高气压环境对红外二氧化碳传感器检测的影响

目的 在失事潜艇及加压舱内等高气压环境下二氧化碳气体浓度的检测要求传感器具备高准确度、灵敏度和高响应速度.高压下常规二氧化碳传感器存在失效或响应失真的问题,只能在减压后间接检测.高压下二氧化碳实时检测,需要探索高气压环境对二氧化碳传感器的影响规律.方法 选取红外二氧化碳传感器作为试验对象,对其元器件进行压力可靠性试验,并利用小型动物加压舱构建一个校准系统,通过理想气体状态方程推算实际气体浓度,对传感器高压下响应曲线进行测定.结果 试验结果表明,在浓度不变的情况下,随着环境静压力的升高,传感器输出电压总体表现出偏小趋势.这种偏差在压力大于20 m后表现得较为明显.结论 在浓度不变的情况下,传感器输出电压随着环境压力的升高而出现的变化可能是由于气体吸收率受压力影响改变而引起的.     

高压氧舱内应用容量型输液泵的安全性和准确性研究

目的:观察高压氧舱内气压变化对容量型输液泵使用安全性和泵速准确性的影响。方法:在高气压(表压0～0.10 MPa)和常压(北京地区大气压力)环境下,使用容量型输液泵泵速实时监测系统,测定输液泵设定流量为50、100 ml/h时的瞬时流量和平均流量,每种流量重复测定7次。观察容量型输液泵在高气压环境下(表压0～0.10 ...     

潜水员在100～800kPa气压下呼吸不同气体时肺呼吸功能的变化(论著)

目的：探讨在高气压下呼吸不同气体介质对肺呼吸功能的影响。方法：用日本产ＬＡＭ—２５型电子呼吸分析仪以及配套的ＲＶＳ—４０９Ａ型Ｘ—Ｙ记录仪，检测６名海军职业潜水员在绝对压１００～８００ｋＰａ气压下呼吸不同气体介质时多种呼吸功能指标。结果：随着暴露压力的增高，最大通气量（ＭＶＶ）、时间肺活量（ＴＶＣ）、最大呼气流量（ＰＥＦ）显著降低；用力肺活量（ＦＶＣ）则逐渐增加。在相同压力下，各项指标的变化程度，呼吸压缩空气比呼吸氦氧混合气更为显著。不同个体之间各项指标的变化程度存在较大差异。结论：呼吸压缩空气对呼吸功能的影响明显高于呼吸氦氧混合气，个别潜水员与其他潜水员相比，呼吸功能的变化程度存在显著差异（Ｐ＜０．０５）。作者建议不要让对高气压敏感的人从事潜水员工作     

热球式气体小流量传感器的研制

本文阐述了一种专为某卫星压力控制系统研制的新型气体小流量传感器。该传感器是一种质量流量传感器,采用热式测量中的旁热式换能原理,在被测气体介质的温度和压力波动的条件下,可以直接测定气体的标准流量,不需要进行温度和压力修正。与国内同量程的气体流量计相比,这种传感器具有体积小、重量轻、设计新颖、反应灵敏、精度高、压力损失小等重要特点。本文简述了传感器的原理和结构特点,列举了试验项目和数据分析结果。通过实际地面试验和飞行考验证明,该传感器各项性能指标均达到设计要求,是一种理想的气体小流量传感器。     

氦氧暴露对潜水员最大握力和手眼协调能力的影响

目的 研究0～2.5 Mpa氦氧暴露对潜水员最大握力和手眼协调能力作业绩效影响.方法 采用握力计测试不同压力环境中潜水员的左右手握力,徒手使用棉质线穿纽扣孔的方法测试不同压力环境中潜水员的手眼协调能力,对结果采用重复测量方差分析.结果 结果0～2.5MPa高气压环境动态地降低了氦氧暴露条件下潜水员的左右手最大握力和手眼...     

