The denitrogenation by breathing oxygen-rich gas to prevent altitude decompression sickness

Objective While the technology of the molecular sieve oxygen generation system(MSOGS) onboard was used,pilots could not breathe pure oxygen to eliminate nitrogen during a high altitude flight.There is no report whether it is a threat to altitude decompression sickness(ADS) or not in that condition.This experiment was intended to observe the effects of breathing different oxygen-rich gases of MSOGS on denitrogenation,so that we could make the medical physiological requirements for MSOGS on-board and provide experimental basis for aeromedical supply.Method Eight healthy males were breathed oxygenrich gases(60%,70%,80%,90%and 99.6%) in turn for 60 min,and the concentration of nitrogen,oxygen,carbon dioxide and argon at the end of expiration interval in the oxygen mask were continuously measured by a flight mass spectrometer through the oxygen mask.According to the variety of the denitrogenation rate by breathing different oxygen-rich gases,its change law was analyzed.Results There were significant differences(P<0.05) about denitrogenation rate in different oxygen-rich gases due to different oxygen concentration and breathing time.The denitrogenation rate of pure oxygen was higher than that of the others.It was indicated that the concentration of nitrogen in lung would decrease along with the increase in oxygen concentration of oxygen-rich gases,and the nitrogen concentration in the lung almost decreased by 50% or even more if people were breathed 60%～90% oxygen-rich gas longer than 60 s.Conclusion The man-made respiration environment of low nitrogen can be provided by breathing oxygen-rich gases,although the denitrogenation velocity of breathing oxygen-rich gases is lower than that of breathing pure oxygen.So it can be used as a measure to eliminate and lower the nitrogen in the body to prevent from ADS.

Rong Shuan Jiao Nang in the treatment of acute mountain sickness and high altitude myocardial ischemic syndrome in Yushu

To evaluate the therapeutic effects of Rong Shuan Jiao Nang （RSJN） on treatment of acute mountain sickness （AMS） and high altitude myocardial ischemic syndrome in workers in Yushu, three groups were studied： group A （60 patients with AMS, given RSJN）, group B （15 patients with altitude myocardial ischemic syndrome, given RSJN）, and group C （control, without drugs）. All studied subjects were lowland workers who were first time entry to Yushu for work at an altitude of 4 250 m. During the course of treatment, a routing physical examina- tion was performed, AMS Lake Louise Scores were estimated, arterial oxygen saturation （SaO2）, electrocardiography and hemoglobin concentration were measured before and after using RSJN for 10 days. In group A, the effective rate was 68 %, symptomatic improvement in 54 cases （90 %） within 5 days. In group B, the effective rate was 93 %, episodes of angina pectoris stopped in 12 patients within 3 - 7 days, one lasted 8 days. After treatment, the level of SaO2 increased 15.5 %, 21.8 % and 5.6 % in group A, group B and group C, respectively. RSJN tak- en at the start of the arrival at Yushu can decrease AMS scores and facilitate cure. If taken after the illness has begun, RSJN may help lessen symptoms, especially effectively improved angina pectoris of the high altitude myocardial ischemic syndrome. Symptoms usually subside after 3 - 8 days. RSJN should be continually used lbr at least 7 days after ascent.

SNPs and TFBS Associated with High Altitude Sickness

The rSNPs for the genes AKT3 (rs4590656), EGLN1 (rs480902), eNOS3 (rs1007311), and VEGFA (rs699947, rs13207311, rs1570360, rs2010963) have been significantly associated with the physiological parameters in high altitude sickness Han or Tibetan Chinese patients at the Qinghai-Tibetan plateau. The alleles of each rSNP have been found to create unique transcriptional factor binding sites for transcription factors that affect the process of hypoxia gene expression in this high altitude hypoxia environment.

