Page 605 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Blood Transfusion and Blood Substitutes 593

COLLECTION OF BLOOD PRETRANSFUSION
COMPATIBILITY TESTING
DOGS
Selection and transfusion of compatible blood is one
Dogs that have not previously donated blood may require
component of the process to provide a safe and efficacious
sedation, whereas dogs that have previously donated
red cell transfusion. With the identification of a new
often do not. If sedation is necessary, the author prefers
red blood cell antigen in both dogs and cats,
butorphanol (0.1 mg/kg intravenously, 10 to 15 minutes
recommendations for appropriate compatibility testing
before donation). This calms the donor but does
before the first transfusion are a currently being
not induce lateral recumbency. Some prefer to collect
revaluated. Because each unit of red blood cells is antigen-
blood from dogs in lateral recumbency, especially if the ically distinct, the recipient may form antibodies after
femoral artery is used. 98 The choice is strictly a matter transfusion of any unit of blood. The immune system will
of personal preference and skill. Acepromazine is not take a minimum of 5 days to make antibodies against
recommended because it causes hypotension and platelet transfused red blood cells; therefore, a crossmatch should
dysfunction.
be performed if more than 4 days elapse between
The flow of blood into the bag can occur by gravity or
transfusions. Performing a crossmatch will not prevent
suction. Blood collected by suction does not have a
an immune reaction to subsequent transfusions; it can
greater rate of hemolysis than that collected by gravity only identify those units of blood with potential to cause
flow, and it can be collected more rapidly. 27 Suction col-
acute hemolytic transfusion reactions.
lection of blood is facilitated using a vacuum chamber
manufactured by the Animal Blood Resources Interna- DOGS
tional (Stockbridge, Mich.). This device requires an
Because of the lack of clinically significant preformed
external vacuum source during collection of blood.
alloantibodies in the dog, blood typing and
CATS crossmatching are not routinely performed before the
first transfusion. When DEA 1.1-positive blood is trans-
It is unusual to find a feline blood donor that does fused, ideally it would be given to a DEA 1.1-positive
not require sedation during blood donation. The recipient to prevent sensitization of a DEA 1.1-negative
author prefers a combination of ketamine (10 mg) and dog. DEA 1.1 status can be determined by using the typ-
diazepam (0.5 mg) intravenously for cats, whereas ing systems described below. Crossmatching should be
others recommend using midazolam, and isoflurane or performed before any subsequent transfusion to identify
sevoflurane. 98,114 If the sedative agent is to be given intra- a compatible unit of red blood cells. Blood typing or
venously, a peripheral vein (cephalic or medial saphenous) crossmatching is not required before transfusion of
should be used to preserve the jugular veins for blood canine plasma.
collection.
No commercially available system is manufactured for CATS
the collection of blood from cats because of the small vol- Previously, blood typing was considered adequate
ume of blood that can safely be withdrawn from a cat. pretransfusion testing before administration of red blood
Typically, anticoagulant can be withdrawn from a blood cells or plasma to cats. Blood typing prevented adminis-
bag port using a syringe. It is placed in one or two large tration of type B blood to a type A cat and vice versa.
syringes (25 to 60 mL) depending on the volume of However, transfusion of A-B mismatched blood results
blood to be collected (see Table 24-1). A large (19- in decreased red blood cell survival or a potentially fatal,
gauge) butterfly needle is used for jugular venipuncture acute hemolytic transfusion reaction. 38 Blood typing will
so that if a second syringe of blood is to be collected, not identify the Mik antigen and its naturally occurring
the full syringe can be removed and the second syringe alloantibody; however crossmatching will detect the
connected without a second venipuncture. By the defini- anti-Mik antibody and crossmatching may become
tion of the American Association of Blood Banks, this is the preferred compatibility test for all feline transfusions
an “open” system, and blood collected in this manner to prevent incompatible transfusions due to anti-A,
should not be transfused more than 4 hours after collec- anti-B, or anti-Mik alloantibodies.
tion. 118 Alternatively, a standard blood collection bag Determining A-B blood type in the cat has been
containing CPDA-1 can be used. All CPDA-1 is expelled simplified by the availability of in-clinic typing systems
from the bag except for the amount remaining in the tub- (Figure 24-1). A special situation with regard to blood
ing. Feline blood is collected directly into the bag. 93 typing and crossmatching exists in cats. When blood
A commercially available vacuum system can be used typing is unavailable, crossmatching will administration
for collecting blood from cats, but some authors find this of an incompatible transfusion due to A, B, or Mik
63,98
system less satisfactory than the syringe method. alloantibodies. When crossmatching is performed with