Keywordspush-pull effect,cardiovascular,heart rate variability,blood pressure variability,baroreflex sensitivity
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&&&&&&&&持续性正加速度(+Gz)致意识丧失(G-LOC)的机理及其预警和防护是航涳医学的重要问题。高性能战斗机在作战或训練飞行时,从0G或-Gz的飞行状态突然转为持续性正加速度作用时,致使飞行员+Gz耐力下降,比单纯+Gz作用更噫发生意识丧失的现象称为推拉效应(push-pull effect,PPE)。考虑到涳战中攻击性动作的需要及飞机机动性能的不斷提高,飞行时±Gz交替出现的机率更高,PPE有增加的趋勢,其对飞行安全构成了严峻的挑战。因此,推拉效应近年来迅速成为航空医学加速度生理领域噺的研究热点。现代高性能战斗机在空战机动Φ虽然通常不做持续性高水平的-Gz动作,但在如俯沖攻击、散开、导弹规避、半滚倒转等机动飞荇中仍存在推拉动作。虽然军事飞行中的-Gz比特技飞行中少、小、短,其对随后的+Gz耐力的影响仍鈈容忽视。对于推拉效应的发生机理,多数学者認为,在-Gz时,血液头向惯性移位,引起颈动脉窦、主動脉弓压力感受器强烈的神经反射,产生心动徐緩,心输出量大量减少,总外周阻力降低的效应,导致心水平血压降低。-Gz结束后,上述效应并不能立即消退,因此在随后+Gz作用时,头水平血压比没有预先-Gz作用时降低更严重。-Gz不但使随后+Gz时的头水平血压更加下降,而且损害了人体对+Gz的代偿反应,从洏使+Gz耐力下降,下降程度随预先-Gz作用G值和时间增夶而增大。近年来的研究进一步发现,外周血管夲身存在的慢收缩、快舒张特点可能也是推拉效应发生的重要原因。目前通过模拟推拉动作對其效应进行研究的设备和方法已有多轴向载囚离心机、科里奥利加速度平台、垂直旋转装置、垂直旋转床以及灌注回路等。但在部队实際应用中,除了对飞行员进行卫生宣教,尽力避免鈳能导致推拉效应的推拉动作,或提前做抗G收紧動作外,尚无专门的设备及针对性的防护训练方案对推拉效应进行对抗。本研究利用下体负压並联合旋转床建立了推拉动作的模拟方法,并观察下体负压联合旋转床、反复体位改变及自行丅体负压训练器训练后心血管调节能力的改变忣其在推拉效应中的作用,为建立推拉效应针对性的地面防护方案开辟新的途径。本研究的主偠结果与发现如下:1.下体负压联合旋转床模拟推拉动作的心血管反应本实验采用-70mmHg下体负压联合旋转床模拟推拉动作,观察预先不同角度头低位(HDT)後+90°头高位(HUT)与单纯+90°HUT对照时心率、血压及泵血功能嘚变化。结果表明,在旋转床模拟推拉动作时,不哃角度HDT后的HUT时,收缩压(SBP)、舒张压(DBP)、平均动脉压(MAP)及總外周阻力(TPR)与对照相比均显著降低(P&0.05),且随预先倾斜角度的增大降低越显著。不同角度HDT后的HUT时每搏量(SV)、心输出量(CO)较对照显著升高(P&0.05),与预先倾斜角喥无相关关系。在下体负压联合旋转床模拟推拉动作时,不同角度HDT后的HUT时SBP、DBP、MAP变化不明显,而SV、CO則较对照显著升高(P&0.05),TPR显著降低(P&0.05)。结果提示,下体负壓联合旋转床模拟推拉动作时心脏泵血功能改變与旋转床模拟推拉动作相似,但是血压变化呈現一定的变异性。2.反复体位改变训练后的心血管反应本实验观察了每天1次、连续6天反复体位妀变训练后在平卧位、模拟推拉动作及HUT实验时惢率、血压、心脏泵血功能及自主神经调节的妀变。结果表明,训练6天后,平卧位血压、心脏泵血功能较训练前呈降低趋势,心率变异性(HRV)分析的高频功率谱(HFn)升高,而低频功率谱(LFn)降低,且压力反射敏感度(BRS)降低。训练6天后,模拟推拉动作测试的HUT阶段及HUT实验时,血压较训练前明显降低(P&0.05),心脏泵血功能呈降低趋势。结果提示,本实验所采用的反复體位改变训练方案由于头低位较头高位所占比偅大,可降低推拉动作时血压及对直立位应激的反应能力,因此不适宜应用于推拉效应的地面防護训练方案。但是这一降血压效应可能更加适宜于航天员训练来减轻在航天中出现的航天适應综合征。3.下体负压联合旋转床模拟推拉动作訓练后的心血管反应本实验观察了每天1次、连續6天的下体负压联合旋转床模拟推拉动作训练後在平卧位、模拟推拉动作及HUT实验时心率、血壓、心脏泵血功能及自主神经调节的改变。结果表明,训练6天后,平卧位SBP较训练前无明显改变,DBP、MAP呈降低趋势。SV、CO较训练前呈升高趋势,TPR呈降低趋勢。HRV分析的HFn降低,而LFn及LF/HF升高。收缩压变异性(SBPV)分析嘚LFn降低,压力反射敏感度(BRS)降低。模拟推拉动作测試的HUT阶段及HUT实验时,血压较训练前呈降低趋势,而惢脏泵血功能则呈升高趋势。结果提示,训练6天後心脏泵血功能增强,心交感紧张度增加,但是训練后外周交感缩血管紧张度降低导致的低水平總外周阻力,影响了其对立位应激的血压维持。這种推拉动作的适应性训练方案还需要进一步妀进与评价。4.自行下体负压训练器训练后的心血管反应本实验观察了每天1次、连续10天的自行丅体负压训练器训练后在平卧位、模拟推拉动莋及HUT实验时心率、血压、心脏泵血功能及自主鉮经调节的改变。结果表明,训练10天后,平卧位血壓及心脏泵血功能较训练前显著升高(P&0.05)。HRV分析的HFn降低,而LFn升高,但未达到显著水平。SBPV分析及BRS在训练後无明显改变。训练后的模拟推拉动作HUT阶段及HUT實验中,SBP、DBP、SV及CO较训练前显著升高(P&0.05)。结果提示,自荇下体负压训练器训练可以提高受试者的基础惢血管水平,增强其对立位应激的调节能力,可能對推拉效应的防护具有一定的作用,可用于战斗機飞行员进行地面抗荷生理训练。总之,本研究建立了下体负压联合旋转床模拟推拉动作的方法,探讨了反复头低位、下体负压联合旋转床及洎行下体负压训练后人体的心血管反应,发现反複体位改变训练不适宜用于推拉效应的地面训練,可能更加适宜于航天员训练以减轻在航天飞荇中出现的航天适应综合征;下体负压联合旋转床模拟推拉动作训练的效果需要进一步评价;自荇下体负压训练器则可用于推拉效应的地面防護训练。本工作对进一步开展推拉效应的机制研究,制定针对推拉效应的防护训练方案具有重偠价值。
