Predicting Acute Mountain Sickness Using Regional Sea-Level Cerebral Blood Flow

Objective To investigate the role of sea-level cerebral blood flow(CBF)in predicting acute mountain sickness(AMS)using three-dimensional pseudo-continuous arterial spin labeling(3D-pCASL).Methods Forty-eight healthy volunteers reached an altitude of 3,650 m by air after undergoing a head magnetic resonance imaging(MRI)including 3D-pCASL at sea level.The CBF values of the bilateral anterior cerebral artery(ACA),middle cerebral artery(MCA),posterior cerebral artery(PCA),and posterior inferior cerebellar artery(PICA)territories and the laterality index(LI)of CBF were compared between the AMS and non-AMS groups.Statistical analyses were performed to determine the relationship between CBF and AMS,and the predictive performance was assessed using receiver operating characteristic(ROC)curves.Results The mean cortical CBF in women(81.65±2.69 mL/100 g/min)was higher than that in men(74.35±2.12 mL/100 g/min)(P<0.05).In men,the cortical CBF values in the bilateral ACA,PCA,PICA,and right MCA were higher in patients with AMS than in those without.Cortical CBF in the right PCA best predicted AMS(AUC=0.818).In women,the LI of CBF in the ACA was different between the AMS and non-AMS groups and predicted AMS with an AUC of 0.753.Conclusion Although the mechanism and prediction of AMS are quite complicated,higher cortical CBF at sea level,especially the CBF of the posterior circulatory system,may be used for prediction in male volunteers using non-invasive 3D-pCASL.

Association between acute mountain sickness(AMS) and age: a meta-analysis

Background: Acute mountain sickness(AMS) is a potentially lethal condition caused by acute hypoxia after ascending to altitudes higher than 2500 m in a short time. The main symptom of AMS is headache. Numerous risk factors of AMS have been examined, including gender, obesity, ascent rate, age and individual susceptibility. In previous studies, age was considered a predisposing factor for AMS. However, different opinions have been raised in recent years. To clarify the association between AMS and age, we conducted this meta-analysis.Methods: We obtained observational studies that explored risk factors for AMS by searching PubMed, Embase, China National Knowledge Internet(CNKI), the Wanfang database and CQVIP for articles published before March 2017.The studies included were required to provide the mean age and its standard deviation for subjects with and without AMS, the maximum altitude attained and the mode of ascent. The Lake Louse Score(LLS) or the Chinese AMS score(CAS) was used to judge the severity of AMS symptoms and incidence. Studies were pooled for the analysis by using a random effects model in RevMan 5.0. Meta-regression and subgroup analyses were conducted to identify sources of heterogeneity using Stata 14.2 and RevMan 5.0.Results: In total, 17 studies were included, and the overall number of subjects with and without AMS was 1810 and3014, respectively. The age ranged from 10 to 76 years. Analysis of the 17 included studies showed that age was not associated with AMS(mean difference(MD)=0.10; 95%CI: —0.38-0.58; P=0.69).Conclusions: This meta-analysis suggests that there is no association between age and the risk of AMS. Race, age,and ascent mode are common sources of heterogeneity, which may provide an analytical orientation for future heterogeneity analyses.

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.

Traditional Chinese medicine for acute mountain sickness prevention: A systematic review and meta-analysis of randomized controlled trials