Early Warning of Acute Altitude Sickness by Physiological Variables and Noninvasive Cardiovascular Indicators

Objective To examine if the variations at sea level would be able to predict subsequent susceptibility to acute altitude sickness in subjects upon a rapid ascent to high altitude.Methods One hundred and six Han nationality male individuals were recruited to this research.Dynamic electrocardiogram,treadmill exercise test,echocardiography,routine blood examination and biochemical analysis were performed when subjects at sea level and entering the plateau respectively.Then multiple regression analysis was performed to construct a multiple linear regression equation using the Lake Louise Score as dependent variable to predict the risk factors at sea level related to acute mountain sickness(AMS).Results Approximately 49.05%of the individuals developed AMS.The tricuspid annular plane systolic excursion(22.0+2.66 vs.23.2+3.19 mm,t=l.998,P=0.048)was significantly lower in the AMS group at sea level,while count of eosinophil[(0.264+0.393)×109/L vs.(0.126+0.084)×109/L,t=-2.040,P—0.045],percentage of diflerences exceeding 50 ms between adjacent normal number of intervals(PNN50,9.66%±5.40%vs.6.98%±5.66%,t=-2.229,P=0.028)and heart rate variability triangle index(57.1+16.1 vs.50.6+12.7,t=-2.271,P=0.025)were significantly higher.After acute exposure to high altitude,C-reactive protein(0.098+0.103 vs.0.062+0.045 g/L,t=-2.132,P=0.037),aspartate aminotransferase(19.7+6.7275.17,3±3.95 U/L,t=-2.231,P=0.028)and creatinine(85.1±12.9 vs.77.7±11.2 mmol/L,t=3.162,P=0.002)were significantly higher in the AMS group,while alkaline phosphatase(71.7+18.2 vs.80.6+20.2 U/L,t=2.389,P=0.019),standard deviation of normal-to-normal RR intervals(126.5+35.9 vs.143.3+36.4 ms,t—2.320,P—0.022),ejection time(276.9+50.8 vs.313.8+48.9 ms,t—3.641,P—0.001)and heart rate variability triangle index(37.1+12.9 vs.41.9+11.1,t=2.O2O,P=0.047)were significantly lower.Using the Lake Louise Score as the dependent variable,prediction equation were established to estimate AMS:Lake Louise Score=3.783+0.281Xeosinophil-0.219Xalkaline phosphatase+O.O32XPNN50.Conclusions We elucidated the differences of pl^siological variables as well as noninvasive cardiovascular indicators for subjects after high altitude exposure compared with those at sea level.We also created an acute high altitude reaction early warning equation based on the physiological variables and noninvasive cardiovascular indicators at sea level.

Association between physiological responses after exercise at low altitude and acute mountain sickness upon ascent is sex-dependent

Background:Acute mountain sickness(AMS)is the mildest form of acute altitude illnesses,and consists of nonspecific symptoms when unacclimatized persons ascend to elevation of≥2500 m.Risk factors of AMS include:the altitude,individual susceptibility,ascending rate and degree of pre-acclimatization.In the current study,we examined whether physiological response at low altitude could predict the development of AMS.Methods:A total of 111 healthy adult healthy volunteers participated in this trial;and 99(67 men and 32 women)completed the entire study protocol.Subjects were asked to complete a 9-min exercise program using a mechanically braked bicycle ergometer at low altitude(500 m).Heart rate,blood pressure(BP)and pulse oxygen saturation(SpO2)were recorded prior to and during the last minute of exercise.The ascent from 500 m to 4100 m was completed in 2 days.AMS was defined as≥3 points in a 4-item Lake Louise Score,with at least one point from headache wat 6–8 h after the ascent.Results:Among the 99 assessable subjects,47(23 men and 24 women)developed AMS at 4100 m.In comparison to the subjects without AMS,those who developed AMS had lower proportion of men(48.9%vs.84.6%,P<0.001),height(168.4±5.9 cm vs.171.3±6.1 cm,P=0.019),weight(62.0±10.0 kg vs.66.7±8.6 kg,P=0.014)and proportion of smokers(23.4%vs.51.9%,P=0.004).Multivariate regression analysis revealed the following independent risks for AMS:female sex(odds ratio(OR)=6.32,P<0.001),SpO2 change upon exercise at low altitude(OR=0.63,P=0.002)and systolic BP change after the ascent(OR=0.96,P=0.029).Women had larger reduction in SpO2 after the ascent,higher AMS percentage and absolute AMS score.Larger reduction of SpO2 after exercise was associated with both AMS incidence(P=0.001)and AMS score(P<0.001)in men but not in women.Conclusions:Larger SpO2 reduction after exercise at low altitude was an independent risk for AMS upon ascent.Such an association was more robust in men than in women.Trial registration:Chinese Clinical Trial Registration,ChiCTR1900025728.Registered 6 September 2019.

