Objective To establish the evaluation and assessment system for the construction of medical selection system of Air Force flying cadets and to provide references for improving the theory of Air Force cadets selection system and the work efficiency of medical service organization.Methods The assessment essential indexes were screened and defined by literature review,on site investigation and systemic analysis,and the evaluation index system framework was built then.With the principle of compromising the composition of the specialists and their familiarity with medical selection of military flying cadets,22 specialists,including 19 senior professionals and 3 official staffs,were selected to complete questionnaire and analytic hierarchy process (AHP).Three rounds of questionnaire investigation were carried out in accordance with the rule of Delphi consultation and each round lasted for 25 to 35 d.The framework of index system of medical selection system of Air Force flying cadets was revised upon specialists' feedback and scores and the evaluation and assessment system and weight of index at each level of the system were determined.Results ①One hundred and thirty-nine questionnaires were issued.The recovery rate was 90.65％ and the available rate was 89.68％.Since middle and late 1980s,China's medical selection system of military flying cadets has developed rapidly,but such inefficiencies as low management efficiency,imperfect system,unreasonable specialist team composition and outdated equipment were still there.②The recovery rate of 3 rounds questionnaire was 90.9％,95.0％ and 94.7％ respectively and the harmonious coefficient was 0.543,0.706 and 0.799.The specialists' feedbacks showed unisonous reliability (χ2 =39.08,50.82,57.53,P＜0.01).③The determined construction of medical selection system of Air Force flying cadets included 5 primary indexes,13 secondary indexes and 35 third class indexes.The primary indexes were the organization construction,system construction,team construction,equipment construction and business construction correspondingly with the weight of 0.162,0.172,0.400,0.184 and 0.082.The final weight of index passed the coincidence test (CR ＜ 0.1).Conclusions This study builds an index system to evaluate the construction of medical selection system of Air Force flying cadets.The result of this study can provide the theoretical support and reference to the evaluation of the construction of medical selection system of Air Force flying cadets.

Background: This study explores the responses of the cardiovascular system as humans exercise in an oxygen-enriched room at high altitude under various concentrations of CO2. Methods: The study utilized a hypobaric chamber set to the following specifications: 3800 m altitude with 25% O-2 and different CO2 concentrations of 0.5% (C1), 3.0% (C2) and 5.0% (C3). Subjects exercised for 3 min three times, separated by 30 min resting periods in the above-mentioned conditions, at sea level (SL) and at 3800 m altitude (HA). The changes of heart rate variability, heart rate and blood pressure were analyzed. Results: Total power (TP) and high frequency power (HF) decreased notably during post-exercise at HA. HF increased prominently earlier the post-exercise period at 3800 m altitude with 25% O-2 and 5.0% CO2 (C3), while low frequency power (LF) changed barely in all tests. The ratios of LF/HF were significantly higher during post-exercise in HA, and lower after high intensity exercise in C3. Heart rate and systolic blood pressure increased significantly in HA and C3. Conclusions: Parasympathetic activity dominated in cardiac autonomic modulation, and heart rate and blood pressure increased significantly after high intensity exercise in C3.

人体对高原缺氧环境的耐受能力有明显个体差异,研究表明个体差异除家族遗传性因素以外,还与个体的年龄、性别、体型、身体状况、心肺功能、体内激素和酶活性、心理因素以及吸烟等生活习性相关[1-8].世居平原地区人群进入高原地区工作生活,由于缺氧会引起急性高原反应(acute mountain sickness,AMS),严重影响作业能力,严重者更有可能发生危及生命安全的并发症[5].因此在进入高原地区前,筛选出AMS易感者加以针对性的训练或进入高原地区后给予重点关注,对减轻AMS反应程度、保持作业能力具有重要的意义.

