6. Fluid and Hemodynamics

Question 1

What is generally the major determinant of osmolality?

Answer 1

Sodium (you can basically double Na + 10) - glucose sometimes but in general it’s mostly sodium

Question 2

Which osmole freely moves from ECF to ICF?

Answer 2

Urea

Question 3

Do sodium and glucose move freely from ECF to ICF?

Answer 3

No - limited to the ECF component

Question 4

What happens to the brain in hypo vs. hypernatremia?

Answer 4

Mental status changes (hyponatremia - swelling of cells, hypernatremia - shrinking of cells)

Question 5

Why is there essentially no glucose, fructose, or galactose in cells?

Answer 5

Gets metabolized instantly

Question 6

What happens to serum sodium when you have hyperglycemia?

Answer 6

Hyponatremia because water leaves cells - dilution effect

Question 7

When we lose isotonic fluid, where does it come from?

Answer 7

ECF

Question 8

When do we get isotonic loss of fluid?

Answer 8

Hemorrhage, diarrhea

Question 9

When do we get isotonic gain of fluid?

Answer 9

Too much saline

Question 10

What is it called when we lose more salt than water?

Answer 10

Loss of hypertonic solution (e.g. when we use diuretics)

Question 11

What is the most common cause of gaining pure water without salt?

Answer 11

SIADH

Question 12

What cancer has SIADH as a paraneoplastic syndrome?

Answer 12

Small cell lung cancer

Question 13

What is the treatment of choice for SIADH?

Answer 13

Free water restriction because you’re constantly absorbing pure water

Question 14

When ADH is present do you concentrate or dilute your urine?

Answer 14

Concentrate

Question 15

Serum sodium < 120 - be suspicious of?

Answer 15

SIADH

Question 16

What diabetic medications produce SIADH?

Answer 16

Oral sulfonylureas

Question 17

What compartment is all the total body sodium in?

Answer 17

ECF

Question 18

What clinical sign always accompanies increase in total body sodium?

Answer 18

Pitting edema (because of the increase in sodium in interstitial fluid)

Question 19

What do you call it when we lose pure water?

Answer 19

Diabetes insipidus

Question 20

What should you give an infant with diarrhea?

Answer 20

Hypotonic salt solution because they have hypotonic diarrhea

Question 21

Sodium has to be combined with what to be absorbed in the GI for oral replacement?

Answer 21

Glucose because of cotransport

Question 22

What is the tonicity of sweat?

Answer 22

Hypotonic salt solution

Question 23

What is the sympathetic response to hypovolemia (decreased cardiac output)?

Answer 23

Catecholamines!

1. Venoconstriction - increase return to the right side of the heart
2. Increase HR and contractility
3. Upregulate RAA axis - increase aldosterone to reabsorb salt and water

Question 24

Where are the receptors that sense blood flow in the kidney?

Answer 24

JGA in afferent arteriole

Question 25

What do you give in hypovolemic shock if you don’t have blood?

Answer 25

ISOTONIC saline - you need to keep the fluid in ECF (normal saline is basically plasma without the protein)

Question 26

What is the tonicity of the fluid you absorb in the PCT?

Answer 26

Roughly isotonic

Question 27

What is the tonicity of the fluid you absorb via aldosterone?

Answer 27

Roughly isotonic

Question 28

What is the tonicity of the fluid you absorb via ADH?

Answer 28

Pure water (hypotonic)

Question 29

What does ANP do?

Answer 29

Gets rid of salt - only released in volume overloaded states (when right or left atria are dilated)

Question 30

What is the ADH level in central diabetes insipidus?

Answer 30

Low

Question 31

What does skin turgor tell you?

Answer 31

Total body sodium (normal if skin snaps back)

Question 32

What’s your nonpharmacologic treatment for any pitting edema state?

Answer 32

Restrict salt and water