快速增长率G－LOC的生物力学假说─—颅内高应力学说

快速增长率Ｇ－ＬＯＣ的生物力学假说─—颅内高应力学说郝卫亚，张立藩（西安第四军医大学空军医学系７１００３２）战斗飞行员暴露在高＋Ｇｚ下可引起意识丧失（Ｇ－ＬＯＣ）。美国空军在１９８２～１９９０年由于Ｇ－ＬＯＣ造成飞行事故共１８起，其中１４人死亡，３人...     

下体负压致兔意识丧失的监测

目的用下体负压（ＬＢＮＰ）技术建立兔意识丧失（ＬＯＣ）的模型，旨在找出一些切实可行的ＬＯＣ监测指标。方法按阶梯下降的方法，将８只兔暴露于不同的负压值下（－１．３３ｋＰａ、－２．６７ｋＰａ、－４．００ｋＰａ、－５．３３ｋＰａ和－６．６７ｋＰａ），每种负压值持续作用１ｍｉｎ，观察兔发生ＬＯＣ的动态过程，并记录有关生理指标。结果ＬＢＮＰ可致兔发生ＬＯＣ、ＥＥＧ拉平，但滞后于颈总动脉血流量（ＣＢＦ）降到零后３９．７５±６．４０ｓ；ＣＢＦ与动脉血压的变化关系密切（ｒ＝０．９７１，Ｐ＜０．０１），其直线回归方程为Ｑ＝１．４０ＢＰ－４．７２（Ｑ为ＣＢＦ，Ｑ＝０时，ＢＰ＝３．３７ｋＰａ）。结论可选用ＣＢＦ降为零作为发生ＬＯＣ的监测指标；以ＥＥＧ拉平作为监测指标，会夸大ＬＯＣ的病理损害性；离心机实验时，眼水平动脉血压降为０ｋＰａ似乎可代替ＣＢＦ作为ＬＯＣ的监测指标。     

高过载飞行对飞行员的影响及防护

现代高性能战斗机的机动性能好，耐受载荷大，如Ｆ－１５和Ｆ－１６的加速度过载已远远超过飞行员的生理耐受力。在高过载作用下，飞行人员会发生视觉障碍，出现灰视、黑视等症状；严重时，飞行员可在毫无视觉先兆的情况下，突然发生意识丧失。对这种由高过载引起的意识丧失（简称Ｇ－ＬＯＣ）若不采取有效的防护措施，可引起严重飞行事故。在高Ｇ值（惯性力与重力相比的倍数）机动飞行期间，加速度惯性力的作用使心脏射血阻力增大，血液淤积于身体下部，超过飞行员的加速度耐力，便会引起脑部缺血而造成意识丧失。通常在飞机过载不太高的情…     

OSTEOGENIC POTENTIAL OF RABBIT DERMAL FIBROBLASTS CULTURED IN VITRO: A HISTOCHEMICAL AND RADIOAUTO-GRAPHICAL STUDY

ＯＳＴＥＯＧＥＮＩＣＰＯＴＥＮＴＩＡＬＯＦＲＡＢＢＩＴＤＥＲＭＡＬＦＩＢＲＯＢＬＡＳＴＳＣＵＬＴＵＲＥＤＩＮＶＩＴＲＯ：ＡＨＩＳＴＯＣＨＥＭＩＣＡＬＡＮＤＲＡＤＩＯＡＵＴＯ┐ＧＲＡＰＨＩＣＡＬＳＴＵＤＹＣＨＡＩＢｅｎ－ｆｕ（柴本甫），ＴＡＮＧＸｕｅ－...     

无导电膏生物电极新技术

无导电膏生物电极新技术超重引发意识丧失（Ｇ－ＬＯＣ）探测器、心电图（ＥＣＧ）同步压力服、医监仪器等航天仪器的发展，需要有适合座舱环境的生物电极。本文介绍的无胶生物电极采用了“强阳极氧化”、微型高阻抗射频部件、弹性印刷电路板等新技术。使用这种生物电极记...     

