Fluid Therapy Flashcards
What is the calculation for correcting fluid loss?
Deficit (dehydration) + Ongoing Losses + Maintenance over 24hr
What are the characteristics of a 5% dehydrated horse?
Skin Tent: 1-3 sec
MM/CRT: Moist to slightly tacky, normal
HR: Normal
Other: Decreased Urine output
What are the characteristics of an 8% dehydrated horse?
Skin Tent: 3-5 sed
MM/CRT: Tacky, often 2-3 sec
HR: 40-6 bpm
Other: Decreased arterial BP
What are the characteristics of a 10-12% dehydrated horse?
Skin Tent: 5 or more sec
MM/CRT: Dry, often >4 sec
HR: 60 bpm or more
Other: Reduced jugular fill, barely detectable peripheral pulse, sunken eyes
What are the characteristics of a 12-15% dehydrated horse?
- Obvious sunken eyes
- Obvious shock
At what percent dehydration is the horse closet death or dead?
15%
T/F: Sunken eyes are more obvious in food animals and may not be very apparent in horses.
True
What is the best way to administer fluids to an animal with an intestinal obstruction?
PO- helps to break up the blockage and return mobility to GIT
What instances would we want to over-hydrate a horse?
- Impaction
- Pneumonia or dried respiratory secretions in airways
- Renal failure to provide diuresis
What are the advantages of oral administration of fluids?
- Most physiologic
- Least expensive/invasive/ complication
- Can give large volumes
- Useful for GI impaction
Horses with what issue would be best to administer fluids PO rather than IV?
Horses with decreased jugular filling
What are the disadvantages to oral administration of fluids?
Contraindicated in gastric distension and ileus
What kind of needles/catheters are typically used to administer IV fluids?
14g 5.5” needles
What veins can be used to administer IV fluids?
- Jugular vein (first choice)
- Lateral thoracic vein (dysfunctional jugular)
- Cephalic Vein
- Saphenous vein
What direction should jugular catheters be placed in order to administer fluids?
Tip towards the heart
What is the disadvantage to lateral thoracic catheters in recumbent animals?
Dislodge easily; typically only placed for low volume of fluids or for medication administration
What is the first choice for limb vein catheters?
Cephalic vein- may clot easily
What is a disadvantage of saphenous catheter placement?
Easily bent by limb motion and poorly tolerated
When is a saphenous catheter going to be beneficial?
Severely depressed horses when other places have been overused/can’t be accessed
What are the advantages of IV fluid administration?
- Easy access
- Nearly unlimited fluid volume limit
- Allows for easy changes in fluid plan
What are the disadvantages of IV fluid administration?
- Dangerous in compromised veins
- Sepsis- requires sterility
- Expensive
- Requires monitoring and hospitalization
Why is SQ fluid administration nearly never used in adult horses?
Skin is not very elastic
Can sometimes be used in foals
What kind of needles/catheters are used for IP fluid administration?
Same as for jugular- 14g 5.5”
Where are IP fluid administered?
Dorsal aspect of the left flank at the paralumbar fossa on the left
Why are IP fluids ONLY administered on the left?
The cecum lives on the right and you don’t want to poke it
What are the disadvantages to IP fluid administration?
You cannot give large volumes of fluid (can lead to colic) and risk of septic peritonitis if not done sterile
What position should the horse be in for rectal administration of fluids?
Hind end on an incline above the head
What are the advantages of rectal fluid administration?
- Allows for absorption across rectum mucosa
- Large volumes at rapid rates
- Easy for severely dehydrated animals to increase circulating volume
- Good choice when PO would be ideal but is contraindicated (reflex)
What are the disadvantages of rectal fluid administration?
- Unlikely to help in moderate to severe ileus
- Contraindicated in severe colitis and diarrhea
What are the flow rates for a 14Gx 5.25” catheter?
219 mL/min or 13.1 L/hr
What are the flow rates for a 12Gx 5.25” catheter?
449 mL/min or 26.9 L/hr
What are the flow rates for a 10Gx 5.25” catheter?
609 mL/min or 36.5 L/hr
What are the characteristics of a long term catheter?
Can be left in for several weeks
More expensive
Typically made of polyurethane or silicone
What are the characteristics of a short term catheter?
Should be removed or replaced with relative frequency
Typically made of teflon or polyethylene
What is the limiting factor for flow rate in the Stat IV set up with 14g, 12g, and 10g catheter?
