Modulus of elasticity of solid materials is determined by an experimental static tensile test on usual terms. The test is insufficient for hoses. Therefore, there is provided a special test for the determination of modulus of elasticity of hoses in reference to pressure and temperature of working liquid and environment temperature. The aim of the paper is to experimentally determinate modulus of elasticity of hoses depending on pressure of working liquid. and Za běžných podmínek se modul pružnosti pevných materiálů stanovuje experimentální statickou tahovou zkouškou. U hadic je tato zkouška nedostačující, proto se provádí speciální zkouška pro stanovení modulu pružnosti hadic s ohledem na tlak a teplotu pracovní kapaliny a teplotu okolního prostředí. Předmětem tohoto příspěvku je experimentální stanovení modulu pružnosti hadic v závislosti na tlaku pracovní kapaliny.
Real liquids are compressible. The compressibility of liquids is described by modulus of elasticity (or by coefficient of volume compressibility) analogous to solids. A value of modulus of elasticity at liquids depends on many factors, above all on volume of free gases in liquids and further on pressure and temperature of liquids. and Skutečné kapaliny jsou stlačitelné. Stlačitelnost kapalin je určena modulem pružnosti (resp. součinitelem objemové stlačitelnosti) podobně jako u pevných látek. Velikost modulu pružnosti u kapalin závisí na mnoha faktorech, zejména na obsahu volných plynů v kapalinách a dále na tlaku a teplotě kapalin.
A higher mean arterial pressure (MAP) achieved by norepinephrine up-titration may improve organ blood flow in critically ill, whereas norepinephrine-induced afterload rise might worsen myocardial function. Our aim was to assess the effects of norepinephrine dose titration on global hemodynamics in cardiogenic shock. We prospectively evaluated 12 mechanically ventilated euvolemic patients (aged 67±12 years) in cardiogenic shock (10 patients acute myocardial infarction, 1 patient dilated cardiomyopathy, 1 patient decompensated aortic stenosis). Hemodynamic monitoring included arterial and Swan-Ganz catheters. The first data were obtained at MAP of 65 mm Hg, then the norepinephrine dose was increased over 40 min to achieve MAP of 85 mm Hg. Finally, the norepinephrine-dose was tapered over 40 min to achieve MAP of 65 mm Hg. Norepinephrine up-titration increased MAP to the predefined values in all patients with concomitant mild increase in filling pressures and heart rate. Systemic vascular resistance increased, whereas cardiac output remained unchanged. During norepinephrine down-titration, all hemodynamic parameters returned to baseline values. We observed no changes in lactate levels and mixed venous oxygen saturation. Our data suggest that short-term norepinephrine dose up-titration in cardiogenic shock patients treated or pretreated with inotropes was tolerated well by the diseased heart., R. Rokyta, Jr ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy