Anesthesiology - Fluid Therapy

drraythe's version from 2015-04-18 23:05


Question Answer
how much of the body is water? what about neonates?60%, neonates are like 80%
Difference between cats and dogs regarding the volume of their extracellular fluid?cat 8% dogs 10% (of total body)
*Extracellular compartment--> the intravascular space is what % of the body fluids, and what % of the BW? (know that #s are only an average)15% of body fluids and 9% of body weight
Extracellular compartment--> the interstitial space is what % of body fluids, and what % of the BW? (know that #s are only an average)25% of body fluids and 15% of body weight
**intracellular space is what % of body fluids, and what % of the BW? (know that #s are only an average)60% of fluids and 36% of body weight
main intracellular electrolyte?K+
main plasma electrolyte?Na+
main interstitial electrolyte?Na+
which three electrolytes primarily determine the extracellular water content?Na, Cl, HCO3
which three electrolytes mainly dominate the intracellular fluid compartment?potassium, phosphates, and proteins
rough guideline formula for how much fluid to replace in a deficit?(%dehydrated x bodyweight in kg) / 100
The intracellular fluids differ form extracellular fluids mainly inthe high K and low Na levels
what is osmosis?Movement of water through semipermeable membranes
what is osmotic pressure?Pressure on one side of the membrane that prevents movement of water
explain osmolarity vs osmolalityosmoLARITY= (particles/l solution) which has to do with VOLUME. osmoLALITY is (particles/kg H2O) which has to with WEIGHT (which is why she always says osmolaLity even though we all learned osmolaRity...because we are referring to the weight of the animal) (also you think the one with the L would be Liters but its not, it's weight of course)
explain what is going on with oncotic pressurepressure created by large molecules which cannot pass the membrane
**what is serum osmolality? what kinda __tonic is it?ISOTONIC--- 300mOsm/kg (270-350)
what is hydration? what is volaemia?hydration=state of extracellular volume (interstitial and intravascular space). volaemia= refers to ONLY the intravascular volme
Assessment of hydration status--> signs at: <5%?not detectable
Assessment of hydration status--> signs at: 5%?dry MM, normal skin turgor
Assessment of hydration status--> signs at: 6-7%?dry MM, mildly decreased skin turgor
Assessment of hydration status--> signs at: 10%?eye sunken in orbits, highly decreased skin turgor, increased CRT
Assessment of hydration status--> signs at: 12-15%?signs of shock, death imminent
to determine what KIND of fluid has been lost in a pt, what must you do?look at LAB paramteres (is it crystalloid, colloid, or pure water loss?)
what are crystalloids?solutions of small solutes (<200) such as electrolytes (Na,K,Cl, HCO3), dextrose, mannitol
when are some situations where you'd use NaCl INSTEAD of LRS?acute kidney failure, postrenal uremia,addisons, or alkalosis (bc LRS is converted into Bicarb by the liver, so dont want a MORE basic solution, addisons= imbalance of Na, low Na, so want Na, and LRS has K+. Also in post-renal uremia also high K and LRS has high K, and in acute kidney failure, cant excrete K, don't want MORE K from LRS)
when would you use colloids instead of LRS?hypoproteinemia, EDEMA, or not responding to crystalloids
max infusion rate of K+0.5 mmol/kg/hr
calculation for how much bicarb to give?Base excess x kg x 0.3
how do you lose crystalloids from the body?vomiting, diarrhea, duiresis(pee)
how do you gain crystalloids?gain fluids with Na concentrations near plasma
what are colloids? (exs?)solutions of large solutes (>20,000) such as albumin, dexTRANS, hetastarch
how do you lose colloids from the body?whole blood or plasma-rich fluid losses
how do you gain colloids?dextran, gelatin, hetastarch, albumin, plasma, blood
*how much for how long of crystalloids stay in the blood stream after infusion? what problem can this lead to?only 1/3-1/4 of volume infused is still present in the intravascular space after 1 hour-- this can lead to edema
which fluids shouldnt be used for shock fluid therapy? why?fluids with low or no sodium...because they're basically just water which then diffuses into the cells and doesnt help much with blood volume
examples of free water/hypotonic fluid solutions?free water, dextrose in water solutions, hypotonic saline solutions,
