mean number of words correctly recalled in the CVLT Long Delay Free Recall test improved (p = 0.002), and a reduction in fatigue was observed (p = 0.001). Biochemical tests showed a reduction in levels of malondialdehyde (p < 0.001), with increased levels of Cu Zn superoxide dismutase (p < 0.001), Neurotrophin 4 (p = 0.0001) and brain-derived neurotrophic factor (p = 0.001). A significant increase in nitric oxide synthase 2 (Z = 2.29, p = 0.02) and Club cell secretory protein (p = 0.015) was also noted. Baroreceptor function was significantly improved after normobaric exposures (p = 0.003). Significant effect of normobaric exposures and BDNF in CVLT Long Delay Free Recall was noted. Conclusions: This study demonstrates that 10 exposures in a normobaric chamber have a positive impact on visual information and set-shifting processing speed and increase auditory-verbal short-term memory, neurotrophic levels and baroreceptor function. A response of the respiratory tract to oxidative stress was also noted. There is a need to rigorously examine the safety of normobaric therapy. Further studies should be carried out with physician examination, both pre and post treatment.

Publication metadata

Author(s): Kujawski S, Slomko J, Morten KJ, Murovska M, Buszko K, Newton JL, Zalewski P

Publication type: Article

Publication status: Published

Journal: Medicina

Year: 2020

Volume: 56

Issue: 4

Print publication date: 01/04/2020

Online publication date: 10/04/2020

Acceptance date: 08/04/2020

Date deposited: 06/05/2020

ISSN (print): 1010-660X

ISSN (electronic): 1648-9144

Publisher: MDPI AG


DOI: 10.3390/medicina56040172


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