Colloidal plasma volume expanders

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...

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... 

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. 

Hetastarch (Hespan) [Plasma Volume Expander] Uses Plasma volume expansion adjunct in shock leukophoresis Action Synthetic colloid acts similar to albumin Dose Volume expansion 500-1000 mL (1500 mL/d max) IV (20 mL/kg/h max rate) Leukapheresis 250-700 mL X- in renal failure Caution [C, +] Contra Severe bleeding disorders, CHF, oliguric/anuric renal failure Disp Inj SE Bleeding (T PT, PTT, bleed time) EMS Observe for anaphylactic Rxns OD Unlikely but may cause fluid overload in susceptible pts... 

Use Photographic film sizing textile and paper adhesives cements capsules formedicinals matches light filters clarifying agent desserts, jellies, etc. culture medium for bacteria blood plasma volume expander microencapsulation printing inks nutrient protective colloid in ice cream. 

Dissolved in normal saline with a concentration of about 6%, dextran exhibits similar colloid osmotic pressure and viscosity as human blood. Therefore, dextran has been used as plasma volume expander for several decades.Dextran 40 and 70, with molecular weight of 40 and 70 kDa, respectively, are prescribed for the treatment of shock or impending shock due to hemorrhage, bums, or trauma. 

HES are S5mthetic colloid solutions used as plasma volume expanders in a range of clinical settings, including hypovolaemia. The EU Pharmacovigilance Risk Assessment Committee reviewed the benefits and risks of HES products in different patient groups. The review concluded that there was a clear indication of harm when HES was used for fluid resuscitation and there was no evidence of extended benefit when compared with crystalloid solutions [34 ]. 

Alternatively, colloidal plasma expanders (Table 9.3) are used. When administered at appropriate concentrations, they exert an osmotic pressure similar to that of plasma protein, hence vascular volume and blood pressure are maintained. The major disadvantages of colloidal therapy include its relatively high cost, and the risk of prompting a hypersensitivity reaction. Determined elforts to develop blood substitutes were initiated in 1985 by the US military, concerned about the issue of blood supply to future battlefields. 

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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