The rapid developments in Internet of Medical Things open up new avenues for personalized healthcare. Continuously monitored physiological data can be collected by wearable devices and are transmitted to a remote server for real-time monitoring and diagnosis. This article concerns a risk assessment problem of acute mountain sickness (AMS) with data transmitted according to an event-triggered transmission schedule. An event-triggered signal processing approach is introduced to reconstruct the untransmitted information, based on which, a dynamic SpO $_{\bf 2}$ index (DSI) is further proposed for AMS risk evaluation. The performance of the proposed approach is analyzed through physiological data collected in a proof-of-the-concept study ( N =12). Statistical significant correlation of the DSI with AMS ground truth including Lake Louise score, deep sleep duration, deep sleep ratio, and mean SpO $_{\bf 2}$ during sleep is observed. More importantly, it is observed that the proposed event-triggered signal processing procedure can dramatically reduce the data transmission rate while maintaining the performance of the DSI assessment, through comparison of the DSI obtained using the proposed event-triggered approach with those obtained based on event-triggered raw data and continuously transmitted time-triggered data. The obtained results indicate the feasibility of adopting event-triggered data scheduling and signal processing to achieve AMS risk evaluation using data from wearable devices with limited communication/battery resources.

Intermittent hypoxia training (IHT) is a promising approach that has been used to induce acclimatization to hypoxia and subsequently lower the risk of developing acute mountain sickness (AMS). However, the effects of IHT on cognitive and cerebrovascular function after acute hypoxia exposure have not been characterized. In the present study, we first confirmed that the simplified IHT paradigm was effective at relieving AMS at 4300 m. Second, we found that IHT improved participants’ cognitive and neural alterations when they were exposed to hypoxia. Specifically, impaired working memory performance, decreased conflict control function, impaired cognitive control, and aggravated mental fatigue induced by acute hypoxia exposure were significantly alleviated in the IHT group. Furthermore, a reversal of brain swelling induced by acute hypoxia exposure was visualized in the IHT group using magnetic resonance imaging. An increase in cerebral blood flow (CBF) was observed in multiple brain regions of the IHT group after hypoxia exposure as compared with the control group. Based on these findings, the simplified IHT paradigm might facilitate hypoxia acclimatization, alleviate AMS symptoms, and increase CBF in multiple brain regions, thus ameliorating brain swelling and cognitive dysfunction.

Zhang, Guangbo, Yanzhao Zhou, Zhengtao Cao, Xiang Cheng, Xiangpei Yue, Tong Zhao, Ming Zhao, Yongqi Zhao, Ming Fan, and Lingling Zhu. Preliminary intermittent hypoxia training alleviates the damage of sustained normobaric hypoxia on human hematological indexes and cerebral white matter. High Alt Med Biol. 23:273-283, 2022. Background: We aimed to examine the effects of preliminary intermittent hypoxia training (IHT) on human hematological indexes and cerebral white matter (WM) after exposure to a simulated altitude of 4,300 m. Methods: We recruited 20 young healthy volunteers. Participants were then randomized to either the IHT group (n = 10) or the control group (n = 10). We measured the physiological function of the control group at sea level and after exposure to a simulated altitude of 4,300 m, respectively. The IHT group performed the above tests at three time points: before and after hypoxia training, and after exposure to a simulated altitude of 4,300 m, respectively. Results: We found that mean SpO2 during day 10 of hypoxia training showed a significant increase compared with mean SpO2 on day 1 (88.3% ± 1.5% vs. 90.0% ± 1.6%, p < 0.05), and erythrocyte P50 of post-training was significantly increased compared with pretraining (37.8 ± 2.9 mmHg vs. 45.9 ± 6.4 mmHg, p < 0.05). Mean SpO2 measures after acute exposure to high altitude exhibited a significant difference, with the IHT group showing significantly greater SpO2 than the control group (73.8% ± 3.7% vs. 77.4% ± 3.2%, p < 0.05), and the Lake Louise Score was also lower than the control group (2.55 ± 2.1 vs. 6.67 ± 2.5, p < 0.05). After daily IHT, brain-derived neurotrophic factor plasma levels of participants in the IHT group did not change but significantly increased in response to high-altitude hypoxia (103.5% ± 70.4% vs. 29.7% ± 73.2%, p < 0.05). Interleukin-10 (IL-10) plasma level did not change before and after IHT in the IHT group, whereas the IL-10 plasma level of the control group after high-altitude exposure was significantly higher. Furthermore, we found that fractional anisotropy values in the left corticospinal tract and splenium of the corpus callosum in the IHT group were significantly higher than those in the control group after high-altitude hypoxia. Conclusions: These results demonstrate that IHT alleviates the damage of sustained normobaric hypoxia on human hematological indexes and cerebral WM.

