急性轻、中度缺氧对人的短时记忆能力的影响

目的 研究急性轻,中度缺氧对人的短时记忆能力绩效的影响。方法 利用低压舱模拟２８００ｍ、３６００ｍ及４４００ｍ高度缺氧暴露１ｈ,考察１８名健康男性青年的记忆长廊、记忆扫描,连续识别记忆和空间记忆测验绩效的变化。     

Effects of Acute Moderate Hypoxia on Human Performance of Arithmetic

为观察急性中度缺氧对人计算能力的影响，利用低压舱模拟３００ｍ（对照）、３６００ｍ、４４００ｍ、５０００ｍ高度的缺氧暴露，考察１６名健康男性青年的连续计算、系列加减及心算测验综合绩效的变化。结果显示，３６００ｍ缺氧暴露１ｈ，连续计算测验的错误率增加、系列加减运算的反应时延长、综合绩效下降，均达到显著水平（Ｐ＜０．０５）。４４００ｍ缺氧暴露各项测验的绩效均显著下降（Ｐ＜０．０５）。５０００ｍ暴露时各项测验的绩效进一步降低（Ｐ＜０．０１）。提示：急性中度缺氧１ｈ对人的计算能力有一定影响，且随高度的增加而加重     

急性轻、中度缺氧对人的感知觉能力的影响

为研究急性轻中度缺氧对人感知觉能力的影响。我们利用低压舱模拟2800m、3600m、4400m高度缺氧暴露1小时,观察18名健康男性的长度判断、数字检索等测验绩效的变化。发现2800m缺氧暴露1小时,长度判断的综合绩效低于对照组（P＜0．05）。3600m暴露1小时,各项测验的反应时间明显延长（P＜0．01）,综合绩效显降低;但图案比较和数字检索测验的错误率无显改变（P＞0．05）。4400m暴露1小时,各项测验综合绩效进一步降低,仅为对照值的47％、84％、84％（P＜0．01）。错误率也显增加（P＜0．05）。提示急性轻度缺氧（2800m高度）对感知觉能力即产生影响,随高度增加而加重。不同测验项目受影响的特性和阈值不同。     

急性轻、中度缺氧暴露对心理运动及反应时的影响

目的：研究急性轻,中度缺氧暴露对人的心理运动及视觉反应时的影响。方法 利用低压舱模拟300m（对照高度）,2800m,3600m,4400m高度缺氧暴露1h,考察了18名健康男性青年被试者指82％和74％,2800m缺氧暴露1h心理运动绩效的各个参数并无显著改变（P＞0．05）,3600米缺氧步加重（P＜0．01）。而简单反应时和指测验的绩效暴露于4400米时仍无显著改变（P＞0．05）,结论 以上高度时会对选择反应时等复杂反应产生负面影响,且随着主度的增加而加重。     

急性轻、中度低压缺氧对手动作业工效的影响

目的 探讨急性轻、中度低压缺氧对手动作业工效的影响.方法 利用低压舱模拟高空缺氧环境,设计4种客观工效项目(插钉板、拧螺母、形状感知和握力包括疲劳和耐力)和1种主观感觉项目(问卷),观察9名被试者在5种模拟高度(3 500、4 000、4 500、5 000、5 500 m)缺氧暴露(25±5)min手动作业工效的变化.结果 与地面(50 m,北京地区实际海拔高度)对照组相比,插钉板、拧螺母完成时间绩效在5种模拟高度均显著降低(P＜0.01),在5 000、5 500 m高度缺氧反应进一步加剧(P＜0.001).但在4 500 m高度时,绩效降低水平反低于4 000 m;形状感知反应时、反应时绩效和感知综合(反应时间与正确率综合)绩效在5种模拟高度均发生显著变化(P＜0.01);握力绩效仅在4 000、5 500 m显著降低(P＜0.05),疲劳绩效在5种模拟高度均未发生显著改变,耐力绩效(最大握力和疲劳综合绩效)在5 000、5 500 m高度显著降低(P＜0.05);主观测试项目在5种模拟高度均发生了显著变化,且随高度增加,观感觉分值也相应增加.结论 急性轻、中度低压缺氧对手动作业工效产生显著的负面影响.插钉板、拧螺母、形状感知和主观问卷调查4种工效测试项目对缺氧比较敏感,在5种模拟高度其工效均显著降低;耐力绩效对缺氧不敏感,仅在5 000、5 500 m模拟高度显著降低.     

