Fluids

Question 1

What body compartment are blood cells considered part of?

Answer 1

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.

Question 2

Interstitial fluid is actually more of a

Answer 2

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.

Question 3

Where is the thoracic duct?

Answer 3

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.

Question 4

Movement across semipermeable membranes

Answer 4

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.

Question 5

This is the primary determinant of plasma osmolarity

Answer 5

Sodium

Question 6

Hypertonic, isotonic, and hypotonic fluids

Normal plasma osmolarity is 280-290

Answer 6

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.

Question 7

Crystalloids stay in the intravascular space for how long?

Answer 7

About 30 minutes

Question 8

Dose of hetastarch should not exceed

Answer 8

20mL/kg

Question 9

Albumin can cause this electrolyte abnormality

Answer 9

hypocalcemia, because it binds to calcium

Question 10

Colloids increase plasma volume for how long?

Answer 10

3-6 hours

Crystalloids only last 30 minutes in the intravascular space

Question 11

This colloid is used to decreased blood viscosity

Answer 11

Dextran 40

Question 12

Potential for anaphylaxis is greatest with this colloid

Answer 12

Dextran

Question 13

Risk of coagulopathy with colloids

Answer 13

Dextran > Hetastarch > Hextend

So dextran has highest risk of coagulopathy AND anaphylaxis

Question 14

Why can saline cause hyperchloremic metabolic acidosis?

Answer 14

All the Cl causes bicarb excretion in the kidneys to maintain electroneutrality

Question 15

These are the major intracellular ions

Answer 15

K+
Mg+
Phosphate

Question 16

These are ht major extracellular ions

Answer 16

Na+
Ca+
Cl-
Bicarb