All Topics  
Perfusion

 

 
   Email Print
   Bookmark   Link
 

 

Perfusion
 
 
  Topics Perfusion Topic Home

In physiology
Physiology

Physiology is the study of the mechanical, physical, and biochemical functions of living organisms. Physiology has traditionally been divided between plant physiology and animal and all living things physiology but the principles of physiology are universal, no matter what particular organism is being studied....
, perfusion is the process of nutritive delivery of arterial blood
Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
 to a capillary
Capillary

Capillaries are the smallest of a body's blood vessels, measuring 5-10 micrometre in diameter, which connect arterioles and venules, and enable the interchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissue s....
 bed in the biological tissue
Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. Hence, a tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function....
. 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
Triage

Block quoteTriage is a process of prioritizing patients based on the severity of their condition. This rations patient treatment efficiently when resources are insufficient for all to be treated immediately....
 performed by medical or emergency personnel in a mass casualty incident.

usion ("F") can be calculated with the following formula, where Pa is mean arterial pressure
Mean arterial pressure

The mean arterial pressure is a term used in medicine to describe a notional average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle....
, Pv is mean venous pressure, and R is vascular resistance
Vascular resistance

Vascular resistance is a term used to define the resistance to flow that must be overcome to push blood through the circulatory system. The resistance offered by the peripheral circulation is known as the systemic vascular resistance , while the resistance offered by the vasculature of the lungs is known as the pulmonary vascular re...
:

The term "Pa - Pv" is sometimes presented as "?P", for the change in pressure.

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
Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 are considered overperfused and receive more blood than would be expected to meet the metabolic needs of the tissue.






Discussion
Ask a question about 'Perfusion'
Start a new discussion about 'Perfusion'
Answer questions from other users
Full Discussion Forum



Encyclopedia


In physiology
Physiology

Physiology is the study of the mechanical, physical, and biochemical functions of living organisms. Physiology has traditionally been divided between plant physiology and animal and all living things physiology but the principles of physiology are universal, no matter what particular organism is being studied....
, perfusion is the process of nutritive delivery of arterial blood
Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
 to a capillary
Capillary

Capillaries are the smallest of a body's blood vessels, measuring 5-10 micrometre in diameter, which connect arterioles and venules, and enable the interchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissue s....
 bed in the biological tissue
Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. Hence, a tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function....
. 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
Triage

Block quoteTriage is a process of prioritizing patients based on the severity of their condition. This rations patient treatment efficiently when resources are insufficient for all to be treated immediately....
 performed by medical or emergency personnel in a mass casualty incident.

Calculation

Perfusion ("F") can be calculated with the following formula, where Pa is mean arterial pressure
Mean arterial pressure

The mean arterial pressure is a term used in medicine to describe a notional average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle....
, Pv is mean venous pressure, and R is vascular resistance
Vascular resistance

Vascular resistance is a term used to define the resistance to flow that must be overcome to push blood through the circulatory system. The resistance offered by the peripheral circulation is known as the systemic vascular resistance , while the resistance offered by the vasculature of the lungs is known as the pulmonary vascular re...
:

The term "Pa - Pv" is sometimes presented as "?P", for the change in pressure.

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
Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
 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
Thermoregulation

Thermoregulation is the ability of an organism to keep its core temperature within certain boundaries, even when the surrounding temperature is very different....
. In addition to delivering oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
, the blood helps dissipate
Dissipation

In physics, dissipation embodies the concept of a dynamical system where important mechanical modes, such as waves or oscillations, lose energy over time, typically due to the action of friction or turbulence....
 heat by redirecting warm blood close to the surface where it can cool the body through the sweating
Sweating

Perspiration is the production of a fluid, consisting primarily of water as well as various dissolved solids , that is excreted by the sweat glands in the skin of mammals....
 and thermal radiation
Thermal radiation

Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the object's temperature. Infrared radiation from a common household radiator or electric heater is an example of thermal radiation, as is the light emitted by a glowing incandescent light bulb....
.

Measurement using MRI

Two main categories of magnetic resonance imaging
Magnetic resonance imaging

GaneshMagnetic resonance imaging , or nuclear magnetic resonance imaging , is primarily a medical imaging technique most commonly used in radiology to visualize the structure and function of the body....
 (MRI) techniques can be used to measure tissue perfusion in vivo
In vivo

In vivo means that which takes place inside an organism. In science, in vivo refers to experimentation done in or on the living tissue of a whole, living organism as opposed to a partial or dead one or a in vitro....
.
  • The first is based on the use of injected contrast agent that changes the magnetic susceptibility
    Magnetic susceptibility

    In electromagnetism the magnetic susceptibility is the degree of magnetization of a material in response to an applied magnetic field....
     of blood and thereby the MR signal which is repeatedly measured during bolus
    Bolus (medicine)

    In medicine, a bolus is the administration of a medication, drug or other compound that is given to raise blood concentration to an effective dose....
     passage.
  • The other category is based on arterial spin labeling (ASL), where arterial blood is magnet
    Magnet

    A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials and attracts or repels other magnets....
    ically 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.


See also

  • Reperfusion injury
    Reperfusion injury

    Reperfusion injury refers to damage to tissue caused when blood supply returns to the tissue after a period of ischemia. The absence of oxygen and nutrients from blood creates a condition in which the restoration of circulatory system results in inflammation and oxidation damage through the induction of oxidative stress rather than restorat...
  • Machine perfusion
    Machine perfusion

    Machine perfusion is a technique used in organ transplantation as a means of preserving the Organ s which are to be transplanted. To some degree, it emulates natural perfusion....
  • Perfusionist
    Perfusionist

    A perfusionist, also known as a clinical perfusionist, is a trained health professional who operates the heart-lung machine during cardiac surgery and other surgeries that require cardiopulmonary bypass....


External links