Fluid Therapy - Exam 4 Flashcards
Total body water (TBW) represents about _% of lean body mass
60%
_ volume represents about 2/3 of TBW and _ volume represents about 1/3 of TBW.
Intracellular
Extracellular
ECV
-primary cation
-primary anion
Sodium
Chloride
ICV
-primary cation
-primary anion
Potassium
Phosphate
Resting membrane gradient of electrolytes in the ECV and ICV are maintained by the ++_ pump in the cell membrane which actively brings Na+ into the cell.
Na, K, ATPase pump
Under normal circumstances, the daily fluid volume needed to maintain TBW homeostasis is:
25-35mL/kg per day
(~2-3L/day)
1/4 of the ECV is made up of the _ compartment while the other 3/4 is made up of the _ compartment
Intravascular
Interstitial
_ _ _ (Pc) is the intravascular blood pressure, driven by the force of the _ and impacted by the _ tone
Capillary hydrostatic pressure
CO
vascular
_ _ _ (Pif) is the hydrostatic pressure of the interstitial space.
Interstitial fluid pressure
The Pif of most tissues is _ (positive/negative) likely from the effects of the lymph vessels in the interstitium. However, the tissues of the kidneys, brain, skeletal muscle, and bone marrow are _ (positive/negative)
negative
positive
_ _ _ (πp) is the osmotic force of _ proteins within the vascular space
Plasma oncotic pressure
colloidal
_ _ _ (πif) is the osmotic force of _ proteins within the interstitial space
Interstitial oncotic pressure
colloidal
_ is the primary determinant of plasma and interstitial oncotic pressures.
Albumin
-bc of its low molecular wt and high concentration
Increasing πif and Pc favor fluid filtration into the _ space whereas increasing πp and Pif favor fluid absorption into the _ space.
interstitial
intravascular
What equation is this?
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πif])
Starling Equation
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πif])
-What does Jv represent?
Net fluid movement between compartments
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πif])
-What does Kf represent?
filtration coefficient accounting for capillary surface area and endothelial permeability to water (or capillary hydraulic conductivity)
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πif])
-What does [Pc-Pif]- σ[πp-πif] represent?
net driving force
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πif])
-What does σ represent?
reflection coefficient ranging from 0-1accounting for different degrees of endothelial permeability to different substances like albumin and large polar molecules
-σ = 0 = endothelium is freely permeable
-σ = 1 = it’s completely impermeable
-during capillary filtration, 100% of substance is reflected back into the vascular lumen
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πif])
Increasing the Kf favors _ (filtration/absorption)
filtration
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πif])
-When net filtration (Jv) is positive, fluid moves towards the _ and is _.
tissues
filtered
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πif])
-When net filtration (Jv) is negative, fluid moves towards the _ and is _.
vasculature
absorbed
At the arterial end of the capillaries, the net filtration is slightly _ (+/-) and the venous end is slightly _ (+/-)
arterial- positive
venous - negative
Normally, the overall balance of filtration pressures in capillaries in the whole body is slightly _ (+/-), so a small % of intravascular volume is constantly filtered into interstitial space at _mL/min.
positive
2mL/min
-this volume is sent back intravascular via the lymphatic system
When euvolemic, net filtration is ~ _ (>,<, = ) lymphatic flow.
equal
The _ is the gel layer on the luminal surface of the vascular endothelium and plays a major role in the _ _ effect.
glycocalyx
double barrier
Processes supported by the glycocalyx:
-transcapillary fluid exchange
-microcirculatory flow
-blood component rheology
-plasma oncotic pressure
-signal transduction
-immune modulation
-vascular tone
The glycocalyx is about _ to _ mcM in diameter.
