高原世、移居者对低、高氧通气反应的研究

本文报告了５名从平原移居海拔４７５０ｍ２０～８０天的汉族、１６名从平原移居该高度３～２０年的汉族和５名当地世居藏族对低、高氧通气的反应性。结果显示：①呼吸空气时，短居组Ｖ＿Ｅ／ＳａＯ＿２明显大于久、世居组，后两组之间无差异；②进行性低氧时，第１、２、３分钟短居组Ｖ＿Ｅ／ＳａＯ＿２均明显大于久、世居组，后两组之间也无明显差异。但在进行性低氧过程，三组Ｖ＿Ｅ／ＳａＯ＿２均呈进行性增大；③吸高氧时，第１分钟三组Ｖ＿Ｅ／ＳａＯ＿２均明显小于其呼吸空气时，第２分钟后略增大。     

海拔4300m世居藏族和移居汉族青年氧自由基代谢对比研究

目的：探讨高原世居藏族和移居汉族青年体内自由基代谢的差异;方法：对世居西藏阿里地区的２０名藏族士兵和移居该地区的２０名汉族士兵检测红细胞压积（ＨＣＴ）、红细胞超氧化物歧化酶（ＲＢＣ－ＳＯＤ）、丙二醛（ＭＤＡ）、全血和血浆谷胱甘肽过氧化物酶（ＧＨＳ－ＰＸ）、维生素Ｃ（Ｖｃ）和维生素Ｅ（ＶＥ）的活性或含量;结果：世居藏族青年ＲＢＣ－ＳＯＤ、血浆ＧＨＳ－ＰＸ活性和ＶＥ含量均高于移居汉族青年（Ｐ〈０．０１     

高原红细胞增多症病理生理的研究Ⅰ.关于“最适红细胞压积”及其生理 …

目的：最适红细胞压积对于判定人体高原适应的优劣以及评定高原红细胞增多的生理及病理范围增多有意义；方法：对海拔３４１７到４２８０ｍ地区的世、移居人群作出Ｈｃｔ分布曲线、再建立Ｈｂ与ＰａＯ２、Ｈｃｔ与ＳａＯ２、Ｈｃｔ与ＣＯｍａｘ、Ｈｃｔ与ＶＯ２ｍａｘ及Ｈｃｔ与全血粘度的相关关系，以确定Ｈｃｔ在提高血氧水平、提高氧传送能力及供氧后最大功效上的最适位置；结果：世居藏族的Ｈｏ为０．４５－０．４８Ｌ／Ｌ，移居     

高原红细胞增多症病理生理的研究 Ⅰ.关于“最适红细胞压积”及其生理意义

目的：最适红细胞压积（Ｈｏ）对于判定人体高原适应的优劣以及评定高原红细胞增多的生理及病理范围增多有意义；方法：对海拔３４１７到４２８０ｍ地区的世、移居人群作出Ｈｃｔ分布曲线，再建立Ｈｂ与ＰａＯ２、Ｈｃｔ与ＳａＯ２、Ｈｃｔ与ＣＯｍａｘ、Ｈｃｔ与ＶＯ２ｍａｘ及Ｈｃｔ与全血粘度的相关关系，以确定Ｈｃｔ在提高血氧水平、提高氧传送能力及供氧后最大功效上的最适位置；结果：世居藏族的Ｈｏ为０．４５～０．４８Ｌ／Ｌ，移居汉族０．５０～０．５２Ｌ／Ｌ，仍处于适度位点。Ｈｃｔ＞０．６０Ｌ／Ｌ时对人体已不再有利，＞０．６５Ｌ／Ｌ进入病理范围，＞０．７５Ｌ／Ｌ为危险信号；结论：Ｈｏ值可作为高原血液生理适应的一个标志，也有助于确立ＨＡＰＣ诊断标准的依据，但许多理论问题待进一步探讨     

