Rate pressure product and oxygen saturation in tourists at approximately 3000 m above sea level

Using modern transportation technology, many travelers easily access moderate altitudes of approximately 3000 m above sea level. In the present study the effects of this altitude on cardiovascular parameters were studied among office workers dwelling at sea level. Methods: Heart rate, blood pressure, arterial oxygen saturation (SpO₂), and electrocardiography were monitored before and after Master's double-step exercise at 2700 and 3700 m. The test consisted of stepping onto and off of two 23-cm steps for 3 min at a predefined rate. Results: The resting values recorded for the heart rate and mean blood pressure at 2700 and 3700 m did not statistically significantly differ from those noted at sea level. However, the increases in these values after exercise were significantly greater at high altitude. The rate pressure product more than doubled after exercise at 3700 m. Electrocardiographic abnormalities were observed in some cases. The postexercise blood lactate concentration was significantly higher at 3700 m than at sea level or at 2700 m, suggesting that the oxygen supply-demand relationship was not balanced at this altitude. Furthermore, exercise provoked an acute reduction in SpO₂ at 2700 and 3700 m but showed no effect at sea level. Conclusion: These observations suggest that the oxygenation status of the heart might be at risk in many travelers and workers during and after exercise load at an altitude of approximately 3000 m. Received: 23 March 1998 / Accepted: 4 August 1998     

Estimation of the degree of acclimatization to high altitude by a rapid and simple physiological examination

The recent expansion in the geographical areas open to human activity has made it desirable to have an objective method to evaluate the degree of high-altitude acclimatization. In this study, we measured the arterial oxygen saturation value at rest and just after exercise in healthy high-altitude trekkers using a transportable pulse oximeter. During a 100-day stay at high altitude (around 4000 m), the degree of arterial hemoglobin saturation measured at rest was relatively stable. However, shortly after arrival at high altitude, even light exercise induced an acute reduction in the degree of arterial hemoglobin saturation; this reduction was ameliorated as the trekkers became acclimatized to the high altitude. Preliminary short trekking to high altitudes does not appear sufficient to induce this response. It is suggested that this rapid and simple physiological examination, the measurement of arterial oxygen saturation value after light exercise, could be a convenient means of estimating the level of high-altitude acclimatization among healthy subjects.     

Oxygen enrichment of room air to improve well-being and productivity at high altitude.

Increasingly, commercial activities, such as mines, and scientific facilities, such as telescopes, are being placed at very high altitudes, up to 5,000 m. Frequently workers commute to these locations from much lower altitudes, or even from sea level. In addition, large numbers of people permanently live and work at high altitudes. The hypoxia of high altitude impairs sleep quality, mental performance, productivity, and general well-being. Recently it has become feasible to raise the oxygen concentration of room air by injecting oxygen into the air conditioning. This is remarkably effective at reducing the equivalent altitude. For example, increasing the oxygen concentration by 1% (e.g., from 21% to 22%) reduces the equivalent altitude by about 300 m. In other words, a room at an altitude of 4,500 m containing 26% oxygen is effectively at an altitude of 3,000 m. Oxygen enrichment has now been tested in several studies and shown to improve sleep quality and cognitive function. The fire hazard is less than in air at sea level. This innovative technique promises to improve productivity and well-being at high altitude.     

不同海拔驻地及兵种部队进驻高海拔地区后体能现状比较

目的对比分析不同海拔驻地及不同兵种部队进驻更高海拔地区作训时的体能状况,为在高原地区作训部队的体能保障提供依据。方法选择常驻海拔3700 m的步兵部队(n=50)、技术兵部队(n=149)和常驻海拔500 m的技术兵部队(n=107)为调查对象,在进驻海拔4400 m地区2周后,测量心率、血压评估习服程度,测量最大摄氧量(VO2max)评估体能状况。结果进驻高海拔地区2周后,各部队可达初步习服;原驻海拔3700 m步兵部队和技术兵部队、原驻海拔500 m技术兵部队的VO2max与原驻地中等标准水平比较,分别下降7%~20%、8%~21%、25%~33%;原驻海拔3700 m步兵部队的VO2max(33.5±1.6)ml/(kg·min)略高于原驻海拔500 m技术兵部队的VO2max(32.9±2.1)ml/(kg·min)(P0.05),但原驻海拔3700 m技术兵部队的VO2max(33.1±2.0)ml/(kg·min)接近于原驻海拔500 m技术兵部队的VO2max。结论进驻更高海拔地区初期,不同驻地及兵种部队的体能均有所下降,尤其是原驻海拔较低的技术兵部队下降更明显。     

