Remote Ischemic Conditioning Improves Attention Network Function and Blood Oxygen Levels in Unacclimatized Adults Exposed to High Altitude.

Sijie Li,Yuchuan Ding,Jiali Xu,Ming Li,Zhiwen Liu,Lingling Zhu,Lian Duan,Karam Asmaro,Kai Wang,Shanyi Quan,Wenbo Zhao,Changhong Ren,Xunming Ji,Jun Zhang,Cong Han,Peng Zhang

doi:10.14336/ad.2019.0605

Abstract

Remote ischemic conditioning (RIC) confers protection on major organs from hypoxic/ischemic injuries; however, its impacts on attention network function and blood oxygen levels in unacclimatized adults exposed to high altitudes have yet to be elucidated. In this study, we recruited 120 healthy male volunteers, of which one was exposed to high altitude and the other was exposed to low altitude. The two cohorts were further divided into RIC and sham control groups. The attentional network test (ANT) was performed to evaluate cognitive function before and after RIC treatment. Other outcomes such as heart rate, blood pressure, blood oxygen saturation, cerebral tissue oxygenation index (CTOI), and cerebrovascular hemodynamic indices were also evaluated. Prior to RIC treatment, there were no significant differences in orienting or executive function between the treatment and control arms of either cohort. Alerting function was significantly lower in the high-altitude cohort than in the low-altitude cohort. There were significant reductions in both blood oxygen and CTOI in the high-altitude cohort relative to the low-altitude cohort, while the pulse index (PI) of the former cohort was significantly increased. After RIC treatment, there was a significant difference in alerting function between the high-altitude RIC group and its associated control. The CTOI of the treatment group increased from 60.39±3.40% to 62.78±4.40%, and blood oxygenation also improved. Furthermore, this group showed a significant reduction in its PI. Exposure to high-altitude environments had a significant impact on alerting function, blood oxygen, CTOI, and PI. RIC ameliorated changes in attentional function, as well as blood oxygen and CTOI, suggesting that it potentially alters cerebrovascular compliance upon exposure to high altitude.

Highlights

High altitude has been shown to cause a series of pressure, cold, and other environmental factors [1], which pathophysiological changes via hypoxia, low atmospheric may lead to acute, subacute, or chronic mountain sickness
The cerebral tissue oxygenation index (CTOI) of the Remote ischemic conditioning (RIC) group was 62.78±4.40%, which was higher than that of the sham-RIC group (60.39±3.40%, P=0.022), and the blood oxygenation was higher with RIC than with sham treatment (92.87±1.68 vs. 90.53±2.06, P
The pulse index (PI), was significantly (P

Summary

Introduction

High altitude has been shown to cause a series of pressure, cold, and other environmental factors [1], which pathophysiological changes via hypoxia, low atmospheric may lead to acute, subacute, or chronic mountain sickness. RIC has been shown to delay the onset of acute mountain sickness in normobaric hypoxia [16], improve oxygen saturation, and decrease hypoxic pulmonary vasoconstriction in high-altitude areas [17], suggesting a potential benefit in the prevention of high-altitude disease [18]. It remains unclear whether RIC can improve neuronal hypoxic tolerance during high-altitude exposure and help mitigate cognitive dysfunction. We aim to investigate the impact of high-altitude exposure on attention and cognitive function in young healthy volunteers who are unacclimatized to high-altitude areas and evaluate the effects of RIC on cerebral protection in highaltitude hypoxia

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