Fluids and Fluid Therapy
Card Set Information
Fluids and Fluid Therapy
Fluids and fluid therapy in pharm and tox
total body water (TBW) in adults and neonates
neonatals 80%. Easy to over-hydrate
factors affecting TBW
age, body fat
Distribution of TBW
40% in intracellular space
20% in extracellular space (15% interstitial, 5% intravascular)
Body water solutes, particularly in ECF vs. ICF
Electrolytes become ions
cations = anions. Balanced
cations in ECF are Na
cations in ICF are K and Mg
anions in ECF are Cl and HCO3 (bicarb)
anions in ICF are phosphates and proteins
ECF - Na, Cl, HCO3
ICF - K, Mg, phosphate, protein
What is balanced therapeutic fluid?
resembles ECF (Na, Cl, HCO3)
unit of measure expressing electrolyte concentration.
1:1000 of an equivalent weight (weight of element that will combine with 1 g of H+, gram molecular weight/positive valance)
Osmolarity of dog/cat plasma or serum
What shouldn't you do while administering calcium
blood transfusion, calcium precipitates out red blood cells.
relative number of solute particles in 1 kg of solution. More particles = more pressure
number of solute particles per liter of solution
When effective solute particles attract water to cross a semipermeable membrane, the pressure required to stop them or the pressure until equilibrium is reached.
effective vs. ineffective osmoles
not all particles contribute to osmotic pressure. Effective are Na and glucose, for example. Albumin pulls water very well. Ineffective are not clinically useful.
total osmolarity or osmolality of a solution
tonicity (effective osmolarity) approximately equal to tonicity of blood plasma
tonicity less than that of blood plasma.
Fluid is pulled into ECF
tonicity greater than that of blood plasma.
Fluid is pulled into IVF (critical care patients, faster hydration from inside)
Fluid disturbances in patients (3)
changes in volume (dehydration or blood loss)
changes in content (hyperkalemia in a blocked cat, etc)
changes in distribution (pleural effusion)
dehydration and how you recognize it
hydration status, water loss>water intake.
Check history (V? D? Bleeding?), physical exam (skin turgor, mucus membranes, heartbeat, pulses, breathing), MDB (basic tests)
Also check for ongoing fluid loss, and think of replacing electrolytes etc.
Ways of taking food in
water from ingested food (especially cats)
ways of losing water
urine, feces, sweat (horses), respiration (dogs)
anorexia, PU, V, D, third spacing, extensive burns
includes sensible and insensible losses
early dehydration. drop in skin turgor and dry mucous membranes.
Weight or age of animals can affect skin turgor
more serious dehydration.
hypotension (low BP), tachycardia, pale mucous membranes, increased CRT, weak pulse. Increased skin turgor and dry membranes.
Massive dehydration leading to cerebral obtundation.
Shock, nonresponsive, can't stand up or move.
< 5% dehydration
history of fluid loss but no findings in physical examination
dry oral mucous membranes but no panting or pathological tachycardia
mild to moderate decreased skin turgor, dry oral mucous membranes, slight tachycardia, and normal pulse pressure
moderate to marked degree of decreased skin turgor, dry oral mucous membranes, tachycardia, and decreased pulse pressure
marked loss of skin turgor, dry oral mucous membranes and significant signs of shock.
Three things you need to calculate amount if IV fluid to administer
amount of fluid that must be replaced to bring animal back to normal hydration status.
%dehydration x body weight = lbs of fluid lost.
500mL = 1 lb
Use 75% over 24 hours because this is an ESTIMATE
(add to maintenance requirement and ongoing loss to replace)
mL to lb conversion
500mL to 1 lb
Maintenance requirements, traditional method
Volume of fluid needed to replace normal sensible and insensible losses.
(add to hydration deficit and ongoing losses to replace)
alternate calculation of maintenance requirements, or wheel maintenance
30 x kg +70 = mL
new AAHA maintenance
cat = 80 x kg
= 2-3 ml/kg/hr
dog = 132 x kg
= 2-6 ml/kg/hr
Blood volume in cats and dogs and why it's important
don't bolus more than the blood volume per hour.
cat = 40-60 ml/kg
dog = 90 ml/kg
Bolus in 25% increments, 15 minutes at a time.
Ongoing or continuing abnormal losses
Estimated fluid losses from vomiting, diarrhea and/or excessive urination.
Add to hydration deficit and maintenance requirement.