EXPERIMENTAL STUDY OF GUNSHOT INJURY OF THESPINAL COKD：THEMECHANISMANDCLASSIFICATION

ＥＸＰＥＲＩＭＥＮＴＡＬＳＴＵＤＹＯＦＧＵＮＳＨＯＴＩＮＪＵＲＹＯＦＴＨＥＳＰＩＮＡＬＣＯＫＤ：ＴＨＥＭＥＣＨＡＮＩＳＭＡＮＤＣＬＡＳＳＩＦＩＣＡＴＩＯＮＳｉｕＳｈａｏ－ｔｉｎｇ肯少汀ＺｈａｎｇＬｉ－ｒｅｎ张立仁ＧｅＺｈｅｎ－ｓｈａｎ葛振山Ｃｈｅｎｇ...     

健身跑对中老年人血脂、脂蛋白及载脂蛋白的影响

中老年健身跑８６例和对照组８０例进行血脂、脂蛋白及载脂蛋白Ａ１·Ｂ（ＡＰＯＡ１·Ｂ）水平的测量。结果两组间胆固醇（ＴＣ）、甘油三酯（ＴＧ）水平无显著差异（Ｐ＞０．０５），健身跑组低密度脂蛋白胆固醇（ＬＤＬ－Ｃ）、ＡＰＯＡ１水平及ＡＰＯＡ１／ＡＰＯＢ比值则显著高于对照组（Ｐ＜０．０５，Ｐ＜０．０１）。研究变量包括年龄、身高、体重、吸烟及ＴＣ、ＴＧ、ＨＤＬ－Ｃ、ＬＤＬ－Ｃ、ＡＰＯＡ１·Ｂ等。多变量相关分析表明，超重和吸烟与ＴＧ、ＨＤＬ－Ｃ、ＬＤＬ－Ｃ、ＡＰＯＡ１·Ｂ水平有显著相关性。     

正加速度致意识丧失的综合监测

目的 概述正加速度致意识丧失(G-induced loss of consciousness,G-LOC)的生理监测指标、方法和手段. 资料来源与选择 国内外相关领域的学术论著及综述. 资料引用 相关文献28篇. 资料综合 正加速度致意识丧失是当前威胁飞行安全的仅次于空间定向障碍的主要因素.本文回顾了G-LOC生理监测的指标、方法和手段,分析了飞机机动状态、生理指标、头部位置和眨眼等相结合的意识丧失系统监测方案. 结论 目前为止,尚没有实际应用的综合监测方法和机载G-LOC监测系统;生理指标和飞机机动状态相结合的综合评估是G-LOC监测的发展趋势.     

EXPERIMENTAL STUDY AND CLINICAL OBSERVATION ON CHANGES OF β-ENDORPHIN AFTER HEAD INJURY

ＥＸＰＥＲＩＭＥＮＴＡＬＳＴＵＤＹＡＮＤＣＬＩＮＩＣＡＬＯＢＳＥＲＶＡＴＩＯＮＯＮＣＨＡＮＧＥＳＯＦβ┐ＥＮＤＯＲＰＨＩＮＡＦＴＥＲＨＥＡＤＩＮＪＵＲＹＺＨＡＮＧＧｕａｎｇ－ｊｉ（张光霁），ＺＨＵＣｈｅｎｇ（朱诚），ＪＩＡＮＧＪｉ－ｙａｏ（江基尧），...     

INTRADURAL HERNIATION OF LUMBAR INTERVERTEBRAL DISC：ARE－PORTOFSEVENCASESANDDISCUSSIONOFTHEPATHOLOGICALMEC

ＩＮＴＲＡＤＵＲＡＬＨＥＲＮＩＡＴＩＯＮＯＦＬＵＭＢＡＲＩＮＴＥＲＶＥＲＴＥＢＲＡＬＤＩＳＣ：ＡＲＥ－ＰＯＲＴＯＦＳＥＶＥＮＣＡＳＥＳＡＮＤＤＩＳＣＵＳＳＩＯＮＯＦＴＨＥＰＡＴＨＯＬＯＧＩＣＡＬＭＥＣＨ－ＡＮＩＳＭＬｉａｎＰｉｎｇ连平ＳｕｎＲｏｎｇ－...     