two uses for hypotonic crystalloid fluid solutions?replace water deficit/losses, drug admixtures
how can you end up misusing hypotonic crystalloids?if you give large doses rapidly, you can cause water intoxication. also you can cause cellular edema (free water/hypotonics tend to basically go right into the cells)
what "tonic" are the REPLACEMENT fluids?ISOTONICS
what are three examples of isotonic fluids?lactated ringers(Na 130), saline (Na 154), Plasmalyte 148 (Na 140)
where do isotonic fluids tend to go?into the interstitial (extracellular) space
where do hypotonic fluids tend to go?into the intracellular space
which fluids do not tend to alter normal electrolyte values?polyionic cyrstalloids (types of isotonic solutions)
disadvantage--> crystalloids are usually rapidly redistributed to the ___ compartment, meaning about only _________% is retained intravascularly. Because of this you need to...Interstitial, only 25% retained intravascularly, which means you need to admin LARGE volumes
crystalloids can cause what kinda edema? give three examplesinterstitial edema, such as cerebral, pulmonary (esp cats), and systemic interstitial
what causes hemodilution? describe it a littlecrystalloids can cause hemodilution. with will dilute RBCs, albumin, AND coagulation factors which can lead to bleeding
what are the two main crystalloid replacement solutions?lactated ringers solution, 0.9% NaCl
LRS versus NaCl--> what kinda __tonic? is it balanced? which is more commonly used? any other disadvantages?BOTH are isotonic. NaCl is NOT balanced, LRS IS balanced because it has mult. electrolytes and also has lactate as a buffer (in the liver lactate is converted into bicarbonate). LRS is very commonly used because of its buffering abilities. NaCl CAN cause a metabolic acidosis if overdosed
will improper use of a crystalloid cause a metabolic acidosis or alkalosis?acidosis (too much LRS can cause alkalosis tho)
**normal replacement of normal ongoing losses, aka maintainance, RATE?2-3ml/kg/hr
**what is the rate for support of circulating blood volume during general anesthesia? (maintainance)10ml/kg/hr (10 is the standard-- can be 5 too, if the pt has congestive heart failure, kidney problems, or there is risk of overhydration)
**what is the rate of fluid for moderate to severe hypovolemia (shock)?20-40-80ml/kg (NO TIME UNIT HERE)
whos at big risk for pulmonary edema?cats
risk of fluid therapy pertaining to bloodhemodilution can lead to a coagulopathy
when might you want to give a little extra fluid during intraoperative fluid maintainance? (also say normal rate and what inc rate would be)normal intraoperative fluid maintainance rater would be 5-10ml/kg/hr. Higher rate would be 20ml/kg/hr. You might want a higher rate if the pt is mildly hypovolemic, hypotensive, dehydrated, has had mild hemorrhage
you must be extra careful giving fluids (use a decreased rate) in what types of patients?(1) pts with pulmonary edema or lung contusions (2) kidney failure (3) congestive heart failure (4) hypertensive or hypervolemic (5) brain edema (6) cadiac pts in general
in an isotonic crystalloid solution, what % of the infused solution is still present in the vessels after 30 minutes?25-30% (30 min only 30 percent...ISO hate when that happens)
hypotonic solutions usually used for?hypertonic dehydration, possibly cardiac pts (bc low Na)
isotonic saline solution is best used when?correct hyponatremia or metabolic alkalemia
when are hypertonic solutions usually used?hypovolemia, shock, and cerebral edema
when are dextrose solutions usually used?when glucose substitution is necassary, such as in young animals, badly managed diabetic pts, or low glucose levels due to other reasons
what are three synthetic colloids?HES (aka hydroxyethyl starch aka hetastarch), dextrans, gelatins
what are two natural colloids? (and two "others" colloids)natural: plasma, whole blood. Others: oxyglobin, human albumin
are colloids homo or heterogenous?heterogenous (all sorts of diff sized molecules)
what are the Hyperoncotic and iso-osmotic colloids? what is their osmolality?the 6% or 10% hetastarch, or the 6% dextran. their osmolality (in saline) is 308
how much of synthetic colloids is retained in the intravascular space, and for how long?60-80% retained intravascular, for SEVERAL DAYS (im gonna 68 some large mollecules, because 69ing them would just be too much!)
