Page 441 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Perioperative Management of Fluid Therapy 429

organ. 132 Additional studies in human patients showed it to 38 C. Stated differently, an infusion of 25 to

an increased frequency of infections in patients receiving 30 mL/ kg of blood at 4 C can decrease body tempera-

allogeneic blood transfusions. 54 These included wound ture by as much as 1 C. Given these facts, it is best if

infections, UTI, and respiratory tract infections, and blood can be warmed before it is given. This can be
the frequency of infection increased with the number of achieved by placing the blood in warm water (up to
units of blood received. 107,181 Patients receiving their 42 C but no higher) before infusion or by running the

own blood did not have such an increase in infection rate, blood through a warming device as it is being infused.
and studies have focused on reducing the white cell count Warming can be as simple as running the line through
in transfused blood to determine whether this will alter a container of warm water or as sophisticated as using a
the infection rate. 17 This approach seems to have met device specifically designed to heat blood safely as it is
with success, but further analysis is required before its being infused. The effectiveness of these techniques
efficacy is understood. 89 Another effect of immunosup- depends on the length of line exposed to the heat and
pression caused by blood transfusions is its effect on can- the rate of infusion. Most of the commercial devices that
cer development. In several animal models, allogeneic are designed for this purpose require the addition of an
infusions have been associated with increased tumor extra length of line that conforms to the heating device.
growth, but the results of studies in humans are not Such devices further increase the cost of blood or blood
clear. 17,63,154 Leukocyte removal before transfusion component therapy.
may reduce the effect on cancer growth. 17
Leukoreduction has been used in collecting blood from HEMOGLOBIN SOLUTIONS
dogs, but this procedure has not been reported with Various hemoglobin solutions have been tested over the
25
regard to its effect on cancer recurrence. years, but only one has been licensed for veterinary
Another concern with the administration of blood use. 47 Oxyglobin (Biopure Corporation, Cambridge,
products is that citrate present in stored blood will Mass.) is an ultrapure glutaraldehyde polymerized hemo-
decrease the availability of calcium in the recipient. In globin of bovine origin made up in a modified LRS. This
normal humans, the amount of citrate found in 1 unit hemoglobin solution has a P50 (oxygen tension at 50%
of blood (approximately 32 mg/kg) can be metabolized saturation) of 35 mm Hg, a molecular weight of 64 to
in 3 to 5 minutes without the person developing hypocal- 500 kDa, and a colloid osmotic pressure of approximately
cemia. However, the rate of metabolism of citrate 20 mm Hg. 135 It comes as a purple-colored solution and
decreases with decreased hepatic perfusion (e.g., shock), contains 13 mg/dL of hemoglobin. The solution may be
decreased hepatic function, and hypothermia. In these stored at room temperature and has a shelf life of 24
settings, plasma citrate concentration may increase rap- months. This latter feature makes it an attractive product
idly. This effect is of concern mainly when blood is given for veterinarians who use canine or feline blood infre-
rapidly (>30 mL/kg/hr), and calcium salts may be given quently and who do not have access to blood donors of
when rapid transfusion of blood or plasma is required. 2 known status. When given to a patient, it acts as a colloidal
Calcium must be given through a separate intravenous solutionbuthastheaddedadvantageofprovidingoxygen-
line because it may cause the transfused blood to clot in carryingcapacity.Itcanbegivenintraoperativelyinanysit-
the line if it is given concurrently. Calcium chloride uation in which blood would normally be used except in
should be given at a dosage of 5 to 10 mg/kg and calcium circumstances requiring clotting factors or platelets.
gluconate at 18 to 35 mg/kg for an equivalent effect. 43 Administration leads to jaundice and hematuria in many
The patient is less likely to have a hypotensive response patients, and interference with a number of biochemical
if calcium can be given before or during the rapid admin- tests (e.g., sodium, potassium, chloride, blood urea)
istration of citrate-containing blood products. 44 If serum may occur. 29 Monitoring the patient by use of pulse oxim-
ionized calcium concentration can be measured, suffi- etryreflectschanges inarterialhemoglobinsaturation,but
cient calcium should be given to return the ionized cal- measurement of hematocrit alone no longer provides an
cium concentration to normal, but the animal should accurate indication of hemoglobin content. 90 Measure-
be treated only if serum ionized calcium concentration ment of total protein concentration using a refractometer
is decreased. If blood is not being given rapidly or is also will be affected because of the presence of free hemo-
not needed on a continuous basis, it rarely is necessary globin. The recommended rate of administration for
to administer calcium because the serum calcium concen- Oxyglobin is 10 mL/ kg/hr in dogs and 5 mL/kg/hr
tration will be corrected rapidly by the animal as a result of incats,butbolusesof1to2 mL/kgmaybeusedinanimals
changes in parathyroid hormone concentration and by suffering from acute hypovolemia. Special care needs to be
mobilization of calcium stores in the body. 2,167 taken when giving Oxyglobin to cats because pulmonary
Stored blood usually is kept at 4 C and is more likely edema has been reported in a number of cats and is proba-

to cause arrhythmias and decreased cardiac output if bly related to acute circulatory overload. 68 Some degree of
administered without being warmed first. A 250-mL systemic vasoconstriction may occur with Oxyglobin

unit of blood at 4 C requires 7.2 kcal of heat to warm administration because of the scavenging effect of free