高原红细胞增多症病理生理的研究Ⅱ.HAPC是一个与年龄相关的疾病吗？

目的：南美学者挽近提出高原红细胞增多症是一个与年龄相关、自然发生的疾病。本文验证这一学说是否符合青藏高原人群，特别世居藏族的发病规律；方法：在海拔３４１７－４２８０ｍ间对世居藏族及移居汉族，测定Ｈｂ、Ｈｃｔ、静息每分通气量及血气有关指标，求与年龄间的相关关系，自然人群中ＨＡＰＣ症状诊断记分的分布，ＨＡＰＣ的年龄患病率等，综合判定；结果：在世居藏族中Ｈｃｔ、静息通气与年龄间并无明显相关、Ｈｂ及ＨＡＰ     

海拔4300m世居和移居青年血清细胞间粘附分子—1的表达

目的：观察高原民居和移居青年血管内皮细胞间粘附分子－１（ＩＣＡＭ－１）的表达;方法：在海拔４３００ｍ对２０名藏族青年和２０名汉族青年运用酶联免疫分析法（ＥＬＩＳＡ）进行血清ＩＣＡＭ－１含量检测;结果：高原移居汉族青年较世居藏族青年血清ＩＣＡＭ的表达增强（Ｐ〈０．０５）;结论：低氧引志内皮细胞粘附分子的表达增强,促进循环白细胞与内皮细胞粘附。高原世居藏族对氧的利用更经济有效,具有最佳的生理适应模式,     

急进海拔5200m移居青年不同时间血液循环动力学动态观察

目的：为探讨急性暴露天高原低氧环境移居青年血液循环动力学变化规律及其在急性高原反应防治的关系；方法：随机对急进海拔５２００ｍ高原第３、３０天２０名部队健康青年进行了血液循环动力学动态观察；结果：急进高原第３天，ＳＶ，ＳＩ，ＳＶＬ，ＥＴＫ、ＡＣ和ＢＶ显著降低，Ｐ、ＳＤＰ、η显著升高，统计学处理。     

不同海拔地区人群T细胞亚群观察

本文应用Ｔ细胞单克隆抗体ＯＫＴ系列检测了西宁（海拔２２６０ｍ）和海晏（海拔３２００ｍ）两地健康人外周血Ｔ细胞亚群的分布。结果显示，海晏地区世居藏族人群ＯＫＴ和ＯＫＴ细胞明显地高于移居汉族，提示世居藏族人群有着较高的总Ｔ细胞和Ｔｓ细胞，这为世居藏族人群对高原适应机制提供了又一个有意义的生理参数。     

不同海拔高度青少年无氧代谢阈值的特征及其影响因素的探讨

为探讨高原低氧环境对青少年无氧代谢阈值（ＡＴ）的影响，本实验采用气体交换法，分别测定了移居海拔２２６０Ｍ，３４１７Ｍ和４２８０Ｍ高度的１３－１６岁男生的ＡＴ值，并同步测定了动脉血氧饱和度（ＳａＯ＿２）和心输出量（ＣＯ），分析其间的相互关系。结果，ＡＴ值随海拔高度的上升而下降，以氧耗量表示，分别为２７．４４±６．５０、２２．８８±５．３８和１６．９５±５．９７ｍｌ／ｍｉｎ／ｋｇ。ＡＴ值的降低与ＳａＯ＿２和ＣＯ的降低呈正相关。提示ＳａＯ＿２和ＣＯ是影响ＡＴ值的重要因素。研究证明，长期移居高海拔的青少年其ＡＴ值低于平原值，海拔越高其降低越明显。     

