The role of oxygen-increased respirator in humans ascending to high altitude

Sleep Quality Among Pilgrims at High Altitude: A Cross-Sectional Study From Gosaikunda Lake, Nepal (4380 m)

Introduction Nepal is a touristic country; globally, many people visit Nepal for mountaineering, trekking, sightseeing, and pilgrimages. Gosaikunda, located at an elevation of 4380 m (14,370 ft) in the Rasuwa district, Nepal, is a popular pilgrimage site. At high altitudes, hypobaric hypoxia is the primary cause of sleep disturbances and is characterized by difficulty falling asleep, frequent nighttime awakening, difficulty returning to sleep, and waking up earlier in the morning than desired, ultimately resulting in a reduction in total sleep duration and quality. Objective The primary objective of this study was to evaluate the quality of sleep patterns of pilgrims while undergoing acute high-altitude exposure on their journey to Gosaikunda, Nepal, which is a pilgrimage site situated at an altitude of 4380 meters (14,370 feet) above sea level. Methodology A cross-sectional descriptive study from August 7 to 14, 2022, was conducted among Gosaikunda pilgrims who visited the sacred lake in Rasuwa district in Nepal at an altitude of 4380 m, where weather is unpredictable and adverse climatic events are prevalent. The subjective sleep quality was evaluated by using the Athens Insomnia Scale (AIS). Individual participants rated each item (sleep symptoms) as 0 to 3, 0 = no problem, 1 = slight problem, 2 = marked problem, and 3 = very marked or no sleep at all. The total range of the score is 0 to 24, with a cutoff point score ≥ 6 being considered poor sleep. Results Out of 229 participants, 42 (18%), 24 (11%), and three (1%) of them experienced mild, moderate, and severe insomnia, and 160 (70%) had no sleep disturbances. Based on the Athens Insomnia Scale cutoff points, 69 (30.13%) had a score of ≥ 6, indicative of insomnia, and 160 (69.86%) had a score of less than 6, suggestive of no insomnia. Daytime sleepiness was the most common subjective sleep issue among the pilgrims suffering from insomnia (40, 57.97%) and no insomnia (96, 60%). The majority of pilgrims, 207 (99.12%), stayed overnight while ascending at Gosiakunda (4380 meters). The mean body mass index (BMI) in kg/m2 of pilgrims suffering from insomnia and those not suffering from insomnia was 25.29±5.3 and 24.58±4.47, respectively, with a P-value greater than 0.05. The mean age among pilgrims suffering from insomnia and pilgrims who didn't was 41.64±13.39 and 41.64±13.44, respectively, with a P-value greater than 0.05. The majority of the pilgrims took an average of two days to reach Gosaikunda Lake, of which 207 (99.12%) remained at altitude for one night and 22 (0.96%) stayed for more than one night. Conclusion Acute exposure to high altitude results in frequent arousal due to hypobaric hypoxia, which in turn causes pilgrims to feel mentally and physically fatigued and somnolent due to the poor sleep they experience. An elevated BMI, advanced age, and male sex were associated with poor sleep quality after acute altitude exposure. Further research is needed to better understand the mechanisms underlying these associations and to develop effective interventions to improve sleep quality during rapid ascent.

Notoginsenoside R1 treatment facilitated Nrf2 nuclear translocation to suppress ferroptosis via Keap1/Nrf2 signaling pathway to alleviated high-altitude myocardial injury

High-altitude myocardial injury (HAMI) represents a critical form of altitude illness for which effective drug therapies are generally lacking. Notoginsenoside R1, a prominent constituent derived from Panax notoginseng, has demonstrated various cardioprotective properties in models of myocardial ischemia/reperfusion injury, sepsis-induced cardiomyopathy, cardiac fibrosis, and myocardial injury. The potential utility of notoginsenoside R1 in the management of HAMI warrants prompt investigation. Following the successful construction of a HAMI model, a series of experimental analyses were conducted to assess the effects of notoginsenoside R1 at dosages of 50 mg/Kg and 100 mg/Kg. The results indicated that notoginsenoside R1 exhibited protective effects against hypoxic injury by reducing levels of CK, CK-MB, LDH, and BNP, leading to improved cardiac function and decreased incidence of arrhythmias. Furthermore, notoginsenoside R1 was found to enhance Nrf2 nuclear translocation, subsequently regulating the SLC7A11/GPX4/HO-1 pathway and iron metabolism to mitigate ferroptosis, thereby mitigating cardiac inflammation and oxidative stress induced by high-altitude conditions. In addition, the application of ML385 has confirmed the involvement of Nrf2 nuclear translocation in the therapeutic approach to HAMI. Collectively, the advantageous impacts of notoginsenoside R1 on HAMI have been linked to the suppression of ferroptosis via Nrf2 nuclear translocation signaling.