中度急性缺氧对血浆内皮素含量的影响

为了观察急性低压缺氧对人体血浆中内皮素（ＥＴ）含量的影响，将４８名空、地勤人员分为实验组、对照组和动态监测组。ＥＴ浓度用放射免疫法测定。结果发现，缺氧前空、地勤人员的血浆ＥＴ含量基本一致（Ｐ＞０．０５），提示飞行因素对人体血浆ＥＴ的合成与释放无明显影响。急性低压缺氧后，实验组血浆ＥＴ含量明显增加，与对照组相比，差异显著（Ｐ＜０．０５），说明急性中度低压缺氧能够促进血管内皮细胞对ＥＴ的释放。但急性低压缺氧时的血浆ＥＴ升高程度远较病理情况低。轻度的ＥＴ浓度升高，对人体是否会构成重要损害，还需观察确定。     

急性低压缺氧对人的感知觉能力的影响

目的　研究急性低压缺氧对人的感知觉能力的影响。　方法　用低压舱模拟２ ８００ ｍ 、３ ６００ ｍ 、４ ４００ ｍ 三个高度的急性缺氧暴露１ ｈ,考察１８ 名健康男性青年对长度判断、图案比较、数字检索等测验绩效的变化。　结果　以３００ ｍ 高度所测参数作为正常对照值,２ ８００ ｍ 缺氧暴露１ ｈ,长度判断的综合绩效已低于对照值（Ｐ＜ ０．０５）,３ ６００ ｍ 暴露１ ｈ 各项测验的反应时间明显延长（Ｐ＜ ０．０１）,综合绩效显著降低。但图案比较和数字检索测验的错误率无显著改变（Ｐ＞ ０．０５）,４ ４００ ｍ 暴露１ ｈ 各项测试的综合绩效进一步降低。错误率也显著增加（Ｐ＜ ０．０５）。　结论　２ ８００ ｍ高度的低压缺氧即对感知觉能力产生一定负面影响,且随着高度的增加进一步加重。不同测验项目受缺氧影响的特性和阈值不同     

急性缺氧对大鼠血浆内皮素影响的研究

本文采用特异性放免法测定了不同缺氧条件下大鼠血浆内皮素含量,结果发现对照组(n=20)、单次缺氧组(n=17)、反复缺氧组雄鼠(n=11)以及雌鼠(n=9)的血浆内皮素含量分别为50.29±1.89、71.27±5.40、106.11±8.82和77.88±8.45pg/ml。单次或反复缺氧组与对照组相比差异非常显著(p<0.01或0.001)。本研究证实急性中度缺氧能引起血浆内皮素含量明显增加,而且雄性大鼠在反复缺氧以后还能进一步提高。目前已知内皮素是作用最强、持续时间最久的缩血管活性物质,体内含量过高可对心血管系统和脑微循环产生严重影响,应尽量避免。     

人体严重急性缺氧耐力的评定

15名男青年吸含氧7.1%的低氧混合气进行缺氧耐力检查,用倒序书写数字的方法测量了有效意识时间,词时记录了睁眼脑电。我们发现,额导脑电图出现阵发性长程高幅δ波的时间同用书写方法测量的有效意识时间的终点很接近。在有效意识时间之后继续缺氧进行了听觉检测,其反应时比对照值延长了一倍。有效意识时间终点的潮气末氧分压为4.0±0.2kPa。在此后1分钟,潮气末氧分压为3.7±0.2kPa,这时受试者仍能用电钮回答声音信号,该数据对应急救生有重要意义。     

噪声对人心理旋转能力的影响

为探讨低频中等强度噪声对人的心理旋转作业绩效的影响，２４名健康青年男性在８５、９５ｄＢ（Ａ）噪声下，进行了心理旋转和判别方向作业任务测试。结果显示：在８５ｄＢ（Ａ）噪声条件下暴露１２０ｍｉｎ期间，与对照组比较，心理旋转的平均反应时显著延长（Ｐ＜０．０５），反应时绩效和综合绩效显著下降（Ｐ＜０．０１）；暴露１２０ｍｉｎ时的反应时绩效和综合绩效均显著高于暴露３０ｍｉｎ时的作业绩效（Ｐ＜０．０５）。在９５ｄＢ（Ａ）噪声条件下暴露１２０ｍｉｎ期间，与对照组比较，判别方向的平均反应时显著延长（Ｐ＜０．０１），反应时绩效和综合绩效显著下降（Ｐ＜０．０１）；暴露１２０ｍｉｎ时的反应时绩效显著高于暴露３０ｍｉｎ时的作业绩效（Ｐ＜０．０５）。本实验８５、９５ｄＢ（Ａ）两种强度噪声条件下暴露２ｈ，对心理旋转作业任务的绩效有一定的影响，表明在卫生学标准容许范围的中等强度噪声对较为复杂或脑力负荷较大的作业任务的工效会有一定的影响。     