高原劳动能力降低的机理探讨和训练提高劳动能力的人体实验研究

对生长于低海拔地区的１１名男性健康青年志愿者，训练前、后于低压舱内进行３００ｍ、３５００ｍ、４５００ｍ的自身对比人体实验研究．结果发现高原劳动能力下降是由于乳酸性和非乳酸性氧债增高；表明心肌有早期轻度损害的Ｍｂ和ＣＫ显著增加，以及心电ＱＲＳ波和Ｔ波出现亚临床征候；肌球蛋白和肌动蛋白合成赶不上分解，与高原劳动能力下降呈现负相关，并有显著的统计学意义，采用复合锻炼４周后，在３５００ｍ高度劳动能力接近于平原水平，４５００ｍ则可恢复至未训练时的３５００ｍ劳动强度，但较平原劳动仍偏低１２．１２％。     

High altitude dives from 7000 to 14,200 feet in the Himalayas

Indian Navy divers carried out no-decompression dives at altitudes of 7000 to 14,200 ft (2134-4328 m) in the Nilgiris and Himalayas from May to July 1988. Seventy-eight dives on air and 22 dives on oxygen were carried out at various altitudes. The final dives were at Lake Pangong Tso (4328 m) in Ladakh, Himalayas, to a maximum of 140 feet of sea water (fsw) [42.6 meters of sea water (msw)] equivalent ocean depth in minimum water temperature of 2 degrees C. Oxygen diving at 14,200 ft (4328 m) was not successful. Aspects considered were altitude adaptation, diminished air pressure diving, hypothermia, and remote area survival. Depths at altitude were converted to depths at sea level and were applied to the Royal Navy air tables. Altitude-related manifestations, hypoxia, hypothermia, suspected oxygen toxicity, and equipment failure were observed. It is concluded that stress is due to effects of altitude and cold on man and equipment, as well as changes in diving procedures when diving at high altitudes. Equivalent air depths when applied to Royal Navy tables could be considered a safe method for diving at altitudes.     

Effect of cold exposure, exercise and high altitude on plasma endothelin-1 and endothelial cell markers in man

The aims were to examine the effect of cold exposure, exercise and high altitude on plasma concentrations of big endothelin-1, endothelin-1, von Willebrand factor and serum e-selectin in twenty five healthy male volunteers. Clinical evaluation and venesection were performed before and after 24 hours of low altitude mountaineering, exposure to temperatures of -18 degrees C and +4 degrees C and whilst ascending from sea level to an altitude of 5000 m in the Karakoram. Plasma big endothelin-1, plasma endothelin-1 and serum soluble e-selectin concentrations were significantly elevated after two hours at -18 degrees C (p < 0.05, p < 0.05 and p < 0.01 respectively). At +4 degrees C, plasma big endothelin-1 and endothelin-1 concentrations rose significantly after 5 hours (p < 0.005 for both) but not after 2.5 hours. Low altitude mountaineering did not alter circulating marker concentrations. At high altitude, big endothelin-1 and endothelin-1 (p < 0.01 for both) rose significantly at 2500 m and initially at 5000 m but returned to sea level values after prolonged exposure to 5000 m. Serum e-selectin rose at all altitudes greater than sea level (p < 0.05). In conclusion, exposure to high altitude, moderate cold or freezing temperatures, but not exercise, selectively activates endothelial cells increasing endothelin-1 production. Cold exposure may contribute to the observed increase in plasma endothelin-1 in mountaineers at high altitude.     

增氧呼吸器在不同海拔高度下对血氧饱和度和心率的影响

目的：探讨增氧呼吸器在高原不同海拔环境下对机体血氧饱和度和心率的影响;方法：140名受试者分别在高原（海拔3 700,3 750,3 950,4 700,4 900,5 300m）进行运动负荷实验,首先检测静息状态下不使用仪器的血氧饱和度（blood oxygen saturation,SaO2）和心率.而后进行运动负荷实验（不佩戴增氧呼吸器）,检测数据,并检测1,2,3min的恢复心率和血氧饱和度.24h后佩戴仪器后,重复以上检测;结果：静息状态下,与不使用单兵高原增氧呼吸器的试验结果相比较,在高原不同海拔环境下使用增氧呼吸器后,SaO2明显增加,心率明显降低,其差异具有统计学意义（P＜0.05）.运动负荷实验结束后,佩戴增氧呼吸器后在3 750,3 950,4 900m的高度下机体SaO2明显升高,差异特别显著（P＜0.01）;结论：增氧呼吸器在高原不同海拔高度下能有效地提高和改善士兵的军事作业能力,而且效果显著,对高原习服有明显的促进作用.     