14g- Catheter
12g- Catheter
10g- Stat IV set
What is the max flow rate of the Stat IV set?
27-28 L/hr for a standard 10ft ceiling (8ft bag height)
What is the flow rate from a free flow system determined by?
- Height from the base of the heart
- Size of the tubing in the entire system
- Length of the system
- Fluid viscosity
- Catheter gauge and length
How many bags are hooked up to the system in a Stat IV set?
4x 5L bags
What are some common catheter complications?
- Perivascular leakage
- Thrombosis
- Phlebitis
- Thrombophlebitis (can be septic)
- Breakage
What is perivascular leakage from a catheter typically caused by?
Cracks at the edges of the catheter and hub
What are some consequences of perivascular leakage?
Local abscessation, neurological dysfunction, sloughing of tissue (especially if medications are cytotoxic)
What is the most concerning complication of catheter placement?
Septic thrombophlebitis- may necessitate the removal of the jugular vein
T/F: Catheter breakage is not too big of a deal.
Yes and no- not the worst thing in the world but you do want to go find the broken catheter within 24 hours or risk it moving into the lungs
What is typically the maximum amount of fluids you want to administer in one hour?
One blood volume or 8% BW in kg
What is the maximum shock dosage in a horse?
60-90 mL/kg/hr (can be up to 9% of bw)
Is it appropriate to administer more than one blood volume if indicated clinically?
Depends on the case
What strength is isotonic saline?
0.9%
What strength is hypotonic saline and what horses do we use it most in?
0.45%
Typically used in foals
What strength is hypertonic saline?
1.8% or tup to 7-7.4%
What does hypertonic saline do?
Rapid increase in circulating volume and decrease in peripheral resistance
What are the advantages of hypertonic saline?
- Requires small volumes which makes transport easier
- Does not support bacterial growth
- Inexpensive
- No special management
What are the local effects of hypertonic saline?
Draws fluid from extravascular areas, 3rd space, and intracellular environment
What are the central effects of hypertonic saline?
Stimulates a CNS response favoring CV stability
What are the adverse effects of hypertonic saline?
Hemolysis and cardiovascular alterations
When is hemolysis most likely when administering hypertonic saline?
When it is given in a small vessel
Counteract with 25% HS and 24% Dextran
What cardiovascular alterations can occur with hypertonic saline administration?
Arrhythmias and VPCs
What are the contraindications of hypertonic saline administration?
Uncontrolled hemorrhage, severe hypernatremia, sever hypokalemia
What condition of horses do you particularly want to avoid hypertonic saline administration in?
Ruptured uterine artery prior to foaling (unless the foal is more important than the mare via owner)
T/F: Dehydration is a contraindication of hypertonic saline administration.
False- dehydration alone is fine
Dehydration with hypernatremia is not fine
What are other fluids that can be administered to horses?
LRS, Normosol, Plasmalyte, Dextrose
Why is PCV labile in the horse?
Splenocontraction can alter PCV dramatically very quickly
Why would chloride be retained while sodium is lost?
In an attempt to balance electroneutrality if bicarb is being lost
What can sodium and chloride losses be used to predict?
Likelihood of metabolic acidosis (anion gap)
What kind of acidosis should you NOT administer bicarb in?
Respiratory acidosis- can make it worse
What is the calculation for bicarb dosages in metabolic acidosis cases?
Deficit (normal is 25) x distribution (0.3, 0.4 or 0.5)
Administer 1/2 dose over 1 hr and re-evaluate need
What should bicarb be administered in?
Isotonic fluid- typically LRS if bicarb is around 17-18
Why might an animal with normal potassium suddenly become hypokalemic once fluids are administered?
Potassium uptake back into the cells
When should you always supplement potassium?
In cases of decreased feed intake
T/F: Calcium should always be supplemented more conservatively than potassium.
Yes- horses have massive calcium stores in their bones
What is the maximum potassium supplementation rate?
0.5 mEq/kg/hr
What is the typically guideline?
10-20 mEq/L per horse
What kind of fluids should you NOT administer potassium in?
Replacement fluids- rate is too high and can lead to over dose
T/F: Horses will typically have isotonic sodium losses if related to GI disease
True
T/F: Both hyper- and hyponatremia will result in CNS dysfunction due to fluid shifts in the cells.
True
What may hyponatremia be due to?
Chronic dehydration- triggers thirst centers and will drink massive amounts which increases renal excretion
