心阻抗容积图的传统理论及其局限性

本文就心阻抗容积图的传统理论及其局限性展开讨论。由于传统理论模型与人体胸部结构差异太大，使这一方法存在很多问题。而实践中关于心输出量（ＣＯ）的计算，误差较大，可靠性差。     

骨水泥性能及其对人工关节柄固定强度的影响

本文研究了骨水泥三种不同临床使用方法所形成的内部气泡结构状态,测定了骨水泥的抗压强度、收缩率、疲劳强度、变形积累量等物理机械性能,以及关节固定强度,用气泡状态解释了不同临床使用方法对骨水泥性能及固定强度所带来的各种影响。     

Blockade of pulmonary stretch receptors reinforces diaphragmatic activity during high-frequency oscillatory ventilation

During apneic periods elicited by high-frequency oscillatory ventilation (HFOV) a tonic diaphragmatic activity was observed, contrasting with the absence of diaphragmatic activity during apnea induced by lung inflation. To clarify the mechanism underlying the persistence of the diaphragmatic activity during HFOV-induced arrest of breathing the reflex responses to short periods of HFOV, and to periods of lung inflation with airway pressure (P _aw) equal to the meanP _aw and/or to maximalP _aw during HFOV were examined both before and after the blockade of slowly adapting stretch receptors (SR) by inhalation of sulphur dioxide (SO₂) in anaesthetized rabbits. In animals with intact SR, the HFOV-induced reflex apnea lasted longer than that induced by lung inflation, the associated diaphragmatic activity being in the most cases higher than the diaphragmatic activity during quiet expiration; inflation, however, completely inhibited diaphragmatic activity. After blockade of SR, spontaneous breathing continued during periods of lung inflation, i.e., the Hering-Breuer inflation reflex was abolished, whereas HFOV still led to a cessation of spontaneous breathing, the associated diaphragmatic activity even exceeding the level observed during quiet inspiration. From these results we conclude that only one part of the reflex response to HFOV is due to SR-stimulation and that in addition other vagal pulmonary receptors (irritant-and/or C-fibre-receptors) are involved. The stimulation of the latter counterbalances the concomitant stimulation of SR, giving rise to the tonic activity of the diaphragm.     

人体体温下UHMWPE人工髋臼材料压缩性能的试验研究

模拟人体体温下对超高分子量聚乙烯（UHMWPE）人工髋臼材料进行了压缩力学性能的试验研究,并与室温下的试验结果进行了对比.当由室温22℃升高到体温37℃和40℃时,其屈服应力呈明显的下降趋势,分别下降了23.1%和31.9%,由体温37℃升高到40℃时,二者仅差3℃,其屈服应力亦下降了11.5%.同时还对不同加载速度下UHMWPE试件压缩变形过程进行了红外辐射温度的监测与分析.不同加载速度下试件压缩变形过程中的红外辐射温度均有明显升高,加载时间越长,试件平均红外辐射温度越高.试验结果分析表明,不能忽视植入人体后UHMWPE人工髋臼局部受压时温度的升高,特别不能忽视植入人体后在人体体温作用下其力学性能的改变和下降,人体体温的作用是UHMWPE人工髋臼出现过早失效的原因之一.本试验研究为UHMWPE材料在人体环境中的应用研究提供了参考.     

Acrylic‐Based Polyurethane/Silica Hybrids Prepared by Acid‐Catalyzed Sol–Gel Process: Structure and Mechanical Properties

Summary: Silica sols were first prepared based on different ratios of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) by an acid‐catalyzed sol–gel process, and then incorporated into acrylic‐based polyurethanes. The structures and morphologies of silicone‐oxo clusters were studied by ²⁹Si NMR, SAXS, and scanning electron microscopy (SEM), whereas the mechanical properties of polyurethane/silica hybrids were characterized by DMA and tensile tests. The silicone‐oxo clusters in both silica sol and polyurethane hybrids became denser and larger at a higher molar ratio of TEOS/MTES and higher silica content, and the silica‐oxo clusters of polyurethane/silica hybrids even became more compact and larger than those of silica sols, increasing the elastic modulus and tensile strength of polyurethane/silica hybrids.

