Fluid Management

Question 1

What percentage of water is found in the intracellular compartment?

Answer 1

67%

Question 2

What percentage of water is found in the extracellular compartment? What are the two sub compartments of ECF?

Answer 2

33% : blood plasma (20%) and interstitial fluid (80%)

Question 3

What is the indication for IV fluids?

Answer 3

A pt whose needs can’t be met by oral or enteral routes. Ex. NPO before sx, vomiting/diarrhea, hypovolemic as a result of blood loss.

Question 4

What are the fluid requirements for a healthy 70kg adult/day?

Answer 4

2.5 L of water, 70mEq Na+ and 40mEq K+

Question 5

What are signs of fluid deficit?

Answer 5

-tachycardia
-tachypnea
-dry mucus mbs
-decreased tissue turgor
-supine hypotension
-low UO (<0.5 ml/kg/h)
-low JVP

Question 6

Differences b/w crystalloid and colloid fluids.

Answer 6

-crystalloids have water soluble molecules while colloids have insoluble molecules (ex. blood and blood products)
-colloids have a higher osmotic pressure

Question 7

In reference to crystalloid fluids, what does isotonic, hypertonic, and hypotonic mean?

Answer 7

Isotonic: no net movement of fluid b/w compartments

Hypertonic: net movement of fluid from the cell into the vascular space

Hypotonic: net movement of fluid from the vascular space into the cell

Question 8

What is the Osm of normal saline (0.9%) vs. Ringer’s Lactate?

Answer 8

NS= 308
RL= 273

Question 9

Pros of normal saline (0.9%)

Answer 9

-good for initial resus
-cheap, long shelf life
-readily available, multiple sizes
-used a lot for OR maintenance fluid
-compatible with all drugs and blood products

Question 10

Cons of normal saline (0.9%)

Answer 10

-hyperchloremic and/or hypernatremia metabolic acidosis (use 3L or less) –> may cause increased WOB
-big sodium load
-use care with heart failure, renal failure, brain injury, and old age

Question 11

Pros of Ringer’s Lacate

Answer 11

-good for resus
-more “physiologic”
-contains K+
-no hyperchloremia

Question 12

Cons of Ringer’s Lactate

Answer 12

-more expensive
-not compatible with some drugs or with blood
-may worsen brain swelling (not as bas as NS)
-use caution with elevated K+, renal failure

Question 13

What is 3% NS used for?

Answer 13

-draws fluid from the cell into the ECF
-used to treat cerebral edema

Question 14

What is 0.45% NS used for?

Answer 14

-moves fluid from extracellular space into cells
-used to replace free water deficit

Question 15

What are dextrose solutions, and what are they used for?

Answer 15

-contain carbohydrates
-used primarily as a source of calories and water (but they are not an efficient volume expander)

Question 16

What are side effects of dextrose solutions?

Answer 16

-hyponatremia and hyperglycemia

Question 17

Why are colloids more effective volume expanders than crystalloids?

Answer 17

Due to large poorly diffusible solutes they have an increased capillary osmotic pressure.

Question 18

What is an example of a non-blood colloid?

Answer 18

Pentaspan: starch solution, no O2 carrying capacity

Question 19

What is the 4-2-1 rule? How is it used?

Answer 19

-fluid replacement method
-first 10 kg x 4cc/kg/h
-next 10 kg x 2cc/kg/h
-remaining kg over 20kg x 1cc/kg/h
-half of the deficit is corrected prior to induction and remaining half intra-operatively