Performance and physiological effects of acceleration-induced (+ Gz) loss of consciousness

Loss of consciousness (LOC) was intentionally induced by exposing eight volunteers to individually-titrated levels of head-to-foot acceleration (+ Gz) using 2- and 4-s onset rates (mean = 6.1 + Gz required to induce LOC) and a gradual, .067 G X s-1 onset rate (mean = 7.2 Gz required). Subjects were trained over a prior 2-week period on a multitask battery comprising three simultaneously executed tasks representative of those required in piloting, and then centrifuged to LOC at each of the three onset rates on alternate days. Performance was assessed for 5 min prior and 7 min after each LOC. Primary results indicated: a) significant and substantial impairment in the two discrete response secondary tasks (choice reaction time and arithmetic computation), with mean recovery to pre-LOC levels within 3 min on each task, b) no group mean impairment for the primary, compensatory tracking task, c) substantial individual variation in physiologically and behaviorally defined recovery from LOC, d) a negative influence of aerobic fitness on G tolerance and LOC recoverability, and e) that recovery effects were not generally dependent upon onset rate. Mean absolute incapacitation (head dropped) for the rapid onset rates was 12.1 s. For the gradual onset rate, mean absolute incapacitation was 16.6 s. Mean relative incapacitation (head erect, no voluntary task engagement) for the rapid onset rates was 11.6 s; for the gradual onset rates, mean relative incapacitation was 15.7 s. Evidence for retrograde amnesia effects was equivocal.     

Recovery from Gz-induced loss of consciousness: psychophysiologic considerations

Eight healthy male volunteer members of the USAFSAM acceleration panel were exposed to two consecutive acceleration runs of +1 Gz to +7 Gz at 6 G.s-1 onset rates. The subjects were instructed to relax during the acceleration exposure in order to voluntarily induce loss of consciousness (LOC). The subjects were asked to relate dreams, thoughts, or other mental illusions experienced during G-LOC episodes. Most subjects were amused and surprised, as well as interested in, relating their experience, although they were embarrassed about the G-LOC episode itself. Early post-G-LOC transient paralysis, as well as late LOC myoclonic (flailing) movements, were evident. Heart-rate response to the acceleratory stress was uneventful; maximum heart rate occurred 3.2 s after the onset of LOC. The study of dreams during normal sleep stages has been reviewed by many investigators, but this research has not extended to acceleration/hypoxic types of unconsciousness where dreams also seem to occur. G-LOC dream-state analysis, post-G-LOC paralysis, and their possible repercussions upon performance and incapacitation periods should be investigated, not only as curious events, but as operationally important and psychophysiologically significant.     

Concurrent loss of consciousness and sino-atrial block during +Gz stress.

Current USAF fighter aircraft easily exceed human physiologic limits with their rapid onset of head-to-foot acceleration forces (+Gz). Sudden in-flight incapacitation caused by these increased +Gz forces could be disastrous with loss of materiel and human life. The physiologic mechanisms responsible for loss of consciousness (LOC) secondary to high +Gz must be fully understood so that maximum protection against it can be provided. An interesting case of an episode of LOC with concurrent sino-atrial block occurring during a relaxed rapid onset (1 G/s) centrifuge run is presented. The patient was undergoing flight medical evaluation for an episode of syncope, etiology unknown. An unusual characteristic of the patient was his high level of endurance training. The possibility of an excessive increase in vagal tone, developed by endurance training, is discussed as a probable etiology for this patient's prolonged time of incapacitation evidenced after +Gz-induced loss of consciousness.     

Physiological implications of mechanical effects of +Gz accelerations on brain structures

BACKGROUND: In certain flight configurations, fighter pilots are exposed to high Gz acceleration (G) which may induce inflight loss of consciousness (G-LOC). When acceleration is of high amplitude, and the onset rate very rapid, G-LOC can occur extremely suddenly. HYPOTHESIS: Mechanisms other than brain hypoxia could be involved, enhancing its effects. In order to study the mechanical effects induced by such accelerations on cerebral structures, we estimated the stresses imposed on cerebral tissue when the brain is exposed to +Gz acceleration forces. METHODS: An "in vitro" experiment was performed to measure brain deformations during centrifugation. A finite element model of the brain was formulated. RESULTS: Computations indicate that traction and shear stresses are enhanced around the tentorial notch, and that compression stresses increase at the base of the cerebral hemispheres. CONCLUSION: The amplitude of these stresses is not sufficient to directly disturb proper nerve cell functioning. However, they could interfere with brain vessels as external surface forces, thus enhancing vessel collapse and brain ischemia.     

