Exam 2: Lecture 13/14: Fluid Therapy Flashcards
T/F: fluid therapy is a common practice in veterinary medicine and a standard of care during the perioperative period
true!
Why can fluid therapy be risky?
because of fluid overload!
T/F: All fluid therapies are based on human models, even in vet med
true! after the cholera epidemic
What are the 3 things considered in fluid physiology
distribution, circulations, eliminations
IMPORTANT! Why should we give fluids?
perfusion, O2, electrolytes, and acid base disoders
T/F: Dosing of fluids should be uniform regardless of the context of the case
FALSE! It should be individualized looking at the type of anesthesia and the disease severity
What is the only accurate way to monitor fluids given
fluid responsiveness
Historically, how did we know that we gave too much fluids?
because the patient would have pulmonary edema
if you have >10% increase in body weight, what does that mean for our patient?
this is the zone where death can occur from fluid overload
T/F: All fluids dilute what they dont contain
true!!!
what are the 7 things that can happen from fluid overload
- pulmonary edema
- cerebral edema
- myocardial edema
- increased renal venous pressure and rental interstitial edema
- gut edema
- tissue edema with impaired lymphatic drainage and microcirculatory derangements
- hepatic congestion
What % of the patients body weight is their blood volume
8%
what % is total body water
60% (40 intracellular and 20 extracellular)
what 2 things does extracellular fluid break down into and what are the %’s
15% interstitial
5% plasma
how is the extracellular fluid separated in the body
via a vascular wall (capillary wall)
what is the avg blood volume for dogs
80 ml/kg
what is the avg blood volume for cats
60 ml/kg
what is the avg blood volume for horses
70 ml/kg
what is the avg blood volume for cows
55 ml/kg
T/F: There is also another distribution of fluids called transcellular fluids and they make up about 2%
true!
how does the lymphatic circulation get back into the systemic circulation
through the thoracic duct
For the starling equation, what are the 2 biggest contributors of effect on fluid flux
Pc = capillary hydrostatic pressure
πc = capillary colloid osmotic pressure
what is important to remember about the revised starling principle
Fluid is NOT normally reabsorbed from capillaries except in the gut and kidney or during acute hypotensive episodes
What is the endothelial glyucocalyx
a slimy-like wall that lines the blood vessels
what is the purpose of the endothelial glycocalyx
It helps to keep fluid in the vascular system
what happens if you destroy the endothelial glycocalyx and how can you damage/destroy it
you can damage/destroy it via if you are diseased or giving too much fluids
this no longer allows you to keep fluids in the vascular system leading to edema and higher likelihood of fluid overdose
What is the interstitium
a series of fluid filled spaces made of flexible connective tissue
Why is the interstitium like a slinky
you have to use force to get it to stretch but if you stretch it toooo far it wont come back together completely
In the interstitial fluid, what compartment has rapid exchange and is working around normal pressure
Vt1
In the interstitial fluid, what compartment has slow exchange and is usually over stretched
Vt2
what are the 8 reasons to use IV fluid therapy
- maintain hydration (30-60ml/kg/day)
- treat/prevent dehydration
- treat/prevent hypovolemia
- treat hypotension
- normalize acid-base balance
- normalize electrolytes
- supply calories
- provide access to a vein
What is something important to remember when we are giving fluids to prevent or treat dehydration
must be VERY careful on how fast you give them! It can take 16 hours to 1.5 days to get fluids back into vessels
what are the 7 most common problems with general anesthesia
- arousal and breakthrough pain
- hypoventilation
- hypotension
- arrhythmia
- temp regulation
- airway complications
- recovery delirium
What are some of the causes for hypotension
- volume deficiency
- drugs
- hypothermia
- hypercarbia
- acidemia
- hyperkalemia
- heart failure or arrhythmia
- sepsis
How does anesthesia produce hypotension when there is MINIMAL or NO blood loss
Because almost every drug is a vasodilator which takes blood from the arteries and puts them into veins leading to a drop in BP
What is the golden hour in vet med
the period of time after an injury when there is the highest likelihood that medical/surgical treatment will prevent death
What is a compensatory response to hypovolemia
suppression or loss of lymphatic return
If there is blood loss, what happens once MAP gets below about 45 mmHg
the body starts to pick what organs it can stop supplying blood to, to maintain vital function
T/F: Healthy animals should not be able to compensate for up to 10-15% loss of their blood volume
false! They should be able to compensate for that % of blood loss
T/F: Hypotension due to hemorrhage happens when blood loss is > 10 to about 30 ml/kg
true!
