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Guidelines for plasma and red cell therapy in critical patients (Proceedings)

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Apr 01, 2008

Plasma

Plasma might be administered for its albumin or coagulation factor content. Albumin is important to colloid osmotic pressure and because it is negatively charged is an important carrier of certain cations, drugs, hormones, metals, enzymes, chemicals, and toxins.

Plasma, which has been separated from collected whole blood, could be administered to supplement albumin concentration and colloid osmotic pressure, but is expensive (compared to artificial colloids) and not very effective, particularly in the face of ongoing protein losses. Prepared plasma products, when they are diluted with anticoagulant, have an albumin concentration that is lower than it was in the donor. Large volumes would be necessary to affect albumin concentrations in the recipient.

The provision of coagulation factors is the most common reason to administer plasma. Whole blood and fresh plasma (within 8 hours of its collection) contains all of the coagulation factors and, depending on how it was separated, most of the platelets contained in the whole blood from which it is derived. A hard spin at 5000 rpm for 5 minutes places the platelets in the buffy coat; the plasma supernatant has no platelets. Platelet rich plasma is produced with a soft spin of about 2500 rpm for 2.5 minutes which does not separate the platelets from the plasma. Platelet rich plasma is produced by harvesting the buffy coat after a hard spin. Whole blood and plasma products intended for use for its platelets should be maintained at room temperature and gently rocked. Refrigeration or freezing destroys platelet activity. Fresh plasma and fresh frozen plasma is efficacious for the treatment of all coagulation disorders. Fresh frozen plasma (within 6 to 8 hours) preserves all of the labile (V, VII, and vonWillebrand's) and stabile (fibrinogen, II, VII, IX, X, XIII, and antithrombin) coagulation factors (Nilsson L, 1983; Sidhu RS, 2006; Furianello T, 2006). Refrigerator storage is associated with a significant loss of factor VIII and vonWillebrand's activity by 24 hours and of factors V and XI by one week (Nilsson L, 1983; Sidhu RS, 2006; Furianello T, 2006). Cryoprecipitate provides a concentrated source of factor VIII, XIII, von Willebrand's, fibrinogen, and fibronectin (Lundberg GD, 1994). Refrigerator stored plasma, plasma frozen after 8 hours post-collection, and fresh frozen plasma beyond one year still contains the stabile factors and is effective for the treatment of warfarin-related rodenticides.

In addition to worsening of congestive heart failure, rebleeding, and dilutional anemia, plasma administration is relatively expensive. Homologous albumin infusions may occasionally be associated with a transfusion reaction. Twenty-five percent human albumin has been administered to dogs and very effectively augments plasma protein concentration and colloid osmotic pressure (Mathews KA, 2005). First time infusions, however, have been associated with acute and delayed transfusion reactions (Francis AH, 2007; Cohn LA, 2007).

Hemoglobin

Blood must be anticoagulated when it is collected into an artificial container for subsequent administration. Heparin could be used if the blood is to be immediately re-transfused (a minimum of 1 unit of heparin/ml of whole blood). However, acid-citrate-dextrose (ACD) or citrate-phosphate-dextrose (CPD) (0.15 ml of solution/ml of whole blood) are more commonly used. CPD-A1 provides 70% red cells viability for up to 5 weeks. After this time, the plasma can be separated and stored frozen. Infused blood should be filtered.

Although many canine erythrocyte antigens have been identified, only 6 (DEA 1.1, 1.2, 3, 4, 5, and 7) are commonly tested (Hale AS, 1995). Dog erythrocyte antigen 1.1 and 1.2 are the most antigenic and are present in approximately 62% of the canine population (Hale AS, 1995). Fortunately naturally-occurring isoantibodies to DEA 1.1 and 1.2 do not exist and, in this regard, first-time transfusions are relatively safe. Donors and recipients should be DEA 1.1 and 1.2 typed to assure that recipients receive type-similar blood. DEA 1.1 and 1.2 negative recipients should not receive type-positive blood because it would prime them from a second-time transfusion reaction. The other four canine blood groups are weak antigens as are any naturally-occuring isoantibodies and transfusion reactions are mild if they occur at all. In vitro cross matching would help sort out potentially incompatible transfusion from any cause and may be important for sequential transfusions and in immune-mediated hemolytic anemia.