what is the needed volume like for a colloid versus a crystalloid?60-80% of colloids are retained, which means they need a much smaller resusitation volume (crystalloids only 1/3-1/4 volume retained after 1hr)
3 main indications for using colloids?(1) shock/hypotension (2) protein loss, eg increased vascular permeability (sepsis), loss via GIT or kidneys, exudate (3) hypoproteinemia/edema
what are 2 major disadvantages to synthetic colloids?(1) intersitial deficits are usually not corrected (meaning they are not suitable in case of pure loss of crystalloid) (2) dilution of coag factors possible--> bleeding tendency
HES is aka? what does it do to the oncotic pressure? how long can you give it and through what route?hydroxyethylstarch, aka hetastarch. it is used to inc the oncotic pressure, and can be given up to 24hr intravenously (I did the HES program for one day with results! -TV commercial)
why do you want to give hetastarch with crystalloids?acts so fast due to oncotic pressure it can cause dehydration (if not given with crystalloid) or they can irritate the BVs
**if you want to bolus hetastarch, you give how much over what amount of time?5-10ml/kg over 10-15 minutes
how much hetastarch would you give in a CRI to replace or maintain oncotic pressure?CRI of 1-2ml/kg/hr (I only want 1 or two packets of starch if you're going to keep giving it to me, because i dont use it that often)
*what is the max amount of hetastarch you can give in one day?max 20ml/kg/day (5-10 trannies a day and 20 heteros a day)
what is "hyperhes" and what do you use it for? what is the MAX amount you can give and why?this is a combination of a hypertonic(7.5%) saline solution with hyperoncotic(6%) hetastarch (HES). This is helpful in shock (esp cats) because it can treat both dehydration and and dec oncotic pressure at the same time. MAX DOSE is 5ml/kg because any more can lead to hypernatreamia (Five is hyper)
dextran solution-->what is a dextran? what is it used for? how does it affect oncotic pressure? what is the half-life like? what is a caution about using this?it is a polysaccharide which works as a plasma expander by increasing oncotic pressure. Its half life is less than hetastarch's. **ANAPHYLACTIC REACTION IS POSSIBLE!!!!!!** (I'm allergic to sugar-sweet trans people)
what is the max amount of dextran solution you can give in a day?5-10ml/kg/day max (5-10 trannies a day is all I can handle, he said)
what are the natural colloids and what is their inherent risk?plasma/whole blood-- risk of a transfusion reaction.
what are three indications for natural colloids?(1) anemia (indication for whole blood) (2) coagulation disorders (fresh frozen plasma or fresh whole blood) (3) extreme hypoproteinemia (indication for plasma)
what is 25% human albumin used for, and what risk is there?colloid osmotic pressure support in critically ill patients mostly without adverse affects- however there have been some immediate or delayed transfusion reactions in dogs
what is oxyglobin I? what is it used for? how long is the shelf life?it is purified polymerized bovine hemoglobin, which can be used as a UNIVERSAL Hb DONOR TO ALL VET SPECIES(licensed for use in dogs in europe), and no cross matching is necessary. It works as a colloidal solution with O2 carrying capacity which can be used if no blood products are available. it has a 3 YEAR shelf life at room temp!
oxyglobin II --> how quickly can you admin it? what is its half life? what are the risks of using it?SLOW admin, with a half life of 30-40 hours. there is a risk of CIRCULATORY OVERLOAD (esp in cats), and it can cause jaundice and hematuria.
what is oxyglobin II most often used for?IMHA (bc the RBCs are just gonna get destroyed anyway)
5 major disadvantages of colloids?(1) doesnt replace INTERSTITAL deficits (2) not good replacement fluid for GI losses (3) hemodilution (dilute RBCs and coag factors) (4) rebleeding from damaged blood vessels (5) can cause coagulopathies (impaired factor VIII (8) and VwB factor activity, as well as dec platelet fxn)
what bad things happen if you give too much dextran solution?(colloid) allergic reactions, renal insufficiency, and hemorrhage
why are some reasons you'd totally want intraoperative fluid therapy?maintain blood volume, CO, and BP because of anesthetics having negative inotropic and vasodilatory effects
when should fluid deficits be corrected?PREOPERATIVELY IF AT ALL POSSIBLE
**whats the intraoperative fluid rate?5-10ml/kg/hr
**what is the intraoperative fluid rate if you are doing a laparatomy?20ml/kg/hr
**if there is hypotension/hemorrhage, what can you increase your intraoperative fluid rate to?up to 20-60ml/kg/hr (start with 10 though and see how it is)
**what is the intraoperative fluid rate you'd give for cardiac patients, patients with pulmonary edema, or hypertension?2-5ml/kg/hr
a large drip set will have _________ drops per mL of fluid10, 15 or 20
a small drip set will have _________ dops per mL of fluid60 drops/ml (Small, Sixty)
**what is the equation for drops/min?(BW (kg) x rate (ml/kg/hr) x infusion set calibration (drops/ml) ) / 60 (min/hr)
ex for drops/min equation: 10kg dog with a planned infusion rate of 10ml/kg/hr, and there is a set calibration of 15drops/min..... how many drops per minute, or drops per second?( 10kg x 10ml/kg/hr x 15drops/ml) / 60= 25 drops per minute OR 0.4 drops per second which would better be said as about 1 drop every 2 seconds
ex for drops/min equation: 500kg horse, infusion rate 10ml/kg/hr, set 10 drops/min... how many drops a sec?(500kg x 10ml/kg/hr x 10drops/min) / 60= 13.8 (roughly 14) drops per second
**explain how you'd go about giving a shock infusionstart with LRS, you can give up to 90ml/kg to effect! do it in a bolus of 20ml/kg at a time, and reassess after each bolus. ALSO you can give a colloid, 5ml/kg as a bolus repeated up to a max of 20ml/kg a DAY