模拟沉箱作业环境对人体心电的影响

<正>随着社会发展,地铁、桥梁、涵洞等工程建设越来越多,需要进行大量的沉箱作业。沉箱作业时人体处于空气加压所致的高气压环境,压力往往超过0.2 MPa,作业人员呼吸的是高气压空气,返回时也需要按照一定减压方案以保证安全。这种异常环境将对人体生理指标产生影响,研究人员在沉箱环境中的生理变化,对保障作业安全具有重要的意义。本次试验是对某建筑单位工人进行沉箱作业耐受性测试,研究沉箱作业环境对人体心电的影响。     

Method for Measuring Respiratory Mechanics Parameters and Implementing it Under Weightlessness Condition

目的 研究失重情况下的航天员呼吸运动,准确获取其呼吸力学参数.方法 在对国内外相关研究成果进行调研的基础上,提出基于气体流量传感器和压力传感器的呼吸力学参数检测方法.结果 设计并完成了硬件电路与软件编写.采用三次拟合法对标定数据进行曲线拟合,所得气体流量拟合的相关系数达到0.99,而压力拟合的相关系数达到0.995.对硬件电路测试,测得最大相对误差小于1％.经实验结果分析得出系统最大相对误差仅为4％,且结果稳定性良好,符合系统的要求,且实现了测试设备的小型化.结论 样机具有良好的稳定性和精度,参数实时显示.     

高气压暴露对心脏功能影响的研究进展

随着高压氧治疗的广泛应用、娱乐潜水的逐渐普及,以及水下沉箱作业、饱和潜水技术的深入发展,人类在高气压环境中从事的活动越来越多,高气压暴露时,高静水压、高分压氧、高密度的呼吸气体都会对人类心脏功能有一定的影响.本文结合国内外相关研究结果,从心脏电生理、心脏血流动力学、心脏内分泌等方面,分析高气压暴露对心脏功能的实际影响及其可能机制.     

高压氧干预对颈动脉弹性影响的定量评价

目的 应用回声跟踪( echo tracking,ET)技术对受试者双侧颈动脉参数进行分析,定量评价高压氧干预对颈动脉弹性的影响.方法 41例行高压氧治疗的患者为高压氧组,20名健康者为高气压组,另20名健康者为高流量组.前2组于进舱前及出舱后即刻、高流量组于吸氧前及吸氧后即刻,应用ET对双侧颈动脉弹性进行检测,检测参数包括血管的压力-应变弹性系数(Ep)、硬化参数(β)及血管顺应性(AC).结果 高压氧组干预后Ep[(112.38±50.94)kPa]及β值(8.29±3.66)较干预前均减小(129.04±52.4)kPa,(9,75±3.83),AC值增大[干预前(0.86±0.34) mm2/kPa,干预后(0.99±0.45)mm2/kpa],差异均有统计学意义(P＜0.01),高气压组干预后β及Ep较值进舱前减小,AC值较进舱前增加,差异均有统计学意义(P＜0.01或P＜0.05);高流量组吸氧前后Ep、β及AC值差异均无统计学意义(P＞0.05);年龄＜40岁的高压氧组及高气压组干预后Ep、β及AC值均有改善,且高压氧组较高气压组改善更明显,2组比较差异有统计学意义(P＜0.05或P＜0.01).结论 高压氧干预即刻即可改善颈动脉弹性.     

饱和潜水对机体肺功能的影响

在潜水过程中 ,肺生理是最早受关注也是最重要的因素。在高气压环境下 ,肺脏同时受环境中多种危险因素影响。这种影响在各种方式的潜水中均存在 ,但根据潜水方式的不同 ,影响的程度也不同。这一程度取决于高气压暴露的时间和最高累积减压分数 (highest accumulated decompressionscore,HADCS) [1 ]。常规潜水是指呼吸空气或混合气进行潜水作业后 ,立即减压出水的潜水过程。高气压下暴露的时间明显较短 ,对肺功能的影响有限 ,一般认为安全的常规潜水无长期的器质性影响。饱和潜水是使潜水员体内惰性气体达到饱和 ,在饱和深度下居留 ,进行一…     

