Volume expanders

Whole blood is seldom used ia modem blood transfusion. Blood is separated into its components. Transfusion therapy optimizes the use of the blood components, using each for a specific need. Red cell concentrates are used for patients needing oxygen transport, platelets are used for hemostasis, and plasma is used as a volume expander or a source of proteins needed for clotting of the blood. 

History. Methods for the fractionation of plasma were developed as a contribution to the U.S. war effort in the 1940s (2). Following pubHcation of a seminal treatise on the physical chemistry of proteins (3), a research group was estabUshed which was subsequendy commissioned to develop a blood volume expander for the treatment of military casualties. Process methods were developed for the preparation of a stable, physiologically acceptable solution of alburnin [103218-45-7] the principal osmotic protein in blood. Eady preparations, derived from equine and bovine plasma, caused allergic reactions when tested in humans and were replaced by products obtained from human plasma (4). Process studies were stiU being carried out in the pilot-plant laboratory at Harvard in December 1941 when the small supply of experimental product was mshed to Hawaii to treat casualties at the U.S. naval base at Pead Harbor. On January 5, 1942 the decision was made to embark on large-scale manufacture at a number of U.S. pharmaceutical plants (4,5). 

Hydroxyethylstarch [9005-27-0] has been investigated by hydrodynamic and magnetic spectroscopic methods (128) because of its increasing use as a plasma volume expander. 

The quantity of all gas originally present in a reservoir prior to production, expressed as the volume expanded to standard conditions. 

This isotonic volume expander contains sodium, potassium, chloride, and lactate that approximates the fluid and electrolyte composition of the blood. Ringer s lactate (also known as lactated Ringer s or LR) provides ECF replacement and is most often used in the perioperative setting, and for patients with lower GI fluid losses, burns, or dehydration. The lactate component of LR works as a buffer to increase the pH. Large volumes of LR may cause metabolic alkalosis. Because patients with significant liver disease are unable to metabolize lactate sufficiently, Ringer s lactate administration in this population may lead to accumulation of lactate with iatrogenic lactic acidosis. The lactate is not metabolized to bicarbonate in the presence of liver disease and lactic acid can result. 

Human albumin is a colloid used as a plasma volume expander and is not a source of nutrition. Albumin should be administered separately from PN because it may be incompatible and... 

When most liquids cool down, their volume gradually contracts. Water also contracts when it cools down, but only until the temperature reaches 4°C, when it is at it lowest volume, expanding as the temperature decreases or increases. 

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers have shown efficacy in preventing the clinical progression of renal disease in patients with type 2 DM. Diuretics are frequently necessary due to volume-expanded states and are recommended second-line therapy. 

Serum sodium concentration is generally maintained by an increase in fractional excretion of sodium, resulting in a volume-expanded state. The most common manifestation of increased intravascular volume is systemic hypertension. 

Medical Management Immediate decontamination after exposure is the only way to prevent damage to victims, followed by symptomatic management of lesions. Hospital care tends to be supportive. It should be repeated that liquid arsenical vesicants produce more serious lesions on dermal surfaces than do liquid mustard. In toxic victims, liberal fluids by mouth or intravenous, and high-vitamin, high-protein, high-carbohydrate diets could be indicated. For those victims where shock is in evidence, provide the usual supportive measures such as intravenous administration, blood transfusions, or other vascular volume expanders should be indicated. 

Roberts IS, Bratton SL. Colloid volume expanders. Problems, pitfalls and possibilities. Drugs 1998 55 621. 

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. 

Three colloids are currently employed as plasma volume expanders— the two polysaccharides, dextran and hydroxyethyl starch, as well as the polypeptide, gelatin. 

Plasma Protein Fraction (Plasmanate, Others) [Plasma Volume Expander] Uses Shock 4- BP Action Plasma volume expander Dose Adults. Initial, 250-500 mL IV (not >10 mL/min) subsequent inf... 

HSA Plasma volume expander Human plasma/placenta... 

Table 9.3. Some colloidal plasma volume expanders currently in therapeutic use. In addition to these, albumin and plasma protein fraction may also be used...

Rarely is it necessary to keep a patient in bed for prolonged periods. Those with serious cardiovascular disease, should have their doses increased even more slowly, with blood pressure frequently monitored. Acute orthostasis can usually be managed by having the patient lie down with feet elevated. On rare occasions, volume expanders or vasopressors may be required. 

Special reference should be made to resin-liquid systems, where the phenomenon of swelling makes the case more complex. A resin s matrix is flexible and when immersed in a liquid, its volume expands, leading to an increase in its particle diameter and in turn, to a decrease in particle density (mass of diy resin per volume of swollen particle). Furthermore, the loading of the resin with ions results in further changes in its volume (Helfferich, 1995). Thus, in these cases, the particle density and diameter as well as the hydraulic density should be referred to for the swollen and loaded resin. In practice, a mean value is frequently used. 

Plasma volume expanders and artificial blood substitutes... 

Human plasma has a colloid osmotic pressure of 3.6 kPa, of which 2.8 kPa is contributed by albumin. Volume-for-volume, 4.5% albumin is approximately four times more effective in expanding the plasma volume than crystalloid solutions, and the effect lasts 6-8 hours, compared to only 15-20 min with crystalloids. Although popular in the past as volume expanders, albumin solutions have fallen into disfavour. They are prepared from pooled human plasma, with all the inherent risks of pooled blood products. Albumin can cause adverse reactions, similar to other transfusion reactions, such as chills, urticaria, and vasodilatation. These may be caused by organic or inorganic substances formed during the processing... 

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