Objective: To evaluate the efficacy of traditional Chinese medicine(TCM) for preventing acute mountain sickness(AMS).Methods: We included randomized controlled trials(RCTs) which evalueded the effect of TCM for preventing AMS, compared with a placebo, no treatment or acetazolamide. The literature was searched in 6major databases. RevMan 5.4 software was used for the meta-analysis. The relative risk for discrete variables and the mean difference for continuous variables with 95% confidence intervals(CIs) were applied to express the effect size. The risk of bias in the included studies was evaluated using the Cochrane risk assessment tool 2.0(RoB 2.0), and the evidence certainty was assessed using the Grading of Recommendations Assessment and the Development and Evaluation(GRADE) approach.Results: Twenty RCTs involving 3015 participants and 16 TCM patent drugs were included. The overall risk of bias in the majority of studies(15/20) was of some concerns. In terms of the AMS incidence,Rhodiola rosea(R. rosea, Hong Jing Tian) and Ginkgo biloba(G. biloba, Yin Xing Ye) were equivalent to the placebo/no treatment [RR(95% CI): 0.66(0.43-1.01), 0.82(0.63-1.06), respectively]. The AMS incidence in the G. biloba group was higher than that in the acetazolamide group [RR(95% CI): 2.92(1.69-5.06)]. In terms of improving the AMS symptom score on days 1 and 3 in the plateau, R. rosea and G. biloba were superior to the placebo or no treatment [MD(95% CI):-0.98(-1.71,-0.25),-2.05(-3.14,-0.95), respectively]. The other 14 Chinese patent medicines were evaluated in a single trial, and the majority of the results were negative. The subgroup analysis showed that the effect of R. rosea was related to the intervention time, way of ascending, and altitude.Conclusion: R. rosea and G. biloba were effective in improving AMS symptoms but had no effect in reducing the AMS incidence. There was insufficient evidence to support the use of other TCM patent drugs to prevent AMS. More randomized double-blind placebo-controlled trials are warranted to evaluate and screen effective Chinese patent medicines for AMS prevention.

A specific objective supplemental factor in evaluating acute mountain sickness: ΔHR in combination with SaO_2

Background: So far, there have been no measurements confirmed useful in diagnosing acute mountain sickness(AMS). The aim of this study was to determine the role of heart rate(HR) difference(ΔHR) and oxygen saturation(Sa O2) as objective risk factors in aiding the diagnosis of AMS.Methods: A total of 1,019 participants were assigned to either the acute exposure group(AEG): from 500 m to 3,700 m by flight within 2.5 hours(n=752); or the pre-acclimatization group(PAG): ascended to 4,400 m from 3,650 m within three hours by car after adapting 33 days at 3,650m(n=267). The questionnaires or measurements of resting Sa O2 and HR were completed between 18 and 24 hours before departure and after arrival.Results: Incidence of AMS was 61.3%(461) in AEG, with 46.1%(347) mild cases and 15.2%(114) severe cases. In PAG, the incidence was 38.9%(104), with 30.7%(82) mild cases and 8.2%(22) severe cases. The AMS subjects showed a significant increase in HR and a decrease in Sa O2 levels compared with the non-AMS subjects in both groups. ΔHR and post-exposure Sa O2 were significantly correlated with the Lake Louise Score(LLS) in both groups. Stepwise logistic regression analysis revealed the ΔHR >25 and Sa O2 <88% in AEG as well as ΔHR >15 and Sa O2 <86% in PAG to be independent risk factors of AMS. Combining these two measurements could specifically indicate participants with AMS, which showed a positive predictive value of 89% and specificity of 97% in AEG as well as 85% and 98% in PAG.Conclusion:ΔHR or Sa O2, as objective measurements, correlate with AMS. Combination of these two measurements may be useful as an additional specific and objective factor to further confirm the diagnosis of AMS.

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.

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.

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.

Sex-based differences in the prevalence of acute mountain sickness: a meta-analysis

Background:When lowlanders rapidly ascend to altitudes>2500 m,they may develop acute mountain sickness(AMS).The individual susceptibility,ascending velocity,time spent at altitude,activity levels and altitude reached are considered risk factors for AMS.However,it is not clear whether sex is a risk factor.The results have been inconclusive.We conducted a meta-analysis to test whether there were sex-based differences in the prevalence of AMS using Lake Louise Scoring System.Methods:Systematic searches were performed in August 2019 in EMBASE,PubMed,and Web of Science for prospective studies with AMS data for men and women.The titles and abstracts were independently checked in the primary screening step,and the selected full-text articles were independently assessed in the secondary screening step by the two authors(YPH and JLW)based on pre-defined inclusion criteria.The meta-analysis was performed using by the STATA 14.1 software program.A random-effects model was employed.Results:Eighteen eligible prospective studies were included.A total of 7669 participants(2639[34.4%]women)were tested.The results showed that there was a statistically significant higher prevalence rate of AMS in women than in men(RR=1.24,95%CI 1.09–1.41),regardless of age or race.However,the heterogeneity was significant in the analysis(Tau2=0.0403,Chi2=50.15,df=17;I2=66.1%,P=0.000),it was main caused by different numbers of subjects among the studies(coefficient=–2.17,P=0.049).Besides,the results showed that there was no evidence of significant publication bias in the combined studies on the basis of Egger’s test(bias coefficient=1.48,P=0.052)and Begg’s test(P=0.130).Conclusions:According to this study,the statistically significant finding emerging from this study was that women have a higher prevalence of AMS.However,the authors could not exclude studies where patients were on acetazolamide.Our analysis provided a direction for future studies of the relationship of sex and the risk of AMS,such as the pathological mechanism and prevention research.