Use of a mass spectrometer for direct respiratory gas sampling from the hyperbaric chamber

BACKGROUND: When conducting respiratory gas measurements during hyperbaric chamber research, it is preferable to carry out gas concentration analysis by mass spectrometry. Gas samples for the mass spectrometer are normally taken from a bypass flow exiting the high pressure chamber to the ambient atmosphere. Under these conditions, mixing in the sampling line smoothes the concentration profile, and much of the advantage of low sampling flow is lost. We propose to use a direct sampling method by mass spectrometer that overcomes these deficiencies. METHODS: In the present study, the original high resistance capillary of a QP 9000 mass spectrometer was inserted through the wall of a hyperbaric chamber. Series A: Air and pure nitrogen flowed alternately (1 s each) via the sampling tip of the mass spectrometer. Series B: End expired CO2 from 15 immersed, professional divers exercising at 405 kPa was measured in a screening test for CO2 retention for nitrox diving. RESULTS: There was no difference in the recorded rise time, fall time and plateau reached in the concentration of oxygen at pressures of 101, 202, 303, 405 and 506 kPa. The new sampling method functioned correctly throughout the full-scale experiment, and the recording of end tidal CO2 was more precise than in the conventional method. CONCLUSIONS. Direct sampling of gases from a hyperbaric chamber by the QP 9000 mass spectrometer has many advantages over sampling of the same gases once they are outside the chamber.     

高压暴露条件下清醒大鼠脑电图和脑血流联合实时记录方法的建立

目的 探讨高压暴露条件下清醒大鼠脑电图和脑血流联合实时监测和记录的方法.方法 将激光多普勒光纤探头固定于大鼠颅骨上,并在大鼠颅骨上安装电极联合,再将光纤和导线引到加压舱外的生理记录仪上,对脑电图和脑血流进行监测.结果 用此方法可以清晰地记录到脑血流量和脑电图随暴露时间延长而出现的细微变化.结论 此方法可以用于需要对暴露于高压环境中的大鼠及其他动物的脑皮层局部血流量和脑电图进行实时监测和记录的实验研究.     

Dyspnea during exercise in hyperbaric conditions

INTRODUCTION: Length-tension and force-velocity characteristics of respiratory muscles and hyperinflation are the likely determinants of dyspnea in subjects exercising under hyperbaric conditions. We hypothesize that hyperinflation plays a minor role and that the reduced velocity of shortening of the respiratory muscles modulates dyspnea for any given pleural pressure. METHODS: We studied five normal subjects who performed an incremental exercise test on a cycloergometer in both normobaric (SL) and hyperbaric (4 ATA) conditions. We measured breathing pattern, inspiratory pleural pressure swing (Pessw), Delta Pes (i.e., the difference between the most and the less negative pleural pressures during tidal breathing), and dyspnea intensity (Borg score). End-expiratory lung volume (EELV) changes were evaluated by measuring changes in inspiratory capacity. Mean inspiratory flow (VT/TI) was used as an index of velocity of shortening of respiratory muscles. RESULTS: Compared with SL, at 4 ATA, peak exercise ventilation (VE) (84.5 vs 62.2 L x min(-1)) and VT/TI (2.99 vs 2.16 L x s)(-1) were lower, Pessw (30.9 vs 38.6 cm H2O) and Delta Pes (43.8 vs 62.2 cm H2O) were higher, and Borg score was not different (7.60 vs 8.20 au). EELV decreased progressively during exercise but remained higher than at SL. Borg score was greater for a same VE and lower for a same Delta Pes. VT/TI was lower for a same Pessw. The differences in EELV between SL and 4 ATA did not relate with the concurrent changes in Borg score. CONCLUSION: The results confirm our hypothesis that during exercise in hyperbaric conditions, decreased velocity of shortening of respiratory muscles modulates pressure-induced increases in dyspnea, with hyperinflation playing a minor role.     

