Simultaneous records of wedged pulmonary capillary pressure and left atrial pressure have been made in I2 patients. The pressure changes in the left atrium preceded those in the pulmonary capillary bed by o-o6 to O0I4 sec. This delay, together with the damping of the wedged pulmonary capillary pressure, may result in a false appearance of an end-diastolic gradient between the left atrium and th...

VENOUS obstruction is known to increase capillary pressure in the obstructed area. Most observers have believed that in the normal subject pressure in the large veins draining a part gives a good indication of the pressure distal to the venous ends of the capillaries and that, if the pressure in large veins is not elevated, changes in the venous system are not important in causing change in the...

Albumin plays an important role in maintaining homeostasis within the body and depends on the cell membrane and the transport mechanism, including diffusion, osmosis, filtration, and active transport. The dissolved proteins, which are the only substances that do not penetrate the pores of the capillary membrane, are responsible for the osmotic pressure of the capillary membrane. Approximately 7...

BACKGROUND Invasive hemodynamic exercise testing is commonly used in the evaluation of patients with suspected heart failure with preserved ejection fraction (HFpEF) or pulmonary hypertension. Saline loading has been suggested as an alternative provocative maneuver, but the hemodynamic changes induced by the 2 stresses have not been compared. METHODS AND RESULTS Twenty-six subjects (aged, 67±...

Proper selection of capillary tube it is essential to study the effect of capillary tube geometry on the performance of refrigeration systems. The literature review is focused on the influence of geometrical parameters like tube length, diameter, coil pitch, number of twist and twisted angle on pressure drop and coefficient of performance (COP) of the system. These parameters can be optimized u...

The surface free energy, or surface tension, of a liquid interface gives rise to a pressure jump when the interface is curved. Here we show that a similar capillary pressure arises at the interface of soft solids. We present experimental evidence that immersion of a thin elastomeric wire into a liquid induces a substantial elastic compression due to the solid capillary pressure at the bottom. W...

To assess the effects of vasopressors on plasma levels of immunoreactive atrial natriuretic factor (ANF), 13 normal men were studied on two occasions. On the experimental day, subjects received sequential 15-minute intravenous infusions of angiotensin II in doses of 4, 8, and 16 pmol/kg/min. Following a 30-minute recovery period, subjects received sequential 15-minute infusions of phenylephrine...

The capillary pressure–saturation relationship, Pc(Sw), is an essential element in modeling two-phase flow in porous media (PM). In most practical cases of interest, this relationship, for a given PM, is obtained experimentally, due to the irregular shape of the void space. We present the Pc(Sw) curve obtained by basic considerations, albeit for a particular class of regular PM. We analyze the ...

Capillary force actuation is a new technology holding particular promise for microelectromechanical systems. Relying upon the ability of electrical fields to alter the capillary pressure in a liquid, this technology permits larger actuation forces and strokes than conventional microactuators. Herein, the physical principles of electrowetting are discussed along with the relationships between ch...

This paper presents the design, fabrication, and testing of passive plastic microfluidic valves and active injectors driven by capillary forces. The passive valves stop the flow of a liquid inside a capillary using a capillary pressure barrier that develops when the channel cross section changes abruptly. Two types of valves with vertical and horizontal neck regions were fabricated yielding pre...