Objective To dynamically observe characteristics and rules of the incidence of central sleep apnea (CSA) of the personnel who rushed to plateau with different ways,as well as preliminarily explore the correlation between the incidence of CSA and the changes of distinctive indexes for the subjects exposing in high altitude environment.Methods Twelve healthy subjects,who rushed to 3800 m plateau and stationed there under hypoxia environment for 48 d,were averagely divided into pre-acclimatization group,oxygen-supply group and control group.Pre-acclimatization group was experienced stepped altitude climbing training in hypobaric chamber 210 min a day for 10 days before entering plateau.Oxygen-supply group was implemented progressive hypoxic exposures in the first 10 d of entering plateau.Control group entered and stationed in plateau without any acclimatization training or extra oxygen supplement.The CSA episode of subjects was monitored by micro-movement sensitive mattress sleep measurement system and their blood red cell and blood hemoglobin were detected.Results ①During the 48 d exposure,CSA index of 12 subjects gradually raised and the maximal of CSA index was appeared on the 18th day (9.62 times/h) and declined to 2.72 times/h on the 48th day.The incidence of CSA was continuously increased and reached peak (41.67％) on the 16th day,then decreased to 8.33％ on the 48th day.②In the first 10 d,the incidence of CSA in the preacclimatization and oxygen groups was significantly lower than that in control group (x2 =12.984,12.984,P＜0.01).Moreover,the average value of CAS index in pre-acclimatization and oxygen group was lower than 1 time/h while control group's was higher than that.③The correlations between CSA index and variation ratio of blood red cell count and hemoglobin concentration were positive (r=0.747,0.934,P＜0.01).Conclusions Stepped exposing to hypoxia can significantly improve subject＇ s sleep quality.CSA index can be used as an indicator to evaluate hypoxia acclimatization or severity of chronic mountain sickness.

Objective To study the effects of autonomic nervous biofeedback training on heart rate variabitity (HRV) and blood pressure of the military personnel stationed on plateau and to supply them with psychological support.Methods Seventy-one male military personnel (average age:27.6±6.5 yr) were selected as subjects.They were stationed on plateau of 3780 m for 60 d.Autonomic nervous biofeedback training that combined deep breath with HRV biofeedback was performed on them.HR,HRV and blood pressure of subjects were collected at sitting state and biofeedback state.Only 47 subjects' blood pressures were collected becauseof experimental condition limitation.Results ①Mean heart rate under autonomic nervous biofeedback state was significantly lower than that under sitting state (t=2.010,P＜0.05).Subjects' standard deviation of HRV in N-N interval and low frequency under autonomic nervous biofeedback state were significantly higher than those under sitting state (t 3.700,5.401,P＜0.01).②Ratio of diastolic pressure higher than 90 mm Hg was 31.91％under sitting state.Both systolic pressure and diastolic pressure under biofeedback state were significantly lower than those under sitting state (t=4.062,7.632,P＜0.01).The level of blood pressure was positively correlated to age under both states (r=0.363-0.605,P ＜ 0.05).Conclusions Autonomic nervous biofeedback training can reduce heart rate and blood pressure,but increase HRV of the subjects on plateau.It is suggested to strengthen psychological support for the military personnel stationed on plateau because of its benefits on moderating the hypoxia effects on physiology and improving mental state.

Objective To develop a normobaric hypoxic chamber for hypoxia experiment and hypoxic acclimatization training before entering the plateau. Methods A nitrogen generator was used to lower the oxygen concentration from original20.9% to the desired concentration. A gas exchange model in the chamber was established to control the concentrations of CO2 and O2. Results The chamber had a size of 5 m×3 m×2.3 m, and the simulated altitudes from 0 m to 800 m with an error of 25 m or so, which could hold 10 persons for hypoxia experiment or 4 ones for sleep experiment in hypoxia condition with CO2 concentration not more than 3 000 ×10-6. Conclusion The normobaric hypoxic chamber is safe and convenient, and thus may be worth popularizing in plateau hypoxia experiment.