高原移居和世居者低,高氧通气的反应变化

目的探讨高原移居者和世居者对低氧和高氧的通气反应性。方法对５名从平原移居海拔４７５０ｍ２０天～８０天的汉族（Ⅰ组）、１６名从平原移居该高原３年～２０年的汉族（Ⅱ组）和５名当地世居藏族（Ⅲ组）受试者做了呼吸空气、进行性低氧和１００％氧的通气反应测定，以ＶＥ／Ｓａ０２（Ｌｍｉｎ－１）表示通气反应大小。结果呼吸空气时，Ⅰ组ＶＥ／Ｓａ０２值（０．１８±０．１４）明显高于Ⅱ组（０．１３±０．０３）和Ⅲ组（０．１３±０．０３），Ｐ＜０．０５，Ⅱ、Ⅲ组间无显著性差异。进行性低氧１ｍｉｎ、２ｍｉｎ和３ｍｉｎ，Ⅰ组ＶＥ／Ｓａ０２值（分别为０．２０±０．０４、０．２７±０．０４和０．５６±０．０７）明显高于Ⅱ组（０．１４±０．０４、０．２０±０．０４和０．３４±０．０５）和Ⅲ组（０．１３±０．０２、０．１５±０．０３和０．２２±０．０４），Ｐ＜０．０５，Ⅱ、Ⅲ组间第１ｍｉｎ和第２ｍｉｎ无显著性差异，第３ｍｉｎ有显著性差异（Ｐ＜０．０５）。三组吸入１００％氧时，通气量均明显降低。结论平原人移居高原初期，低氧通气反应敏感，而久居和世居高原者则迟钝。三组吸高氧时，通气均被抑制。     

Cardiopulmonary function in high altitude residents of Ladakh

We studied residents of high altitude in Ladakh, India, to determine the effects of altitude, age, gender, and ethnicity on gas exchange and pulmonary function. Physical examinations, including pulse oximetry, hemoglobin concentration, end-tidal PCO2, and pulmonary function, were conducted on resting Ladakhi and Tibetan subjects at altitudes of 3300, 4200, and 4500 m. A total of 574 men and women, ranging in age from 17 to 82, were studied. At 3300 m, Ladakhis had higher heart rates than Tibetans in both genders and higher PETCO2 in women. Above 4000 m, 21 of the 141 men studied (15%) had Hb concentrations higher than 20 g/dL, with one confirmed case of Monge's disease. There was no gender difference in SaO2 at any altitude except for pregnant women. At 4600 m, Tibetans had significantly higher peak flows and lower PETCO2 than Ladakhis. Ladakhi men had higher diastolic BP than women (91 vs. 81), with no difference in systolic BP. There was no gender difference in BP for Tibetans. An important spirometry finding for both groups was high air flows, with mid-maximal expiratory flow (MMEF) at 130% to 150% of predicted values, compared with 85% for sojourner controls, and FEV1/FVC at 115%, compared with sojourner controls at 98%. Improved lung mechanics may be an important adaptation to the lifelong sustained increase in resting ventilation as well as to indoor biomass smoke and outdoor dust exposure of these populations at high altitude.     

海拔4300m地区高原居民红细胞压积与心缩间期的关系

为探讨高原居民红细胞及其压积对心缩间期的影响 ,在海拔 43 0 0m地区用心阻抗图法和心机械图法对 1 1 3名不同红细胞压积者的左室收缩功能进行了检测。结果 :红细胞压积与每搏量、射血分数呈显著负相关 ,而与射血前期与射血时间比值呈显著正相关(P <0 .0 0 1 )。随着红细胞压积值的增高 ,受试者的射血前期延长、左室射血时间缩短 ,射血前期与射血时间比值增大 ,射血分数下降。高原红细胞增多症患者的每搏量、心排出量明显下降。结论 :红细胞及其压积的高低对心缩间期和心泵功能的影响较大 ,红细胞增多是引起高原人体心功能降低的重要因素之一。     

