Fluid Therapy Flashcards
roles of water
solvent for reactions
transportation of substances
heat regulation
essential for organ function - circulation, renal excretion
total body water
~ 60% bodyweight in an average adult
~80% in new-born
less in obese animals
distribution of fluids
40% ICF
5% intravascular
15% interstitial
what is the skeleton of ICF
K+
what is the skeleton of ECF
Na+
what is the skeleton of IVF
protein (albumin)
osmolality
number of particles (osmoles) per kg of water
noraml osmolality in ECF and ICF
~300 mOsm/kg
osmolality of solutions are categorized on their effect on…
red cell volume
isotonic
no change in RBC volume
hypotonic
RBC volume increase (hemolysis)
hypertonic
RBC volume decreases
oncotic pressure
form of osmotic pressure exerted by proteins
tens to pull water into vasular space
physioogical plasma oncotic pressure
23 mmHg
edema formation is likely when albumin
<1.5 g/dL
hypoalbuminemia is common in
severely ill patients (sepsis)
prognostic factor
other causes: emaciation, liver disease, ongoing bleeding
hydrostatic pressure
drives fluids outward of vascular space
oncotic pressure
drives fluid inward
crystalloid solutions
crystalline solisd (NaCl, glucose etc) dissolved in water
T/F crystalloid solutions can be isotonic, hypotonic, or hypertonic
true
balanced electrolyte solutions
have a composition similar to ECF
ringer, normosol
balanced electrolyte solutions
= replacement solutions
can be given fast in large volumes
causes no change in plasma electrolytes
how much replacement solution stays in intravascular compartment after 30 min
1/3
when are replacement fluids indicated
rapid volume expansion
replacement of blood loss (3x the volume), initial phase of shock treatment
maintenance solution
replace daily fluid loss
not generally appropriate for peri-operative use
daily volume demand: 40-60 mL/kg over 24 hours
maintenance fluids contain
less Na
more K
physiological saline
0.9% NaCl (308 mOsm/L)
used for rapid ECF volume expansion if balanced solutions are not available
excessive use of physiological solution may lead to
dilution of other EC electrolytes
hyper-chloremic metabolic acidosis
hypertonic saline
7.5 % NaCl
rapidly draw water from ICF to ECF
enhance cardiac function
fast onset but short duration
dose of hypertonic saline
4-6 mL/kg over 3-5 min
1-4 mL/kg only for cats
indications for hypertonic saline
quick IV volume expansion
severe shock (initial phase)
head injury with elevated ICP
contraindications of hypertonic saline
uncontrolled hemorrhage
dehydration
cardiac dysrhythmias
dextrose (glucose) solution
5% dextrose is isotonic
becomes hypotonic after metabolism
good source of free water (dehydration)
not generally appropriate for peri-operative use
dextrose solutions are a component of
maintenance solutions
5% dextrose in combination with 0.9% NaCl and 20 mmol/L KCl
colloids
large molecules that stay intravascular
increase plasma oncotic pressure and vascular volume
indication for use of colloids
albumin is low (alb. <1.5 or TP < 3.5 g/dL)
or expected to become low (shock, SIRS-systemic inflammatory response syndrome)
issues with colloids
volume overloading
allergic reaction
possible effect on hemostasis (tendency to bleed)
types of colloids
hydroxy-ethyl starch (HES)
dextran
gelatin
albumin (5%)
plasma
whole blood
HES
chemically altered starch
hetastarch, vetstarch
metabolized by serum amylase
eliminated by kidney or RES
T/F HES may alter hemostasis at high doses and in already sick animals (von Willebrand disease)
true
concerns with HES
renal failure in septic patients
recommendations with HES
use crystalloids as first line of treatment of shock
try to delay use and minimize amount of given colloids
max dose of HES
20 mL/kg/day
routes of administration for crystalloid solutions
IV
IO
SQ
IP
anesthestized patients almost invariable IV
types of water losses
physiological - renal, GI, respiration
pathological - vomitting, diarrhea, bleeding
anesthesia
reasons for giving IV fluids during anesthesia
maintain patient IVC
compensate for drug induced vasodilation
compensate for dehydration (fasting)
increase preload therefore CO
replace ongoing fluid losses
maintenance rate of crystalloids during anesthesia
10mL/kg/hr
what should be given in cases of hypotension
10mL/kg fluid boluses (within 15 min)
blood loss should be replaced immediately with
crystalloids (3x volume of lost blood) or
colloids (exact volume)
>20% total blood volume lost - consider whole blood transfer
FFP - tx of coagulopathy