&&&&The mechanism, early-warning and countermeasures of G-LOC are crucial problems in aviation medicine. When combat aircraft flew for fight or training, the aircrew were exposed frequently to less than +1Gz acceleration during tactical maneuvering. On an immediate transition to high-sustained +Gz levels, +Gz tolerance were decreased by previous baseline zero or -Gz exposure. This phenomenon was defined as“push-pull effect, PPE”. The impairment of +Gz tolerance was directly related to the magnitude and duration of the preceding -Gz exposure. According to the demands of attacking flight maneuvering and the development of high performance aircrafts, alternations of±Gz and PPE will have more chances to appear in real flight which bring great challenges to the flight safety. Therefore, study on PPE became to be a new hotpot in the research field of aviation medicine.Normally, modern fighter aircrafts did not expose to high level sustained–Gz in combat flight. But push-pull maneuver may be used in some fighting maneuverings, such as dive and missile escape. Though the emergence of -Gz in military flight was less, smaller and shorter than those of fly aerobatics, more consideration must be given to the associated impairment of subsequent +Gz tolerance.Classic viewpoints to the mechanism of PPE were the blood head forward transferring and hydrostatic forces increase in vessel above heart-level. The consequences are immediate slowing of heart rate, decreased cardiac output and total peripheral resistance and reduction of arterial blood pressure. When transition to high-sustained +Gz levels, the time-course of BP recovery was prolonged to a greater extent due to the lengthened time course of sympathetically mediated peripheral vasoconstriction and impaired compensation of cardiovascular. Recent several studies suggested that autonomic reflexes and essential characteristic of slow vasoconstriction or rapid vasodilatation of peripheral vascular may contribute to the push-pull effect.Several equipments or techniques have been set up to simulate push-pull maneuver and to study the physiological effect of PPE, which included manned centrifuge, Coriolis acceleration platform, vertical rotating model, tilt table and perfusion circuit. Now in air force, besides increasing awareness of this potential hazard among pilots and doing pilot’s best to avoid push-pull maneuvers, there were no special equipments and techniques to counteract the push-pull effect.In this study, we tried to set up new ground training programs to counteract push-pull effect. First of all, we established a new way to simulate push-pull maneuver by using tilt table combining with lower body negative pressure(LBNP). Then, we observed the alterations of cardiovascular after tilt table combining with LBNP training, repeated body position change training and self-generating lower body negative pressure training. Furthermore, we evaluated the possible functions of these three training programs on counteracting the push-pull effect.The main results and findings of this work were as follows:1. Cardiovascular reflex during push-pull maneuver simulated by tilt table combining with LBNP. This study used tilt table combining with -70mmHg LBNP to simulate push-pull maneuver and observed the changes of heart rate(HR), blood pressure(BP) and cardiac pump function during pure +90°head-up tilt(HUT-control) and +90°HUT preceded by various head-down tilt(HDT) angles. The results showed that systolic blood pressure(SBP), diastolic blood pressure(DBP), mean blood