Fluid Plans
•Replacement: Determining Rate
• New : 'Fluid Challenge' Method:
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Volumes are based on "fluid challenges" rather 'estimates' of deficits
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Traditional method is with estimates of % of water loss
o
Riddled with errors....
"Fluid Challenge Method"
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20 mL/kg boluses of isotonic crystalloid over 30-60 minutes, then reassess for more
o
Repeat boluses until signs of shock abate or plateau, or until limits reached, indicating the need for vasopressors
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10 L for an average adult horse
o
1 L for average neonatal foal
Fluid Challenge for Colloids
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Lower rates because they stay within the vascular space
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3-10 mL/kg hetastarch
How much to give?
Base it on Clinical response
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Mentation
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Increase alertness
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Foal that is kicking is rarely severely hypovolemic
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Urination
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In general, sufficient fluids have been given when the horse/foal begins to pass urine
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Decrease heart rate
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Improvement in membrane color or capillary refill
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In hospital= blood pressure (> 60 mmHg in foal, 80 in adult)
Crystalloids vs. Colloids?
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Crystalloids only contain electrolytes or glucose in water
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Colloids contain large MW particles
o
Proteins or synthetic polysaccharides
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Human studies fail to show an advantage of 1 over the other
o
Use together may be ideal
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Isotonic crystalloids hydrate entire ECF
o
25 % to plasma volume; 75 % to interstitium
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Colloids expand the intravascular space only
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Rapid expansion of plasma volume
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Large particles stay within vessels
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Colloids are better in horses concurrently hypovolemic and hypooncotic
Replacement Crystalloids
• Choices:
o
Lactated Ringer's Solution (LRS)
o
Normosol-R
o
Plasma-Lyte 148 or A
o Normal saline (0.9%)