Ataxia,acute mountain sickness,and high altitude cerebral edema

Previous investigations suggest that ataxia is common and often one of the most reliable warning signs of high altitude cerebral edema(HACE). The aim of this study was to investigate the diagnostic role of ataxia in acute mountain sickness(AMS)and HACE among mountain rescuers on the quake areas,and in approaching the relation between AMS and HACE. After the earthquake on April 14,2010,approximately 24 080 lowland rescuers were rapidly transported from sea level or lowlands to the mountainous rescue sites at 3 750 ~ 4 568 m,and extremely hardly worked for an emergency treatment after arrival. Assessments of acute altitude illness on the quake areas were using the Lake Louise Scoring System. 73 % of the rescuers were found to be developed AMS. The incidence of high altitude pulmonary edema(HAPE)and HACE was 0.73 % and 0.26 %,respectively,on the second to third day at altitude. Ataxia sign was measured by simple tests of coordination including a modified Romberg test. The clinical features of 62 patients with HACE were analyzed. It was found that the most frequent,serious neurological symptoms and signs were altered mental status(50/62,80.6 %)and truncal ataxia(47/62,75.8 %). Mental status change was rated slightly higher than ataxia,but ataxia occurred earlier than mental status change and other symptoms. The earliest sign of ataxia was a vague unsteadiness of gait,which may be present alone in association with or without AMS. Advanced ataxia was correlated with the AMS scores,but mild ataxia did not correlate with AMS scores at altitudes of 3 750~4 568 m. Of them,14 patients were further examined by computerized tomographic scanning of the brain and cerebral magnetic resonance imagines were examined in another 15 cases. These imaging studies indicated that the presence of the cerebral edema was in 97 % of cases who were clinically diagnosed as HACE(28/29). Ataxia seems to be a reliable sign of advanced AMS or HACE,so does altered mental status.

Physiological Variables Associated with the Development of Acute Mountain Sickness

Objective To identify the physiological variables associated with the development of acute mountain sickness(AMS).Methods Eighty four young Chinese men residing at low altitude were taken to an altitude of 4000 m within 40 hours.At sea level and at high altitude,we measured the heart rate,blood pressure,and peripheral oxygen saturation(SpO2)respectively.We also collect blood samples from each participants before and after the altitude elevation.The blood routine and biochemical examinations were performed for all blood samples.The revised Lake Louise Criteria was adopted to diagnose AMS after the subjects arrived at the target high altitude.The association between the presence of AMS and subjects’physiological variables were analysed statistically.Results Of 84 participants,34(40.5%)developed AMS.Compared with non AMS group,in the AMS group,the percentage of neutrophils was significantly higher(64.5%±11.2%vs.58.1%±8.8%,P=0.014),while the level of SpO2 was significantly lower(79.4%±5.4%vs.82.7%±5.6,P=0.008).Binary logistic regression analyses emphasized the association of neutrophils(OR:1.06,95%CI:1.01-1.12,P=0.034)and SpO2 level(OR:0.87,95%CI:0.79-0.95,P=0.004)with the development of AMS.Conclusion The ability to sustain SpO2 after altitude elevation and the increase of neutrophils were associated with the development of AMS in young males.

