Right Atrial Pressure Affects the Interaction between Lung Mechanics and Right Ventricular Function in Spontaneously Breathing COPD Patients

INTRODUCTION: It is generally known that positive pressure ventilation is associated with impaired venous return and decreased right ventricular output, in particular in patients with a low right atrial pressure and relative hypovolaemia. Altered lung mechanics have been suggested to impair right ventricular output in COPD, but this relation has never been firmly established in spontaneously breathing patients at rest or during exercise, nor has it been determined whether these cardiopulmonary interactions are influenced by right atrial pressure. METHODS: Twenty-one patients with COPD underwent simultaneous measurements of intrathoracic, right atrial and pulmonary artery pressures during spontaneous breathing at rest and during exercise. Intrathoracic pressure and right atrial pressure were used to calculate right atrial filling pressure. Dynamic changes in pulmonary artery pulse pressure during expiration were examined to evaluate changes in right ventricular output. RESULTS: Pulmonary artery pulse pressure decreased up to 40% during expiration reflecting a decrease in stroke volume. The decline in pulse pressure was most prominent in patients with a low right atrial filling pressure. During exercise, a similar decline in pulmonary artery pressure was observed. This could be explained by similar increases in intrathoracic pressure and right atrial pressure during exercise, resulting in an unchanged right atrial filling pressure. CONCLUSIONS: We show that in spontaneously breathing COPD patients the pulmonary artery pulse pressure decreases during expiration and that the magnitude of the decline in pulmonary artery pulse pressure is not just a function of intrathoracic pressure, but also depends on right atrial pressure

Methodology of calculation of construction and hydrodynamic parameters of a foam layer apparatus for mass-transfer processes

Промислова реалізація методу стабілізації газорідинного шару дозволяє значно розширити галузь застосування пінних апаратів і відкриває нові можливості інтенсифікації технологічних процесів з одночасним створенням маловідходних технологій. У статті встановлені основні параметри, що впливають на гідродинаміку пінних апаратів, розглянуті основні конструкції та режими роботи пінних апаратів. Виявлено зв'язок гідродинамічних параметрів. Розглянуто гідродинамічні закономірності пінного шару. Вказані фактори, що впливають на процес масообміну, як в газовій, так і в рідкій фазах. Проведений аналіз ряду досліджень показав, що перспективним напрямком інтенсифікації процесу масообміну є розробка апаратів з трифазним псевдозрідженим шаром зрошуваної насадки складних форм із сітчастих матеріалів. Отже, необхідне проведення спеціальних досліджень гідродинамічних режимів роботи апарату з сітчастою насадкою і визначенням параметрів, що впливають на швидкість переходу насадки з одного режиму в інший.Industrial implementation of the stabilization method of the gas-liquid layer can significantly expand the field of use of foaming apparatus and opens up new opportunities for intensifying technological processes with the simultaneous creation of low-waste technologies. The article establishes the basic parameters influencing the hydrodynamics of foam apparatus, considers the basic constructions and operating modes of foam apparatus. The connection of hydrodynamic parameters is revealed. The hydrodynamic laws of the foam layer are considered. The indicated factors affecting the process of mass transfer, both in the gas and in the liquid phases. The conducted analysis of a number of studies showed that the perspective direction of intensification of the mass transfer process is the development of apparatuses with a three-phase fluidized bed of an irrigated nozzle of complex forms with mesh materials

A METHOD FOR THE DETERMINATION OF THE VOLUME OF AIR IN THE LUNGS: MEASUREMENTS IN CHRONIC PULMONARY EMPHYSEMA

The present study is concerned with the meas-urement of the functional residual capacity (FRG) in chronic pulmonary emphysema by a gas dilution method, i.e., the washout of nitrogen from the lung during prolonged oxygen breathing. There have been many methods in use to measure the FRC (or the residual volume) since Davy in 1800 measured his own residual volume by rebreathing hydrogen, which he had made himself, from a balloon (1). These methods, both the open circuit (washout) and closed circuit (rebreathing fromn a balloon or spirom-eter), have in general followed a consistent historic trend in that longer and longer periods of washout or rebreathinig have been required in later methods: Davy in 1800 rebreathed for 20 sec-onids (1), Grehant in 1864 for 6 inspirations (2), Van Slyke and Binger in 1923 for 5 minutes (3), Christie and Bates for 7 minutes (4, 5), Darling, Cournand and associates for 7 or 11 minutes (6, 7) and Briscoe, Becklake and Rose for 12 minutes (8, 9). In justice to these earlier workers it should be mentioned that most of those quoted above and others (10, 11) realized that to get the best results in emphysema some-what longer studies were desirable. M\ore recent studies of the N2 or helium wash-out in patients with chronic pulmonary emphy-sema have found detectable quantities of these inert gases being washed out of the lungs, dis-tinct from those washed out from tissues, even after 20 to 40 minutes of 02 breathing (12-18). The present study describes a method in which all the N2 eliminated from the lung during 15 minutes, or longer, of oxygen breathing is meas-ured. Moreover, the quantity of N2 which would be eliminated in a longer study is esti-* This investigation was supported by a research gran