Page 577 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Shock Syndromes 565

TABLE 23-3 Fluid Choices for Circulatory Support

Fluid Type Dose Comments
Isotonic crystalloids Dog: up to 90 mL/kg Used in animals for intravascular and interstitial volume
Cat: up to 60 mL/kg deficits. May cause edema in animals with capillary leak or
a low oncotic pressure.
Synthetic colloid Dog: 5-20 mL/kg Used in animals for volume replacement and oncotic
solutions Cat: 5-10 mL/kg support. May cause coagulopathies.
(hydroxyethyl
starches)
Human serum albumin 2 g/kg or calculate albumin deficit (g): Used for albumin and oncotic support and volume
10 (desired-patient albumin) replacement. Monitor closely for reactions. One time dose
weight (kg) 0.3 recommended.
Canine serum albumin 1-2 g/kg/day Limited safety studies thus far. Use with caution.
Fresh frozen plasma 10-15 mL/kg as needed Used to treat clotting factor deficiencies and provide
albumin-containing oncotic support.
Frozen or cryo-poor Used to provide albumin-containing oncotic support or
plasma treatment of rodenticide toxicity.
Packed red blood cells 10-15 mL/kg to raise PCV by 10%-15% Used to treat anemia.
Fresh whole blood 20-25 mL/kg Used to treat anemia, thrombocytopenia, clotting factor
deficiencies, and provide albumin-containing oncotic
support.
Modified with permission from Silverstein DC. Daily intravenous fluid therapy. In: Silverstein DC, Hopper K, editors. Small animal critical care. St Louis:
Saunders Elsevier, 2009.

platelets can occur. Therefore, anemia, hypoproteinemia, might be preferable over another. Examples of specific
and hypocoagulability should be anticipated following clinical scenarios when a specific kind of isotonic
large-volume crystalloid administration. crystalloid might be desirable are listed here:
Since it is hard to predict how a given animal will 1. The isotonic crystalloid of choice for animals with
respond to a rapid fluid bolus, it is recommended that head trauma is 0.9% NaCl, if possible, because this
initially only one third to one half of the shock dose be fluid has the highest sodium concentration and is
given as quickly as possible (often using a pressurized therefore least likely to cause a decrease in osmolarity
fluid infusion system), followed by additional boluses as and subsequent water movement into the brain
indicated by clinical parameters and repeated physical interstitium.
examinations. Animals with recently lacerated or rup­ 2. Animals with severe hyponatremia or hypernatremia
tured blood vessels are susceptible to rebleeding follow­ should receive crystalloid fluids that most closely
ing aggressive fluid therapy and a rapid increase in match the patient’s sodium concentration during
vascular hydrostatic pressure (and “pops the clot”). resuscitation to prevent a rapid increase or decrease
Hypotensive fluid resuscitation (to a mean arterial in serum osmolarity and subsequent central pontine
pressure of 60 mm Hg) may help prevent rebleeding myelinolysis (often delayed in onset) or cerebral
while helping to maintain perfusion to vital organs. 66 edema, respectively.
Not all isotonic fluids are created equal, as seen in 3. Animals with severe liver disease should receive
Table 23-4. Isotonic saline solution (0.9% NaCl) contains nonlactate fluids. Neonates may not be able to ade­
a higher concentration of sodium and chloride compared quately metabolize the lactate and animals with dia­
with normal plasma, and will cause proportional changes betic ketoacidosis could have delayed clearance of
(increases) in a normal animal’s electrolytes. Therefore, ketones following lactate administration; however,
large amounts of 0.9% NaCl will cause a mild increase there is a lack of evidence to support these theories.
in sodium, a marked increase in chloride, and a moderate 4. Patients with a hypochloremic metabolic alkalosis may
decrease in bicarbonate and potassium. The kidneys will benefit from 0.9% NaCl because this is the highest
typically compensate, if possible, by excreting the excess chloride-containing fluid.
electrolytes and conserving potassium. Animals with
hypochloremia, mild hyponatremia, or a metabolic alka­ SYNTHETIC COLLOIDS
losis will often benefit from the administration of 0.9% Synthetic colloids are polydisperse solutions with large
NaCl. molecules (molecular weight >20,000 Da) that do not
Although all isotonic crystalloids have a similar com­ readily sieve across the vascular membrane. Most
position, there are situations when a certain fluid type synthetic colloidal particles are suspended within a