Serum testosterone levels and excessive erythrocytosis during the process of adaptation to high altitudes

Populations living at high altitudes （HAs）, particularly in the Peruvian Andes, are characterized by a mixture of subjects with erythrocytosis （16 g dl-1〈haemoglobin （Hb）≤21 gdl-1） and others with excessive erythrocytosis （EE） （Hb〉21 g dl-1）. Elevated haemoglobin values （EE） are associated with chronic mountain sickness, a condition reflecting the lack of adaptation to HA. According to current data, native men from regions of HA are not adequately adapted to live at such altitudes if they have elevated serum testosterone levels. This seems to be due to an increased conversion of dehydroepiandrosterone sulphate （DH EAS） to testosterone. Men with erythrocytosis at HAs show higher serum androstenedione levels and a lower testosterone/androstenedione ratio than men with EE, suggesting reduced 17beta-hydroxysteroid dehydrogenase （17beta-HSD） activity. Lower 17beta-HSD activity via A4-steroid production in men with erythrocytosis at HA may protect against elevated serum testosterone levels, thus preventing EE. The higher conversion of DHEAS to testosterone in subjects with EE indicates increased 17beta-HSD activity via the A5-pathway. Currently, there are various situations in which people live （human biodiversity） with low or high haemoglobin levels at HA. Antiquity could be an important adaptation component for life at HA, and testosterone seems to participate in this process.

Association between smoking and the risk of acute mountain sickness： a meta-analysis of observational studies

Background: People rapidly ascending to high altitudes(>2500m) may suffer from acute mountain sickness(AMS). The association between smoking and AMS risk remains unclear. Therefore, we performed a meta-analysis to evaluate the association between smoking and AMS risk.Methods: The association between smoking and AMS risk was determined according to predefined criteria established by our team. Meta-analysis was conducted according to the PRISMA guidelines. We included all relevant studies listed in the Pub Med and Embase databases as of September 2015 in this meta-analysis and performed systemic searches using the terms "smoking", "acute mountain sickness" and "risk factor". The included studies were required to provide clear explanations regarding their definitions of smoking, the final altitudes reached by their participants and the diagnostic criteria used to diagnose AMS. Odds ratios(ORs) were used to evaluate the association between smoking and AMS risk across the studies, and the Q statistic was used to test OR heterogeneity, which was considered significant when P<0.05. We also computed 95% confidence intervals(CIs). Data extracted from the articles were analyzed with Review Manager 5.3(Cochrane Collaboration, Oxford, UK).Results: We used seven case-control studies including 694 smoking patients and 1986 non-smoking controls to analyze the association between smoking and AMS risk. We observed a significant association between AMS and smoking(OR=0.71, 95% CI 0.52–0.96, P=0.03).Conclusion: We determined that smoking may protect against AMS development. However, we do not advise smoking to prevent AMS. More studies are necessary to confirm the role of smoking in AMS risk.

Relationship between excessive erythrocytosis and acute mountain sickness: A field study

Background: Alterations in hematology, especially erythroid changes, may be involved in acute mountain sickness(AMS) at high altitude. This study aimed to identify the relationship between excessive erythrocytosis and AMS following different durations of high-altitude exposure.Methods: A total of 692 healthy young Chinese men were recruited for the study in June and July of 2012 and were divided into the following five groups: I) the 24-h group(24 hours after arrival at Lhasa, 3,700 m, n=261); II) the 7-d group(exposed at Lhasa, 3,700 m for seven days, n=99); III) the re-exposure group(re-exposed at Yang Bajing, 4,400 m for seven days after 】1 year of acclimation at 3,700 m, n=94); IV) the acclimated group(】1 year of acclimation at 3,700 m, Lhasa, n=42); and V) the sea-level control(control group, Chengdu, n=196). Case report forms were used to record the subjects’ demographic information and AMS-related symptoms. All of the subjects underwent routine blood tests.Results: The red blood cell(RBC) count fell slightly but was not significant upon acute exposure to high altitude, whereas the hemoglobin concentration([Hb]) increased significantly. After high-altitude re-exposure, both of the [Hb] and RBC count showed significant increases. The incidence of AMS was 65.1%, 26.3% and 51.1%, respectively in the 24-h, 7-d and re-exposure groups. The [Hb](P=0.024) and hematocrit(P=0.017) were greater in the AMS+ individuals than in the AMS– individuals in 7-d group. A correlation analysis revealed that the [Hb] and hematocrit were closely related with AMS score in 7-d and re-exposure groups, while the RBC showed a correlation with AMS score only in the re-exposure group. The AMS incidence was lowest when the [Hb] was between 140 and 160 g/L in the 24-h and 7-d groups.Conclusions: AMS is associated with both [Hb] and excessive erythrocytosis. Additionally, our findings indicate the existence of an optimal [Hb] for preventing AMS.