Objective To study on the improvement of cognitive performance in mental fatigue state through biofeedback relaxation at 3780m altitude.Methods Experiments were conducted in 12 male testees who have stayed at 3780 m altitude for 50 d.Mental fatigue state was induced by 90 min successional simulative flight.Then in experiment 1,cognitive performance including multi-task performance,memory scanning,visual reaction time,visual choice reaction time and target tracting were tested after 15min rest.In experiment 2,cognitive performance were tested after 15min biofeedback relaxation.Results In experiment 2,cognitive performance including multi-task performance,visual choice reaction time and memory scanning ((73.28 ± 16.29) scores,(0.54 ± 0.11) s,(0.50 ± 0.12) s,respectively) were significantly better than those in experiment 1 ((68.66 ± 13.14) scores,(0.60 ± 0.13) s,(0.63 ± 0.17) s,respectively) (P ＜ 0.05).Conclusion Biofeedback relaxation can improve cognitive performance in mental fatigue state at 3780m altitude.

Objective To investigate the effects of plateau flight on physiological parameters and flight workload of high performance fighter pilots.Methods Thirteen healthy male highperformance fighter pilots entered plateau in 2 batches,8 pilots stationed for 3 months and the others stationed for 1 week.Pilots' heart rate was tested before flight and compared with the referenced value that previously tested at normal altitude level.Pilots＇ physiological parameters were detected for 25 sorties that covered 4 flight conditions (patrol,air combat,night flight,virgin flight on plateau).The changes of heart rate and respiratory rate were analyzed.Results ① Pilots' heart rate detected before flight was significant higher than the referenced value (t=5.447,3.269,P＜0.05).②Heart rate significantly varied in different flight phases and among different flight conditions (F=9.831-204.906,P＜0.01).Pilots' heart rate in preparation,taxiing and taking-off,approaching and landing phases was significant higher than that in level flying phase (P＜0.01).Condition 4 (virgin flight on plateau) caused higher heart rate than that in other flight conditions in all phases except in quiet (P＜0.01).③There was significant difference on respiratory rate in different flight phases and conditions (F=1.971-140.035,P＜0.01).Pilots＇ respiratory rate in the landing of condition 2,3 and 4 was much higher than that in condition 1.Pilots' respiratory rate in all phases of flight condition 4 was the highest (P＜0.05 or 0.01).④Pilots' heart rate significantly reduced when backup oxygen supplied in landing and the mean decrease was (15.89±6.37) beat/min (t=5.580,P＜0.01).Conclusions For the pilots stationed on plateau the physiological and flight workloads are much higher than theirs on plain.It is recommended that keeping pilots mask wearing and backup oxygen supply in landing would be beneficial to reduce the cardio-pulmonary loads caused by hypoxia.

航空救生是指航空器在飞行中发生严重故障、损毁或飞行人员身体发生意外等情况时,飞行人员离机、降落、求生和营救的全过程[1].目的是保障飞行人员安全,保持部队战斗能力,对鼓舞部队士气具有重要作用.由于高原环境恶劣、人烟稀少以及地形复杂,给遇险飞行人员的生存、搜索和营救带来了更大的困难.为迅速营救,提高航空救生的成功率,必须根据高原航空救生的特点及需求,建设和完善高原航空救生体系,包括:高效的组织指挥、合理的救生流程、优良的救生装备、专业的施救人员以及针对性的训练等.