Advances in wearable devices and medical internet of things (IoT) have enabled the intelligent measurement and monitoring of key physiological variables. In this work, we aim to build an acute mountain sickness (AMS) risk evaluation index based on data from wearable devices from a performance monitoring perspective, made possible by the medical IoT architecture. Through exploring the dynamic properties of real-time data and exploiting the underlying relationship between the AMS risk and the bandwidth of the hypoxic stress response, a dynamic SpO2 (peripheral oxygen saturation) index (DSI) with AMS risk evaluation potential is proposed and a robust index evaluation procedure is developed to rule out the effect of measurement noises and deep-breath related disturbances. The effectiveness of DSI was assessed based on physiological data from a proof-of-the-concept clinical study ($\mathrm{N}=12$). The relationship of DSI with existing AMS metrics is analyzed through correlation analysis. Statistically significant correlation between DSI and AMS metrics (Lake Louise Score (LLS); deep sleep duration; deep sleep ratio; and mean SpO2) was observed. A benchmark value for DSI was determined based on the critical value of LLS. The proposed method and experimental results indicate the feasibility of improving AMS risk evaluation performance using intelligent monitoring techniques.

目的 探讨急性高原低氧对脑电(Electroencephalogram,EEG)功率的影响.方法 采用低压低氧舱模拟海拔4300 m低氧环境,采集并分析EEG信号.结果(1)各频段功率受氧气环境影响显著,低氧环境下功率增强,尤其是alpha、delta、theta频段功率显著增强.(2)急性低氧后,常氧下额区活动呈左偏侧化的个体,偏侧化指标有所降低;常氧下额区活动呈右侧化的个体,偏侧化指标则略为上升.结论 模拟低氧环境影响了个体的额区偏侧化指标,导致个体情绪调节灵活性变差.

Objective: To investigate the effects of acute high altitude hypoxia on EEG power in different emotional states. Methods: This study was two-factor within-subject design (2 levels of oxygen environment ×4 levels of emotion type). Twelve male subjects aged between 20 and 25 years old were induced to produce four different types of emotions by emotional picture evoked paradigm: low valence and low arousal(LVLA), high valence and low arousal(HVLA), low valence and high arousal(LVHA), high valence and high arousal(HVHA). Brain Products 32 was used to collect EEG signals under different emotional states. The next day, a constant depressed oxygen chamber was used to simulate a 4 300 m plateau hypoxia environment, and the same group of subjects used the same experimental paradigm to collect EEG signals 10h after hypoxia. The collected EEG signals were analyzed by power spectrum (FFT), and the five frequency bands (Delta, Theta, Alpha, beta, gamma) of the frontal lobe (F3\Fz\F4) were analyzed by variance analysis of two-factor repeated measurements. Results: FFT analysis found that before and after acute hypoxia, the whole brain distribution of alpha wave in four emotional states was mainly concentrated in frontal and parietal leaves; the distribution of alpha wave in the whole brain was the least in relaxed emotional state. The results of the two-factor repeated measurement ANOVA showed that: ①the power of delta\ beta band was significantly affected by the oxygen environment(P＜0.05), and the power was enhanced under hypoxia. ②The power index of theta\ alpha band showed a significant interaction between the oxygen environment and emotional types(P＜0.05). Except for the HVLA emotional state, the power of theta alpha band was significantly enhanced under hypoxia. ③ The two factors had no significant influence on the gamma band(P＞0.05). Conclusion: Under the four kinds of emotional states, the difference of the influence of oxygen environment on brain activity was mainly in the frontal lobe, parietal lobe and part of temporal lobe. Of the four types of emotions, the oxygen environment had the least significant effect on brain activity in HVLA emotional states, while the rest showed significant differences.

Intermittent hypoxia (IH) has preventive and therapeutic effects on hypertension, myocardial infarction, cerebral ischemia and depression, but its effect on post-traumatic stress disorder (PTSD) has not been known. In this study, we used inescapable electric foot shock combined with context recapture to build PTSD mouse model. The levels of fear and anxiety were valued by the open field, the elevated plus maze (EPM) and the fear conditioning tests; the level of spatial memory was valued by Y maze test; the number of Fos positive neurons in hippocampus, amygdala and medial prefrontal cortex was valued by immunohistochemical staining; and the protein expressions of hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and brain derived neurotrophic factor (BDNF) in these brain area were valued by Western blot. The results showed that IH and model (foot shock) had an interaction on percentage of entering open arms (OE%) in EPM and freezing time and the number of fecal pellets in fear conditioning test. IH increased OE% in EPM and reduced the freezing time and the number of fecal pellets in fear conditioning test in PTSD model mice. At the same time, IH reduced the number of Fos positive neurons in the hippocampus, amygdala and medial prefrontal cortex of PTSD model mice, and increased the protein expression levels of HIF-1α, VEGF and BDNF in these brain tissues. In conclusion, IH pretreatment can relieve fear and anxiety behavior in post-traumatic stress model mice, suggesting that IH may be an effective means of preventing PTSD.

高原低氧从多方面对机体产生影响,而脑又是对氧需求最高的器官.因而,长时间高海拔低氧环境对脑功能,如记忆力、判断力、计算力、反应能力等产生一系列的影响,严重时可导致高原脑水肿等.目前,对于高原病的发病机制不甚明了,近年来随着神经影像技术的发展,利用磁共振成像(MRI)进行高原环境脑结构和功能的影像研究,取得了一系列新的进展,如急性和慢性高原暴露后脑总体积、脑灰质、白质体积以及脑血流、脑血管等都会发生不同程度的变化.该文综述了近年来高原低氧脑影像方面的研究成果,并对高原低氧致脑损伤的防护研究进行了展望.