Page 9 - 2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats

2013 AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats

Dehydration
Estimating the percent dehydration gives the clinician a guide
in initial fluid volume needs; however, it must be considered an
estimation only and can be grossly inaccurate due to comorbid
conditions such as age and nutritional status (Table 5).

Fluid deficit calculation
Body weight (kg)  % dehydration = volume (L) to correct
General principles for fluid therapy to correct dehydration
include the following:
y Add the deficit and ongoing losses to maintenance
volumes. Replace ongoing losses within 2–3 hr of the loss,
but replace deficit volumes over a longer time period. The
typical goal is to restore euhydration within 24 hr (pending
limitations of comorbid conditions such as heart disease).
y Frequency of monitoring will depend on the rate at which
fluid resuscitation is being administered (usually q 15–60
min). Assess for euhydration, and avoid fluid overload
through monitoring for improvement. ©2013 AAHA
y Maintenance solutions low in Na should not be used
to replace extracellular deficits (to correct dehydration)
because that may lead to hyponatremia and hyperkalemia TABLE 3
when those solutions are administered in large volumes. Recommended Maintenance Fluid Rates 49

Hypovolemia Cats Dogs
Hypovolemia refers to a decreased volume of fluid in the vascular Formula: Formula:
system with or without whole body fluid depletion. Dehydration is 80  body weight (kg) per 24 hr 132  body weight (kg) per 24 hr
0.75
0.75
the depletion of whole body fluid. Hypovolemia and dehydration Rule of thumb: Rule of thumb:
are not mutually exclusive nor are they always linked. Hypotension 2–3 mL/kg/hr 2–6 mL/kg/hr
may exist separately or along with hypovolemia and dehydration
(Figure 1). Hypotension is discussed under “Fluids and Anesthesia.”
Common causes of hypovolemia include severe dehydration,
rapid fluid loss (gastrointestinal losses, blood, polyuria), and TABLE 4
vasodilation. Hypovolemic patients have signs of decreased tis- Recommendations for Anesthetic Fluid Rates
sue perfusion, such as abnormal mentation, mucous membrane
color, capillary refill time, pulse quality, pulse rate, and/or cold y Provide the maintenance rate plus any necessary replacement
extremity temperature. rate at  10 mL/kg/hr
Hypovolemia due to decreased oncotic pressure is suspected in y Adjust amount and type of fluids based on patient
patients that have a total protein  35 g/L (3.5g/dL) or albumin assessment and monitoring

 15 g/L (1.5 g/dL). Patients in shock may have hypovolemia, y The rate is lower in cats than in dogs, and lower in patients
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decreased BP, and increased lactate ( 2 mmol/L). 20–22 Note that with cardiovascular and renal disease
cats in hypovolemic shock may not be tachycardic.
y Reduce fluid administration rate if anesthetic procedure lasts
Treating hypovolemia  1 hr
When intravascular volume expansion without whole blood is y A typical guideline would be to reduce the anesthetic
needed, use crystalloids, colloids, or both. IV isotonic crystalloid fluid rate by 25% q hr until maintenance rates are reached,
fluids are the initial fluid of choice. If electrolytes such as K are provided the patient remains stable
needed in the emergent situation, administer through a second IV Rule of thumb for cats for initial rate: 3 mL/kg/hr
catheter. High K administration rates may lead to cardiac arrest; Rule of thumb for dogs for initial rate: 5 mL/kg/hr
therefore, do not exceed 0.5mmol/kg/hr. 23–25

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