富氧水对急进高原和高原人体运动血气的影响

目的探讨富氧水对急进高原和高原人体运动血气的影响。方法(1)在海拔3700m选择10名已习服半年的男性士兵,在海拔5380m选择10名已习服2个月的男性士兵,均采用口服富氧水前(对照组)后(试验组)的自身对比运动负荷双盲试验,试验组口服5%葡萄糖注射液制成的富氧水,对照组口服5%葡萄糖注射液,均每次500ml,2次/d。运动结束检测pH,PCO2,PO2,HCO3-,AaDO2及SaO2。(2)对首次进驻海拔5200m的36名男性青年,自海拔1400m驻地乘汽车2d到达海拔3700m当日随机分试验组(18人,口服富氧水)和对照组(18人,口服5%葡萄糖注射液),口服富氧水,方法同前。直至进入海拔5200m某哨卡第6天,共服9d,检测血气指标。结果(1)海拔3700m和5380m负荷运动,试验组较对照组pH,PaO2,HCO3-,SaO2增高,两者比较差异有统计学意义(P<0.01或0.05),PaCO2,AaDO2降低,也有统计学意义(P<0.01)。(2)进驻海拔5200m的青年,试验组较对照组pH,PaO2,HCO3-,SaO2增高,差异有统计学意义(P<0.01),PaCO2,AaDO2降低,也有统计学意义(P<0.01)。结论富氧水可增加组织对氧的利用,有效提高机体血液中PaO2和SaO2,缓解高原缺氧症状。为预防急性高原病的发生,为高原供氧开辟一条新的途径。     

高住高练低训对优秀女子中长跑运动员心功能的影响

目的:探讨高住高练低训对优秀女子中长跑运动员心功能的影响。方法:7名国家女子中长跑运动员,进行为期4周的高住高练低训(HiHiLo):在每日完成正常平原训练计划的基础上,每周进行三次低氧训练,训练方式为蹬功率自行车,强度为个体80%VO2max,时间为40分钟,氧浓度为14.7%左右(相当于海拔2800米高度)。此外,每晚在低氧房居住10小时,房内氧含量为14.7%(相当于海拨2800米高度),实验期为4周。采用负荷彩色超声多普勒监测高住高练低训前后心功能的变化,并且监测高住高练低训前后最大摄氧量、血压和体重的变化。结果显示,高住高练低训后的左室重量、左室重量指数、室间隔舒张末期厚度,左室后壁收缩末期厚度在安静状态下较高住高练低训前显著增加(P<0.05),收缩压和舒张压较高住高练低训前明显升高(P<0.05),右心室前后径较高住高练低训前明显减小(P<0.05)。二尖瓣舒张期充盈时间(DFT)在安静及运动负荷状态下均较高住高练低训前显著增加(P<0.05)。高住高练低训前后空腹体重无明显差异,高住高练低训后血压较训练前明显升高(P<0.05)。高住高练低训后最大摄氧量相对值较训练前有所增加,但无显著性差异。结果提示高住高练低训对心脏功能无不良影响,HiHiLo在某种程度上有利于心力储备功能的增强。     

富氧水对高原人体耐缺氧抗疲劳作用机制的探讨

目的探讨富氧水对高原人体血液流变学的影响。方法(1)在海拔3 700 m选择10名已习服半年的男性士兵,在海拔5 380 m选择10名已习服2个月的男性士兵,均采用口服富氧水前后的自身对比运动负荷双盲实验。第一次运动口服5%葡萄糖注射液,第二次运动口服5%葡萄糖注射液制成的富氧水,每次均500 m l,2次/d。运动结束后检测血中超氧化物歧化酶(SOD)、丙二醛(MDA),乳酸(BLA),尿素氮(BUN),一氧化氮(NO)及其合酶(NOS)的含量。(2)对首次进驻海拔5 200 m的36名男性青年,自海拔1 400 m驻地乘汽车2 d到达海拔3 700 m当日随机分实验组(18人,口服富氧水)和对照组(18人,口服5%葡萄糖注射液),口服富氧水,方法同前。直至进入海拔5 200 m某哨卡第6天,共服9 d,检测血液生化指标。结果(1)海拔3 700 m和5 380 m负荷运动,口服富氧水后较未服富氧水时SOD,NO和NOS增高(P<0.01或0.05);MDA,BLA,BUN降低(P<0.01或0.05)。(2)进驻海拔5 200 m的青年,实验组较对照组NO增高(P<0.01);SOD,NOS也增高(P<0.05);MDA,BLA降低(P<0.01);BUN无统计学意义(P>0.05)。结论富氧水可增加组织对氧的利用,具有耐缺氧、抗疲劳的作用,对预防急性高原病有重要意义。     