Acceleration in other axes affects +Gz tolerance: dynamic centrifuge simulation of agile flight

BACKGROUND: Modern, thrust-vectored jet aircraft have the capability of developing multi-axis accelerations, especially during the performance of "supermaneuvers." These "agile" aircraft are capable of unconventional flight. The human consequences of this agile flight environment are unknown. METHODS: This multi-axis acceleration environment was studied on the Dynamic Environment Simulator gimbaled centrifuge. There were nine relaxed, unprotected subjects who were exposed to either lateral (+/- 1, +/- 2 Gy), transverse chest-to-back (+1, 2.5, or 4 Gx), or back-to-chest (-1 Gx) sustained acceleration. Positive C (+Gz) acceleration was then added beginning at 1.0 Gz by gradual onset (0.1 Gz x s(-1)) until the subjects lost nearly all of their vision. Baseline +Gz-only relaxed tolerances were measured before and after all combined Gy/Gz and Gx/Gz exposures. Heart rate, percent cerebral oxygen saturation, and cerebral blood volumes were collected during each exposure. RESULTS: Adding moderate transverse (+Gx) acceleration significantly reduced +Gz tolerance. Relaxed, unprotected +Gz tolerance was reduced approximately 0.25 G when 1.0 or 2.5 Gx was added to the increasing +Gz exposure. Adding moderate lateral Gy significantly increased +Gz tolerance. Relaxed, unprotected +Gz tolerance was increased approximately 0.5 G when +2 Gy or -2 Gy was added to the -Gz exposure. The decrease in cerebral blood volume was significantly less when +Gz was added to -1 Gx compared with the addition of +Gz to +Gx. CONCLUSIONS: Multi-axis sustained accelerations, such as those experienced during thrust-vectored aircraft maneuvers, can either enhance or reduce the +Gz tolerance of the pilot depending on the direction of the net gravitoinertial force. Gy acceleration in conjunction with Gz acceleration can enhance G tolerance. Gx acceleration in addition to Gz acceleration can reduce G tolerance.     

Anti-G training of Japanese Air Self Defense Force fighter pilots

Recently developed high-performance fighter aircraft (HPF) are capable of producing high sustained +Gz (HSG) with a rapid onset rate. This G-producing capability is now beyond human physiologic G tolerance. Many techniques to raise the tolerance to HSG have been used operationally. In order to cope with HSG effectively, the Japanese Air Self Defense Force has given high-G training for certain fighter pilots since 1982. So far, 138 pilots (62 F-15 Trainees, 76 F-4 Trainees) have completed centrifuge training at our laboratory. The 1-week program consists of: physical examination and briefing on high-G stress and its protective methods on day 1; centrifuge rides in two basic patterns--a tracking performance and a simulated aerial combat maneuver (SACM)--during the period from day 2-5; and debriefing and questionnaires on day 6. Gradual onset run (GOR) relaxed tolerance is + 5.5 +/- 0.7 Gz and rapid onset run (ROR) relaxed tolerance is + 4.9 +/- 0.6 Gz (n = 126). The difference in G tolerance between F-15 and F-4 trainees was not significant in either GOR or ROR. Loss of consciousness (LOC) occurred in 18 F-15 trainees and 15 F-4 trainees during basic patterns but all F-15 trainees met the training goal and completed the SACM pattern on day 5 without LOC. More than half of the trainees developed a variety of arrhythmias, including PVC, SVPC, A-V dissociation, S-A block, and atrial fibrillation (AF). The AF case developed WPW syndrome and atrial fibrillation followed by LOC during a 4-G warm-up pattern.(ABSTRACT TRUNCATED AT 250 WORDS)     

