Plasma substitutes

Poly(vinyl pyrrolidone). Another commercial polymer with significant usage is PVP (7). It was developed ia World War II as a plasma substitute for blood... 

The major use of vinylpyrrohdinone is as a monomer in manufacture of poly(vinylpyrrohdinone) (PVP) homopolymer and in various copolymers, where it frequendy imparts hydrophilic properties. When PVP was first produced, its principal use was as a blood plasma substitute and extender, a use no longer sanctioned. These polymers are used in pharmaceutical and cosmetic appHcations, soft contact lenses, and viscosity index improvers. The monomer serves as a component in radiation-cured polymer compositions, serving as a reactive diluent that reduces viscosity and increases cross-linking rates (see... 

First developed in Germany by I. G. Farben (W. Reppe) during the 1930s, PVP was subsequentiy widely used in Germany as a blood-plasma substitute and extender during World War II (69). In the United States, it has been manufactured since 1956 by ISP, and more recentiy by BASF. 

Poly(vinyl pyrrolidone) (PVP) was introduced by the Germans in World War II as a blood plasma substitute.A water-soluble polymer, its main value is due to its ability to form loose addition compounds with many substances. 

A number of other polysaccharides, such as glycogen, dextran, chitin, etc., possess interesting structures for chemical modification [103,104]. Dextran has been used as a blood plasma substitute. Although it can be converted to films and fibers, chitin s relatively small resource restricts its commercialization. 

Dextrans are particularly useful and are employed as a plasma substitute. A concentration of about 6% dextran (50,000-100,000 relative molecular weight) has equivalent viscosity and colloid-osmotic properties to blood plasma. Dextran can also be used as non-irritant absorbent wound dressings, an application also suited to alginate gels. 

Other important examples are blood and blood products, which are collected and processed in sterile containers, and plasma substitutes, for example dextrans and degraded gelatin. Dextrans, glucose polymers consisting essentially of (1 - 6) a-links, are produced as a result of the biochemical activities of certain bacteria of the genus Leuconostoc, e.g. L. mesenteroides (see Chapter 25). 

Dextrans are produced commercially for use as plasma substitutes (plasma expanders) which can be administered by intravenous injection to maintain or restore the blood volume. They can be used in applications to ulcers or bum wounds where they form a hydrophilic layer which absorbs fluid exudates. 

When plasma is ON , the NO conversion is rising from 2 to 40%, at 280°C (553 K). Figure 5.16 shows the presence, at the outlet of the catalytic reactor, of unreacted 0 0., and RNO species, demonstrating that the plasma substitutes the catalytic function 2 of the DeNO process. 

Gelatin is a plasma substitute. Plasma substitutes should not be used to maintain plasma volume in burns or peritonitis. In these scenarios albumin should be given. Close monitoring, including monitoring of fluid and electrolyte balance and urine output, is required in patients being administered plasma and plasma substitutes. Plasma substitutes should also be used with caution in patients with cardiac disease, liver disease or renal impairment. 

To eliminate the threat of shock, replenishment of the circulation is essential. With moderate loss of blood, administration of a plasma volume expander may be sufficient Blood plasma consists basically of water, electrolytes, and plasma proteins. However, a plasma substitute need not contain plasma proteins. These can be suitably replaced with macromolecules ( colloids ) that like plasma proteins, (1) do not readily leave the circulation and are poorly filtrable in the renal glomerulus and (2) bind water along with its solutes due to their colloid osmotic properties. In this manner, they will maintain circulatory filling pressure for many hours. On the other hand, volume substitution is only transiently needed and therefore complete elimination of these colloids from the body is clearly desirable. 

Compared with whole blood or plasma, plasma substitutes offer several advantages they can be produced more easily and at lower cost, have a longer shelf life, and are free of pathogens such as hepatitis B or C or AIDS viruses. 

Secondary hypotension is a sign of an underlying disease that should be treated first. If stroke volume is too low, as in heart failure, a cardiac glycoside can be given to increase myocardial contractility and stroke volume. When stroke volume is decreased due to insufficient blood volume, plasma substitutes will be helpful in treating blood loss, whereas aldosterone deficiency requires administration of a mineralocor-ticoid (e.g., fludrocortisone). The latter is the drug of choice for orthostatic hypotension due to autonomic failure. A parasympatholytic (or electrical pacemaker) can restore cardiac rate in bradycardia. 

In addition to murein, bacterial polysaccharides include dextrans—glucose polymers that are mostly al 6-linked and al 3-branched. In water, dextrans form viscous slimes or gels that are used for chromatographic separation of macromolecules after chemical treatment (see p.78). Dextrans are also used as components of blood plasma substitutes (plasma expanders) and foodstuffs. 

On the positive side, dextran itself has been refined and employed as a therapeutic agent in restoring blood volume for mass casualties. Natural dextrans have very high molecular weight (on the order of 10 -10 Da) and are found to be unsuitable as a blood-plasma substitute. Lower molecular weight (about 10 Da) dextran is suitable and often referred to as clinical dextran. 

Oligemic shock may be managed by rapid infusion of blood plasma or plasma substitutes/expanders and simultaneously the source of blood / fluid loss in identified and corrected. 

Plasma substitutes/expanders are high molecular weight substances when infused intravenously into blood stream retain fluid in the vascular compartment and exert oncotic pressure. But before infusing into the blood stream, the following requirement may be present. 

It is a plasma substitute which corrects circulatory insufficiency due to plasma/ blood volume deficiency, absolute (e.g., resulting from bleeding) or relative (e.g., resulting from a shift in the blood volume between the circulatory compartments). 

WATER SOLUBLE POLYMERS. Water-soluble polymers find application in a wide variety of areas that include polymers as food sources, plasma substitutes, and as diluents in medical prescriptions. Other areas of importance for water-soluble polymers include detergents, cosmetics, sewage treatment, stabilizing agents in the production of commodity plashes, rheology modifiers in the various processes for petroleum, textile, paper, and latex coatings production. The water-soluble polymers discussed in this article have significant commercial impact. 

Poly(vinyl pyrrotidone). Another commercial polymer with significant usage is PVP. It was developed in World War II as a plasma substitute lor blood. This monomer polymerizes faster in 50 water than it does in bulk, an abnormality inconsistent with general polymerization kinetics. This may be due to a complex with water that activates the monomer it may also be related to the impurities in the monomer that are difficult to remove. See also Vinyl Acetal Polymers. 

Many pioneer structural investigations were carried out in other groups of polysaccharides, notably on inulin, on the xylan from esparto, on the mannan from yeast and on a series of bacterial polysaccharides amongst the latter were included somatic and lipoid-bound polysaccharides from M. tuberculosis. Noteworthy also was the work on the dextran produced by strains of Leuconostoc, which is showing grqat promise as a blood plasma substitute. 

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