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.

EPAS1 and VEGFA gene variants are related to the symptoms of acute mountain sickness in Chinese Han population: a cross-sectional study

Background: More people ascend to high altitude(HA) for various activities, and some individuals are susceptible to HA illness after rapidly ascending from plains. Acute mountain sickness(AMS) is a general complaint that affects activities of daily living at HA. Although genomic association analyses suggest that single nucleotide polymorphisms(SNPs) are involved in the genesis of AMS, no major gene variants associated with AMS-related symptoms have been identified.Methods: In this cross-sectional study, 604 young, healthy Chinese Han men were recruited in June and July of 2012 in Chengdu, and rapidly taken to above 3700 m by plane. Basic demographic parameters were collected at sea level, and heart rate, pulse oxygen saturation(Sp O2), systolic and diastolic blood pressure and AMS-related symptoms were determined within 18–24 h after arriving in Lhasa. AMS patients were identified according to the latest Lake Louise scoring system(LLSS). Potential associations between variant genotypes and AMS/AMS-related symptoms were identified by logistic regression after adjusting for potential confounders(age, body mass index and smoking status).Results: In total, 320 subjects(53.0%) were diagnosed with AMS, with no cases of high-altitude pulmonary edema or high-altitude cerebral edema. Sp O2 was significantly lower in the AMS group than that in the non-AMS group(P=0.003). Four SNPs in hypoxia-inducible factor-related genes were found to be associated with AMS before multiple hypothesis testing correction. The rs6756667(EPAS1) was associated with mild gastrointestinal symptoms(P=0.013), while rs3025039(VEGFA) was related to mild headache(P=0.0007). The combination of rs6756667 GG and rs3025039 CT/TT further increased the risk of developing AMS(OR=2.70, P<0.001).Conclusions: Under the latest LLSS, we find that EPAS1 and VEGFA gene variants are related to AMS susceptibility through different AMS-related symptoms in the Chinese Han population;this tool might be useful for screening susceptible populations and predicting clinical symptoms leading to AMS before an individual reaches HA.Trial registration: Chinese Clinical Trial Registration, Chi CTR-RCS-12002232. Registered 31 May 2012.

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.

Identification of susceptibility to acute mountain sickness by detecting vascular tone using a photoplethysmographic sensor

Objective: Vascular tone had shown the potential susceptibility to acute mountain sickness(AMS), however the detailed tendency has not been studied. Methods: Vascular tone, SpO_2 and Rate pressure product(RPP) were studied in seventeen healthy subjects before and after rapid ascent from sea level to 3658 m. Human acute mountain sickness was evaluated by the Lake Louise Score(LLS). Results: Nine of the seventeen participants were diagnosed with AMS. On initial exposure, there was a significant decrease in vascular tone between subjects with and without AMS. Significance was also found in the decrease of SpO_2 before and after rapid ascent but the differences between subjects with and without AMS did not reach significance during the initial phase. Conclusions: Vascular tone on initial exposure in response to rapid ascent is a possible sign of susceptibility to AMS. Conclusion: measurement of vascular tone using a wearable sensor throughout the acute phase response will provide numerical values of pathophysiology throughout the development of AMS.

