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A quantum limit in physics is a limit on measurement accuracy at quantum scales. [1] Depending on the context, the limit may be absolute (such as the Heisenberg limit), or it may only apply when the experiment is conducted with naturally occurring quantum states (e.g. the standard quantum limit in interferometry) and can be circumvented with advanced state preparation and measurement schemes.
An example of this phenomenon is measurement of blood pressure using the "pulse obliteration method" with a sphygmomanometer. At resting state the arterial critical closing pressure is ~ 20 mmHg . Critical closing pressure in arteries is higher than the mean vascular filling pressure that develops after death (~7 mmHg).
A pulse pressure is considered abnormally low if it is less than 25% of the systolic value. [2] If the pulse pressure is extremely low, i.e. 25 mmHg or less, it may indicate low stroke volume, as in congestive heart failure. [3] The most common cause of a low (narrow) pulse pressure is a drop in left ventricular stroke volume.
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 ...
The pulse is the rate at which the heart beats while pumping blood through the arteries, recorded as beats per minute (bpm). [11] It may also be called "heart rate". In addition to providing the heart rate, the pulse should also be evaluated for strength and obvious rhythm abnormalities. [11] The pulse is commonly taken at the wrist (radial ...
Blood pressure measurement using the auscultatory method based on the (first) Korotkoff-sound. Korotkoff sounds are the sounds that medical personnel listen for when they are taking blood pressure using a non-invasive procedure.
The pulse-repetition frequency (PRF) is the number of pulses of a repeating signal in a specific time unit. The term is used within a number of technical disciplines, notably radar . In radar, a radio signal of a particular carrier frequency is turned on and off; the term "frequency" refers to the carrier, while the PRF refers to the number of ...
Pulse wave velocity (PWV) is the velocity at which the blood pressure pulse propagates through the circulatory system, usually an artery or a combined length of arteries. [1] PWV is used clinically as a measure of arterial stiffness and can be readily measured non-invasively in humans, with measurement of carotid to femoral PWV (cfPWV) being ...