郑州市正常新生儿脑组织氧饱和度正常参考值范围的研究

目的:探讨近红外光谱测定技术(near-infrared spectroscopy,NIRS)检测正常新生儿局部脑组织氧饱和度(regional oxygen saturation,rSO2),建立新生儿脑rSO2的正常值参考值范围。方法:应用TSAH-100型近红外组织血氧参数无损监测仪,测定我院正常新生儿出生后1、2、3、10~15天时的脑组织氧饱和度变化,并进行比较。结果:正常新生儿脑rSO2在出生后第1天为(62.02±2.86)%、第2天为(62.06±2.40)%、第3天为(61.91±2.29)%、第10天后为(61.96±2.40)%,比较差异无统计学意义(P>0.05);不同性别正常新生儿的rSO2在出生后第2、3、10天比较差异有统计学意义(P<0.05);rSO2与SPO2总体呈正相关。结论:郑州市正常足月新生儿脑rSO2测定值参考范围为(62.03±2.51)%,如果低于57.9%则提示有脑组织缺氧。     

急性缺氧对动物血液,肝,脑中酮体含量的影响

为观察大鼠在不同海拔高度和不同缺氧时间血液、肝、脑组织酮体含量变化，大鼠分别在５０００ｍ、７０００ｍ、９０００ｍ模拟高度，每高度度均分别停留２、４和８ｈ。结果表明，在７０００ｍ高度停留２及４ｈ，以及在９０００ｍ高度停留２、４及８ｈ，血中酮体浓度显著高于海平时，而肝组织中酮体含量则显著地低于海平时，脑组织中酮体含量在上述３个模拟高度，均未见明显改变     

Urban Ectopy in the Mountains: Carbon Monoxide Exposure at High Altitude

Environmental exposure to inhaled carbon monoxide (CO) increases coronary artery disease risk. Sudden cardiac death, a frequent manifestation of coronary artery disease, is usually a result of ventricular dysrhythmia. The effect of exposure to CO at sea level (CO/SL) and simulated high (2.1 km) altitudes (CO/HA) on the incidence of cardiac ectopy in subjects with coronary artery disease was investigated. A double-blind crossover study was conducted, with random-order assignment, and each subject served as his own control. Seventeen men with documented coronary artery disease and stable angina pectoris performed cardiopulmonary exercise stress tests after random exposure to either CO or clean air (CA) at sea level (CA/SL) or at a simulated 2.1-km high altitude (CA/HA). The individual CO and HA exposure conditions were each selected to reduce the percentage of oxygen saturation of the subjects' arterial blood by 4%. Subjects' blood carboxyhemoglobin levels were increased from an average of 0.62% after clean-air exposure to 3.91% of saturation after CO exposure. The percentage of oxygen saturation in arterial blood was reduced from a baseline level of 98% to approximately 94% after CO/SL or CA/HA and to approximately 90% after CO/HA. Compared with the CA/SL (i.e., 10 premature ventricular contractions [PVCs]), the average incidence of exercise-induced ventricular ectopy was approximately doubled after all exposures (CO/SL = 18 PVCs, CA/HA = 16 PVCs, and CO/HA = 19 PVCs), and a significant trend (p < .05) of increased ectopy with decreased oxygen saturation in arterial blood was observed. Yet, among subjects who were free from ectopy (n = 11) on CA/SL, only 2 subjects developed ectopy after CO/HA. No episodes of ventricular tachycardia or fibrillation occurred. The findings indicated that exposure to increased levels of hypoxemia, resulting from hypoxic and/or CO exposures, increased the susceptibility to ventricular ectopy during exercise in individuals with stable angina pectoris; however, this risk was nominal for those without ectopy.     