What % of blood volume loss is class I of hemorrhagic shock and what are the key components
Less than or equal to 15% of blood volume lost
usually fully compensated by transcapillary refill, blood volume is maintained, and clinical findings are absent or minimal
What % of blood volume loss is class II of hemorrhagic shock and what are the key components
15-30% blood volume lost
clinical findings may include in HR and BP, BP and perfusion of vital organs is maintained, urine output may decrease to <1.0 mL/hr and splanchnic flow may be compromised
What % of blood volume loss is class III of hemorrhagic shock and what are the key components
30-40% blood volume lost
onset of uncompensated hypovolemia, hypotension, and reduced urine output
What % of blood volume loss is class IV of hemorrhagic shock and what are the key components
> 40% blood volume lost
profound hypotension and oliguria, changes may be irreversible
At what class or classes of hemorrhagic shock will we most likely see death
III or IV
What is osmolarity
refers to the number of solute particles per 1L of solvent
what is tonicity
the ability for water to move in or out of a cell by osmosis
what is colloid osmotic pressure
osmotic pressure exerted by large soluble molecules referred to as oncotic pressure
Why are fluids technically considered drugs
because a drug is a medicine or other substance which produces a physiological effect when introduced into the body and thats what fluids do
what is maintenance fluid therapy
daily metabolic requirements
what is replacement fluid therapy
replace lost fluids, includes insensible losses from respiratory, skin, and water excreted in the stool
what is resuscitative fluid therapy
acute restoration of hemodynamics, tissue perfusion, and oxygen delivery
what are the types of crystalloid fluids
saline vs balanced solution
what are colloid fluids
gelatin vs dextran vs hydroxyethyl starch vs polyethylene glycol
What is the normal PCV in a healthy animal
hemoglobin > 7- 10 g/dl
Who was sydney ringer (1834-1910)
made ringers solution
who was hartog jacob hamburger (1859-1924)
hamburgers solution aka normal saline solution
who was alexis f hartmann (1898-1968)
made hartmanns solution aka lactated ringers
What are crystalloids
Na, Cl, K, and others solution that may contain metabolizable small molecules in water
what are balanced crystalloid solutions
physiological normal electrolytes, pH
what are colloid solutions
a solution that contains large molecules which are retained within the vascular endothelium
what are colloid solutes
metabolizable large molecules that should not pass through semipermeable membranes so that when infused they remain in the vascular system for prolonged periods of time
what determines the ability of colloids to remain in the vascular space
- molecular size (30-40kD up to >700kD)
- rate of degradation
- permeability of the endothelium
how much salt is in one L of saline
9000 mg/L (its 0.9%)
what % of water do most tissues contain
> 60%
what % of water does bone contain
about 30%
what % of water does fat contain
10-20%
T/f: Lean tissue contains less water than fatty tissue
FALSE! fatty tissue contains less water than lean muscle
What % of cardiac output does the vessel rich group get
about 75%
What % of cardiac output does the muscle group get
18%
What % of cardiac output does the vessel poor group get
2%
What % of cardiac output does the fat group get
5%
what are the best fluids?
depends on what is wrong!
what are the 4 things we should ask/consider for fluid therapy
- what type of fluid?
- what rate? (ml/kg/hr)
- what volume? (ml/kg)
- when? and for how long?
What was the original shock dose and why did we change it
80-90 ml/kg/hr and we changed it because that high of a dose can kill the patient
what is the new shock dose
40-60 ml/kg/hr
what is the one question to ask yourself when monitoring fluid therapy
are they fluid responsive??
what is central venous pressure good for when monitoring fluids
it is a good guide if you have given too much fluid volume but NOT if you have given enough
T/F: CVP does not always correspond to RA (right atrial??????) pressure
true!
T/F: CVP can correlate and predict cardiac output/stroke volume in response to fluid administratino
false! CVP can NOT correlate or predict cardiac output or stroke volume
T/F: Monitoring CVP to determine fluid administration almost always leads to fluid overload
TRUE!
Why doesn’t arterial blood pressure accurately monitor fluid infusion during anesthesia
because arterial BP is a LATE indicator of hypovolemia so by maintain arterial BP to me greater than or equal to 70mmHg with high fluids can produce fluid overload!
T/F: Volume therapy is not always effective in anesthetized animals and many animals are partially or completely fluid non-responsive
true! In about 25-75% of animals
what are some causes of fluid non-responsiveness
vasoplegia, heart failure, sepsis, or anesthetic overdose
how can we treat hypotension without producing fluid overload?
- decrease anesthetic depth
- utilize dynamic monitoring
- administer vasoactive drugs
how can we decrease anesthetic depth
by using multimodal anesthesia
what is multimodal anesthesia
using different things to help with anesthetic plane rather than just IV drugs (ex: nerve blocks, pain control)
what are some vasoactive drugs
norepinephrine, vasopressin, or dobutamine
how many ml/kg of packed RBCs will raise PCV by 0.1%
1ml/kg
how many ml/kg of packed RBCs will raise the hemoglobin by 0.3g/dl
1ml/kg