Study on the Optimization and Oxygen-Enrichment Effect of Ventilation Scheme in a Blind Heading of Plateau Mine

There are abundant mineral resources in plateau areas, but it is difficult to extract them safely because the problem of hypoxia in plateau mines seriously affects the life and health of workers. In order to address the problem of hypoxia in the blind heading of a plateau metal mine, a three-dimensional roadway model was established based on field data of the Pulang copper mine in Yunnan province, China. The computational fluid dynamics (CFD) method was used to explore the optimal type of oxygen supply duct outlet, and to reveal the oxygen diffusion law influencing different ventilation factors. Grey correlation analysis was used to study the correlation values of the ventilation factors on the oxygen-enrichment effect in blind headings, such as forcing duct position, exhausting duct position, and extraction pressure ratio. The results demonstrated that the oxygen-enrichment effect of a slit oxygen outlet was better than that of the traditional oxygen supply method. When the direction of the oxygen outlet hole was 30° and the height above the roadway floor was 1.95 m, the oxygen increase effect was better than other forms of oxygen supply duct outlets. Grey correlation analysis revealed that the major influencing factors of the oxygen-enrichment effect in the roadway of the plateau mine, were, in descending order, as follows: forcing duct position, extraction pressure ratio, and exhausting duct position. This study has a positive guiding significance for improving the respiration environment in blind headings of plateau mines.

Study on the Oxygen Enrichment Effect of Individual Oxygen-Supply Device in a Tunnel of Plateau Mine

Complex characteristics of the plateau environment such as low oxygen content seriously restrict the exploitation of abundant mineral resources in plateau areas. To regulate the hypoxia environment and improve the comfort of workers engaged in intense physical labor like tunnel excavation operations in plateau mines, an individual oxygen-supply device for tunnel of plateau mine was proposed to create local oxygen enrichment in the area around the human nose. The Computational Fluid Dynamics (CFD) method was used to judge the application’s effect of the individual oxygen-supply device in plateau mine, revealing the oxygen diffusion law under the influence of different oxygen enrichment factors. The orthogonal design and range analysis were used to measure the degree of influence of major factors such as oxygen-supply velocity, oxygen-supply concentration, and tunnel airflow velocity. The results demonstrate that the oxygen mass fraction of the air inhaled by the human had a positive correlation exponential function, a positive correlation linear function, and a negative correlation exponential function, respectively, concerning oxygen-supply velocity, oxygen-supply concentration, and tunnel airflow velocity. The range analysis revealed that the major influencing factors of oxygen enrichment in the tunnel of the plateau mine were, in a descending sequence, as follows: oxygen-supply concentration, tunnel airflow velocity, and oxygen-supply velocity, and the corresponding ranges were 2.86, 2.63, and 1.83, respectively. The individual oxygen-supply device achieved the best oxygen enrichment effect when the oxygen-supply velocity was 5 m/s, the oxygen-supply concentration was 60%, and the tunnel airflow velocity was 0.2 m/s, which increased the oxygen mass fraction of air inhaled by the human to 30.42%. This study has a positive guiding significance for the improvement of the respiration environment in the tunnel of plateau mine.

Circadian and Sex Differences After Acute High-Altitude Exposure: Are Early Acclimation Responses Improved by Blue Light?

OBJECTIVE

The possible effects of blue light during acute hypoxia and the circadian rhythm on several physiological and cognitive parameters were studied.

