Ch.32: Fluid Therapy (Pablo) Flashcards
body fluids consist of:
water (solvent) and dissolved particles (solutes)
electrolyte
compound which dissociates in water to form electrically charged particles (ions). Ex: NaCl and KCl
osmotic pressure
pressure which tends to pull water into the compartment containing the solutes
oncotic pressure
total osmotic effect of a non-diffusible colloid (proteins)
hydrostatic pressure
pressure which tends to push water into the compartment containing less solute
osmolarity
number of osmoles per liter of water; depended upon the number of particles in solution
osmolality
number of osmoles per kilogram of water. The difference is usually negligible to osmolarity because of the low solute concentrations in the body fluids
effective osmolality
osmolality that tends to maintain an effective osmotic pressure because the solute cannot easily diffuse across the membrane
tonicity
refers to effective osmolality
colloid sollution**
solution that contain large particles that don’t readily leave the vascular space
crystalloid solution**
solution that contain electrolytes or solutions of glucose in water. doesn’t stay in IV space for a long time
body weight is what percent water at maturity
60%
BW is what percent water in newborns
80%
BW is what % water in intracellular space?
40%
BW is what % water in extracellular space?
20% (15% interstitial and 5% IV)
capillary walls are permeable to:
water, solutes; only slightly permeable to proteins
Factors that affect water distr. and movement in body
Electrolytes
Hydrostatic and oncotic P
Lymphatic drainage
Hydrostatic P tends to push water/solutes where?
into interstitial space
Oncotic P tends to push water/solutes where?
IV
plasma water loss –> water movement?
from intracellular/interstitium to IV
protein loss –> water movement?
IV to interstitial/intracellular space
what does lymphatic drainage do?
remove excess fluid in the interstitial space
Abnormal processes affecting water distribution
- vascular injury –> edema
- changes in electrolyte conc.
- lymphatic injury
- altered intravascular osmolality –> inc. plasma osmolality
- hypoproteinemia –> dec. plasma oncotic P
3 Indications for fluid therapy
1) restore normal circulation in patients with hypovolemia or shock
2) correct fluid deficits in dehydrated patients
3) maintain fluid balance in patients with decreased fluid intake/increased fluid loss
name 3 replacement solutions
LRS –> most commonly used in SA!
Normosol –> most commonly used in LA!
Normal Saline
chars. of replacement solutions
isotonic sodium-based
used for replacement of fluid deficits
similar composition as plasma water
can be given rapidly
“sensible” fluid loss
via kidneys/bladder. We are aware of it
“insensible” fluid loss
via LI, lungs, skin. We are unaware of it
If ECF and ECF are the same, movement of H2O is at ____
homeostasis
Is LRS a colloid or crystalloid?
crystalloid
which fluid stays in interstitial fluid the longest?
LRS
Which stays IV longer: colloids or crystalloids?
colloids
2 types of crystalloid solutions. How do they differ in composition?
replacement (conc. electrolytes similar to body)
maintenance (lower Na and Cl, higher K than replacement fluids)***
Basic components of LRS. alkylizing or acidifying solution?
ALKYLIZING AGENT Na K Ca** Cl lactate
lactate is precursor for:
bicarbonate (converted in liver)
Basic components of Plasma-Lyte A. alkylizing or acidifying solution?
ALKYLIZING AGENT Na K Mg** Cl Gluconate Acetate
acetate and gluconate converted to:
bicarbonate (converted in lungs)
Basic components of Normosol. alkylizing or acidifying solution?
Same as Plasma-Lyte A
can you add bicarbonate to LRS/Normosol?
LRS: No (interacts with Ca)
Normosol: Yes
disadvantage of giving normosol alone?
can develop hypocalcemia. Add Ca glutamate to counteract.
Basic components of Ringer’s Solution. alkylizing or acidifying solution?
ACIDIFYING SOLUTION: Na K Ca Cl** NO BUFFER BASE
use of Ringer’s solution
tx for metabolic alkalosis
use of 0.9% saline solution. Alkylizing or acidifying solution?
Acidifying solution. tx for hyperkalemic animals, metabolic alkalosis
-not ideal replacement solution
use of 7.5% saline solution
short-lived increase in IV volume in severely hypovolemic animals; used in emergencies only
use of 5% dextrose solution
free water source**
NO electrolytes, buffer base
Tx for hyperkalemia, hypernatremia, hypoglycemia (as in liver dz, sick neonates, hepatic shunts)
contraindication for dextrose solution
brain trauma; results in additional brain swelling
a true maintenance fluid has low ___
Na
1/2 strength LRS and 2.5% dextrose can be used as:
maintenance fluid if given slowly
Choose solution based on:
hydration status
history
PE
lab data
What is lost in vomiting dogs?
H and Cl. Use acidifying solution to help
What is lost in diarrhea dogs?
Na and bicarb. Use alkylizing solution to help restore water and electrolytes
T/F: horses lose less fluid per kg of body weight lost than small animals?
T
What should be included in a lab workup when assessing fluid status?
Plasma protein** PCV** blood gas electrolytes osmolality urinalysis
Dehydration –> PCV, plasma protein?**
both increase
Dehydration + anemia –> PCV, plasma protein?**
PCV unchanged, plasma protein increases
dehydration + hypoproteinemia –> PCV, plasma protein?**
PCV increases, plasma protein unchanged or decreases
When developing a fluid therapy plan, must calculate:
- existing deficit
- maintenance requirement
- contemporary loss
Deficit in L =
% Dehydration x bw (kg)
total maintenance requirement = **
sensible loss (urine) + insensible losses **usually 40-60ml/kg/day**
big dogs have higher/lower fluid requirements than small dogs
lower!
contemporary loss
loss of fluids via v/d, internal bleeding, etc.
-hard to keep track of
Total fluid volume to administer over 24 hrs =
deficit + maintenance + ongoing loss
How quickly should you restore blood volume in case of severe dehydration?
within 1 hr
Ways to monitor fluid therapy
PE**
lab work**
urine output
central venous pressure
specific gravity is higher/lower when animal is dehydrated?
higher
signs of improvement
more elastic skin turgor moister MM animal looks brighter inc. BW PCV, TP, specific gravity dec. HR dec. eyes less sunken in
Which fluid therapy should you NOT give SC?
dextrose
T/F: fluids are only a supportive therapy
T
<5% of dehydration CS
not detectable
9-12% of dehydration CS
tented skin stands in place prolonged CRT sunken eyes dry MM possible signs of shock
When normal saline given IV, where does most of it go?
most stays in ECF
contraindication of using normal saline
animal with CHF