Page 12 - 2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats

2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats

cerebral edema. Do not exceed changes in Na levels of 1 mmol/hr in refractometry. Therefore, patient assessment determines
acute cases or 0.5 mmol/hr in chronic cases because of the risk of cere- response. Use up to 20 mL/kg/day of hetastarch for dogs
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bral edema. Although the complexities of managing Na disorders and 10–20 mL/kg/day for cats. 29–31
often benefits from the involvement of a specialist/criticalist, this
is not always feasible. The amount of free water (in the form of Hyperglycemia
D5W) to infuse over the calculated timeframe (to decrease the Na Fluid therapy in hyperglycemic patients is aimed at correcting
concentration by the above guidelines) can be calculated as follows: dehydration and electrolyte abnormalities. Monitor the patient
Volume (L) of free water (D5W) needed = to guide the rate of correction. As with hyperkalemia, the choice
([current Na concentration/normal Na concentration] – 1) of initial replacement fluid is not as important as correcting the
 (0.6  body weight [kg]) 33 patient’s hydration status. See the AAHA Diabetes Management
Guidelines for details on managing hyperglycemia. 44
Hyponatremia
Hyponatremia is most commonly seen in DKA and with water Hypoglycemia
intoxication. Changes in serum Na levels must occur slowly, as Initial therapy for hypoglycemia is based on severity of clini-
with hypernatremia. Monitor electrolyte levels frequently, and use cal signs more than on laboratory findings. Treatment options
a fluid with Na content similar to the measured plasma Na to keep include oral glucose solutions, IV dextrose-containing fluids, or
the rate of change at an appropriate level. food (if not contraindicated). To prepare a dilute dextrose solu-
In patients with water intoxication, restrict water and/or use tion of 2.5–5 dextrose, add concentrated stock dextrose solution
%
diuretics with caution. Patients with DKA may have pseudohypo- (usually 50% or 500 mg/mL) to an isotonic balanced electrolyte
natremia associated with osmotic shifts of water following glucose solution (e.g., add 100 mL of 50% dextrose to 900 mL of fluid to
into the intravascular space. In pseudohyponatremia, a relation- make a solution containing 5% dextrose).
ship exists between serum glucose and serum Na levels: the higher
the glucose, the lower the Na. Specifically, for every 100 mg/dL Anemia and Polycythemia
increase in serum glucose over 120 mg/dL, the serum Na will Blood products may be needed to treat anemia. The decision to
decrease by 1.6mmol/L. 39 transfuse the anemic patient is not based on either the packed cell

volume or hematocrit alone, but on multiple factors as described
Hypoproteinemia/hypoalbuminemia in the “General Principles and Physical Assessment” section of this
Colloid osmotic pressure is related to plasma albumin and protein document. Use of blood products is not addressed in this document.
levels and governs whether fluid remains in the vascular space. Blood loss and hemorrhage are discussed above in volume changes.
Fluid loss into the pulmonary, pleural, abdominal, intestinal, or Treatment of symptomatic polycythemia involves reducing the
interstitial spaces is uncommon until serum albumin is  15 g/L number of red blood cells through phlebotomy and replacing the
or total protein is  35 g/L. 19,40 Evidence of fluid loss from the vas- volume removed with balanced electrolyte solutions to reduce vis-
cular space is used in conjunction with either serum albumin or cosity and improve blood flow and O2 delivery.
total solid values in determining when to initiate colloid therapy.
Guidelines for fluid therapy when treating hypoalbuminemia Multiple Content Changes
include the following: Many patients present with multiple serum chemistry abnor-
y Nutritional support is critical to treatment of malities, making appropriate fluid choice problematic. The vast
hypoalbuminemia. majority of patients will benefit from early empirical fluid therapy
y Plasma administration is often not effective for treatment while awaiting lab results, knowing that more specific treatment
of hypoalbuminemia due to the relatively low albumin will be tailored to individual needs as diagnostic information
levels for the volume infused. Human serum albumin is becomes available.
costly and can cause serious hypersensitivity reactions. 41
Canine albumin is not readily available in most private Changes in Fluid Distribution
practice settings but may be the most efficient means of
supplementation when available. 42
y Synthetic colloids (e.g., hydroxyethyl starch) are beneficial Examples of Common Disorders Causing
because they can increase oncotic pressure in patients Changes in Fluid Distribution
with symptomatic hypoalbuminemia to maintain fluid Any disease causing pulmonary or peripheral edema
in the intravascular space; however, synthetic colloids Any disease causing pleural or abdominal effusion
will not appreciably change total solids as measured by

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