High altitude medicine in China in the 21st century Opportunities and challenges

China has the largest plateau, Qinghai-Tibet Plateau, where inhabited the most high altitude populations. Moreover, millions of people from plain areas come to the plateau for travel and work purposes and the number of the newcomers has been increasing every year. The hypoxic environment of plateau raised a series of related health issues in the new immigrants, so have created a special medical discipline- High Altitude Medicine. Over the past decades, researches on high altitude medicine have never being ceased in China, and lots of research findings have been reported. Application and practice of these achievements have greatly decreased the mobility and mortality of highaltitude diseases, however, there remained lots of questions to be elucidated. In view of this, the authors were granted a special project from the National Health and Family Planning Commission of China, and conducted a multi-center, prospective, on-scene high altitude medicine study for the acute mountain sickness. Some innovative findings were achieved, and the parameters for diagnosis and application conditions were proposed. Furthermore, the different diagnoses and treatment effects were compared, and a more standardized, reasonable scheme was drawn up. Regarding the unbalanced medical resources in the vast high altitude area, an application system for the public and the army has been established. In the 21 st century, innovations in China and novel research approaches have provided great opportunities for the development of high altitude medicine. It is believed that the researchers in China are able to catch the opportunities and address the challenges.

Hydrogen Therapy Reduces Oxidative Stress-associated Risks Following Acute and Chronic Exposure to High-altitude Environment

Low pressure,low oxygen concentration,and intense ultraviolet（UV）radiation in high-altitude environments,can cause oxidative stress which can trigger mountain sickness.A recent study demonstrated that hydrogen gas with a good permeability in biological membranes can treat various disorders by exerting its selective anti-oxidation and anti-inflammatory effects,indicating that hydrogen therapy plays a role in scavenging free radicals and in balancing oxidation and anti-oxidation systems of ceils. Therefore, we hypothesize that inhaling low-dose hydrogen or drinking hydrogen-saturated water is a novel and simple method to prevent and treat oxidative stress injury caused by low pressure, low oxygen concentration and intense UV radiation in plateaus, thus reducing the risk of mountain sickness.

Changes in oxygen saturation can not help diagnose acute mountain sickness(AMS)： ascending to Lhasa on the Qinghai-Tibet train

Objective: Acute mountain sickness(AMS) is a common condition in individuals who ascend to altitudes over 2 500 m. There is no measurements that can reliably predict or diagnose this condition. We therefore determined whether pulse oximetry data are associated with the development of AMS and can help diagnose AMS. Methods: We studied 58 young male undergraduates who traveled from Chongqing(300 m) to Lhasa(3 658 m) by train. We collected data on the ascent profiles and AMS symptoms based on the Lake Louise Score(LLS). The resting arterial oxygen saturation(R-Sp O2) and pulse rate were then measured using finger pulse oximetry. Results: In Golmud(2 800 m) and Tanggula(5 200 m), R-SpO_2 was significantly lower in the AMS group than in the group without AMS(P<0.05). However, upon arrival in Lhasa(3 658 m), the R-SpO_2 was higher in the AMS group than in the non-AMS group(P<0.05). In Tanggula, the change in the SpO_2(CR-SpO_2) in the AMS group was higher than that in the non-AMS group(P<0.05). But in Lhasa, the CR-SpO_2 in the AMS group was lower than that in the non-AMS group(P<0.05). We also monitored heart rate(HR) throughout the study. In Xining(2 200 m) and Golmud, the HRs in the AMS group were higher than those in the non-AMS group. However, the HRs in the AMS group were lower than those in the non-AMS group in Tanggula and Lhasa. Conclusion: Based on the results of this study, the R-SpO_2 graph was not consistent. We can thus conclude that the utility of SpO_2 remains limited in the diagnosis of AMS. The results suggest that using pulse oximetry to diagnose AMS is not valuable in people ascending to Lhasa on the Qinghai-Tibet train.