Typical structure of silica sol prepared from the hydrolysis and condensation of TEOS and MTES with acid as the catalyst.     

Mechanical heart valve prostheses:: identification and evaluation (erratum)

Mechanical heart value prostheses have been in use since the 1950s. Many prostheses have been used for a while and then discontinued. Today, there are a large number and variety of prostheses in use and an even larger variety that are in place in patients. These may be explanted at any time for a number of reasons. It is essential for the practicing pathologist to be able to identify the prosthesis and be aware of some of its reported complications and modes of failure. This article, and a second one on bioprosthetic heart valves, is designed as a ready reference guide to heart valve prostheses, their important identifying features, their common complications, and modes of failure. It should help in the accurate identification of explanted prosthetic valves and more definitive reports. This accuracy of identification as well as tracking of abnormalities noted will, we hope, permit the identification of new failure modes and the recording of causes of failure of new (or even modified) prosthetic heart valves.     

微机控制的韧带动态力学特性测试系统

本系统是为自动测试人体韧带或类似组织的动态力学特性试验而研制的。在试验时,受控的加载过程和数据采集过程同时进行。系统向韧带试件提供一个快速的匀速可控的拉伸载荷,模拟人体剧烈运动的实况,同时实时采集力和变形的数据。系统还提供对所采集数据的分析手段,从而得到力、变形、应力、应变、弹性模量和变形能等参数之间的关系,并可以图形和文字形式输出。系统亦可将各数据文件转换为其它应用软件包可接受的形式,以便利用标准商品软件包的数据和图象处理能力。系统采用菜单提示的人机对话方式进行监控。     

机械通气气管插管吸痰方法探讨

目的探讨不同的吸痰方法,从而有效地清除气管插管患者的呼吸道分泌物。方法对47例气管插管病人均采用常规法和呛咳法两种方法吸痰,呛咳法要求:吸痰管带负压进入气管插管,随吸痰管插入深度调节负压,适时安全吸痰,适度气道湿化。常规法按临床一般方法进行吸痰。将两种方法吸出的痰量,痰液性状及吸痰前后20min血氧饱和度(SpO2)进行比较。结果两种方法在吸出的痰量,痰液性状和SpO2方面存在着显著差异(P<0.05,P<0.01),呛咳法吸出的痰多且粘稠。吸痰后SpO2明显高于吸痰前和常规法。结论呛咳法吸痰能充分吸出气道深部的痰液,可以有效防止气道阻塞,改善通气功能。     

软骨组织工程中力学因素的影响及应用

力学因素是软骨组织工程中的重要影响因素之一。近年来的研究表明，力学作用可以刺激细胞因子及激素的分泌，改变三维支架上培养的软骨细胞的新陈代谢，从而促进软骨组织的生长与重建。目前已经有诸多关于体外构建软骨组织的报道，但对于其中的力学因素的影响（包括力学因素对软骨细胞增殖的促进及力学刺激的传导机制等）还没有完全认识。就以上几方面做一综述，并简单介绍生物反应器在软骨组织工程中的应用。     

A simple breathing circuit to maintain isocapnia during measurements of the hypoxic ventilatory response

We report the development and testing of a simple breathing circuit that maintains isocapnia in human subjects during hypoxic hyperpnea. In addition, the circuit permits rapid switching between two gas mixtures with different partial pressures of oxygen. Eleven volunteers breathed repeated cycles of exposure to air (2 min of 21% O(2), balance N(2)) and hypoxia (2 min of 8.3+/-0.1% O(2), balance N(2)). Hypoxia induced significant increases in minute ventilation, breathing frequency and tidal volume (P < 0.05) that were consistent over repeated cycles of hypoxia (P > 0.1, one-way ANOVA). The system successfully maintained isocapnia in all subjects, with an average change in end-tidal CO(2) of only -0.2 mmHg during hyperventilation in hypoxia (range 0.4 to -0.8 mmHg). This system may be suitable for repeated tests of the hypoxic ventilatory response (HVR) and may prove useful for exploring intra- and inter-individual variability of HVR in humans.