Page 440 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

428 FLUID THERAPY

cardiopulmonary bypass, ristocetin-induced platelet of plasma products in the future. In dogs and cats with
agglutination was significantly impaired, and this effect portosystemic shunts, there is concern about the ammo-
was not corrected by the use of aprotinin as compared nia content of stored plasma because it tends to increase
with the control group (albumin prime). 179 There also with time. Clinical signs of encephalopathy in these
was a direct correlation between postoperative blood loss patients are related in part to blood ammonia concentra-
and the amount of gelatin used during the operation with tion, and it is advisable not to burden them with an addi-
the greatest blood loss occurring in patients receiving tional source of ammonia.
more than 3.5 L of gelatin (approximately 45 mL/
kg). 179 In another study evaluating human patients ALBUMIN
undergoing orthopedic surgery, no major differences Concentrated solutions of human albumin have been used
were noted between patients receiving similar volumes in dogs to increase colloid osmotic pressure and maintain
of 6% HES or 3% gelatin (<33 mL/kg/day) for colloid blood volume. Early results appeared to be quite
replacement. 13 Despite these findings, gelatin infusions promising, 119,184 but it has become evident that severe
often are given rapidly to veterinary patients before or immune reactions may occur in response to infusion of
during surgery with little evidence of adverse effects on human albumin solutions. 38,62,118,184 A lyophilized
coagulation or histamine release. canine albumin solution has now become commercially
available (Animal Blood Resources International, Dixon,
PLASMA PROTEIN Calif.), but there are no reports yet on its safety or efficacy.
Plasma protein is available either as a fresh or frozen prep-
aration or as liquid or frozen plasma that has been PACKED RED BLOOD CELLS
harvested during the collection and storage of blood. Packed red cells are used primarily in patients with low
Fresh plasma may be prepared so that it contains platelets hematocrits before surgery or in patients that are likely
(platelet-rich plasma) and clotting factors. It must be to have low tolerance for a decreased hematocrit that
used within 4 hours of preparation because of the risk develops during surgery (e.g., a patient with minimal car-
of bacterial contamination at the recommended room diovascular reserve). It is advisable to crossmatch both
temperature storage. Fresh frozen plasma contains clot- dogs and cats before transfusion. Crossmatching requires
ting factors, which are destroyed if the unit has been some time, and it is important to plan for the use of
thawed for more than 8 hours, but contains no platelets. packed red cells by having the crossmatch results available
Fresh frozen plasma can be used in any situation in which before the animal requires transfusion. The indications
blood volume must be expanded, hematocrit is within an for packed red cells are given in the earlier section on
acceptable range, and no allergic reaction to foreign pro- Anemia. Administration of packed red cells can be diffi-
tein is anticipated. If there is no major concern about cult because of the viscosity of the solution and can be
dilution of existing clotting factors, the stored form of facilitated by diluting the cells with warm normal saline,
the plasma can be used. The infusion of plasma tends by using adult rather than pediatric administration sets,
to increase colloid osmotic pressure and increase both and by using the largest venous access possible (ideally
serum albumin and globulin concentrations. The main >20 gauge). Smaller needles (<20 gauge) tend to
concerns about the use of plasma intraoperatively are cost impede the flow of the blood and may lead to hemolysis
and the potential for allergic reactions. Commercially, if external pressure is applied for the administration.
plasma is more expensive than any of the other colloids,
but its use is justified in animals with marginal coagula- WHOLE BLOOD
tion (e.g., use of fresh frozen plasma in a patient with Ideally, whole blood is used when the animal needs all of
low plasma protein concentration related to hepatic dys- the components present in whole blood. Practically,
function) or in surgical cases in which there is concern whole blood often is used because it is more convenient
about dilutional coagulopathy. Life-threatening allergic than individual component therapy. Fresh whole blood
reactions to plasma infusions are not common, but urti- contains all of the normal clotting factors and active
caria may be observed. The author has not seen any platelets. Clotting factors and platelets deteriorate within
episodes of profound hypotension associated with plasma the first 24 hours, and stored whole blood is ineffective at
infusions but has seen considerable swelling of the head restoring normal coagulation. Whole blood typically is
and limbs develop. If such a reaction occurs, the plasma used in patients that are bleeding actively or have already
infusion should be stopped immediately and the animal lost a large volume of blood and are likely to become
treated with antihistamines (H 1 and H 2 blockers). severely hemodiluted if other fluids are used. Some con-
Corticosteroids also may be administered if warranted cern has been expressed about the effect of blood trans-
by the severity of the reaction. This type of therapy rarely fusion on immune function. A beneficial effect was first
reverses the clinical signs but may prevent exacerbation of noticed in renal transplant patients. Patients who had
the condition. A note should be made in the patient’s received blood transfusions in association with renal
medical record to ensure that it does not receive infusions transplantation were less likely to reject the grafted