不同海拔下小学生有氧运动与肺功能心率恢复能力的关联

讨论不同海拔下7~12岁学生有氧运动能力、肺功能及心率恢复能力关联性,为进一步研究不同海拔地区儿童少年运动生理变化提供依据.方法 以塔什库尔干县235名世居3 240m高原(Hi组)、喀什市第十小学300名世居1 290m亚高原(SubHi组)及深塔二中小学部300名世居3 240 m高原下1 290m亚高原(HiSubHi组)7~ 12岁学生为研究对象,进行20 m往返跑(20-mSRT)测试、呼吸功能测试及定量负荷运动后心率恢复能力评价.结果 不同海拔高度下,7~12岁学生的20-mSRT、用力肺活量(FVC)、第1秒肺活量(FEV1)、第1秒肺活量/用力肺活量(FEV1%)及运动后5 min末心率绝对恢复率(V%)随年龄增长呈上升趋势,SubHi组20-mSRT、FVC、FEV1、FEV1%及V%水平高于Hi组,HiSubHi组在1年亚高原环境适应后较Hi组出现上升趋势.除HiSubHi组男生FVC、FEV1及SubHi组男生FEV1%水平外,其余各测试组20-mSRT与肺功能指标间均存在关联(r值分别为0.99,0.97,0.93,0.89,0.85,0.99,0.97,0.95,0.88,0.90,0.91,0.98,0.83,P值均<0.05);SubHi组(r男=0.78,r女=0.81)20-mSRT与心率恢复能力相关有统计学意义(P值均<0.05),其余各测试组20-mSRT与心率恢复能力间相关均无统计学意义(P值均>0.05).结论 不同海拔状态7~12岁学生有氧运动能力、肺功能及心率恢复能力的发育特征可能存在一定差异,20-mSRT、FVC、FEV1、FEV1%及V%间的关联性可能存在海拔适应特征.     

高原低氧环境中一氧化碳苯对小鼠的毒性

本文研究了在高原低氧环境中一氧化碳、苯对小鼠毒性的影响。结果证明一氧化碳和苯的毒性随海拨高度增加而增强,一氧化碳中毒加剧了高原低氧环境下动物的缺氧程度。在同一海拨高度,染毒组动物血氧饱和度和氧分压明显低于对照组,且随染毒浓度增加而降低。说明高原低氧环境中一氧化碳、苯对小鼠的毒性比平原有明显增加。     

Altitude variation of cosmic-ray neutrons

The altitude variation of the cosmic-ray neutron energy spectrum and the dose equivalent rate was measured at an average geomagnetic latitude of 24 degrees N by using the high-efficiency multi-sphere neutron spectrometer and neutron dose-equivalent counter developed by the authors. The data were obtained from a 2-h flight over Japan on 27 February 1985. The neutron energy spectra measured at sea level and at altitudes of 4,880 m and at 11,280 m were compared with the calculated spectra of O'Brien and with other experimental spectra, and they are in moderately good agreement with them. The dose equivalent rate increases according to a quadratic curve up to about 6,000 m and then increases linearly between 6,000 m and 11,280 m. The dependence of dose equivalent rates at sea level and at an altitude of 12,500 m on geomagnetic latitude also is given by referring to other experimental results.     

Distribution of hemoglobin and functional consequences of anemia in adult males at high altitude

In order to assess better the normal hemoglobin (Hb) range among adult males at high altitude, a hematological survey was completed in La Paz, Bolivia (3700 m). Two statistical methodologies were utilized to identify the anemic and polycythemic contributions to the Hb distribution of normal healthy men (n = 526). The Hb of normal men has a Gaussian distribution with mean and SD of 18.8 +/- 1.4 g/dl. Cutoff levels of 15.8 and 22.0 g/dl Hb were selected to identify the anemic and polycythemic subpopulations. Iron status in this high altitude population is similar to that of low altitude populations, and iron deficiency is the cause of most anemia found. An exercise test on a subsample of 56 men was utilized to validate the anemia cutoff level. Anemics as identified by the 15.8 g/dl Hb level showed a significant reduction in aerobic capacity as measured by PWC150 and estimated VO2max.     

不同海拔驻地官兵进驻高海拔地区后睡眠质量及认知功能的比较

目的对比分析不同海拔高度驻地部队进驻同一更高海拔地区后睡眠质量及认知功能的改变,为制定高原睡眠保障措施提供参考依据。方法选择原驻地海拔3700 m官兵109名和原驻地海拔500 m官兵99名作为调查对象。当调查对象进驻海拔4400 m高原2周时,采用匹兹堡睡眠质量指数量表(PSQI)进行睡眠质量问卷调查,并以PSQI总分≥7作为睡眠质量下降的参考界值;采用数字广度、数字译码和目标追踪进行认知功能测试。结果原驻地海拔500 m官兵PSQI总分为(6.39±3.13),明显高于原驻地海拔3700 m官兵(5.13±2.61),P0.05;前者PSQI总分≥7的检出率为33.6%,高于后者的26.6%(P0.05)。在所有PSQI因子项中,原驻地海拔500 m官兵的得分均明显高于原驻地海拔3700 m官兵,其中在主观睡眠质量、入睡时间、睡眠时间、睡眠效率和睡眠障碍上,差异有显著性(P0.05);与原驻地海拔3700 m官兵相比,原驻地海拔500 m官兵的认知功能测试成绩也有降低趋势,其数字广度测试成绩为(17.85±4.43),明显低于原驻地海拔3700 m官兵(19.94±4.73),P0.05。结论进驻高海拔地区对部队官兵睡眠质量和认知功能有负面影响,原驻地海拔500 m部队官兵较原驻地海拔3700 m部队官兵受影响程度更为明显。     