Pathophysiological changes in mitochondria of mammalian exposed to hypoxia at high altitude

As human beings ascend to high altitude,a number of reactions may occur against hypoxic injuries.These hypoxic responses are related to intake,transportation and utility of the oxygen.As a crucial subcellular organelle of oxygen utility,mitochondrion is a central link of high altitude acclimatization,adaptation and mountain sicknesses.In this review,we discussed the recent advances in researches on hypoxic mitochondrial responses at high altitude.

Ginkgo biloba active compounds can modulate the development of acute mountain sickness and ischemic stroke as discovered by network pharmacology and molecular docking

Background:A combination of molecular docking,molecular dynamics simulations,and herbal network pharmacology was used to investigate the shared key targets and potential mechanisms underlying the preventive effects of Ginkgo biloba active compounds against acute mountain sickness(AMS)and ischemic stroke(IS).Material and Methods:The Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform was used to screen the main active compounds of Ginkgo biloba and their corresponding targets.We obtained AMS-related genes by mining several databases and cross-correlated them with key active compounds of Ginkgo biloba to identify relevant action targets for treating AMS.The STRING database was used to construct a protein–protein interaction network of the effect of Ginkgo biloba active compounds on AMS targets.The expression of genes in the network was analyzed in an IS dataset to identify common key targets of Ginkgo biloba active compounds for both AMS and IS prevention.Results:The intersection between the targets of Ginkgo biloba active compounds and AMS-related genes identified 43 overlapping genes.Analysis of the protein–protein interaction network showed that VEGFA,TP53,SERPINE1,and PTGS2 were among the key hub genes.Analysis of the IS dataset identified significant differences in the expression levels of CAT,TP53,CXCL8,NFKBIA,and PTGS2.These genes were used to construct a visual nomogram prediction model for IS prognosis with promising clinical implications.Molecular docking and molecular dynamics simulations indicated that sesamin stably targeted and bound to PTGS2.Conclusions:Active ingredients of Ginkgo biloba,including luteolin,quercetin,and sesamin,have the potential to modulate the development of AMS and IS through targeted interactions with key proteins,including TP53,CXCL8,NFKBIA,PTGS2,and CAT.

Correlation between blood pressure changes and AMS, sleeping quality and exercise upon high-altitude exposure in young Chinese men

Background: Excessive elevation of arterial blood pressure(BP) at high altitude can be detrimental to our health due to acute mountain sickness(AMS) or some AMS symptoms. This prospective and observational study aimed to elucidate blood pressure changes induced by exposure to high-altitude hypoxia and the relationships of these changes with AMS prevalence, AMS severity, sleep quality and exercise condition in healthy young men.Methods: A prospective observational study was performed in 931 male young adults exposed to high altitude at 3,700 m(Lhasa) from low altitude(LA, 500 m). Blood pressure measurement and AMS symptom questionnaires were performed at LA and on day 1, 3, 5, and 7 of exposure to high altitude. Lake Louise criteria were used to diagnose AMS. Likewise, the Athens Insomnia Scale(AIS) and the Epworth Sleepiness Scale(ESS) were filled out at LA and on day 1, 3, and 7 of exposure to high altitude.Results: After acute exposure to 3,700 m, diastolic blood pressure(DBP) and mean arterial blood pressure(MABP) rose gradually and continually(P【0.05). Analysis showed a relationship with AMS for only MABP(P【0.05) but not for SBP and DBP(P】0.05). Poor sleeping quality was generally associated with higher SBP or DBP at high altitude, although inconsistent results were obtained at different time(P【0.05). SBP and Pulse BP increased noticeably after high-altitude exercise(P【0.05).Conclusions: Our data demonstrate notable blood pressure changes under exposure to different high-altitude conditions: 1) BP increased over time. 2) Higher BP generally accompanied poor sleeping quality and higher incidence of AMS. 3) SBP and Pulse BP were higher after high-altitude exercise. Therefore, we should put more effort into monitoring BP after exposure to high altitude in order to guard against excessive increases in BP.

