Oncotic Pressure

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oncotic pressure

[äŋ′käd·ik ′presh·ər]
Also known as colloidal osmotic pressure.
The osmotic pressure exerted by colloids in a solution.
The pressure exerted by plasma proteins.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Oncotic Pressure


the component of osmotic pressure that is contributed by substances of high molecular weight in a solution.

In human blood plasma, oncotic pressure ranges from 3 to 4 kilonewtons per square meter, or from 0.03 to 0.04 atmospheres; this constitutes only about 0.5 percent of the total osmotic pressure. Nevertheless, oncotic pressure plays a major role in the formation of some of the body’s fluids, including the intercellular fluid and capsular urine.

The walls of capillary blood vessels are readily permeable to water and substances of low molecular weight, but not to proteins. The filtration rate of fluid through the capillary wall is determined by the difference between the oncotic pressure, which is contributed by plasma proteins, and the blood’s hydrostatic pressure, which is a function of the heart. The saline solution at the arterial end of the capillary passes into the intercellular space together with nutrients. At the venous end of the capillary the process takes place in the opposite direction, since venous pressure is lower than oncotic pressure, and substances that are eliminated by the cells pass into the blood (see).

The oncotic pressure diminishes in diseases that involve a decrease in the concentration of blood proteins—especially albumins. This pressure decrease may be one of the reasons why fluid accumulates in the intercellular space and causes edema.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Reported diluents have been cell free solutions (Domingo-Pech et al., 1991; Wagner et al., 2003; Erasmus et al., 2006; Friebe et al., 2013b) or autologous plasma (Patan et al., 2009; Patan-Zugaj et al., 2012, 2014), which comes with the added benefit of increasing oncotic pressure. As cell free solutions are associated with low oncotic pressure, resulting in edema formation and weight gain, adding plasma expanders such as plasma proteins (Verbeke et al., 1968; Roets et al., 1974; Patan et al., 2009) and purified albumin (Rehfeld et al., 1982; Barthel et al., 1989; Riviere et al., 1989; Brunicardi et al., 2001) may be necessary.
The oncotic pressure values and FVIII values are presented in Table-III.
Albumin creates the oncotic pressure in the intravascular fluid compartment allowing for the movement of fluid from interstitial tissue to intravascular space (Amato, et al., 2008).
The effect of the reduction of colloid oncotic pressure, with and without reduction of osmolality, on post-traumatic cerebral edema.
Major physiologic functions of albumin include maintaining plasma oncotic pressure, serving as a reservoir of amino acids for incorporation into other proteins, and transporting a wide variety of low-molecular-weight molecules.
This was done in an effort to keep the patients with adequate intravascular oncotic pressure but with a negative fluid balance.
Keep in mind that women with multiple gestations have an elevated risk of cardiovascular complications, such as pulmonary edema resulting from anemia, lower colloid oncotic pressure, and higher blood volume.
The increased blood volume of pregnancy along with the decreased colloid oncotic pressure is going to make a woman particularly vulnerable to heart failure if she also has LVH."
AFP contributes to oncotic pressure in the fetal circulation.
It has been postulated that decreased pulmonary hydrostatic pressure and increased pulmonary oncotic pressure secondary to dehydration or volume depletion may diminish the flux of fluid into the alveoli and interstitium and thus delay or alter the radiographic findings of pneumonia.[19] Cooligan and coworkers[20] found that small increases in pulmonary capillary wedge pressure increased wet lung weight in euvolemic dogs with pneumococcal pneumonia, but no radiographic evaluation was performed.
oncotic pressure Pressure within a fluid compartment that depends on the concentration of proteins.
The artificial cells were rapidly removed from circulation and they give unfavourable oncotic pressure levels crucial for efficient [O.sub.2]-[CO.sub.2] exchange.