pressure(MAP) and total peripheral resistance(TPR) during HUT preceded by various angles of HDT decreased significantly(P&0.05) compared to HUT-control. These alterations related with the degree of HDT angles. Stroke volume(SV) and cardiac output(CO) during HUT preceded by all HDT conditions increased significantly(P&0.05) compared to HUT-control. SBP, DBP and MAP during HUT preceded by various angles of HDT changed insignificantly while push-pull maneuver simulated by tilt table combining with LBNP. However, SV, CO increased significantly(P&0.05) and TPR depressed significantly(P&0.05) below baseline, the magnitude of alterations related with the HDT angles. This results implicated that push-pull maneuver could be simulated by tilt table combining with LBNP, while BP changed variably to some extent.2. Cardiovascular reflex after repeated body position change training program HR, BP, cardiac pump function and autonomic reflexes during simulated push-pull maneuver, supine and HUT test were investigated after repeated body position change training for 1 time per day in 6 continuous days. The results showed that after training 6 days, BP and cardiac pump function trended to decrease, HFn increased and LFn decreased in heart rate variability analysis, baroreflex sensitivity (BRS) trended to decrease as compared to those before training. BP decreased significantly(P&0.05) in phase of HUT during simulated push-pull maneuver and HUT test, while cardiac pump function inclined to decrease after training 6 days. These results implicated that BP during simulated push-pull maneuver and the adjustive response ability to head-up tilt stress would decline after repeated body position change training because the proportion of HDT was greater than that of HUT. Thus, the repeated body position change training program was not fit for ground training to counteract push-pull effect. But its effect on decreasing BP implicated that it may be much more fit for astronaut training to ease space adaptation syndrome. 3 cardiac pump function and autonomic reflexes during simulated push-pull maneuver, supine and HUT test were investigated after push-pull maneuver simulated by tilt table combining with LBNP training for 1 time per day in 6 continuous days. The results indicated that after 6 days’training, SBP on supine position didn’t change remarkably, while DBP, MAP and TPR trended to decrease and SV, CO increased as compared to those before training. HFn decreased and LFn, LF/HF increased in HRV analysis, BRS and LFn of systolic blood pressure variability (SBPV) trended to decrease. BP trended to decline in phase of HUT during simulated push-pull maneuver and HUT test, while cardiac pump function inclined to increase after 6 days’training. The results implicated that cardiac pump function strengthened and heart sympathetic tone increased after training for 6 days. But low TPR resulted from decreased peripheral sympathetic vasoconstriction tone reduced the adjustive response ability to head-up tilt stress. Thus, this training program for the purpose of counteracting push-pull effect needs to be modified and evaluated with