METHODS

Fifty-seven volunteers were randomly assigned to 2 groups: nocturnal (2200-0230 hours) or diurnal (0900-1330 hours) and exposed to acute hypoxia (4000 m simulated altitude) in a hypobaric chamber. The participants were illuminated by blue LEDs or common artificial light on 2 different days. During each session, arterial oxygen saturation (Spo2), blood pressure, heart rate variability, and cognitive parameters were measured at sea level, after reaching the simulated altitude of 4000 m, and after 3 hours at this altitude.

RESULTS

The circadian rhythm caused significant differences in blood pressure and heart rate variability. A 4% to 9% decrease in waking nocturnal Spo2 under acute hypoxia was observed. Acute hypoxia also induced a significant reduction (4%-8%) in systolic pressure, slightly more marked (up to 13%) under blue lighting. Women had significantly increased systolic (4%) and diastolic (12%) pressures under acute hypoxia at night compared with daytime pressure; this was not observed in men. Some tendencies toward better cognitive performance (d2 attention test) were seen under blue illumination, although when considered together with physiological parameters and reaction time, there was no conclusive favorable effect of blue light on cognitive fatigue suppression after 3 hours of acute hypobaric hypoxia.

CONCLUSIONS

It remains to be seen whether longer exposure to blue light under hypobaric hypoxic conditions would induce favorable effects against fatigue.

Comparative sonographic study of cerebral hemodynamic differences and changes after oxygen therapy in healthy youths of different ethnicities in Tibet

OBJECTIVES

The purpose of this study was to sonographically assess the cerebral hemodynamic differences and changes after oxygen therapy in healthy youths of different ethnicities in Tibet.

METHODS

Sixty-six healthy young Han visitors and 29 healthy young Tibetan residents were divided into 4 groups. Basic information was collected. Pulsed Doppler sonography was used to record the cerebral hemodynamic parameters for the internal carotid, vertebral, and middle cerebral arteries. The participants were then instructed to inhale oxygen, and basic information and cerebral hemodynamic parameters were recorded at 1, 2, 4, and 8 minutes, respectively. Differences in these parameters between groups were analyzed.

RESULTS

In comparisons of the flow parameters between sex-matched groups, the mean resistive index values for the internal carotid, vertebral, and middle cerebral arteries in the Han groups were significantly lower than those in the Tibetan groups (P <. 05). The mean peak systolic velocity, end-diastolic velocity, and mean velocity values for the middle cerebral artery in the Han groups were significantly higher than those in the Tibetan groups (P < .05). After oxygen uptake, there were no significant differences in the mean arterial oxygen saturation, heart rate, mean velocity, and resistive index values between the male groups, and similar changes were found for the arterial oxygen saturation and peak systolic velocity values between female groups after 8 minutes of oxygen uptake (P > .05).

CONCLUSIONS

Sonography is a useful modality for noninvasive and real-time detection of changes in cerebral hemodynamics and can provide reference values for the prevention and treatment of cerebrovascular diseases.

Evaluation of the visual analog score (VAS) to assess acute mountain sickness (AMS) in a hypobaric chamber

OBJECTIVE

The visual analog score (VAS) is widely used in clinical medicine to evaluate the severity of subjective symptoms. There is substantial literature on the application of the VAS in medicine, especially in measuring pain, nausea, fatigue, and sleep quality. Hypobaric chambers are utilized to test and exercise the anaerobic endurance of athletes. To this end, we evaluated the degree of AMS using the visual analog scale (VAS) in a hypobaric chamber in which the equivalent altitude was increased from 300 to 3500 m.

METHODS

We observed 32 healthy young men in the hypobaric chamber (Guizhou, China) and increased the altitude from 300 to 3500 m. During the five hours of testing, we measured the resting blood oxygen saturation (SaO2) and heart rate (HR). Using the VAS, we recorded the subjects' ratings of their AMS symptom intensity that occurred throughout the phase of increasing altitude at 300 m, 1500 m, 2000 m, 2500 m, 3000 m, and 3500 m.

