Hyperbaric oxygen preconditioning for prevention of acute high-altitude diseases: Fact or fiction?

Hyperoxic recovery interferes with the metabolic imprint of hypoxic exercise

Supplemental oxygen (hyperoxia) improves physical performance during hypoxic exercise. Based on the analysis of metabolome and iron homeostasis from human athlete blood samples, we show that hyperoxia during recovery periods interferes with metabolic alterations following hypoxic exercise. This may impair beneficial adaptations to exercise and/or hypoxia and highlights risks of oxygen supplementation in hypoxia.

Role of neutrophil myeloperoxidase in the development and progression of high-altitude pulmonary edema

BACKGROUND

Neutrophil infiltration and hypoxic pulmonary vasoconstriction induced by hypobaric hypoxic stress are vital in high-altitude pulmonary edema (HAPE). Myeloperoxidase (MPO), an important enzyme in neutrophils, is associated with inflammation and oxidative stress and is also involved in the regulation of nitric oxide synthase (NOS), an enzyme that catalyzes the production of the vasodilatory factor nitric oxide (NO). However, the role of neutrophil MPO in HAPE's progression is still uncertain. Therefore, we hypothesize that MPO is involved in the development of HAPE via NOS.

METHODS

In Xining, China (altitude: 2260 m), C57BL/6 N wild-type and mpo-/- mice served as normoxic controls, while a hypobaric chamber simulated 7000 m altitude for hypoxia. L-NAME, a nitric oxide synthase (NOS) inhibitor to inhibit NO production, was the experimental drug, and D-NAME, without NOS inhibitory effects, was the control. After measuring pulmonary artery pressure (PAP), samples were collected and analyzed for blood neutrophils, oxidative stress, inflammation, vasoactive substances, pulmonary alveolar-capillary barrier permeability, and lung tissue morphology.

RESULTS

Wild-type mice's lung injury scores, permeability, and neutrophil counts rose at 24 and 48 h of hypoxia exposure. Under hypoxia, PAP increased from 12.89 ± 1.51 mmHg under normoxia to 20.62 ± 3.33 mmHg significantly in wild-type mice and from 13.24 ± 0.79 mmHg to 16.50 ± 2.07 mmHg in mpo-/- mice. Consistent with PAP, inducible NOS activity, lung permeability, lung injury scores, oxidative stress response, and inflammation showed more significant increases in wild-type mice than in mpo-/- mice. Additionally, endothelial NOS activity and NO levels decreased more pronouncedly in wild-type mice than in mpo-/- mice. NOS inhibition during hypoxia led to more significant increases in PAP, permeability, and lung injury scores compared to the drug control group, especially in wild-type mice.

CONCLUSION

MPO knockout reduces oxidative stress and inflammation to preserve alveolar-capillary barrier permeability and limits the decline in endothelial NOS activity to reduce PAP elevation during hypoxia. MPO inhibition emerges as a prospective therapeutic strategy for HAPE, offering avenues for precise interventions.

Effects of hyperbaric oxygen therapy on human psychomotor performance: A review

Psychomotor performance is the coordination of a sensory or ideational (cognitive) process and a motor activity. All sensorimotor processes involved in planning and execution of voluntary movements need oxygen supply and seem to be significantly disrupted in states of hypoxia. Hyperbaric oxygen therapy has become a widely used treatment in routine medicine and sport medicine due to its beneficial effects on different aspects of human physiology and performance. This paper presents state-of-the-art data on the effects of hyperbaric oxygen therapy on different aspects of human psychomotor function. The therapy's influence on musculoskeletal properties and motor abilities as well as the effects of hyperbaric oxygenation on cognitive, myocardial and pulmonary functions are presented. In this review the molecular and physiological processes related to human psychomotor performance in response to hyperbaric oxygen are discussed to contribute to this fast-growing field of research in integrative medicine. Please cite this article as: Olex-Zarychta D. Effects of hyperbaric oxygen therapy on human psychomotor performance: A review. J Integr Med. 2023; 21(5): 430-440.