Relationship between autonomic nervous system function and acute mountain sickness

Objective: To elucidate the role of the autonomic nervous system (ANS) in acute mountain sickness (AMS) during the initial phase at acute high-altitude exposure. Methods: Ninety-nine healthy sea-level residents rapidly ascended to Tibet plateau (3 675 m altitude) by airplane from Chengdu plain (560 m altitude). ANS function was tested in plain and day 2–4 in Tibet by heart rate variability (HRV), cold pressor test (CPT). AMS was evaluated by clinic symptomatic scores. All subjects were divided into non-AMS group (57, scores≤4) and AMS group (42, scores>4). Results: Compared with non-AMS group, AMS group had higher standard deviation of normal to normal intervals (SDNN), root mean square of delta RR (rMSSD), low-frequency (LF) power, and normalized low-frequency (LFnu) power in plain (P<0.05). After arrival at 3 675 m altitude, AMS group had greater reduction in percentage of delta RR>50 ms(PNN50), rMSSD (P<0.01) and SDNN, LF, total power (TP) (P<0.05). Although no significant differences in the increase of SP and DP during CPT were found between 2 groups in plain, the SP increase during CPT of AMS group was less than non-AMS group (P<0.05) at 3 675 m altitude. AMS symptomatic scores was not only positively correlated with SDNN, rMSSD, LF/HF in plain (P<0.05), but also negatively correlated with HFnu in plain (P<0.05). Conclusion: During the initial high altitude exposure, ANS modulation is generally blunted, but the relatively predominant sympathetic control is enhanced, and this characteristic change of ANS function is positively correlated with the development of AMS.

High altitude headache occurs frequently among construction workers in Yushu

The aim was to measure the incidence of high altitude headache （HAH） and to determine clinical features, as well as the relation between acute mountain sickness （AMS） and HAH through a prospective study. We conducted a questionnaire-based study among construction workers in Yushu after a serious earthquake ; they were under reconstruction using a structured questionnaire incorporating International Headache Society （IHS） and AMS Lake Louise Scoring System. A total of 608 workers were enrolled after their first ascent to altitudes of 3 750-4 528 m. The results showed that 96 % reported at least 1 HAil（median 3.8, range from 1 to 10） in workers at a mean altitude of 4 250 m. The magnitude of headache was divided as mild（38 %）, moderate （44 % ） and severe （18 %）. This study indicates that HAH is the most common symptom of acute altitude exposure and closely corre- lated with altitude （r=0.165, p〈0.001）. However, 52 % of headache was one of the main symptoms of AMS, while the other 48 % was the sole symptom of HAH. On the contrary we found that 2 % of AMS without headache, thus the ＂painless AMS＂ actually existed. The clinical features of HAH are presented, and the relationship between AMS and HAH is discussed.