Analysis of the myoglobin gene in Tibetans living at high altitude

Myoglobin, a protein with an important role in muscle oxidative metabolism, is increased in high altitude residents. In the closely related hemoglobins, mutations cause or contribute to human disease. Furthermore, heme-containing proteins may be involved in oxygen sensing. We therefore tested the hypotheses that myoglobin allele frequencies differed in Tibetans, a long-resident human high-altitude population, compared with sea-level residents, and varied in relation to altitude among Tibetans. We obtained the sequence of exon 2 of the myoglobin gene in 146 Tibetans with greater than three generations of stable residence at altitude in rural Tibet. We compared the frequency of known polymorphic sites in this gene among Tibetans living at altitudes of 3000, 3700, and 4500 m and to allele frequencies previously obtained in 525 residents of Dallas, Texas. We also examined the association between different myoglobin genotypes and hemoglobin concentration, used as an index of myoglobin levels. The frequency of the myoglobin 79A allele was higher in the high altitude compared with the sea-level residents, but unchanged with increasing altitude among Tibetans. There was no significant deviation from Hardy-Weinberg equilibrium in any of the Tibetan altitude groups, nor was there any association between myoglobin genotype and hemoglobin concentration. Screening of exon 2 of the myoglobin gene in high altitude Tibetans does not show novel polymorphism or selection for specific myoglobin alleles as a function of altitude of residence or hypoxic challenge.     

The role of the right ventricle during hypobaric hypoxic exercise: insights from patients after the Fontan operation

OBJECTIVES: The principal objective of this study was to examine the importance of the right ventricle for maximal systemic oxygen transport during exercise at high altitude by studying patients after the Fontan operation. BACKGROUND: High-altitude-induced hypoxia causes a reduction in maximal oxygen uptake. Normal right ventricular pump function may be critical to sustain cardiac output in the face of hypoxic pulmonary vasoconstriction. We hypothesized that patients after the Fontan operation, who lack a functional subpulmonary ventricle, would have a limited exercise capacity at altitude, with an inability to increase cardiac output. METHODS: We measured oxygen uptake (VO2, Douglas bag), cardiac output (Qc, C2H2 rebreathing), heart rate (HR) (ECG), blood pressure (BP) (cuff), and O2 Sat (pulse oximetry) in 11 patients aged 14.5+/-5.2 yr (mean +/- SD) at 4.7+/-1.6 yr after surgery. Data were obtained at rest, at three submaximal steady state workrates, and at peak exercise on a cycle ergometer. All tests were performed at sea level (SL) and at simulated altitude (ALT) of 3048 m (10,000 ft, 522 torr) in a hypobaric chamber. RESULTS: At SL, resting O2 sat was 92.6+/-4%. At ALT, O2 sat decreased to 88.2+/-4.6% (P < 0.05) at rest and decreased further to 80+/-6.3% (P < 0.05) with peak exercise. At SL, VO2 increased from 5.1+/-0.9 mL x kg(-1) x min(-1) at rest to 23.5+/-5.3 mL x kg(-1) x min(-1) at peak exercise and CI (Qc x m(-2)) increased from 3.3+/-0.7 L x m(-2) to 6.2+/-1.2 L x m(-2). VO2 peak, 17.8+/-4 mL x kg(-1) x min(-1) (P < 0.05), and CI peak, 5.0+/-1.5 L x m(-2) (P < 0.05), were both decreased at ALT. Remarkably, the relationship between Qc and VO2 was normal during submaximal exercise at both SL and ALT. However at ALT, stroke volume index (SVI, SV x m(-2)) decreased from 37.7+/-8.6 mL x min(-1) x m2 at rest, to 31.3+/-8.6 mL x min(-1) x m2 at peak exercise (P < 0.05), whereas it did not fall during sea level exercise. CONCLUSIONS: During submaximal exercise at altitude, right ventricular contractile function is not necessary to increase cardiac output appropriately for oxygen uptake. However, normal right ventricular pump function may be necessary to achieve maximal cardiac output during exercise with acute high altitude exposure.     

