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A sphygmomanometer (/ ˌ s f ɪ ɡ m oʊ m ə ˈ n ɒ m ɪ t ə r / SFIG-moh-mə-NO-mi-tər), also known as a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, [1] and a mercury or aneroid manometer to measure the pressure.
A minimum systolic value can be roughly estimated by palpation, most often used in emergency situations, but should be used with caution. [10] It has been estimated that, using 50% percentiles, carotid, femoral and radial pulses are present in patients with a systolic blood pressure > 70 mmHg, carotid and femoral pulses alone in patients with systolic blood pressure of > 50 mmHg, and only a ...
Many pressurized gases are actually supercritical fluids. For example, nitrogen has a critical point of 126.2 K (−147 °C) and 3.4 MPa (34 bar). Therefore, nitrogen (or compressed air) in a gas cylinder above this pressure is actually a supercritical fluid. These are more often known as permanent gases.
One example is the liquid–vapor critical point, the end point of the pressure–temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas comes into a supercritical phase, and so cannot be liquefied by pressure alone.
When the heart ejects stroke volume to the arteries, it takes a certain transit time until the blood pressure wave arrives in the periphery. This pulse transit time (PTT) indirectly depends on blood pressure – the higher the pressure, the faster PTT. This circumstance can be used for the noninvasive detection of blood pressure changes.
More specifically, it behaves as a supercritical fluid above its critical temperature (304.128 K, 30.9780 °C, 87.7604 °F) [1] and critical pressure (7.3773 MPa, 72.808 atm, 1,070.0 psi, 73.773 bar), [1] expanding to fill its container like a gas but with a density like that of a liquid. Supercritical CO
Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" refers to the pressure in a brachial artery, where it is most commonly measured.
The relatively uniform pressure in the arteries indicate that these blood vessels act as a pressure reservoir for fluids that are transported within them. Pressure drops gradually as blood flows from the major arteries, through the arterioles, the capillaries until blood is pushed up back into the heart via the venules, the veins through the ...