急进高原发生急性高原肺水肿的早期干预及诊治措施探讨

日的：探讨高原肺水肿（high altitude pulmonary edema,HAPE）的早期干预措施及影响预后的因素。方法：选取我院收治的急进高原地区发生急性高原肺水肿的患者60例,并随机分为对照组30例,治疗组30例。入院行胸片、动脉氧分压、脑钠肽（brain natriuretic peptide,BNP）及心脏彩超（据三尖瓣返流测肺动脉收缩压）检查。根据胸片渗出程度比较动脉氧分压水平,比较两组治疗后Ⅰ型呼吸衰竭发生率,并进行动脉氧分压、BNP及肺动脉收缩压相关性分析。结果：①急进高原肺水肿患者氧分压的高低与肺水肿的严重程度密切相关,轻度、中度、重度之间比较均有统计学差异（P〈0．05）,胸片提示渗出越严重,氧分压越低;②对照组Ⅰ型呼吸衰竭发生率高于治疗组（P〈0．05）,提示高压氧治疗可以明显改善预后,减少并发症的发生;③急进高原肺水肿患者入院氧分压和BNP及肺动脉收缩压均呈负相关。结论：急性高原肺水肿患者胸片渗出越重,动脉氧分压越低,尽快行高压氧治疗改善预后及减少并发症的发生,并且入院动脉氧分压和BNP及肺动脉收缩压均呈负相关。     

Validating volume flow measurements from a novel semiautomated four-dimensional Doppler ultrasound scanner

RATIONALE AND OBJECTIVES: Accurate measurement of blood volume flow (in ml/min) is an important clinical goal. This project compared in vitro and in vivo volume flow measurements obtained with a novel, real-time three-dimensional (i.e., four-dimensional) ultrasound scanner (Encore PV; Vuesonix Sensors, Wayne, PA) with those from an invasive transit time flowmeter. MATERIALS AND METHODS: A flow pump was used to generate pulsatile flow rates from 60 to 600 ml/min. The Encore detected absolute blood velocity vectors within a volume. The scanner determined the centerline of the vessel and volume flow was then automatically calculated. Results were compared with those of an invasive technique for volumetric blood flow measurements utilizing a transit-time flowmeter (TS420; Transonic Systems Inc., Ithaca, NY). In vivo, 10 second datasets of the volume flow in the distal aorta of six rabbits were obtained simultaneously with the Encore PV and the flowmeter. Data were compared using linear regression and Bland-Altman analysis (due to the lack of independence). RESULTS: In vitro, Encore and flowmeter measurements both matched the flow pump (r2 > 0.99; P < .0001) with mean errors of -11.8% and -0.3%, respectively. Marked underestimation of the true flow rates was encountered with the Encore at the lowest pump setting. In vivo mean volume flows between 10.6 and 79.3 ml/min were measured. Mean and maximum volume flows obtained with the two techniques correlated significantly (P < .0001) with r2 values of 0.86 and 0.62, respectively. The corresponding root-mean-square errors were 6.9% for mean flow and 61.2% for maximum volume flow measurements. CONCLUSION: A new semiautomated four-dimensional Doppler device has been tested in vitro and in vivo. Mean volume flow measurements with this unit are comparable to those of an invasive flowmeter.     

A compact respiratory-triggering device for routine microimaging of laboratory mice

A partial-body plethysmograph was developed for measuring the respiratory flow of anesthetized mice during routine microimaging experiments performed in the close confines of an 89-mm-diameter, vertical-bore magnet. Respiratory flow patterns were used for synchronizing conventional T2-weighted spin-echo imaging with the respiratory cycle, thereby, significantly reducing motion-induced artifacts and increasing observed liver lesion contrast.     