0.1-1.2mcM
The glycocalyx is composed of a matrix of _, _, and _ acid.
glycoproteins
polysaccharides
hyaluronic acid
The glycocalyx binds to _ _ _ and _ _, creating a physiologically active barrier in the vascular space.
ionic side chains
plasma proteins
The barrier created by the glycocalyx repels _ charged polar compounds and _ _ , preventing adhesion to the wall and augmenting laminar flow.
negatively charges
blood components
The glycocalyx binds to _ which helps preserve capillary oncotic pressure and _ its permeability to water. This modulates the impact of plasma _ pressure on net filtration. This is called the _ _ effect.
albumin
decreases
hydrostatic
double barrier
Net filtration (Jv) = Kf ([Pc-Pif]- σ[πp-πsg])
-What is this equation?
REVISED Starling Equation
-accounts for the double barrier effect
-πsg represents the oncotic pressure in the subglycocalyx space between the glycocalyx and endothelium
How does the glycocalyx affect the inflammatory process?
-contains inflammatory mediators whose binding sites are within its matrix, preventing leukocyte adhesion except when acute inflammation occurs or the endothelium is damaged
Beyond preventing unwanted adhesions to the vessel wall, facilitating the double barrier effect, and immune modulation, the glycocalyx also scavenges for _ _, binds to and activates _ _, and regulates _ _ from local vasoactive responses to mechanical stress.
free radicals
ANTIcoagulation factors
signal transduction
Normal minute daily alterations in TBW are regulated by _, _, and _ pathways.
RAAS
ADH
ANP
T/F Regulation of the ECV is largely dependent on potassium homeostasis
false
RAAS process
1._and _ afferent arteriole baroreceptors detect hypotension and _ (PNS/SNS) activation
2. The _ cells of the kidney release renin
3. Renin circulates and meets circulating angiotensinogen, cleaving it so it becomes active as _.
4. Angiotensin I causes _ vasoconstriction until it reaches the _.
5. In the , angiotensin I is converted to angiotensin II via _ _ _ ().
6. Angiotensin II is a potent _ and directly acts on the _ _ to reabsorb Na+ and water
7. Angiotensin II also makes the adrenal cortex release _, which increases Na+ and water _ by the kidneys.
- Intracardiac and renal
- juxtaglomerular
- angiotensin I
- local; lungs
- lungs; angiotensin-converting enzyme (ACE)
- vasoconstrictor; renal tubules
- aldosterone; retention
ADH process
1. _ in the hypothalamus detects minor increases in serum osmolality.
2. The _ _ _ releases ADH and the hypothalamus stimulates _.
3. ADH causes _ channels in the kidneys to absorb large amounts of water.
4. This causes preserved volume and drastically _ urine concentration and osmolality.
5. ADH also works as a potent _ _.
6. _ blood volume detected by baroreceptors in the _, _ body and aorta also can stimulate the release of ADH.
- Osmoreceptors
- Posterior Pituitary Gland; thirst
- aquaporin
- increasing
- ARTERIAL vasoconstrictor
- Decreased; atria, carotid body
ANP process
1. _ receptors in the cardiac atrial walls detect -volemia ( preload).
2. This stimulates the release of ANP from cardiac _.
3. ANP released causes the kidney to _ Na+ and water, _ the blood volume and _-loads the heart.
4. ANP also produces specific vasoactive responses in the afferent and efferent renal _ to _ the GFR.
5. This _ in GFR _ the release of renin and ADH.
6. Alternatively, when the preload is _, atrial receptors inhibit the release of ANP.
- Stretch; hypervolemia/ increased preload
2.myocytes - release; reducing; off
- arterioles; increase
- increase; decreases
- low
Daily water fluctuation represents only _% of TBW
0.2%
-bc of regulatory mechanisms maintaining fluid/lyte status
_ are preferred for resuscitation of dehydration conditions such as prolonged fasting, active GI losses, polyuria, and hypermetabolic states.
Crystalloids
-all of those conditions cause a hypertonic state of the plasma
When trying to fix hypertonicity from dehydration conditions, crystalloids can hydrate the entire _, restoring water/lyte homeostasis in both the _ and _ spaces.
