Apex- fluids, lytes, acid-base Flashcards
How many L of total body water in a 70kg person
what’s the equation to remember
42L
60/40/20 (15/5)
60% TBW = 42L
40% ICV = 28L (40% x 70kg = 28L)
20% ECV= 14L
15% of ECV is intersistal fluid - 11L
5% of ECV is plasma - 3L
Major intracellular (3) vs extracellular (4) ions
intracellular = K, Mag, Phosphate
extracellular = Na, CA, Cl, HCO3-
What populations have the highest TBW (1)
vs lowest TBW (3)
Highest = neonates
Lowest = olds, fats, females
Think low muscle mass = less body water = less total body water
What forms a protective layer on the interior wall of the blood vessel
what happens when this is disrupted and what could distrupt it
glycocalyx
disruption > capillary leak (sepsis)
What does the lymphatic system do?
It pretty much filters out proteins, fluids, bacteria, and debris that have entered the intersistium (fluid filled space between structures such as cell membranes)
takes the extra fluid thats lost in the capillary exchange going on in the tissue and mops it up and returns it to the lymphatic ducts
-returns about 3L/day of fblood fluid per day to your ciruclatory system; without it functioning well, all that fluid is going to be outside the vasculature and in the interestial spaces
>swelling, hypotension
How does staph from your skin get into your blood stream from a scrape - outside of direct exposure to vessels
tissue is full of intersistal fluid that drains into your lymphatics which then drain to your heart
What is lymph?
how does it get cleared out from the tissues?
it’s essentally plamsa that leaks out of the capillaries
-see your circulatory system is a pressurized system, so everytime blood circulates through the capillaries, the capillaries have small holes in them that plasma (ECF) will leak out of the vessels and into the surrounding tissues
-small holes allows for larger molecules to get into the cells that are too big to diffuse through the walls of the capillaries like o2 and co2 can (like nutrients such as glucose from the RBCs and other waste products like nitrogen to get back into the vessels)
there are lymph vessels that clear it from the tissues
-build up of lymph fluid in the tissues, compresses the lymphatic vessels which have pressurized valves that open once lymph reaches a certain presssure in the tissues, then gets forced into the lymphatic vessels ; then when the pressure accumulates inside, it forces the valves shut and it cant escape back out
jobs of lymphatic system
- clears lymph from tissues and gets it back into the circulatory system via the veins
- immunity- lymph nodes serve as check points throughout the lymphatic system that will filter out any bacteria that may be in the lymph so it’s not deposited into your bloodstream
- transfers fat - carbs and proteins can leave the intestines and enter the capillaries; but fat cannot, the lymph picks it up and drops it off into the blood stream
your lymphnodes get big as an early sign of infection because once it has bacteria , it recruits RBCs to those lymph nodes to help destroy the bacteria
which pushes vs pulls fluid: onctoic vs hydrostatic
hydrostatic PUSHES fluid out
oncotic PULLS fluid in
The intracellular compartment is what % plasma and what % blood?
what is hematocrit?
what increases/decreases it?
60% plasma , 40% blood
the fraction of blood volume that is occupied by erythrocytes
increased hct = increased # of RBCs (chronic hypoxia) or decreased plasma volume (dehydration)
decreased hct = decreased # RBCs (anemia) or increased plasma volume (hemodilution)
Where is the thoracic duct?
at the juncture of the internal jugular vein and subclavian veins
*left = larger (risk of chylothorax during left IJ placement)
thoracic duct is where lymph is returned to venous circulation
What is fluid that accumulates in a potential space called?