RESULTS

During the phase of increasing altitude in the hypobaric chamber, the patients' SaO2 was 96.8 ± 0.8% at 300 m and 87.5 ± 4.1% at 3500 m (P<0.05) and their HR was 79.0 ± 8.0 beats/minute at 300 m and 79.3 ± 11.3 beats/minute at 3500 m. The incidence of symptoms significantly increased from 21.9% at an altitude of 1000 m to 65.6% at an altitude of 3500 m (P<0.05). The composite VAS score, which rated the occurrence of four symptoms (headache, dizziness, fatigue, and gastrointestinal discomfort), was significantly correlated with elevation (P<0.01).

CONCLUSION

Based on the experimental data, the VAS can be used as an auxiliary diagnostic method of Lake Louise score to evaluate AMS and can show the changing severity of symptoms during the process of increased elevation in a hypobaric chamber; it also reflects a significant correlation with altitude.

The effects of a personal oxygen supplement on performance, recovery, and cognitive function during and after exhaustive exercise

The purpose of this investigation was to examine the effects of a personal oxygen supplement (OS) on performance during exhaustive exercise, respiratory responses during exhaustive exercise, and cognitive function after exhaustive exercise. The participants for this blind placebo-controlled experiment were apparently healthy college-aged adults (n = 20). First, VO2max was assessed (47.6 ± 9.8 ml O2·kg(-1)·min(-1)). Participants then ran 2 trials at 80% of VO2max speed to exhaustion and received either a placebo (compressed air) or personal OS. Psychomotor vigilance testing (PVT) was performed before and after each trial. Performance between treatments was evaluated through repeated measures analysis of variance (ANOVA) and was not found to be different (p = 0.335, ηp2 = 0.052), and order (placebo first or personal OS first) was not significant within the model (p = 0.305, ηp2 = 0.058). Mean times were 1,057.6 ± 619.8 seconds for the oxygen trials and 992.5 ± 463.1 seconds for the placebo trials. Repeated measures ANOVAs were used to assess minute ventilation (Ve, L·min(-1)) and VCO2 (L·O2·min(-1)) during exercise and recovery, mean heart rate during recovery, and PVT results. Treatment was nonsignificant (p > 0.05) nor were any interaction effects (treatment × time, p > 0.05) for any variables. The results of this study suggest that a personal OS had no effect on performance and did not affect ventilation even at the time directly surrounding the application. The results of the study also suggest that personal OS do not enhance exercise recovery or cognition during exercise recovery.

An oxygen enrichment device for lowlanders ascending to high altitude

BACKGROUND

When ascending to the high altitude, people living in low altitude areas will suffer from acute mountain sickness. The aim of this study is to test the hypothesis that whether an oxygen concentration membrane can be made and used to construct a new portable oxygen enrichment device for individuals in acute exposure to the high altitude.

METHODS

The membrane was fabricated using vinylsiloxane rubber, polyphenylene oxide hydrogen silicone polymers, chloroplatinic acid and isopropyl alcohol. The membrane was assembled in a frame and the performance was tested in terms of concentration of oxygen, flow rate of oxygen enriched air, pressure ratio across the membrane and ambient temperature. Furthermore, the oxygen concentration device was constructed using the membrane, a DC fan, vacuum pump and gas buffer. A nonrandomized preliminary field test was conducted, in which eight healthy male subjects were flown to Tibet (Lhasa, 3,700 m). First, subjects wore the oxygen enrichment device and performed an incremental exercise on cycle ergometer. The test included heart rate (HR), saturation of peripheral oxygen (SpO2) and physical work capacity (PWC). Then, after a rest period of 4 hours, the experimental protocol was repeated without oxygen enrichment device.

RESULTS

The testing showed that the membrane could increase the oxygen concentration by up to 30%. Simulation test indicated that although the performance of the oxygen enrichment device decreased with altitudes, the oxygen concentration could still maintain 28% with flow rate of enriched air 110 cm3/s at 5000 m. The field test showed that higher SpO2, lower HR, and better PWC (measured by the PWC-170) were observed from all the subjects using oxygen enrichment device compared with non-using (P < 0.01).

CONCLUSIONS

We concluded that the new portable oxygen enrichment device would be effective in improving exercise performance when ascending to the high altitude.