ECV
intravascular and interstitial
In dehydration states, crystalloid admin is useful for:
-immediate restoration of circulating vascular volume
-preserving microcirculatory flow
-decreasing hormone-mediated vasoconstriction
-correcting plasma hyperviscosity from hemorrhage states
T/F Compared to colloids, crystalloids have a high allergenic potential compared to colloids, metabolize poorly, and have poor renal clearance.
false
-less allergy potential, better metabolized and excreted
T/F Because crystalloids are distributed in the ECV evenly, they expand plasma volume very well
-false
Due to _ molecular wt, crystalloids contribute to _ of plasma proteins and loss of capillary oncotic pressure, causing filtration of _ to _% of volume given into the interstitial space.
low
hemodilution
75-80%
The original and most commonly given crystalloid is:
0.9
Of all the isotonic crystalloids, _ is the least physiologic.
0.9
T/F There is more sodium than chloride in 0.9.
false, they are about equal
-there is more sodium than chloride in normal human plasma
Hyper-_ from high amounts of 0.9 administration could cause acid/base imbalance, leading to dose-dependent metabolic _.
Hyperchloremia
metabolic acidosis
Even with compensatory mechanisms to regulate pH, using 0.9 for volume resuscitation causes marked changes in _ excess from _ load. This can _ volume overload if a _ base excess was the infusion trigger.
base
chloride
worsen
negative
Excess renal absorption of chloride from excessive 0.9 admin can cause a _ in GFR and impair renal handling of _.
decrease
bicarbonate
Increased sodium load from excess 0.9 admin can cause increased sodium and water _, _, and _ edema.
retention
hemodilution
interstitial
Giving _L of 0.9 to healthy pts causes a positive sodium and water balance that takes up to _ days to excrete.
2L
2 days
ERAS strongly recommends the use of _ _ solutions for periop fluid management in the setting of high-volume fluid resuscitation.
balanced crystalloid
Which fluid is preferred for pts AT RISK for cerebral edema?
0.9
-mild hyperosmolality
Why is 0.9 preferred for fluid admin in pts that are anuric and ESRD?
-they would have a harder time excreting the potassium from more balanced crystalloids
3% saline solutions are indicated for:
trauma
head injuries
severe hyponatremia
-can help with intracranial hypertension
Hypertonic saline (3% +) promote volume expansion, pulling fluid from _ and _ spaces into the intravascular space.
intercellular
interstitial
Potential risks of hypertonic saline solutions:
vascular irritation
sudden massive fluid shift into intravascular space
dehydration of neural cells resulting in osmotic demyelination syndrome
The buffering agent (bicarbonate substrate) in LR is:
sodium lactate
T/F 0.9 is more effective in preserving intravascular volume than LR
false
The sodium lactate in LR maintains the electrochemical balance and _ pH while decreasing the anionic requirement for _.
neutral
chloride
Large volumes of LR aren’t recommended for diabetic pts because the byproduct from the _ metabolism can increase the rate of _.
hepatic
gluconeogenesis
T/F LR’s byproduct can increase the rate of glycogenesis and, therefore, isn’t recommended in large volumes to diabetic pts.
false
increases the rate of gluconeogenesis, not glycogenesis
The lactate metabolism pathway found in LR can have an _ effect and cause mild metabolic _.
alkalizing
alkalosis
How can LR contribute to cerebral edema?
it is mildly hypotonic and can cause transient serum hypoosmolality, leading to cerebral edema
T/F LR is the preferred solution to infuse blood products.
FALSE!!!!!!
-it contains citrate which increases the risk of coagulation with calcium!!!!!!
-DO NOT INFUSE BLOOD PRODUCTS WITH LR; CONTRAINDICATED!!!
LR contraindications:
-blood product admin
-pts with TBI, other neurovascular insults
-not CI, but avoid large volumes in diabetic pts (increases gluconeogenesis)
The most isotonic balanced crystalloid solutions are:
-Plasmalyte-A
-Normosol-R
-Isolyte S
T/F 0.9 preserves physiologic pH and renal perfusion better than balanced salt solutions like plasmalyte.
