Fluid Therapy Flashcards
Tell me about the fluid compartments of the body
Body is about 65% water
2/3 of that is found in the intracellular space
1/3 is in the extracellular space
The extracellular space is broken down into interstitial fluid and intravascular fluid
75% of the extracellular fluid is in the interstitial space and 25% is intravascular
Equation for total body water
BW x 0.65
Blood volume is about _____ml/kg water
90
How can you figure out how much plasma is in the body?
Find total blood volume (BW in kg x 90mL/kg)
Blood is made up of about 45% RBCs and 55% plasma
Multiply total blood volume by 0.55
T/F: the concentration of electrolytes varies based on the fluid compartment
True
Discuss electrolyte concentration in the extracellular space
High sodium (~140 mEq/L)
Low potassium (~4mEq/L)
Discuss electrolyte concentration in the intracellular space
High potassium (~140mEq/L)
Low sodium (~30mEq/L)
Water is to ________ as Bailey is to Paul Mescal
Sodium
What determine intravascular volume?
Sodium concentration
Total body sodium determines _______
Hydration
Ex. Whenever I eat a large quantity of ramen noodles, my fingers swell b/c I’ve got a lot of extra sodium for water to hang out with
What is an osmole?
The number of moles in a solution that contribute to its hold on water
What is osmolality?
Number of moles dissolved in a mass of solvent
What electrolyte has the greatest impact on osmolality?
Sodium
What does serum sodium concentration actually mean?
A reflection of total body water NOT total body sodium
Hyponatremia =
Water excess
Serum sodium concentration is low likely due to free water excess
Hypernatremia =
Water deficit
Severe dehydration
There are three types of fluids that can be lost - what are they
Hypotonic
Hypertonic
Isotonic
What type of fluid loss am I: more water loss than solute loss
Hypotonic
Give an example of hypotonic fluid loss
Diarrhea, vomit, sweat
What type of fluid loss am I: isotonic to ECF
Isotonic - sodium concentration likely unchanged
What could hypotonic fluid loss lead to?
Hypernatremia
What is the least common type of fluid loss?
Hypertonic
What kind of fluid loss am I: more solute loss than water loss
Hypertonic
Give an example of how hypertonic fluid loss could occur
Replacing losses with only water and not the solutes
Could lead to hyponatremia
T/F: Dehydration and hypovolemia are the same thing, one is just more severe.
False - differ in where the fluid is lost from, how quickly it is lost, and how quickly it needs to be replaced
What is dehydration?
Fluid losses from the interstitial space
Usually occurs over longer period of time
Can be replaced more slowly
What is hypovolemia?
Loss of fluid form intravascular space
Usually occurs more rapidly than with dehydration
Requires rapid restoration of blood volume
What is the one similarity between hypovolemia and dehydration?
Both should be replaced with fluids that are higher in sodium
What are some good reasons to give fluids?
Dehydration
Hypovolemia
Anorexia (>12-24)
Severe losses
General anesthesia
As a vehicle to get other stuff in the patients
Name some characteristics of a crystalloid fluid
Salt water
Freely moves within the EC space
Redistributes into interstitium rapidly
Name some characteristic about colloids
Contains molecules that don’t readily leave the IV space
Theoretically stays in IV space longer
Synthetic and natural available
What determines the immediate effect of a fluid on blood volume?
Volume delivered
Greatest absolute increase in blood volume seen with crystalloids
What determines the later effect of a fluid on the blood volume?
Type of fluid given
Most sustained increase in blood volume seen with colloids
What are the cons to crystalloids?
Large volume
Transient effect b/c rapidly redistributes to interstitium
Might potentiate edema
What are some cons to colloids?
Potential interstitial leak may lead to edema formation
Changes in coagulation
Kidney injury
Cost
What is tonicity?
Basically osmolality but just looking at the effect of salts
____________ fluids have similar tonicity to ECF
Isotonic fluids
LRS, 0.9% NaCl (normal saline), Normosol R, and Plasmalyte A are examples of _______
Isotonic fluids
T/F: hypotonic fluids are the best choice for patients presenting in hypovolemic shock
False - hypotonic fluids should never be bolused as this will lead to cell lysis
How does hypertonic saline work?
Pulls free water from interstitial and intracellular spaces to increase IV volume
What are the positive physiologic and immunomodulatory effects of hypertonic saline?
Increased tissue oxygen delivery
Vagally mediated reflex to sustain HR and CO
Decreased cellular edema (great for cerebral edema)
When is hypertonic saline contraindicated?
Hypernatremia
Dehydration - minimal fluids in interstitium to pull from
What is mean by balanced versus unbalanced fluids?
Referring to overall electrolyte make up of the fluid
Balanced = major electrolytes are in similar proportion to ECF (lower chloride)
Unbalanced = electrolytes are not in proportion with ECF though often are isotonic
Name some isotonic and balanced fluids
LRS
Normosol R
Plasmalyte A
Name some isotonic and unbalanced fluids
Normal saline (0.9%)
5% dextrose in water (D5W)
Maintenance fluids are ________ in sodium and chloride, but ______ in potassium
Lower; higher
Replacement fluids mimic ________, so they are higher in sodium.
ECF
Name some replacement fluids
LRS
Normal saline
Normosol R
Plasmalyte 148
Name some maintenance fluids
Normosol M
0.45% NaCL (half strength saline)
D5W
Plasmalyte 56
T/F: Though oral fluids are best whenever possible, IV fluids are the best option when PO is not feasible.
True
A dog in suspected hypovolemic shock is in the ER with a potential GDV. You want to give fluids for resuscitation. The vet student says, “since he’s not drinking, we should give them subcutaneously.” What do you say back?
SC fluids are only for stable patients. To best address the hypovolemia, we need to give and intravenous bolus of a replacement fluid like LRS, Normosol R, or 0.9 NaCl.
The delivery rate for crystalloids for shock and hypotension is ________.
10-20mL/kg given as fast as possible or over about 10 minutes
Reassess and repeat as needed (up to 3 times?)
What is the delivery rate for colloids for patients in shock or hypotension?
5-10mL/kg bolus then reassess
What is the delivery rate for hypertonic saline in a shocky or hypotensive patient?
4-6mL/kg bolus
A patient is assessed to be 7% dehydrated. How do we correct this?
% dehydration x BW (in kg) = fluid deficit in L
Replace the deficit over 6, 12, 24, 48 hours.
When blousing fluids, use a _______ diameter and _______ catheter
Large; short
Formulas for maintenance fluids
(BW x 30) + 70 = mL fluid per day
70 x BW^0.75 = mL fluid per day
T/F: once you set a maintenance rate, you are good to go and can leave the patient to rehydrate.
False - should be reassessing hydration status frequently and adjusting fluid rate as needed
T/F: in general, the smaller the dog, the smaller the fluid rate
False - the opposite.
Large/giant breeds - 40mL/kg/dag
Medium dogs and cats - 50mL/kg/day
Small dogs - 60mL/kg/day
What is the maintenance fluid rate for neonates?
80-100mL/kg/day
Complication of fluid therapy
Electrolyte imbalances
Fluid overload
Iatrogenic CHF
Phlebitis
Extra cost
Prolonged hospitalization
When do we stop administering fluids?
Rehydration is complete
Patient is eating and drinking sufficiently to maintain daily losses
Ongoing losses are under control
What are some ways we can monitor fluid therapy?
BW!!!!!
USG
PE
Ins and Outs
Central venous pressure
Left ventricular end-diastolic diameter
Electrolytes