Administer CRI over 24 hours.
drip rate equation
gtt/min = (volume of infusion)/(time of infusion) x drip factor
fluid therapy routes of administration, and how you choose
condition being treated, duration of condition and severity of condition
IV, SQ, PO, IP, IO
IV fluid administration
quickest and most precise
requires IV catheter
Preferred with significant fluid loss or severe condition
For less severe needs
Amount depends on animal size, usu 5-10mL/lb per injection site
Use Isotonic fluids
can't use in severe GI disorders
Allows normal physiological processes to control amount
not good for large volumes
can administer a large volume but absorption is slow
very small animals or poor venous access
rapid delivery of fluids
requires expertise in placing IO needle.
Ways to monitor fluid administration
: weight, skin turgor, mm/crt, lung sounds, oculonasal discharge, urine output
: PCV/TP, CVP
central venous pressure.
To judge central venous pressure
requires placement of jugular catheter.
Extension set, stopcock, manometer, saline.
Hold "O" of manometer at level of heart. Optimal is 5-8 cm H2O. <5 insufficient. > 14 overload.
Fluctuates with respiration.
clinical signs of overhydration
serous oculonasal dishcharge
inappropriate weight gain
Selection of fluids
give fluids that most closely resemble what has been lost
Give in body compartment where fluid deficit lies
true solutions containing small molecular weight particles that can move through pores in capillary walls.
Particles can also move slowly through cell membranes
Includes electrolytes, buffers and/or dextrose
Balanced crystalloids vs non-balanced crystalloids
balanced contain electrolytes in approx same concentrations as blood plasma
balanced also are fluids containing buffers (lactate, acetate or gluconate)
non-balanced do not resemble composition of blood plasma or ICF
balanced crystalloids examples
buffer is lactate (converted by liver to bicarb, buffers against acidosis)
do not administer with blood
balanced crystalloid replacement solution
dual buffer of acetate and gluconate (metabolized outside liver, precursers to bicarb)
Can be administered with blood.
balanced crystalloid replacement solutiondual buffer of acetate and gluconate (metabolized outside liver, precursers to bicarb)Can be administered with blood.
unbalanced crystalloid examples
2.5% dextrose + 0.45% NaCl
contains dextrose at 5g/L and water
dextrose metabolized to H2O and CO2
Not given SQ
not used for maintinence
Isotonic saline, unbalanced crystalloid
: hyperkalemia, increases plasma volume, Na deficiency, bathe tissues intraop
Contraindicated in heart disease
Not used for maintinence
2.5% dextrose and 0.45% NaCl
"half-strength" saline, unbalanced crystalloid
Indicated for patients with Na restrictions (Heart disease, renal disease, hypertension)
maintinence okay with KCl added
contain large molecular weight molecules unable to cross cell membranes
used to increase oncotic pressure (osmotic pressure exerted by colloids in blood plasma)
AKA plasma volume expanders
plasma volume expanders
when to administer colloids
patients with large volume losses where crystalloids are not improving/maintaining blood volume
When increased O2 or tissue perfusion needed
If edema develops before blood volume restoration
decreased oncotic pressure (TP<3.5 or alb<1.5g/dL)
for longer duration of effect
difficult to administer in sufficient amount for resuscitation
goal is least volume with highest CV benefit
whole blood, plasma, albumin
Choose depending on animal problem--whole blood or fresh frozen plasma for coagulation factors, whole blood or packed RBCs for blood cells.
Adverse reactions include bleeding, vomiting, fever, urticaria (rash, hives), facial edema and others
Plasma volume expanders (administer slowly)
Dextran 70 (polysaccharide, can cause allergic reaction or clotting deficits)
Hetastarch (Hespan) (from maize, hydroxyethyl starch, less antigenic than dextran, expensive)
synthetic colloid, plasma volume expander. Administer slowly.
can cause allergic reactions or clotting deficits
derived from maize (hydroxyethyl starch)
less antigenic than dextran
modified biological colloid
ultrapure, bovine-origin polymerized hemoglobin solution (for dogs with anemia)
O2 carrying substitute for RBCs, temporary, universal compatability
stored at room temp (2 yr shelf life, opened 24hr expiration)
adverse reactions include pulmonary edema, V/D, yellow-orange skin discoloration of skin, urine serum, sclera etc.
Common additives to fluids
Vitamin B complex
common additive, prevents k deficits
Usu 2 mEq/ml
amount added depends on serum k level
adverse effects include muscle weakness and cardiac conduction (hyperkalemia)
common additive for hypoglycemic patients or ketosis in ruminants
Vitamin B complex
common additive, water soluble vitamins which are lost in animals with diuresis
Generally add 2mL/L
adverse include hypersensitivity (thiamine)