Mechanical efficiency of the left ventricle as a function of preload,afterload, and contractility

Summary We have recently shown that the mechanical efficiency of the contractile machinery of the canine left ventricle is constant at 30%–50%, independent of its loading, heart rate, and inotropic conditions. In contrast, the conventional mechanical efficiency of the ventricle is known to vary between 0 and 30%, depending on these conditions. In this study, we derived an equation for the conventional mechanical efficiency as a function of ventricular preload, afterload, and contractility, based on the constant mechanical efficiency of the contractile machinery. In deriving this equation, we fully utilized our new concept of the total mechanical energy of the left ventricle, i.e., systolic pressure-volume area, and our recent findings of the linear relationship between left ventricular oxygen consumption and the systolic pressure-volume area as well as the dependence of this relation on the ventricular inotropic state. As a result, the conventional mechanical efficiency of the left ventricle was found to change between 0 and 25% as an explicit function of these cardiodynamic and inotropic conditions. Using this function, we obtained combinations of loading and inotropic conditions to maximize the conventional mechanical efficiency of the left ventricle.     

Lung function in children and adolescents with idiopathic interstitial pulmonary fibrosis

Lung function of 65 patients who had idiopathic interstitial pulmonary fibrosis (IIPF) that had been treated with prednisone was evaluated by tests of ventilatory function, lung mechanics, and gas exchange at rest and during exercise. Ages on initial investigation ranged from 5 to 20 years. In 35 of 65 patients the studies were repeated an average of four times over a period of 1 to 9 years. Results of the first testing were as follows: vital capacity (VC)-significantly reduced in all patients; inspiratory capacity (IC)-significantly reduced in all patients; total lung capacity (TLC)-reduced in 91%; functional residual capacity (FRC)-reduced in 31%; residual volume (RV)-reduced in 6%; elastic recoil of the lungs (Pstl)-significantly increased in 97% at 100% TLC, significantly increased in 52% at 90% TLC, reduced in 68% at 60% TLC; 7) static compliance (Cst)-reduced in 83%; 8) dynamic compliance (Cdyn)-reduced in 88%; 9) specific airway conductance at FRC level (Gaw/TGVex)-significantly increased in 50%; 10) maximum expiratory flow rates at 60% TLC (Vmax 60% TLC, in TLC/s)-significantly reduced in 33%; 11) upstream airway conductance (Gus 60% TLC, in TLC/s/cm H2O)-reduced in 32%; 12) diffusing capacity of the lungs for carbon monoxide (DLco) related to body-surface area-abnormal in 58% (when corrected for lung size, i.e., DLco/TLC, abnormal in only 8%); 13) PaO2 at rest and after 6 minutes submaximal exercise-reduced in 25% and 63%, respectively. Changes in lung function that occurred with growth were assessed in terms of percentages of predicted values. Results showed that the VC and IC remained significantly reduced. An actual reduction of TLC, FRC, RV, breathing frequency, DLCO, and Pstl at 100% and 90% TLC was observed. Increases were seen in Pstl at 60% TLC, Gaw/TGVex, Vmax, and Cst. Indices of lung elasticity suggested that regions of fibrosis and emphysema had become present. Smaller patients were also noted to have stiffer lungs.     

肺组织γ-氨基丁酸A型受体在大鼠内毒素诱发急性肺损伤中的作用

目的 探讨肺组织γ-氨基丁酸A型受体(GABAAR)在大鼠内毒素诱发急性肺损伤中的作用.方法 成年健康雄性Wistar大鼠32只,8周龄,体重200 ～ 230 g,采用随机数字表法,将其随机分为4组(n=8)∶正常对照组(C组)、内毒素组(LPS组)、γ-氨基丁酸预先给药+内毒素组(GABA组)和GABAAR拮抗剂荷包牡丹碱预先给药+内毒素组(BIC组).LPS组、GABA组和BIC组尾静脉注射LPS 5 mg/kg,C组给予等容量生理盐水;GABA组和BIC组分别于给予LPS前30 min时腹腔注射γ-氨基丁酸50 mg/kg和荷包牡丹碱10 μmol/kg.于给予LPS后6h时,采集动脉血样,测定PaO2,然后取肺组织,测定肺湿/干重比(W/D)、GABAAR表达、IL-6、TNF-α、MDA的含量和SOD活性,光镜下观察肺组织病理学结果.结果 与C组比较,LPS组、GABA组和BIC组PaO2降低,LPS组和GABA组肺组织W/D、TNF-α、IL-6和MDA的含量升高,肺组织GABAAR表达上调,肺组织SOD活性降低(P＜0.05);与LPS组比较,GABA组肺组织W/D、TNF-α、IL-6和MDA的含量升高,肺组织GABAAR表达上调,肺组织SOD活性降低(P＜0.05),而BIC组上述指标差异无统计学意义,GABA组和BIC组PaO2差异无统计学意义(P＞0.05).结论 肺组织GABAAR参与了大鼠内毒素诱发急性肺损伤的发展.     