an effusion
Label
Osmolarity vs Osmolality
OsmolaRity = # of osmoles per liteR of a solution
Osmolality- # of osmoles per kg of a solution
What is osmosis
the movement of water across a semipermeable membrane
not solute
T/F- osmotic pressure is a function of molecular weights
false - it’s a function of the number of osmotically active particles in a solution
Calculate the plasma osmolarity:
Sodium= 150 mEq/L
Glucose = 108g/dL
BUN= 14mg/dL
311 mOsm/L
(NA+ x 2) + (Glucose/18) + (BUN/2.8)
so youre adding everything
just remember
NA x 2
Glucose / 18
BUN / 2.8
*from the image you can see sodium is most important determinant and that hyperglycemia nad uremia can also increase the plasma os
Normal Plasma osmolarity
280-290 mOsm/L
What is the most important determinant of plasama osmolarity
Sodium
3 conditions that increase plasma osmolarity
hypernatremia, hyperglycemia, uremia
Rank the tonicity for each fluid, 1 being highest and 4 being lowest:
Albumin 5%
D5 0.45%
D5W
NaCl 3%
- NaCl3%
- D5 0.45%NS
- Albumin 5%
- D5W
Hypo (2) vs Iso (3) vs hypertonic solutions (4)
Hypotonic - lower osmolarity than plasma/cells (cells swell)
→ D5W & NaCl 0.45%
Isotonic- similar osmolarity to plasma/cells (no change)
→ 0.9% NaCl, LR, Plasmalyte
Hypertonic- higher os than plasma/cells
→ 3%NaCl, D5NS, D51/2NS, D5LR
so pretty much the only hypotonic ones are D5W and 0.45%NaCl by themselves
-add them together and its hypertonic
T/F: Albumin 5%, Voluven 6%, and Hespan 6% are all isotonic solutions
True
T/F: Dextran 10% is considered hypertonic
True
How long to crystalloids tend to remain in the intravascular space?
for ~ 30 minutes
Why is LR a better choice for large volume resussitation over NS?
bc NS can cause hyperchloremic metabolic acidosis if given in large amounts
What happens with the lactate in LR?
it’s converted to bicarb by the liver and kidneys and acts as a buffer to reduce the risk of metabolic acidosis .
Is it okay to give LR with blood? why or why not
yes
it used to be avoided due to the calcium content but clinical research shows that LR can be used safely when rapidly transfusing PRBCs
Hetastarch dose should not exceed what?
20ml/kg
True or false: Albumin causes hypocalcemia
True
True or false: Dextran increases blood viscosity
false - reduces blood viscosity
interesting…
it can improve microcirculatory flow during some vascular surgeries
T/F- albumin has pro-inflammatory properties
false- anti-inflammatory
when comparing colloids to crystalloids, which outcomes are shown to be better
both are the same
How long do crystalloids vs colloids expand plasma volume for?
crystalloids = 20-30 mins
colloids 3-6hrs
true or false- colloids have anti-inflammatory effects
true
downside to albumin
it binds calcium and can cause hypocalcemia
black box warning on Dextran 40
risk of renal injury
Coagulopathy & Anaphylaxis
(Dextran > Hetastartch > Hextend)
Which synthetic colloids is coaulopathy not an issue with?
volvulen
dont have to worry about keeping below a rate of 20ml/kg
max dose of dextran/hetastartch/hextend?
20ml/kg
risk of coagulopathy
how does NSS create a hyperchloremic metabolic acidosis?
high chloride load tells kidneys to get rid of bicarb
(too much Cl - ; kidney gets rid of HCO3 - )
True or false- Albumin does not contain antibodies or increase the risk of infectious disease transmission
True
Normal Serum K
3.5-5.5meq/L
What is the most abundant intracellular cation?
Potassium
Which hyperpolarizes cell membranes vs depolarizes them?
Hypo vs Hyperkalemia
Hypokalemia - hyperpolarizes them
Hyperkalemia- depolarizes them
okay so theink with hypokalemia there is less K in the blood, this creates a wider potassium gradient which is going to cause more K to seep outside of the cell and into the ECF, making the inside of the cell more negative
with hyperkalemia, there is more K in the ECF, creating LESS of a gradient, so less K is going to leak out of the cell, making the inside of the cell more positive and more easier to depolarize
What is the most important regulator of potassium homeostasis?
the kidney
*explains why renal failure and decreased GFR, increases seum K