Perfusion

Perfusion

In physiology, perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue. The word is derived from the French verb "perfuser" meaning to "pour over or through."

Tests of adequate perfusion are a part of patient triage performed by medical or emergency personnel in a mass casualty incident.

Calculation

Perfusion ("F") can be measured with the following formula, where Pa is mean arterial pressure, Pv is mean venous pressure, and R is vascular resistance: [cite web| url=http://www.cvphysiology.com/Hemodynamics/H001.htm| title=Cardiovascular Physiology Concepts| author=Richard E. Klabunde| accessdate=9/12/06]

$F = frac\left\{ P_A - P_V \right\}\left\{ R \right\}$

The term "Pa - Pv" is sometimes presented as "ΔP", for the change in pressure. [GeorgiaPhysiology|7/7ch04/7ch04p26 - "Renal Perfusion Pressure and Vascular Resistance"]

The terms "perfusion" and "perfusion pressure" are sometimes used interchangeably, but the equation should make clear that resistance can have an effect on the perfusion, but not on the perfusion pressure.

Overperfusion and underperfusion

The terms "overperfusion" and "underperfusion" are measured relative to the average level of perfusion across all tissues in an individual body, and the terms should not be confused with hypoperfusion and "hyperperfusion", which measure the perfusion level to the tissue's current need.

Tissues like the skin are considered overperfused and receive more blood than would be expected to meet the metabolic needs of the tissue. In the case of the skin, extra blood flow is used for thermoregulation. In addition to delivering oxygen, the blood helps dissipate heat by redirecting warm blood close to the surface where it can cool the body through the sweating and thermal radiation.

Measurement using MRI

Two main categories of magnetic resonance imaging (MRI) techniques can be used to measure tissue perfusion in vivo.
* The first is based on the use of injected contrast agent that changes the magnetic susceptibility of blood and thereby the MR signal which is repeatedly measured during bolus passage.
* The other category is based on arterial spin labeling (ASL), where arterial blood is magnetically tagged before it enters into the tissue of interest and the amount of labeling is measured and compared to a control recording obtained without spin labeling.

ee also

* Reperfusion injury
* Machine perfusion

References

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Look at other dictionaries:

• PERFUSION — PERFUSI Injection continue d’un liquide dans un vaisseau sanguin, la perfusion se pratique ordinairement par la voie veineuse. Chez le grand enfant et chez l’adulte, on utilise surtout les veines superficielles des membres; chez le nourrisson,… …   Encyclopédie Universelle

• perfusión — f. terap. Introducción de líquidos terapéuticos de forma lenta y prolongada, generalmente por vía venosa. Medical Dictionary. 2011. perfusión …   Diccionario médico

• perfusion — 1570s, from M.Fr. perfusion, from L. perfusionem (nom. perfusio) a pouring over, from pp. stem of perfundere pour out, from per throughout (see PER (Cf. per)) + fundere pour (see FOUND (Cf. found) (2)) …   Etymology dictionary

• perfusión — sustantivo femenino 1. Área: medicina Administración terapéutica de un medicamento de forma intravenosa o en el interior de una cavidad orgánica: El médico aconsejó la perfusión de un antibiótico en el suero. 2. Área: medicina Uso/registro …   Diccionario Salamanca de la Lengua Española

• Perfusion — Per*fu sion, n. [L. perfusio.] The act of perfusing. [1913 Webster] …   The Collaborative International Dictionary of English

• perfusion — perfusion. См. перфузия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

• Perfusion — (v. lat.), Begießung, Übergießung …   Pierer's Universal-Lexikon

• Perfusion — Perfusiōn (lat.), Begießung, Übergießung …   Kleines Konversations-Lexikon

• perfusión — 1. f. Acción y efecto de perfundir. 2. Baño, untura …   Diccionario de la lengua española

• Perfusion — Die Perfusion, auch Organperfusion, ist die Durchströmung eines Hohlorgans oder der Blutgefäße mit einer Flüssigkeit oder Körperflüssigkeit. Der Begriff wird vorrangig in Verbindung mit Nahrung, der Reinigung von Gewebe und dem Blutkreislauf… …   Deutsch Wikipedia