HRR: fluid balance

Question 1

What is the total body water percentage in men?

Answer 1

Around 60%

Question 2

What is the total body water percentage in women?

Answer 2

About 50-55%

Question 3

What is the total body water percentage in infants?

Answer 3

About 70%

Question 4

What is the total body water percentage in elderly patients?

Answer 4

About 50%

Question 5

What fraction of total body water is in the extracellular space?

Answer 5

1/3

Question 6

What fraction of total body water is in the intracellular space?

Answer 6

2/3

Question 7

What are the two components of extracellular water?

Answer 7

Interstitial compartment and plasma compartment

Question 8

How much water is in the interstitial fluid in the extracellular space?

Answer 8

¾

Question 9

How much water is in the plasma in the extracellular space?

Answer 9

¼

Question 10

How is plasma osmolality measured?

Answer 10

Freezing point depression

Question 11

What electrolyte is most abundant in plasma?

Answer 11

Sodium

Question 12

What is the formula for calculating plasma osmolality?

Answer 12

(2 x sodium) + [(BUN/28) x 10] + [(glucose/180) x 10]

Question 13

What is the value for normal plasma osmolality?

Answer 13

270-290

Question 14

What is a normal plasma osmolar gap?

Answer 14

Less than 10

Question 15

What is a plasma osmolar gap?

Answer 15

The difference between what is measured and what is calculated; this is due to some other compound that we can’t account for with the calculation. This is abnormal.

Question 16

What are likely culprits for increased plasma osmolar gap?

Answer 16

Ketones, alcohols, lactic acid

Question 17

What are ineffective osmoles?

Answer 17

They freely cross membranes and increase osmolality but do not influence the movement of water. Urea and glucose are big examples.

Question 18

What are effective osmoles?

Answer 18

Solutes impermeable to cell membranes. They change osmolality and influence water movement.

Question 19

What is isotonicity?

Answer 19

Normal osmolality; no change in cell size or net water movement.

Question 20

What is hypertonicity?

Answer 20

High osmolality; cells shrink due to water leaving the cell to balance the osmolality.

Question 21

What is hypotonicity?

Answer 21

Low osmolality; cells swell due to water flooding into them to balance osmolality.

Question 22

Describe sodium as an influence on fluid movement.

Answer 22

Sodium cannot pass through the cell membrane, so it acts as a non-penetrating solute. In order to balance out concentration, the water will have to move as opposed to the sodium moving.

Question 23

What is the charge of plasma?

Answer 23

Electroneutral

Question 24

What is a normal anion gap?

Answer 24

Between 5-12

Question 25

What does it mean if there is an anion gap above 12?

Answer 25

There is an increase in anions other than chloride or bicarb.

Question 26

Which compartment has higher protein concentration: plasma or interstitial?

Answer 26

Plasma

Question 27

Compare the osmolality of intracellular, interstitial, and plasma compartments.

Answer 27

They’re all roughly the same! This is because they’re all permeable to water, so the water moves in order to balance out the osmolality.

Question 28

What generates outward hydrostatic force?

Answer 28

The heart

Question 29

What generates inward oncotic pressure?

Answer 29

Proteins

Question 30

What 3 forces cause edema?

Answer 30

1. Increased net hydrostatic pressure 2. Decreased osmotic pressure due to lowered albumin or loss of proteins 3. Increased membrane permeability/loss of membrane integrity

Question 31

Are pulmonary capillaries leaky to protein?

Answer 31

Yes

Question 32

For edema to be clinically relevant, the interstitium must contain how much additional fluid?

Answer 32

3L

Question 33

Dextrose (D5W) is a ___ solution?

Answer 33

Isotonic

Question 34

When dextrose solution is given, where does the water go?

Answer 34

Proportionally with where water is; 2/3 in intracellular space, 1/3 in extracellular space

Question 35

Is dextrose an effective or ineffective osmole?

Answer 35

Ineffective

Question 36

When isotonic saline is given, where does the water go?

Answer 36

The water is only distributed within the ECC, mostly between the plasma space and interstitial space (3/4 in interstitial and ¼ in plasma)

Question 37

What does hypotonic saline do?

Answer 37

Add water to all 3 body water compartments; can treat hypernatremia and DKA

Question 38

What does hypertonic saline solution do?

Answer 38

Remove water from intracellular compartment; can treat severe hyponatremia

Question 39

What kind of solution is lactated ringers?

Answer 39

Isotonic; it contains similar electrolytes to plasma as well as lactate

Question 40

What are plasma expanders?

Answer 40

Solutions that are made of large molecules that cannot pass capillary walls. They increase plasma volume specifically.

Question 41

What are examples of plasma expanders?

Answer 41

Albumin, blood products, hetastarch

Question 42

What is iso-osmotic volume contraction?

Answer 42

Loss of iso-ismotic fluid; example is hemorrhage. Loss of extracellular volume.

Question 43

What is hyper-osmotic volume contraction?

Answer 43

Loss of pure H2O; sweating, fever, diabetes ins. Volume of all compartments is decreased and osmolality increased.

Question 44

What is hypo-osmotic volume contraction?

Answer 44

Loss of NaCl; adrenal insufficiency. Water shifts from extracellular to intracellular. Both have lower osmolality.

Question 45

What is iso-osmotic volume expansion?

Answer 45

Gain of iso-osmotic fluid; general edema, infusion of isotonic saline. Increase in extracellular volume.

Question 46

What is hyper-osmotic volume expansion?

Answer 46

Gain of NaCl; hypertonic saline infusion. Water shifts from intracellular to extracellular and osmolality of both increases.

Question 47

What is hypo-osmotic volume expansion?

Answer 47

Gain of pure H2O; SIDAH. Volume in both compartments are expanded and osmolality decreased.