False
-they have a better acid/base profile as well
Pros of plamalyte-a, isolyte s, and normosol-r:
-most isotonic of balanced solutions
-most favorable acid/base profile
-preserve pH better than 0.9
-preserve renal function better than 0.9
-use sodium gluconate and sodium acetate as buffers instead of lactate like LR
-no calcium, able to use with blood products
Composition of Plasma:
-all lytes in mEq/L
Na+ = 142
K+ = 4
Cl- = 103
Phosphate = 1.4
Mag = 2
Ca++ = 5
Composition of Plasma:
-pH and osmolality (mOsm/L)
pH =7.4
291 mOsm/L
Composition of Plasmalyte-A/Normosol-R/ Isolyte-S
-all lytes (in mEq/L)
Na+ = 140-141
K+ = 5
Cl- = 98
Phosphate = 1 (only in isolyte)
Mag = 3
Acetate = 27
Gluconate = 23
-no calcium!
Composition of Plasmalyte-A/Normosol-R/ Isolyte-S
-pH and osmolality (mOsm/L)
pH = 7.4
294-295 mOsm/L
Composition of LR
-lytes (mEq/L)
Na+ = 130
K+ = 4
Cl- = 110
Ca++ = 3
Lactate = 28
Composition of LR
-pH and osmolality (mOsm/L)
pH = 6.2
275 mOsm/L
Composition of 0.9%
-lytes (mEq/L)
Na+ = 154
Cl- = 154
Composition of 0.9%
-pH and osmolality (mOsm/L)
pH = 5.6
310 mOsm/L
T/F Crystalloids are high molecular weight molecules and colloids are typically low molecular weight molecules.
False
Colloids DIRECTLY increase plasma oncotic pressure (πp) by causing the endothelial glycocalyx to _ transcapillary filtration
decrease
T/F A fluid sparing method of increasing intravascular volume is giving crystalloids
false,
giving colloids
Only 2 naturally occurring colloids available for infusion:
-albumin
-PRBC
Which 3 ways are colloids classified by?
-molecular wt
-concentration
- half life
Dextran
-molecular wt
-1/2 life
40-70kDa
6-12 hr
Dextrans are derived from _ metabolism of sucrose
bacterial
-not used anymore due to renal and coag issues and anaphylaxis
Dextrans cause acute renal failure in 2 ways:
-INDIRECT hyperosmotic renal injury
-DIRECT renal tubular damage from accumulation
Dextrans cause coagulopathic effects in 4 ways:
-impairs von Willebrand factor
-activates plasminogen
-interferes with platelet aggregation
-adheres to the surface of platelets and RBCs interfering with crossmatching of blood products
T/F Gelatins are derived from porcine components
false
bovine
Gelatin
-molecular wt
-1/2 life
30-35kDa
2-4hr
-limited duration of plasma expansion
Cons of gelatins:
-interferes with platelet function
-cause nephrotoxicity
-high risk for anaphylaxis with urea-based formulations
-concern for bovine spongiform encephalitis (BSE)
Hydroxyethyl starches (HES) are made from starchy plants like _, _, and _.
potatoes
maize
sorghum
-can cause allergies if ppl are allergic to these !
HES are created by substituting hydroxyl groups at the _, _, and _ carbon atoms.
2nd, 3rd, and 6th
HES are classified by:
-molecular wt
-substitution ratios
C2/C6 ratio compares the degree of substitution at the 2nd carbon atom to the 6th and if the ratio is _, the HES will be more difficult to metabolize
high
1st gen HES:
Hetastarches
Hexastarches
1st gen HES
-molecular wt
-sub ratio
Highest molecular wts
>450kDa
0.6-0.7 ratio
1st gen HES
-a/e
-dose-dependent coag issues
-nephrotoxic (interstitial deposits accumulate in tissues/organs)
-pruritis
How do 1st gen HES contribute to dose-dependent coagulopathies?
-hemodilution
-binding up clotting factors
-interfering with platelet adhesion
-inhibiting fibrin polymerization
-alter plasma viscosity
2nd gen HES:
Pentastarches
2nd gen HES
-mol wt
-sub ratio
Medium wt
200-260kDa
sub ratio 0.5