(Mode of Action of Drugs)

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Chapter

1.4

Chapter

4.6 Plasma Expanders

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

• Should have same oncotic pressure
  with plasma.


• Should remain in blood stream for ad-
  equate period.


• Should not be disposed rapidly by
  metabolic degradation or by excretion.


• Should remain stable on storage.


• Should not interfere with blood group-
  ing and cross matching.


• Should be compatible with other IV
  fluid and other drugs.


• Should be easily sterilized.


• Should be pharmacologically inert and
  have a viscosity suitable for infusion
  into blood stream.
  They are used in conditions where
  blood plasma has been lost e.g. shock, burn
  cases, severe trauma and extensive tissue
  damage as a temporary measure till the

Plasma Expanders

blood can be arranged. These do not have

O 2 carrying capacity.

The clinically used plasma expanders

are classified as in table 4.6.1.

HUMAN ALBUMIN

It is obtained from heat treated pooled

human plasma. 100 ml of 20% human albu-

min solution is osmotic equivalent of 800 ml

of whole blood. It draws and holds addi-

tional fluid from tissues. It can used irrespec-

tive of patient’s blood group. For optimum

benefit it should be used with electrolyte

solutions. It does not interfere with coagu-

lation and there is no risk of sensitization.

Table 4.6.1: Classification of plasma substitutes/

expanders.

I. Human albumin (20% solution; ALBUSAFE)

II. Dextran

Dextran 70 (Mol. wt. 70,000; 6% solution;

LOMODEX-70)

Dextran 40 (Mol. wt. 40,000; 10% solution;

LOMODEX-40)

III. Degraded gelatin polymer – polygeline (3.5% in

electrolyte solution; HAEMACCEL)

IV. Hydroxyethyl starch (HES; Hetastarch; 6%

solution; HESTAR)

V. Polyvinylpyrrolidone (PVP; 3.5% solution in

buffered normal saline; OSMOPLASMA)