双重血浆分子吸附系统模式治疗高原慢性肝衰竭患者的效果分析

目的比较世居高原和移居高原慢性肝衰竭患者接受双重血浆分子吸附系统模式(DPMAS)治疗后的临床特征和病死率。方法选取2016年1月—2021年12月于西藏军区总医院重症监护室接受DPMAS治疗的63例慢性肝衰竭患者。根据患者的旅居史将患者分为世居高原组(n=29)和移居高原组(n=34),对比两组患者的基线资料和接受DPMAS治疗前后的临床特征。符合正态分布的计量资料组间比较采用成组t检验;组内治疗前与治疗后比较应采用配对t检验。非正态分布计量资料组间比较采用Mann-Whitney U检验;组内治疗前后比较应采用Wilcoxon秩和检验。计数资料组间比较采用χ^(2)检验。Kaplan-Meier法绘制生存曲线,死亡风险比较采用Log-rank检验。结果移居高原组汉族比例明显多于世居高原组(χ^(2)=41.729,P<0.001);世居高原组患者最近一次高原连续居住时间明显长于移居高原组(Z=3.364,P<0.001);MELD评分、肝性脑病、肝肾综合征和消化道出血发生率均较世居高原组明显增高(Z=2.318,χ^(2)值分别为6.903、5.154、6.262,P值均<0.05)。DPMAS治疗前后两组患者的PLT、HGB、ALT、AST、Alb、TBil、DBil、LDH、Cr、INR比较差异均有统计学意义(P值均<0.05)。DPMAS治疗前,移居高原组ALT、AST、TBil、DBil、LDH、Cr、BUN和INR均较世居高原组高(P值均<0.05),HGB较世居高原组低(P<0.05);DPMAS治疗后,移居高原组患者PLT和HGB数量下降较世居高原组更为显著(P值均<0.05),但ALT、AST、TBil、DBil、LDH、BUN和INR均仍较世居高原组高(P值均<0.05)。世居高原组和移居高原组患者接受DPMAS治疗后60天病死率分别为52.5%(95%CI:41.7~63.8)和81.3%(95%CI:77.9~85.6)。相比于世居高原组(HR=0.47,95%CI:0.23~0.95),移居高原组患者60天死亡风险(HR=2.14,95%CI:1.06~4.32)明显增加(P=0.039)。结论与世居高原慢性肝衰竭患者相比,移居高原患者的肝功能损伤更重,DPMAS治疗后肝功能改善程度较弱,同时病死率更高。临床医护人员需要加强对移居高原慢性肝衰竭患者的重视,尽可能提高患者生存率。

基于7.0T心血管磁共振探究苍艾挥发油对高原心功能损伤大鼠的治疗作用

目的 基于7.0T心血管磁共振(CMR)探索苍艾挥发油(CAVO)对青藏高原低压低氧环境下心功能损伤模型大鼠的心脏保护作用。材料与方法 将40只SD大鼠随机分为正常组、高原模型组、CAVO治疗组和红景天治疗组,每组10只。除正常组外,其余各组大鼠从平原(海拔500 m)转运至青藏高原(海拔4 250 m)饲养2个月后,使用相应药物灌胃给药14 d。使用7.0T高场强CMR测量左心室功能,并采用组织追踪技术分析心肌应变。使用HE染色观察心肌细胞形态,Masson染色观察心肌间质纤维化,小麦胚芽凝集素染色观察心肌细胞肥大情况,透射电镜观察各组线粒体形态学改变。检测血清中肌酸激酶、肌酸激酶同工酶、乳酸脱氢酶、心肌肌钙蛋白T、超氧化物歧化酶、丙二醛和谷胱甘肽过氧化物酶水平。使用流式细胞术检测细胞内活性氧水平。结果 CAVO治疗组大鼠左心室射血分数高于高原模型组[(66.61±1.38)%比(60.94±3.21)%;t=3.969,P=0.032)],左心室整体环向应变高于高原模型组(-25.68±1.30比-22.84±1.17;t=3.967,P=0.003);HE、Masson和小麦胚芽凝集素染色显示高原模型组心肌细胞出现肥大、坏死以及间质纤维化,超微结构破坏,CAVO治疗后有所改善。CAVO治疗组大鼠血清中心肌肌钙蛋白T水平比高原模型组明显下降[(314.03±20.05)pg/ml比(518.30±18.13)pg/ml;t=13.090,P=0.001]。结论 CAVO治疗可减轻高原低压缺氧引起的心脏损伤,其效果可通过7.0T高场强CMR动态、无创性检测。