急性低气压缺氧对人体球结膜微循环的影响

对14名健康飞行员在低压舱以35m／s的上升速度上升至5000m高度，不吸氧，停留30min，用锦州光学仪器厂生产的XOX－IA型微循环显微镜放大40－100倍，进行了球结膜微循环的动态观察。结果表明，随着缺氧时间的延长，球结膜微循环形态、流态、总积分值明显增加（＜0．01），管袢分值无明显改变（P＞0．05）。细静脉扩张、微血管数减少明显（P＜0．01），细动脉无明显改变（P＞0.05）。下降地面后，各项指标基本恢复。提示，这些改变提高了血管的顺应性及心脏的功能。     

中度和严重急性低压缺氧对胃肠粘膜生长抑素的影响

目的 观察中度和严重急性低压缺氧和大鼠胃肠道粘膜生长抑素（ＳＳ）的影响。方法 ２４只雄性Ｗｉｓｔａｒ大鼠随机分成３组：地面组、５０００ｍ组和１００００ｍ组。在低压舱内上升至５０００ｍ、１００００ｍ各停留３０ｍｉｎ,取胃肠道粘膜,用放免法测定胃肠道粘膜ＳＳ含量。结果 （１）５０００ｍ组十二指肠、小肠、盲肠ＳＳ含量均明显高于地面组;（２）１００００ｍ十二指肠ＳＳ含量显著高于地面组,十二指肠,盲肠ＳＳ含     

Effects of sildenafil on the human response to acute hypoxia and exercise

We examined the effects of the 5-phosphodiesterase (5-PDE) inhibitor sildenafil on pulmonary arterial pressure and some oxygen transport and cardiopulmonary parameters in humans during exposure to hypobaric hypoxia at rest and after exercise. In a double-blind study, 100 mg sildenafil or placebo was administered orally to 14 healthy volunteers 45 min before exposure to 5,000 m of simulated altitude. Arterial oxygen saturation (SaO2), heart rate (HR), tidal volume (VT), respiratory rate (RR), left ventricular ejection fraction (EF), and pulmonary arterial pressure (PAP) were measured first at rest in normoxia, at rest and immediately after exercise during hypoxia, and after exercise in normoxia. The increase in systolic PAP produced by hypoxia was significantly decreased by sildenafil at rest from 40.9 +/- 2.6 to 34.9 +/- 3.0 mmHg (-14.8%; p = 0.0046); after exercise, from 49.0 +/- 3.9 to 42.9 +/- 2.6 mmHg (-12.6%; p = 0.003). No significant changes were found in normoxia either at rest or after exercise. Measurements of the effect of sildenafil on exercise capacity during hypoxia did not provide conclusive data: a slight increase in SaO2 was observed with exercise during hypoxia, and sildenafil did not cause significant changes in ventilatory parameters under any condition. Sildenafil diminishes the pulmonary hypertension induced by acute exposure to hypobaric hypoxia at rest and after exercise. Further studies are needed to determine the benefit from this treatment and to further understand the effects of sildenafil on exercise capacity at altitude.     

急性缺氧对大鼠多种心血管活性物质的影响

目的　探讨缺氧对心血管活性物质的影响。　方法　利用低压舱对大鼠进行急性低气压重度缺氧实验 ,模拟升空至 75 0 0 m高度 ,停留 30 min,出舱后立即收集各种样本 ,用放射免疫法测定心血管活性物质含量 ,并分别与无缺氧的对照组大鼠比较。　结果　发现实验组血浆内皮素 (ET)、心钠素 (ANP)和右房肌 ANP明显升高 (P<0 .0 1和 P<0 .0 1) ;而血清内洋地黄素 (EDL S)、右房肌ET、肺组织 ANP和 ET均明显降低 (P<0 .0 0 1和 P<0 .0 1)。　结论　本实验说明急性缺氧能够引起大鼠心血管内分泌功能紊乱 ,导致多种心血管活性物质平衡失调 ,提示这些改变在缺氧性机体损害过程中可能起重要作用。     

急性中、重度低压缺氧对大鼠血脑屏障通透性的影响

目的 观察急性中、重度低压缺氧条件下,大鼠血脑屏障通透性的变化特点,为阐明低压缺氧作用下脑功能障碍的可能机理提供生理学依据。方法 选择雄性ＳＤ大鼠１８只,随机分为对照组、５０００ｍ及８０００ｍ急性低压缺氧暴露组。实验组动物于低压舱内,以２０ｍ／ｓ的速率上升,至５０００ｍ（或８０００ｍ）,停留５ｈ,而后以２０ｍ／ｓ的速率下降至地面,出舱后立即经心脏灌注硝酸镧固定液,开颅取脑,制成切片,置透射电镜下观     

Running-induced changes in lung function are not altered by acute moderate hypoxia

