Fluid Therapy (Key points only) Flashcards
Why fluid therapy?
- Increase cardiac output
- Increases and maintain pre-load
- Maintain or increase oxygen delivery to tissues
- Correct acid-base imbalances
3 phases of fluid resuscitation
- Correct hypovolemia (resuscitation)
- Treat dehydration (rehydration phase)
- Ongoing losses
Major components of ECF?
- Na, Cl
Major component of ICF?
- Potassium!
Why do horses need calcium?
- Normal neuromuscular function
- Cardiac rhythm and contractility
Where do horses get their calcium?
- In their feed
Anion gap formula
[Na+ + K+] - [Cl- + HCO3-]
What does a high anion gap mean?
- Metabolic acidosis
What does a deficit of the extravascular fluid compartment mean clinically?
- Interstitial, intracellular
- Dehydration!
Clinical signs of dehydration?
- Sunken eyes
- Dull cornea
- Dry mucous membranes
Meaning of a high PCV and relatively low TP?
- Means that there is a lot of loss
Clinical signs of hypovolemia
- Tachycardia
- Cold extremities
- Tachypnea
- Decreased pulse pressures
- Reduced jugular fill
Maintenance fluid requirements
- 60mL/kg/day in adult horses
- Neonates - 100-120 mL/kg/day up to about 3 weeks
Foal - 90 mL/kg/day
Estimate of dehydration
% dehydration * body weight in kg
e.g. 10% dehydrated 500 kg horse = 0.1 *500 = 50L deficit
Monitoring for fluid resuscitation
- Monitor HR, PCV/TP, CR to see if keeping up with loss
How would you plan fluids for a 500kg horse that is 10% dehydrated?
- 0.1 *500kg = 50mL deficit
- Give 50% in the first 1-2 hours and remainder over the next 24 hours (i.e. 20-25 liters over 2 hours)
- Calculate maintenance (60 mL/kg/day * 500kg = 30 L)
- Make an estimate of ongoing losses
- Total fluids needed over next 24 hours = (remainder of resuscitation volume) + maintenance + ongoing losses
Clinical parameters to determine if you are keeping up with fluids?
- Heart rate
- Mentation
- Extremity temperature
- Mucous membrane color
- CRT
- Pulse quality
- Urine output
- CBC (PCV, plasma protein)
- Serum biochemistry (BUN/creatinine; TP, albumin, electrolytes)
- Lactate
- Venous or arterial blood gas
Transport of dehydrated horse
- If hospital is 2 hour drive or longer
- Consider bolus of hypertonic saline (7.2%)
Contraindications for hypertonic saline
- Exhaustion
- Uncontrolled hemorrhage
- Salt intoxication
- Heat stroke,
- Hyperosmotic states
- Exhaustion and electrolyte loss in sweat
- Acute kidney injury
Crystalloids examples
- Normal saline
- LRS
- 5% Dextrose in water
- Plasmalyte
- Most are high sodium, low potassium
- Often need to supplement potassium in horses off feed
What electrolytes are commonly decreased with diarrhea?
- sodium, potassium, chloride, and bicarbonate
Potassium supplementation
- If animals are off feed for a prolonged period
- Don’t exceed 0.5mEq/kg/hr (20mEq/L of KCl)
Ways to reduce hyperkalemia?
- Volume replace with K+ free fluids
- DO NOT try to add NaHCO3
- Calcium gluconate can stabilize
- Dextrose
- Oral karo syrup
Electrolytes to supplement in critical horses that are off feed?
- Mg, K, Ca2+