Objective To investigate the effects of transcranial micro-electric current physiological training (TMCPT) on cerebral function (CF) in order to provide technology and methods for maintaining and training CF under altitude hypoxia.Methods Forty healthy volunteers served as subjects,who took flight to the altitude and were trained by TMCPT in the condition of altitude hypoxia (3700 m above sea level).Current intensity of TMCPT was limited within safety physiological range.Subjects were trained 2 times per day (one in the morning and the other in the afternoon) and each lasted 5 min.Neurobehavioral ability index (NAI) were respectively observed in rush entry phase (first 10 days after entry) and in various resident phases (resided in plateau for 1,2,3 months respectively).Self-evaluating questionnaire and Pittsburgh sleep quality index were investigated to evaluate the sleep quality in different phases.Results ① In rush entry phase:the subjects' digit scan (DS),memory scan (MS),simple visual reaction time (SVRT),complex visual reaction time (CVRT),pursuit aiming (PA) and consecutive performance (CP) were significantly increased by 10-d TMCPT training (t=1.982 4.412,P＜0.05) as compared with those of the 1st day.②Resident phase:compared to the NAI in 1st month,only subjects' DS,MS,SVRT out of 6 NAIs were significantly increased by 3-month TMCPT training (t=3.744 5.812,P＜0.05) as compared with those of the 1st month.③ Sleep quality evaluation:subjects' sleep quality indexes had significant reduction as compared with those in rush entry phase (t =1.833-3.552,P ＜ 0.05).Conclusions TMCPT can improve CF and sleep quality under altitude hypoxia.It＇s suggested that to take β frequency brain wave feedback training to promote CF,and to take α frequency brain wave feedback training to improve sleep quality.

Objective To compare the acclimatization effects of progressively intermittent hypoxia training before entering plateau,progressive hypoxia exposure after entering plateau and natural acclimatization.Methods Twelve healthy subjects were averagely divided into training group,oxygensupply group and control group according to different plateau entering methods.Training group ascended to the simulated high altitude in a normal hypobaric chamber 210 min a day for 10 days before entering plateau,and the altitude was progressively varied from 3000 m to 4500 m.Oxygen-supply group was implemented progressive hypoxic exposures in the first 10 days of entering plateau.The gas dispersion (O2 concentration:22 ％-25 ％,physiological equivalent height:2600-3500 m) was respectively applied in dormitory during the daytime and in the oxygen fed sleep tent (O2 concentration:25％-27％,physiological equivalent height:2000-2600 m) at night.Control group entered and stationed in plateau with natural acclimatization.The arterial oxygen saturation (SaO2) and sleep condition were compared among 3 groups.Results ①Compared with that before training,the SaO2 of training group was significantly increased at simulated 3600 m by 10 day training (t=3.66,P=0.035).②There were significant differences on total sleep time,deep sleep time and SaO2 among 3 groups (F=16.253-70.865,P＜0.01).For the first 10 d of entry the total sleep time,deep sleep time and SaO2 of training group and oxygen-supply group were significantly higher than those of control group (t=2.22-7.88,P＜0.05 or P＜0.01).Conclmions Both ways of progressively intermittent hypoxia training before entering plateau and progressive hypoxia exposures after entering plateau can increase person's hypoxia intolerance and improve altitude acclimatization.

Objective To investigate the method of oxygen-supply for oxygen-enriched rooms on plateau for the pilots and to provide evidences for conducting oxygen-enriched room construction and the proper application.Methods Mathematical models of oxygen-enriched rooms were created according to the oxygen concentration varying with time in pilot room and physical exercise training room,and were verified by tests.Eight volunteers entered 3780 m plateau on flight,and were averagely divided into control group and oxygen-supply group according to the number table.Four volunteers of oxygen-supply group lived in oxygen-enriched room during 22:00 to 8:00 next day (successive oxygen supplied with the concentration of 24％-27 ％ for 8 d) while 4 volunteers of control group exposed in natural oxygen environment of pilot room and physical exercise training room.Their data were monitored for 8 d.Heart rate and arterial oxygen saturation of the volunteers in 2 groups were observed.Results The measured oxygen concentrations in pilot room and physical exercise training room had positive correlation to those calculated by mathematical model (r=0.986,0.998,P=0.000).Heart rate of oxygen-supply group was significantly lower than that of control group (F=13.067,P=0.011).Arterial oxygen saturation of oxygen-supply group was significantly higher than that of control group (F =102.885,P =0.000).Conclusions Setting up the mathematical models with the variable of oxygen concentration would be helpful in building oxygen-enriched rooms at high altitude.Oxygen supply for pilot room and physical exercise training room should be in different ways.The physiological equivalent height is proposed lower than 3000 m concerning the oxygen supply in pilot room.