早期肺小动脉栓塞对犬血液动力学、呼吸功能及凝血功能的影响

目的 观察肺小动脉栓塞早期犬全身血液动力学、呼吸功能及凝血的改变。方法 成年犬8只，体重(15．5-16．5)kg，经全麻插管后开放右侧股静脉注入100个自体血栓。同时开放对侧股动、静脉连续测量栓塞前后平均肺动脉压(PMAP)、肺动脉收缩压(PASP)、肺动脉舒张压(PADP)、肺毛细血管嵌压(PAWP)、肺血管阻力(PVR)；动脉血气及凝血指标[D-二聚体(D-dilner)、S反应蛋白(PS)、C反应蛋白(PC)、组织纤溶酶原活化剂(t-PA)]的变化。结果 肺小动脉栓塞即刻PMAP、PASP、PADP和PVR显著性升高，1h后下降，呼吸功能无明显变化，凝血指标D-dimer升高差异有显著性，2h后下降至栓塞前的水平。病理可见肺出血、肺实变和小动脉血栓形成。结论 肺小动脉栓塞可引起肺组织损伤和动脉血栓形成，早期可引起肺动脉高压以及D-dimer的变化，但是对呼吸功能影响不大。     

Ang Ⅱ在pECMO转流早期组织中的表达

目的 探讨血管紧张素Ⅱ(Ang Ⅱ)在新型双侧无泵驱动体外膜肺氧合(pECMO)转流早期的作用和意义.方法 选择家犬10只,建立急性呼吸衰竭动物模型,分别在转流前、转流后1、2、3、4 h采集右心房血和肺脏组织.应用放射免疫方法分别检测血液和肺组织匀浆中的Ang Ⅱ含量;应用免疫组化方法检测肺组织中Ang Ⅱ表达的定位.结果 血浆Ang Ⅱ在模型完成时降低,1 h后回升,3 h达高峰,之后缓慢下降;肺组织匀浆的Ang Ⅱ升高至2 h达高峰,之后缓慢下降.动物模型完成后及转流期间AngⅡ免疫组化检测显示,气管壁及周围、血管壁周围明显阳性表达,少数巨噬细胞中阳性表达,其中以转流2h小血管壁、小细支气管壁、终末细支气管壁及其周围变化最明显.结论 pECMO转流产生的Ang Ⅱ与术后肺部炎性损伤和并发症有一定关系.测定外周血Ang Ⅱ的变化,对反映肺脏组织Ang Ⅱ变化水平和评估肺脏损伤情况有参考价值.     

皮格马利翁效应在围手术期肺癌患者呼吸功能锻炼中的应用

目的探讨应用皮格马利翁效应对围手术期肺癌患者呼吸功能锻炼的影响。方法将96例围手术期肺癌患者按照入科时间先后顺序,随机选为观察组48例,对照组48例。对照组给予常规呼吸功能锻炼指导。观察组在入科时就应用皮格马利翁效应实施呼吸功能锻炼指导。观察两组住院期间平均每次锻炼时间、每天锻炼次数及术后5 d内咳嗽排痰的主动性。结果观察组每次锻炼平均时间较对照组长、每天锻炼次数较对照组多(P0.05)。观察组术后咳嗽排痰也较对照组积极、主动。结论应用皮格马利翁效应能提高患者呼吸功能锻炼的依从性,最大效能地发挥患者主观能动性。     

模拟海上颠簸刺激对严重烧伤家兔心肌力学指标的影响

目的 观察模拟海上颠簸刺激对烧伤早期家兔心肌力学和血流动力学指标的影响.方法 132只家兔随机分成正常对照组(N组,n=6)、单纯颠簸组(DN组,n=42)、单纯烧伤组(S组,n=42)和烧伤颠簸组(DS组,n=42),单纯烧伤组和烧伤颠簸组造成40%全身体表面积(total body surface area,TBSA)Ⅲ度烧伤,分别于2、6、8、12、24、36、48 h等7个时相点经颈动脉左心室内置管,应用RM6240系列生理信号采集仪记录左心室压力波形和主动脉压力波形并应用RM6240系列生理信号采集处理系统处理分析相应波形,测量得出主动脉收缩压(AOSP)、主动脉舒张压(AODP)、平均动脉压(MAP)、左心室收缩压峰值(LVSP)、左心室舒张末压(LVEDP)以及左心室内压变化最大速率(±dp/dtmax)等心肌力学指标.结果 单纯颠簸即可使家兔心肌力学指标显著降低,烧伤颠簸组心肌力学和血流动力学指标均低于单纯烧伤组.伤后2 h,烧伤颠簸组LVEDP即显著低于单纯烧伤组,LVSP、LV-dp/dtmax自伤后6 h开始显著低于单纯烧伤组,AOSP、AODP、MAP、LV dp/dtmax自烧伤后12 h开始均显著低于单纯烧伤组.结论 模拟海上颠簸刺激可明显加剧严重烧伤家兔心肌力学指标的下降和心功能损害.     

941方对衰老大鼠肝线粒体酶活性的影响

目的：通过检测衰老大鼠肝组织细胞线粒体呼吸链氧化功能。探讨大鼠衰老时肝组织细胞线粒体呼吸甸氧化功能的变化规律及941方延缓衰老的作用机制。方法：分别从4月龄（青年组）、24月龄（老龄组）和941方组大鼠的肝组织分离出线粒体,并用双缩脲法测定单位组织的线粒体蛋白,用Clark氧电极极谱法分别测定线粒体呼吸链3个氧化酶活性：NADH氧化酶（NADHOX）、琥珀酸氧化酶（SUCOX）和细胞色素氧化酶（CYTOX）。用差光谱法（联二亚硫酸钠还原减正铁氢化钾氧化的消化值）获得细胞色素a、b、c和c1含量（Cyta、Cytb、Cytc和Cytc1)。结果：与青年组大鼠比较,老年组大鼠的肝组织细胞线粒体含理有一定下和,百3个氧化酶活性却显增加,同时细胞色素含量尤其是Cytb和Cytc显升高,941方组大鼠肝组织细胞线粒体上述指标皆显高于青年组和老年组。结论：衰老大鼠肝组织线粒体酶活性与青年组有显不同,表明衰老过程中肝细胞通过某种反馈机制使残存完好的线粒体氧功能代偿性增强;９４１方使这种作用进一步增强。