BLOOD AND PLASMA VOLUME EXPANDERS

BLOOD AND PLASMA VOLUME EXPANDERSpresented by: shyamu mandal

When blood is lost, the greatest immediate need is to stop further blood loss. The second greatest need is replacing the lost volume.The remaining red blood cells can still oxygenate body tissue.

A volume expander is a type of intravenous therapy that has the function of providing volume for thecirculatory system. It may be used for fluid replacement.These are high molecular weight substances which exerts colloidal osmotic pressure, and when infused intravenously retain fluid in the vascular compartment. They are used to correct hypovolemia due to loss of plasma or blood.Human plasma or reconstituted human albumin would seem to be the best.However, the former carries the risk of transmitting serum hepatitis, AIDS etc. and the latter is expenssive.Therefore, synthetic colloids are more often used. Desirable properties of a palsma expanders are:Should exert osmotic pressure comparable to plasma.Should remain in circulation and not leak out in tissues, or be too rapidly disposed.Should be pharmacodynamically inert.Should not be pyrogenic or antigenic.Should not interfere with grouping and cross matching of blood.

Should be stable, easily sterilizable and cheap.

TYPES OF PLASMA VOLUME EXPANDERS

There are two main types of volume expanders;

Crystalloids:-Crystalloids are aqueoussolutionsof mineral salts or other water-soluble molecules.

The most commonly used crystalloid fluid isnormalsaline, a solution ofsodium chlorideat 0.9% concentration, which is close to the concentration in the blood (isotonic).Ringer's lactateorRinger's acetateis another isotonic solution often used for large-volume fluid replacement. A solution of 5%dextrosein water, sometimes calledD5W, is often used instead if the patient is at risk for having lowblood sugaror highsodium. The choice of fluids may also depend on the chemical properties of the medications being given

Crystalloid solutionsadvantages no allergic reactionseasily availablelow effect on blood coagulationeasily mobiliseddisadvantagesmove quickly from blood vesselsno transport capacity for oxygen

Colloids:- Colloids contain larger insoluble molecules, such asgelatin;blooditself is a colloid. Common colloids used in the medical context includealbumin, Dextran and starch.Colloid solutionsadvantagesstay longer in blood vesselsrapid volume replacement (molecular weight dependent)easily available

disadvantagesallergic reaction possiblevarious effect on blood coagulationdifficulty in mobilisationno transport capacity for oxygen

HUMAN ALBUMIN it is obtained from pooled human plasma; 100 ml of 20% human albumin solution is the osmotic equivalent of about 400 ml of fresh frozen plasma or 800 ml of whole blood. it can be used without regard to patients blood group and does not interfare with coagulation.Unlike whole blood or plasma, it is free from the risk of transmitting serum hepatitis because the preparation is heat treated.The 20% solution draws and holds additional fluid from tissues; therefor crystslloid solutions must be infused concurently for optimum benefit. Uses: Burns Hypovolaemic shockHypoproteinaemiaAcute liver failure and dialysis.

DEXTRANIt is polysaccharide obtained from sugar beat which is available in two forms:Dxtran-70, molecular weight=70,000Dextran-40, molecular weight=40,000

The more commonly used preparation is dextran-70. it expands plasma volume for nearly 24 hours, and is slowly excreted in glomerular filtration as well as oxidised in the boby over weeks. Some amounts is deposited in RE cells.Dextran has nearly all properties of an ideal plasma volume expanders except:It may interfere with blood grouping and cross matching.It may trigger anyphylactic reaction.It can interfere with coagulation and paltelet function.

Dextran-40, acts more rapidly than dextran-70. it reduces the blood viscosity and prevents RBC sludging that occurs in shock. It rapidly filtered at glomerulus, expands plasma volume for shorter duration.

The total dose should not exceed 20ml/kg in 24 hours.DEGRADED GELATIN PLYMERIt is also called as polygeline.It is a polypeptide with averege MW 30,000, which exerts osmotic pressure similsr to albumin and is not allergic, hypersensitivity reactions are rare, but should be watched for it.It is not interfere with grouping and cross matching of blood and remains stable for 3 years.It is not metabolized in the body, excreted slowly by the kidneys.Expands plasma volume for 12 hours.

It is more expensive than dextran.

Hypersensitivity reactions like flushing, rigor, urticaria, wheezing and hypertension can occur.HYDROXYETHYL STARCHIt is a complex mixture of ethoxylated amylopectin of various molecular sizes; averege molecular weight 4.5 lac(range 10,000 to 1 million).The colloidal properties of 6% HES approximate those of human albumin. Plasma volume expands slightly in excess of the volume infused.Haemodynamic status is improved for 24 hours or more.Smaller mplecules(MW