Blood products that do not contain red blood cells are derivatives of plasma. Although the most common blood product transfused is whole blood for the treatment of anemia, transfusion of blood products that do not contain red blood cells are important in the treatment of coagulation disorders. Because there are no uniformly accepted unit size standards, for this discussion a unit of canine whole blood will be the blood plus the anticoagulant collected from 1 dog into a standard blood bag, which contains approximately 450 ml of blood and 63 ml of anticoagulant preservative solution. A "unit" of a component is the volume of a product produced from 1 unit (450 ml of blood and 63 ml of anticoagulant preservative solution) of whole blood. This information will not apply to blood from all blood banks and the reader is referred to the product insert for information regarding a particular blood banks products. Because feline blood is collected in such a small volume and there is a lack of appropriate sized multi-bag systems, it is not typically processed into components, but it is possible to do so.

Volume* in various units of canine blood products.

* Not standardized in veterinary medicine

Fresh Frozen Plasma (FFP)

Plasma obtained from whole blood, and centrifuged, within 6 hours of collection is FFP. The anticoagulant remains in the plasma fraction during processing. When it is frozen at -30C, the clotting factors maintain activity for 1 year. If frozen at -20C in a household upright, non frost free freezer, activity is maintained for 6 months. FFP is an excellent source of clotting factors and can be used to treat a wide variety of hemorrhagic disorders, including inherited disorders such as hemophilia and von Willebrand's disease or acquired disorders such as rodenticide intoxication and DIC. It is not a good source of albumin or nutritional support. Calculations indicate 45 ml/kg of FFP would be required to increase the serum albumin concentration by 1 g/dl, assuming no ongoing protein loss. In veterinary patients, hypoalbuminemia commonly results from protein losing disorders such as enteropathy and nephropathy. Plasma administration in these cases is very likely to be unsuccessful in increasing the plasma albumin concentration due to ongoing losses. FFP may be used in puppies or kittens with failure of passive transfer as a source of immunoglobulin at a dosage of 22-150 ml/kg.

The initial dosage is 6-10 ml/kg one to three times daily depending on the condition being treated and the response to therapy. For cases of anticoagulant rodenticide intoxication, a single dose of plasma and vitamin K therapy may be adequate. Treatment of DIC may involve multiple plasma transfusions and correction of the underlying disease.

Cryoprecipitate is a concentrated source of von Willebrand's factor, fibrinogen (factor I) and factor VIII prepared from 1 unit of FFP. Fresh frozen plasma is thawed at 4C. During thawing, a white precipitate (cryoprecipitate) forms in the plasma and this precipitate contains vWf, factors VIII and I. The cryoprecipitate is separated from the liquid plasma by centrifugation. The liquid plasma is termed cryo-poor plasma. Cryoprecipitate is used to treat von Willebrand's disease, hemophilia A and fibrinogen deficiency. Storage and handling of cryoprecipitate is similar to fresh frozen plasma. It can be stored at--20C for 1 year. Like any plasma component, cryoprecipitate may cause allergic reactions.

The initial dosage is 1 unit per 10 kg of body weight.

Cryo-poor plasma is the plasma, which remains after the cryoprecipitate is removed. Cryo-poor plasma contains factors II, VII, IX and X which makes it useful for the treatment of rodenticide intoxication.

Storage and handling of cryo-poor plasma is similar to fresh frozen plasma. Like any plasma component, cryo-poor plasma may cause allergic reactions.

The initial dosage is 1 unit per 10 kg of body weight.

Platelet rich plasma (PRP) isprepared from fresh whole blood by centrifugation at fewer revolutions per minute than for production of pRBC and plasma. The platelets are suspended in plasma to facilitate transfusion and transfused within hours of collection. Refrigeration destroys platelet function and PRP should be maintained at room temperature until transfused. Allogeneic platelet transfusions should be most useful in cases of decreased platelet production rather than cases of increases consumption or destruction of platelets. Unfortunately, increased destruction of platelets is the most common cause of thrombocytopenia in the dog.

The dosage is 1 unit of platelets per 10 kg of body weight.

Frozen platelets are collected through plateletpheresis. Platelets are preserved by DMSO and also contain a small amount of fresh frozen plasma. Efficacy data on this product has not been published, but it has been suggested to use this product for the treatment of immune mediated thrombocytopenia.

The dosage is 1 unit of platelets per 10 kg of body weight. This should increase the platelet counted 20,000/Ml when counted 1-2 hours post transfusion.

Human immunoglobulin (hIg) is a concentrated source of immunoglobulin produced from the plasma of over 1000 humans via ethanol cold fractionation technique. In a limited number of cases, it has been used to treat acute cases of canine immune mediated hemolytic anemia. It is believed that providing the large number of immunoglobulin molecules overwhelms the reticuloendothelial system and prevents it from destroying additional red blood cells.

The recommended dosage is 0.5-1g/kg and hIg is infused over 6-8 hours.

Adverse events associated withtransfusion of a plasma-containing component are urticaria and fever. Treatment for this reaction is to discontinue the plasma, treat with steroids and antihistamines. In most cases the FFP transfusion can be resumed at a slower rate as the allergic reaction subsides. Plasma containing components are colloid solutions and like any colloid, may provoke transfusion associated circulatory overload (TACO). Because frozen platelets are cryopreserved in DMSO, they must be transfused slowly over 1-2 hours or bradycardia will result. Typically, plasma is administered at 4-6 ml/kg/hr. Fever associated with plasma transfusion may be due to antibodies contained in the plasma or due to infection. Treatment is not required for antibody mediated fever, but infection associated fever is much more serious. Bacteria, either donor derived or from environmental contamination can be transmitted to the plasma recipient. Because hIg is a species-specific protein, multiple administrations of hIg would be expected to cause serious anaphylactic reactions. No serious allergic reactions have been reported in dogs or cats administered hIg. Initial therapy has been associated with thrombosis and thrombocytopenia, but these abnormalities may be a result of the primary disease not the immunoglobulin infusion.

Available plasma containing blood products.

*The dosage of any blood product is simply a guideline for the initial transfusion. All transfusions are given "to effect" meaning until adequate coagulation factors have been transfused to correct the coagulation factor deficiency.
#Transfusion associated circulatory overload

References

1.  Henson MS, Kristensen AT, Armstrong PJ, et al. Feline blood component therapy: retrospective study of 246 transfusions. J Vet Int Med 1994;8:169

2.  Logan JC, Callan MB, Drew K, et al. Clinical indications for use of fresh frozen plasma in dogs: 74 dogs (October-December 1999). J Vet Med Assoc 2001;218:1449-1455.

3.  Meyers KM. Wardrop KJ, Meinkoth J. Canine von Willebrand's disease; pathobiology, diagnosis and short-term treatment. Comp Cont Ed 1992;14:13-22.

4.  Scott-Moncrieff JCR, Regan WJ, Glickman LT, et al. Treatment of non regenerative anemia with human gamma-globulin dogs. J Am Vet Med Assoc 1995;206:1895-1900.

5.  Scott-Moncrieff JCR, Regan WJ, Snyder PW, et al. Intravenous administration of human immune globulin in dogs with immune mediated hemolytic anemia. J Am Vet Med Assoc 1997;210:1623-1627.

6.  Wardrop KJ. Canine plasma therapy. Vet Forum 1997;14:36-40.

7.  Wardrop KJ, Brooks MB. Stability of hemostatic proteins in canine fresh frozen plasma units. Vet Clin Path 2001;30:91-05.