Peripheral circulation monitored by surface temperature and autonomic nervous function in hypobaric hypoxic environment: effects of submaximal exercise

Hypothermia and frostbite are frequently seen in accidents in remote wilderness environment, especially in hypobaric hypoxic conditions. The aim of this study was to clarify how hypobaric hypoxic conditions affects peripheral circulation. Peripheral skin temperature and autonomic nervous functions were assessed in two 1000-m ascent exercises. Subjects (n = 15) ascended from 1000 m above sea level in Study 1, and ascended from 2400 m in Study 2. Conditions other than environmental oxygen pressure were mostly identical in both studies. The autonomic nervous activities were decreased solely in Study 2. The relative sympathetic activity was significantly increased in the lower barometric pressure in Study 2 (p < 0.01). Peripheral skin temperature was significantly decreased after the exercise in Study 2 (p < 0.01). In conclusion, hypobaric hypoxia itself induced peripheral low temperature during exercise at high altitudes. Relative sympathetic hyperactivity may be responsible for the compromised peripheral circulation.     

基于富氧环境的高原习服训练中心的设计与评价

目的建立基于富氧环境的高原习服训练中心,并评价其效果。方法在海拔3570 m利用分子筛制氧机供氧和自动供氧控制系统,模拟较低生理等效高度,建立习服训练中心。将24名男性急性高原反应(AMS)患者随机分成训练组和对照组,每组12人。训练组在O2含量分别为26.0%、24.5%、23.0%和21.5%的富氧环境中进行运动训练各1 d;对照组处于自然低氧环境中,不进行运动训练。将训练组训练期间和训练结束后1 d的收缩压、舒张压、心率、血氧饱和度及AMS评分与同期对照组值进行比较。结果训练组进入习服训练中心训练后,血氧饱和度有所改善,训练1~4 d和训练后1 d,AMS评分分别为2.08±1.17、1.67±0.65、1.50±0.79、1.33±0.89、0.58±0.67,均明显低于对照组(分别为5.50±0.08、5.58±0.09、4.50±1.17、3.92±0.09、3.42±0.79),差异有显著性(P<0.01)。结论在高原习服训练中心通过阶梯式调节生理等效高度并进行运动训练,能及时缓解急性高原反应症状,缩短习服时间。     

青藏高原高原病流行病学的研究

为了搞清高原病的人群发病率及易患因素以利防治,自1978~1985年,在青藏高原广泛地区对三个不同海拔范围(2,261~2,808米、3,050~3,797米、4,068~5,226米)的移居和世居自然人群(儿童15,251人,成人25,618人)进行了一项流行病学研究。结果在进入高原的人群中急性高原病的发生率为:急性高原反应39.50%,高原肺水肿0.47%,高原脑水肿0.28%。久居和世居高原人群中慢性高原病的患病率为:慢性高原反应2.80%,高原心脏病儿童0.96%,成人0.32%,高原红细胞增多症2.51%,高原高血压症0.96%,高原低血压症1.89%。慢性高原病患病率移居较世居人群高9.7倍。
本调查证明高原病存在若干易患因素,如海拔愈高,登高速度愈快,有过劳、受凉、上呼吸道感染、精神紧张等诱因,年幼或老年,原患有心肺等疾患者最易发病。针对这些因素探讨了预防措施。     

Surveillance for early silicosis in high altitude miners using pulse oximetry

Two cross-sectional studies in a high altitude region of Perú evaluated the role of pulse oximetry for detection of silicosis in high-altitude miners. In study one, exercise pulse oximetry and chest radiographs were used to evaluate 343 silica-exposed miners and 141 unexposed subjects for evidence of silicosis. Study 2 investigated the association between exercise oxygen saturation and silicosis in 32 non-silicotic and 65 silicotic miners. In study one, age (Odds Ratio [OR] 1.10, 95% Cofidence Interval (CI) 1.07-1.12) and resting oxygen saturation (OR 0.95, 95%CI 0.90-0.99) were associated with silicosis. In study two, years of mining employment (OR 1.14, 95%CI 1.05-1.23) and exercise oxygen saturation at 30% maximum heart rate (OR 0.86, 95%CI 0.75-0.99) were associated with silicosis. Hypoxemia at rest and with exercise is associated with silicosis in high altitude miners. Pulse oximetry should be further investigated as a screening tool for silicosis at high altitudes.