A near-infrared spectrophotometric method for studying brain O2 sufficiency in man during +Gz acceleration

A technique for the noninvasive monitoring of cerebral oxygen status was evaluated on volunteer subjects on the USAF School of Aerospace Medicine centrifuge. By using multiwavelength near-infrared spectrophotometry, the instrumentation measured changes in the quantities of reduced and oxygenated hemoglobin (and their sum, an indicator of cerebral blood volume), and the quantity of oxidized cytochrome c oxidase within the forebrain. Tests used acceleration of up to 9 G with onset rates from 0.1 to 5.0 G.s-1, anti-G suits and straining maneuvers, and hyperoxic and hypoxic breathing mixtures. In general, +Gz acceleration produced a fall in blood volume within the cerebral microcirculation with a relative increase in the content of reduced hemoglobin and a tendency towards reduction of cytochrome c oxidase. These findings are discussed in relation to accepted changes in arterial blood pressure, cerebral blood flow, and arterial oxygen saturation caused by acceleration exposure.     

葛胺酮对在体和离体动物脑动脉舒张作用的研究

目的研究葛胺酮对在体和离体动物脑动脉的舒张作用。方法在体实验采用激光多普勒血流仪,连续动态观察葛胺酮对正常大鼠脑血流灌注压、血压(收缩压、舒张压、平均动脉压)、心率、心电图指标的的影响。体外实验采用分离犬基底动脉条,分别以重酒石酸去甲肾上腺素(5 mg·L-1),KCl(3 mol·L-1),5-羟色胺(3.3 mg·L-1)收缩效应的百分率作为评价抑制强度的指标,研究葛胺酮对基底动脉的舒张作用强度及特点。结果在体实验观察到葛胺酮25、50、100 mg·kg-1对大鼠脑血流量灌注压均有增加作用,100 mg·kg-1组比给药前脑血流增加了2～3倍。葛胺酮在增加脑血流量的同时对收缩压、舒张压均有短暂的降压作用,舒张压下降幅度大于收缩压,平均血压下降了10～40 mmHg。体外实验发现葛胺酮0.01、0.1 mg·ml-1对重酒石酸去甲肾上腺素、KCl、5-羟色胺诱导的犬基底动脉收缩均有明显的抑制作用,其舒张率达21%～99%。结论葛胺酮具有增加脑血流量同时降低血压的作用,优于葛根素。其增加脑血流量的作用与其舒张动脉的作用有关。葛胺酮可能是一个多靶点的血管紧张抑制剂,对脑缺血可能具有一定的保护作用,值得进一步研究。     

凝血功能检测对脑出血患者的预后判断价值

目的探讨凝血功能检测对脑出血患者的预后判断价值。方法对2005年1月～2011年1月收治的89例脑出血患者进行不同时间段、多个凝血功能指标检测,分析检测结果与患者预后的关系。结果在内皮素-1（ET-1）、抗凝血酶Ⅲ（AT-Ⅲ）、纤溶酶原激活剂抑制物-1（PAI-1）、血栓调节蛋白（TM）以及D-二聚体等5个凝血功能指标上,37例患者变化明显（观察组）,52例患者变化不明显（对照组）;两组凝血功能指标变化比较,在发病48 h后均已有统计学差异（P〈0.05）,观察组除AT-Ⅲ明显降低外,其他指标明显异常升高;观察组治疗良好率明显低于对照组（P〈0.01）,病残率高于观察组（P〈0.01）;观察组有8例死亡,而对照组无死亡病例。结论脑出血患者凝血功能指标变化显著者的预后较差;对脑出血患者进行凝血功能检测,有助于判断患者预后。     

加速度暴露下的心律失常及其航空医学意义

目的 探讨正加速度（＋Gz)作用下心血管自主神经调节与心律失常及G耐力的关系。方法 对36名立位耐力不良和62名健康飞行员＋Gz作用下的ECG及动态心电图进行对比分析。结果 ＋Gz作用下,立位耐力不良者心律失常发生率高,＋Gz耐力低。结论 ＋Gz作用下的心律失常可以作为评价心血管代偿功能及G致意识丧失（G－LOG）的预警指标。