Retinal microvasculature is a potential biomarker for acute mountain sickness

Increased cerebral blood flow resulting from altered capillary level autoregulation at high altitudes leads to capillary overperfusion and then vasogenic cerebral edema,which is the leading hypothesis of acute mountain sickness(AMS).However,studies on cerebral blood flow in AMS have been mostly restricted to gross cerebrovascular endpoints as opposed to the microvasculature.This study aimed to investigate ocular microcirculation alterations,the only visualized capillaries in the central neural system(CNS),during early-stage AMS using a hypobaric chamber.This study found that after high altitude simulation,the optic nerve showed retinal nerve fiber layer thickening(P=0.004–0.018)in some locations,and the area of the optic nerve subarachnoid space(P=0.004)enlarged.Optical coherence tomography angiography(OCTA)showed increased retinal radial peripapillary capillary(RPC)flow density(P=0.003–0.046),particularly on the nasal side of the nerve.The AMSpositive group had the largest increases in RPC flow density in the nasal sector(AMS-positive,?3.21±2.37;AMS-negative,?0.01±2.16,P=0.004).Among multiple ocular changes,OCTA increase in RPC flow density was associated with simulated early-stage AMS symptoms(beta=0.222,95%CI,0.009–0.435,P=0.042).The area under the receiver operating characteristics curve(AUC)for the changes in RPC flow density to predict early-stage AMS outcomes was 0.882(95%CI,0.746–0.998).The results further confirmed that overperfusion of microvascular beds is the key pathophysiologic change in early-stage AMS.RPC OCTA endpoints may serve as a rapid,noninvasive potential biomarker for CNS microvascular changes and AMS development during risk assessment of individuals at high altitudes.

急进高原后男性官兵心功能的变化及其与AMS的关系

目的:评价驻平原官兵急进高原前后心功能的变化情况并探讨其与急性高山病(AMS)的关系。方法:采用超声心动图评价42名健康青年男性官兵进入高原前及快速进入高原后(3 658 m,3 d)的心脏功能,同时观察心率、血压和血氧饱和度等生理指标的变化,以及进入高原后AMS的发病情况。结果:与进入高原前相比,青年男性官兵急进高原后,左房收缩末期内径和左室舒张末期内径显著减小,右房收缩末期内径显著减小,右室流出道和肺动脉内径显著增宽,射血分数显著增大,心输出量显著增多,肺动脉收缩压及平均肺动脉压显著增高,二尖瓣E峰流速显著降低(P<0.05)。进入高原后,42人中有15人发生AMS(AMS组),27人未发病(non-AMS组)。比较2组官兵在平原的心功能发现,AMS组的主动脉窦部内径和左室舒张末期内径显著小于non-AMS组,肺动脉收缩压显著高于non-AMS组。比较2组官兵进入高原后的心功能发现,AMS组左房收缩末期内径显著小于nonAMS组(P<0.05)。AMS评分与进入高原前的心输出量呈显著负相关性(r=-0.3814,P<0.05)。结论:青年男性官兵从平原快速进入高原后,右心功能受损合并左心功能代偿;在平原运用超声心动图进行肺动脉收缩压及心输出量的检查有助于AMS易感人群的筛选。

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.

Smoking is associated with the incidence of AMS: A large-sample cohort study

Background: In recent years, the number of people visiting high altitudes has increased. After rapidly ascending to a high altitude, some of these individuals, who reside on plains or other areas of low altitude, have suffered from acute mountain sickness(AMS). Smoking interferes with the body's oxygen metabolism, but research about the relationship between smoking and AMS has yielded controversial results.Methods: We collected demographic data, conducted a smoking history and performed physical examinations on 2,000 potential study participants, at sea level. Blood pressure(BP) and pulse oxygen saturation(SpO2) were measured for only some of the patients due to time and manpower limitations. We ultimately recruited 520 smokers and 450 nonsmokers according to the inclusion and exclusion criteria of our study. Following acute high-altitude exposure, we examined their Lake Louise Symptom(LLS) scores, BP, HR and SpO2; however, cerebral blood flow(CBF) was measured for only some of the subjects due to limited time, manpower and equipment.Results: Both the incidence of AMS and Lake Louise Symptom(LLS) scores were lower in smokers than in nonsmokers. Comparing AMS-related symptoms between nonsmokers and smokers, the incidence and severity of headaches and the incidence of sleep difficulties were lower in smokers than in nonsmokers. The incidences of both cough and mental status change were higher in smokers than in nonsmokers; blood pressure, HR and cerebral blood flow velocity were lower in smokers than in nonsmokers.Conclusions: Our findings suggest that the incidence of AMS is lower in the smoking group, possibly related to a retardation of cerebral blood flow and a relief of AMS-related symptoms, such as headache.

