Fluids Flashcards
What body compartment are blood cells considered part of?
These are part of the intracellular body compartment (ICF = 40% of total body water).
Even though they’re located in the vascular space, they are cells, so their volume is considered part of the ICF.
This is why plasma volume is 4% of TBW, or 3L, but circulating blood volume is around 5L.
Interstitial fluid is actually more of a
gel.
Less than 1% exists as a free floating fluid. This means that fluid movement that takes places is due to diffusion, not just free movement of water.
Where is the thoracic duct?
There are two. One on the right and left at the junction of the IJ and subclavian veins. The one on the left is much larger. This puts the patient at risk for chylothorax in the event of CV cannulation in the left IJ.
Movement across semipermeable membranes
Mostly just water moves freely. Solutes like ions, proteins, and glucose don’t freely diffuse, but need carrier proteins or channels. Then water follows concentration gradients.
This is the primary determinant of plasma osmolarity
Sodium
Hypertonic, isotonic, and hypotonic fluids
Normal plasma osmolarity is 280-290
Hypertonic
- 3% Saline (1026)
- D5LR
- D5 NaCl 0.9% (560)
- D5 NaCl 0.45% (505)
Isotonic
- LR (273)
- 0.9% Saline (308)
- 5% Albumin (300)
- Plasmalyte (294)
Hypotonic
- D5W (253)
- 0.45% Saline (154, which is exactly half of 0.9% saline)
Even though D5W isn’t THAT hypotonic, it’s rapidly metabolized so what you’re left with is just free water.
Crystalloids stay in the intravascular space for how long?
About 30 minutes
Dose of hetastarch should not exceed
20mL/kg
Albumin can cause this electrolyte abnormality
hypocalcemia, because it binds to calcium
Colloids increase plasma volume for how long?
3-6 hours
Crystalloids only last 30 minutes in the intravascular space
This colloid is used to decreased blood viscosity
Dextran 40
Potential for anaphylaxis is greatest with this colloid
Dextran
Risk of coagulopathy with colloids
Dextran > Hetastarch > Hextend
So dextran has highest risk of coagulopathy AND anaphylaxis
Why can saline cause hyperchloremic metabolic acidosis?
All the Cl causes bicarb excretion in the kidneys to maintain electroneutrality
These are the major intracellular ions
K+
Mg+
Phosphate