Effects of severe hyperbaric pressure on autonomic nerve functions

Autonomic nerve functions under severe hyperbaric pressure were evaluated by measuring heart rate variability (HRV) and catecholamine excretion rate in 16 normal volunteers in submarine experimental facilities simulating conditions 330 m below sea level. HRV and urinary catecholamine levels were evaluated to assess sympathetic and parasympathetic tone. High-frequency HRV increased from 5.6 +/- 1.3 to 6.3 +/- 1.4 ms2 (p < 0.05), and SD of the average normal R to R intervals for 5-minute index (SDNNI) (time domain HRV parameter) increased from 77.2 +/- 32.7 to 93 +/- 33.8 ms (p < 0.05) after 3 days. Adrenaline/creatinine increased by 18% from a basal value of 4.04 +/- 0.44 ng/dL/h. Also, there was significant negative correlation between high-frequency and urinary cathecholamine levels. Evaluation of autonomic nerve functions under hyperbaric conditions by measuring HRV was shown to be a useful method. Thus, the present results indicate that the autonomic nerve functions of people who work under deep-sea conditions can be evaluated adequately by measuring HRV.     

Accuracy of gated equilibrium radioventriculography in measuring left ventricular function in dogs

To assess the precision of gated equilibrium radioventriculography in measuring changes in left ventricular stroke volume (LVSV), we studied five dogs each with a chronically implanted electromagnetic flowmeter on the ascending aorta. Per cent changes in left ventricular stroke counts (LVSC) were compared to those in LVSV following acute changes induced by positive end respiratory pressure. We have compared LVSCs calculated in five different ways: (1) Manual outlining of LV region of interest (LVROI), either single fixed enddiastolic (ED) ROI or ED and endsystolic (ES) ROIs with the aid of functional images (first harmonic of Fourier analysis); (2-5) automatic outlining of LV ROI (the algorithm generated 30 profiles on which the maximum of second derivative delineated the LV edges) was performed either on ED image or both ED and ES images. For these four methods a crescent-shaped ROI for background correction was manually drawn at the border of the LV ROI. The fifth method used an automatically drawn single fixed LVED ROI with interpolative background substraction (IBS) between LV and RV edges. LVSC changes, calculated with the IBS method correlated better with LVSV changes than the other four methods. Thus assessment of small LVSC changes is highly processing-dependent.     

失重条件下呼吸力学参数测试方法及实现

目的研究失重情况下的航天员呼吸运动,准确获取其呼吸力学参数。方法在对国内外相关研究成果进行调研的基础上,提出基于气体流量传感器和压力传感器的呼吸力学参数检测方法。结果设计并完成了硬件电路与软件编写。采用三次拟合法对标定数据进行曲线拟合,所得气体流量拟合的相关系数达到0.99,而压力拟合的相关系数达到0.995。对硬件电路测试,测得最大相对误差小于1%。经实验结果分析得出系统最大相对误差仅为4%,且结果稳定性良好,符合系统的要求,且实现了测试设备的小型化。结论样机具有良好的稳定性和精度,参数实时显示。     

高压氧对缺血再灌注条件下鼠视网膜细胞膜功能的影响(论著)

目的：观察高压氧（ＨＢＯ）对缺血再灌注视网膜细胞膜功能的影响。方法：选择３５只ＳＤ大鼠，随机分为４组：正常组、再灌注组、空气加压组和ＨＢＯ组。采用升高眼内压（ＩＯＰ）致视网膜血管断流造成视网膜缺血模型，然后给予再灌注３小时。其中空气加压组和ＨＢＯ组于再灌注开始后将动物置于ＨＢＯ舱内，在２５２．３８ｋＰａ（≈２．５ＡＴＡ）压力下分别吸空气和纯氧，加压时间为８０分钟。再灌注结束后取眼球制备视网膜细胞膜匀浆液。用定磷法测定视网膜Ｎａ＋－Ｋ＋－ＡＴＰ酶活性，用荧光探针ＤＰＨ标记细胞膜并测定其膜流动性。结果：ＨＢＯ组视网膜细胞膜Ｎａ＋－Ｋ＋－ＡＴＰ酶活性与正常组比较无显著性差异，而与再灌注组比较有非常显著性差异；ＨＢＯ组膜流动性与再灌注组比较有非常显著性差异。结论：ＨＢＯ对缺血及再灌注所造成的视网膜细胞功能的损伤具有明显的治疗作用。