Different physiopsychological changes between AMS-susceptible and AMS-resistant pre-selected Antarctic expeditioners in Tibet

Through dynamically monitoring changes of acute mountain sickness(AMS)occurrences,cardiopulmonary function and mood states from Shanghai(4 m)to Lhasa(3650 m)and Yambajan(4300 m),Tibet,we obtained physiopsychological data of the 37th Chinese Antarctic pre-selected expeditioners for Kunlun Station.Through analyzing different physiopsychological changes between AMS-susceptible(AMS-S)and AMS-resistant(AMS-R)expeditioners,we would explore indicators to screen hypoxia-susceptible expeditioners.According to AMS occurrences evaluated by Lake Louise Score(LLS)in Yambajan,we divided the expeditioners(n=24,31.92±5.76 a)into AMS-S and AMS-R groups.Using a series of medical instrumentsand questionnaires,we monitored their cardiopulmonary function and mood states,and analyzed the differences of physiopsychological parameters between AMS-S and AMS-R groups.Compared with Shanghai,when expeditioners arrived in Yambajan,in both AMS-S and AMS-R groups,oxygen saturation(SpO2)significantly decreased,and blood pressure significantly increased(P<0.05).As for electrocardiogram(ECG),interval from the beginning to the end of QRS complex wave(QRS),interval from the beginning of QRS complex wave to the end of T wave(QT),interval between 2 adjacent P waves(PP)and interval between 2 adjacent R waves(RR)significantly decreased,heart rate(HR)and HR-corrected QT interval(QTc)significantly increased(P<0.05).Cardiac contractility and pumping function significantly decreased,systemic vascular resistance significantly increased(P<0.05).Pulmonary airway patency significantly increased(P<0.05).Compared with AMS-R group,AMS-S group showed significantly lower SpO2 and higher stroke volume variation(SVV)in Shanghai,however,significantly lower maximal expiratory flow at 75%of forced vital capacity(MEF75),higher levels of anxiety,fatigue and confusion in Yambajan(P<0.05).In conclusion,when expeditioners arrived at 4300 m,their cardiopulmonary function and mood states changed significantly.SpO2,SVV,MEF75,anxiety,fatigue and confusion maybe could be used as clues for screening hypoxia-susceptible individuals.

突发公共卫生事件下急进高原作业的医务人员急性高原反应与心理状况调查

目的对突发公共卫生事件下急进高原作业的医务人员的急性高原反应(AMS)与心理状况进行调查,旨在为预防AMS的发生及制订心理干预策略提供科学依据。方法研究对象为2022年8月26日至9月9日紧急进入拉萨市开展医疗支援工作的医务人员。通过AMS临床症状量表将得分0~10分的受试者纳入轻微高原反应(SAMS)组,≥11分的受试者纳入高原反应(AMS)组。调查两组一般资料及情绪状态自评量表、压力感受量表-10(PSS-10)、9项患者健康问卷(PHQ-9)、7项广泛性焦虑障碍量表(GAD-7)评分。结果共调查175名医务人员,其中SAMS组108名,AMS组67名,PHQ-9检出抑郁情绪发生率为49.71%,GAD-7检出焦虑情绪发生率为18.86%。与SAMS组相比,AMS组无高原经历的比例、PHQ-9阳性率、PSS-10评分以及情绪自评量表中疲劳、失眠、食欲减退、担心被感染维度评分均更高,差异有统计学意义(P<0.05)。二元logistic回归分析显示,PSS-10评分(OR=1.091,95%CI 1.020~1.167,P=0.011)及无高原经历(OR=2.614,95%CI 1.047~6.529,P=0.040)是急进高原作业的医务人员发生AMS的危险因素。结论急进高原作业的医务人员容易发生AMS,且存在突出的焦虑抑郁情绪,缺少高原经历及压力感知突出者AMS更显著,有必要对其开展针对性的预防及心理干预。