Physiological profile and predictors of cycling performance in ultra-endurance triathletes

BACKGROUND: To report physiological profiles, and investigate the relationship between selected physiological variables and cycling performance in ultra-endurance triathletes. METHODS: Participants: ten male (mean+/-SD, age; 32+/-5 years) ultra-endurance triathletes participated in the study. Physiological profiles were compared with 10 male age-matched control subjects. Measures: left ventricular structure (wall thickness [LVPWd], internal diameter [LVIDd], and mass [LVM]) and function (diastolic filling, fractional shortening, and stroke volume [SV]) were assessed using standard M-Mode, 2D, and Doppler echocardiography. Maximal and sub-maximal exercise gas exchange responses were measured on-line during a maximal ramping cycle-ergometer exercise test. RESULTS: Ultra-endurance triathletes demonstrated significantly larger LVPWd, LVIDd, LVM, SV, VO2max anaerobic threshold (AT), and power to body-mass ratio compared with controls. Cycling performance for both Ironman and half Ironman were significantly correlated with LVPWd, LVM, and SV. LVIDd was significantly correlated Ironman cycle time alone. Oxygen consumption (VO2) at AT, percentage of VO2max at AT, and peak power to bodymass ratio were significantly correlated to bike finish time in the half Ironman, but not Ironman. CONCLUSIONS: The correlation between cycling performance, LVM and SV suggests that the more conditioned athletes may be better able to maintain a high cardiac output during prolonged cycling. Sub-maximal gas exchange responses are predictors of cycling performance for the half-Ironman but not the Ironman. These results suggest that other factors including the longer duration swim prior to the cycling component, may impact upon cycle performance.     

Altitude illness in Qinghai–Tibet railroad passengers

It takes ≈24 h to travel the ≈3000-km-long Qinghai–Tibet railroad of which 85% is situated above 4000 m with a pass at 5072 m. Each year about 2 million passengers are rapidly exposed to high altitude traveling on this train. The aim of this study was to quantify the occurrence of altitude illness on the train. Three subject groups were surveyed: 160 Han lowlanders, 62 Han immigrants living at 2200 to 2500 m, and 25 Tibetans living at 3700 to 4200 m. Passengers reached 4768 m from 2808 m in less than 1.5 h, after which 78% of the passengers reported symptoms, 24% reaching the Lake Louise criterion score for AMS. AMS incidence was 31% in nonacclimatized Han compared to 16% in Han altitude residents and 0% in Tibetans. Women and older subjects had a slightly greater risk for AMS. Most cases of AMS were mild and self-limiting, resolving within days upon arrival in Lhasa. Some cases of more severe AMS necessitated medical attention. To curb the health risk of rapid travel to altitude by train, prospective travelers should be better informed, medical train personnel should be well trained, and staged travel with 1 to 2 days at intermediate altitudes should be suggested to nonacclimatized subjects.     

Fetal growth restriction and maternal oxygen transport during high altitude pregnancy

High altitude reduces birth weights, averaging a 100-g fall per 1000 m elevation gain, as the result of restriction of third trimester fetal growth. Intrauterine growth restriction (IUGR) raises neonatal or infant mortality at low as well as at high altitude, but existing studies are unclear as to whether IUGR-specific mortality at high altitude is similar to, less than, or greater than at low altitude. Pregnancy increases maternal ventilation and raises arterial O(2) saturation at high altitude, which helps to protect against altitude-associated IUGR. Chronic hypoxia interferes with the maternal circulatory adjustments to pregnancy such that blood volume is lower and the rise in cardiac output diminished compared with sea level. The growth and remodeling of the uterine artery and other uteroplacental vessels is incomplete at high compared with low altitude, with the result that there is less redistribution of common iliac flow from the external iliac to the uterine arteries and lower uterine artery blood flow near term. Adaptations in multigenerational high altitude populations (e.g., Andeans and Tibetans) permit higher uterine artery blood flows and protect against altitude-associated IUGR.