高原地区气候寒冷,海拔5000 m左右的高原地区气温比同纬度海平面低30℃左右.因此,寒冷成为飞行人员高原遇险生存中除缺氧、低气压之外威胁生命的一项主要因素.开展飞行人员高原防寒睡袋研究显得尤为重要.歼击机飞行员遇险生存所需的所有物品都存放在弹射座椅椅盆中,因此睡袋的设计除要考虑到足够的保暖量和防风因素之外,还必须考虑到自身包装体积和重量等因素.飞行人员救生防寒睡袋受限于包装体积的要求,保暖量仅为1.5 clo左右[1],因此要提高飞行人员高原遇险生存过程中抵御寒冷的能力,改善飞行人员救生防寒睡袋的保暖效果,就必须从改进制造材料人手. 关键词：高海拔(Altitude);防护装置(Protective devices);冷(Cold) 分类号：R852.81

Objective To investigate the significance of anti-G physical training on keeping + Gz tolerance of the subjects in plateau.Methods Twelve male healthy volunteers were divided into control group (n=6) and training group (n=6).At 3780 m altitude,the training group subjects were trained according to the designed training program in oxygen enriched room (oxygen concentration:25 ％-27 ％) and the control group subjects were not trained.The subjects' HP maneuver +Gz tolerance was measured with the equipment to test their anti-G and anti-hypoxia capabilities at the 2nd,4th and 6th week after entering plateau.Before entering plateau and after withdrawing,the relaxed and HP maneuver + Gz tolerances of the subjects were determined with human centrifuge.Results ① During 6 week training in plateau,the advancement of HP maneuver +Gz tolerance of control group showed continuously decreased tendency,and +Gz tolerance at 6th week was significantly lower than that at 2nd week (P=0.009).There was no statistical difference of.HP maneuver +Gz tolerance advancement among that at 2nd,4th and 6th week in the training group.The advancement variation of HP maneuver + Gz tolerance was significantly different between control group and training group (t=3.059,P=0.012).②Compared with that before entering plateau,the relaxed centrifuge-test +Gz tolerance of subjects in 2 groups was slightly decreased as they were in plateau.Compared with that before entering plateau,centrifuge-test HP maneuver enhanced +Gztolerance of control group was significantly decreased after entering plateau (t =5.196,P =0.014),while that of training group after entering plateau was significantly increased (t=2.712,P 0.042).Variation on HP maneuver enhanced + Gz tolerances before and after entering plateau had significant difference between 2groups (t=3.480,P=0.008).Conclusions Such anti G physical training measures as choosing proper training items and intensity,exercising in oxygen-enriched environment,while trainings were mainly on strength and were supplemented by endurance,would effectively keep pilot's +Gz tolerance in plateau.

Objective To investigate the establishment of evaluation and assessment system for Chinese Air Force aeromedical evacuation (AE) system and to provide references for constructing AE system and capability assessment. Method The assessment essential indexes of AE were screened and defined by literature review,on site investigation and systemic analysis,and the evaluation index system framework was built then.For determining the evaluation and assessment system and weight of index at each level of the system Delphi based questionnaire was inquired from 21 specialists and analytic hierarchy process (AHP) was applied. Results Upon 3 rounds of questionnaire investigation,the harmonious coefficient was 0.512,0.761 and 0.874 respectively,corresponding to 90.5％,94.7％ and 100.0％ questionnaire response.The x2 test of harmonious coefficient showed statistically significant (P ＜ 0.01). The determined Air Force AE capability assessment system included 5 primary indexes,12 secondary indexes and 36 third class indexes. Among which the primary were the indexes of organization and commanding,supporting,equipment,training and regulation correspondingly with the weight of 0.1309,0.3041,0.3860,0.1186 and 0.0607.The final weight of index passed the coincidence test (CR＜0.1). Conclusion Based on the current status of Air Force AE,it is suggested that to pay more emphasis on the all-around construction of AE system and comprehensive capability assessment but only focus on the improvement of personnel's accomplishment and medical abilities,in order to let the evaluation and assessment system more applicable.