The purpose of this study was to describe the acute changes in pulmonary function and volumes induced by running in a simulated normobaric hypoxic environment. Eleven men (X- = 26 years, 78 kg) ran 5 miles (run time approximately equal to 40 min) under normoxic (N) and hypoxic (H) conditions. A PO2 Aerobic Exerciser was used to approximate an altitude of 2286 m (PIO2 = 113 mm Hg). Impedance cardiography was used to measure cardiac output and segmental transthoracic impedance (Zo) was used to identify thoracic fluid shifts. Similar reductions in vital capacity (7%) and increases in residual volume (10%) occurred after the N and H runs with no change in total lung capacity. Flow rates breathing air or He/O2, closing volume, and closing capacity did not change. The DLCO breathhold maneuver caused a significant fall in pulmonary blood flow after running but diffusing capacity appeared to be unaffected. No changes occurred in Zo at the apex, middle, or base of the lung after either run. The hypoxic pulmonary pressor response failed to modify the pulmonary changes observed after equivalent normoxic exercise. The lung volume changes subsequent to either run were due to expiratory limitation. Previous speculation of an exercise-induced interstitial edema could not be confirmed.     

急性缺氧对飞行员胃液排空功能的影响

为探讨急性缺氧对飞行人员胃液体排空功能的影响，在常压下吸入不同浓度氧（17％、16％、14％、12％、10．5％及9％）的低氧混合气体30min，采用B型超声波在实验前后分别测量了64名男性飞行员的胃液体排空功能。结果表明，吸入17％低氧混合气胃排空延迟，但经统计学处理无显著性差异（P＞0．05），吸入16％以下的低氧混合气后胃排空延迟，经统计学处理有显著性差异（P＜O．01），且随着缺氧程度加重，胃液体排空时间延长更加明显。提示当发生高空缺氧时，应考虑到缺氧对胃排空有抑制作用这一因素。     

Effects of acute hypoxia on cardiopulmonary responses to head-down tilt

Six male subjects were exposed on two separate occasions to simulated microgravity with 28 degrees head-down tilt (HD) for 1 h with baseline followed by recovery at + 17 degrees head-up. Pulmonary ventilation, gas exchange, spirometry, and central and cerebral blood flow characteristics were compared while breathing ambient air (PIO2 = 122 mm Hg) and reduced FIO2 equivalent to 14,828 ft (PIO2 = 81 mm Hg). With hypoxia (HY), the increased tidal volume served to attenuate the drop in arterial saturation by reducing deadspace ventilation. Arterial and mixed venous PO2 values, estimated from peripheral venous samples and cardiac output (CO), were both maintained during HD in HY. Mixed venous PO2 was elevated by an increase in CO associated with a reduction in systemic resistance. Changes in spirometric indices during HD were not accentuated by HY, making the presence of interstitial edema unlikely. Cerebral flow and resistance showed minor reductions with HD. Tissue oxygenation and cardiopulmonary function were not notably effected by HD during HY, but a combination of these two stressors may predispose subjects to subsequent orthostatic intolerance during initial recovery.     

Influence of acute moderate hypoxia on time to exhaustion at vVO2max in unacclimatized runners

Eight unacclimatized long-distance runners performed, on a level treadmill, an incremental test to determine the maximal oxygen uptake (VO2max) and the minimal velocity eliciting VO2max (vVO2max) in normoxia (N) and acute moderate hypoxia (H) corresponding to an altitude of 2,400 m (PIO 2 of 109 mmHg). Afterwards, on separate days, they performed two all-out constant velocity runs at vO2 max in a random order (one in N and the other in H). The decrease in VO2max between N and H showed a great degree of variability amongst subjects as VO2max decreased by 8.9 +/- 4 ml x min(-1) x kg)(-1) in H vs. N conditions (-15.3 +/- 6.3 % with a range from -7.9 % to -23.8 %). This decrease in VO2max was proportional to the value of VO2max (VO2max vs. delta VO2max N-H, r = 0.75, p = 0.03). The time run at vVO2max was not affected by hypoxia (483 +/- 122 vs. 506 +/- 148 s, in N and H, respectively, p = 0.37). However, the greater the decrease in vVO2max during hypoxia, the greater the runners increased their time to exhaustion at vVO2max (vVO2max N-H vs. tlim @vVO2max N-H, r = -0.75, p = 0.03). In conclusion, this study showed that there was a positive association between the extent of decrease in vVO2max, and the increase in run time at vVO2max in hypoxia.     

Hemo- and neurodynamics of the human brain during exposure to moderate hypoxic hypoxia

Synchronous electro- and rheoencephalography were used to study tolerance to moderate hypoxic hypoxia for 30 min at an altitude of 5000 m without additional oxygen supply. As test subject, men with autonomic-vascular dystonia (29-39 years old), 15 men over 40 (41-56 years old), and 16 essentially healthy controls (23-36 years old) were used. The aged volunteers (41-56 years old) did not differ from the controls with respect to their tolerance to hypoxic hypoxia. The men with early symptoms of hypertonic-type dystonia also showed high tolerance to hypoxic hypoxia. The subjects with hypotonic-type dystonia displayed lower tolerance.