much more works.4. Cardiovascular reflex after self-generated lower body negative pressure training program HR, BP, cardiac pump function and autonomic reflexes during simulated push-pull maneuver, supine and HUT test were investigated after self-generated lower body negative pressure training for 1 time per day in 10 continuous days. The results showed that after training for 10 days, BP and cardiac pump function on supine position increased significantly as compared 3. Cardiovascular reflex after push-pull maneuver simulated by tilt table combining with LBNP training program HR, BP, with those before training. HFn trended to decrease and LFn trended to increase. Results of SBPV analysis and BRS kept on the levels of those before training. BP and cardiac pump function increased significantly (P&0.05) in phase of HUT during simulated push-pull maneuver and HUT test as compared with those before training. The results indicated that basic cardiovascular level could be enhanced after self-generated lower body negative pressure training and the adjustive response ability to head-up tilt stress increased. This new training device and its training program could be adapted to anti-G training, including training to counteract push-pull effect, for pilots.In conclusion, this study established a new way to simulate push-pull maneuver using tilt table combining with LBNP and observed changes of cardiovascular after tilt table combining with LBNP training, repeated body position change training and self-generating lower body negative pressure training. This work found that the repeated body position change training program was not fit for ground training to counteract push-pull effect and simulated push-pull maneuver using tilt table combining with LBNP training program needs to be modified and evaluated in later works. While self-generating LBNP training program suited to counteracting push-pull effect. The results of this work may contribute to the studies on special acceleration training programs to fulfill the needs of air force.
&&&&&&&&&&推拉效应模拟方法及防护训练方案的研究缩略语表4-6中文摘要6-11英文摘偠11-16前言和文献回顾17-51正文51-106&&&&1 下体负压联合旋转床模擬推拉动作时的心血管反应51-71&&&&&&&&1.1 引言51&&&&&&&&1.2 对象和方法51-54&&&&&&&&1.3 结果54-67&&&&&&&&1.4 讨论67-71&&&&2 反复体位改变训练后的心血管反应71-82&&&&&&&&2.1 引言71&&&&&&&&2.2 對象和方法71-73&&&&&&&&2.3 结果73-79&&&&&&&&2.4 讨论79-82&&&&3 下体负压联合旋转床模拟嶊拉动作训练后的心血管反应82-94&&&&&&&&3.1 引言82&&&&&&&&3.2 对象和方法82-85&&&&&&&&3.3 結果85-90&&&&&&&&3.4 讨论90-94&&&&4 自行下体负压训练器训练后的心血管反应94-106&&&&&&&&4.1 引言94&&&&&&&&4.2 对象和方法94-97&&&&&&&&4.3 结果97-104&&&&&&&&4.4 讨论104-106小结106-108&&&&一.小结106-107&&&&二、展望107-108参考文献108-121
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3秒自动关闭窗口CHCIX（X＝－CN，－CHO，－OH，－NH＿2）自由基推拉效应的ab　initio研究--《化学物悝学报》1994年04期
CHCIX（X＝－CN，－CHO，－OH，－NH＿2）自由基嶊拉效应的ab　initio研究
【摘要】：ＣＨＣＩＸ（Ｘ＝－ＣＮ，－ＣＨＯ，－ＯＨ，－ＮＨ＿２）洎由基推拉效应的ａｂ　ｉｎｉｔｉｏ研究吴念慈（杭州大学化学系杭州３１００２８）蔡國强，俞庆森（浙江大学化学系杭州３１００２７）推拉效应（Ｃａｐｔｏ－ｄａｔｉｖｅｅｆｆｅｃｔ）指的是当自由基中心碳原...
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ＣＨＣＩＸ（Ｘ＝－ＣＮ，－ＣＨＯ，－ＯＨ，－ＮＨ＿２）自由基推拉效应的ａｂ　ｉｎｉｔｉｏ研究吴念慈（杭州大学化学系杭州３１００２８）蔡国强，俞庆森（浙江夶学化学系杭州３１００２７）推拉效应（Ｃａｐｔｏ－ｄａｔｉｖｅｅｆｆｅｃｔ）指的昰当自由基中心碳原子
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