Fluids & Electrolytes

Question 1

Osmolarity

Answer 1

number of particles per LITER of solvent (mOsmoles/L)

Question 2

Osmolality

Answer 2

number of particles per KG of solvent (mOsmoles/kg)

Question 3

Tonicity

Answer 3

effective Osmoles in soln

i.e. solutes that don’t freely cross the mem & determine osmotic pressure gradients

Question 4

Plasma

Answer 4

aq portion of blood WITH clotting factors (not RBC & WBC)

Question 5

Serum

Answer 5

plasma WITHOUT clotting factors

Question 6

Serum osmolality calculation

Answer 6

mOsm/kg = 2 Na + Glucose/18 + BUN/2.8

Question 7

Serum osmolality normal range

Answer 7

275-295 mOsm/kg

reflects tonicity of serum

Question 8

Hypovolemic presentation

Answer 8

• hypotension/orthostasis
• tachycardia
• poor skin tugor/dry mucus mem
• slow capillary refill
• cool extremities

Question 9

Hypervolemic presentation

Answer 9

• hypertension
• edema
• weight gain
• jugular venous distention

Question 10

Part(s) of kidney that secrete water

Answer 10

collecting duct via aquaporins

Question 11

Part(s) of kidney that reabsorb water

Answer 11

prox tubule, ascending loop, distal tubule (Na reabs, water follows)

Question 12

Causes of hypovolemia

Answer 12

• poor PO intake
• infection/fever
• hypermetabolic states (burn/trauma)
• blood loss

Question 13

Maintenance fluids for adults

Answer 13

30-35 mL/kg

Question 14

Maintenance fluids in peds

Answer 14

1st 10 kg -> 100 mL/kg/day
2nd 10 kg -> 50 mL/kg/day
> 20 kg -> 20 mL/kg/day

Question 15

Adjustment for maintenance fluids in CKD, chronic liver disease, and mild HF

Answer 15

x 0.75

Question 16

Adjustment for maintenance fluids in severe HF, and ESRD

Answer 16

x 0.5

Question 17

Use normal maintenance fluids for..

Answer 17

• NPO for procedure
• CKD w/ mild dehydration
• HF w/ mod dehydration
• ESRD w/ severe dehydration

Question 18

Adjustment for maintenance fluids in mild dehydration

Answer 18

x 1.25

Question 20

Adjustment for maintenance fluids in mod dehydration

Answer 20

x 1.5

Question 21

Adjustment for maintenance fluids in severe dehydration

Answer 21

x 2

Question 22

Adjustment for maintenance fluids in hemodynamic shock

Answer 22

use a large vol bolus

Question 23

Hypotonic fluid loss

Answer 23

insensible, sweat, urine

Question 24

Isotonic fluid loss

Answer 24

blood, vomiting, diarrhea

Question 25

D5W

Answer 25

- hypotonic - no electrolytes - 1000 mL free water - shifts water intracell

Question 26

1/2 NS

Answer 26

- hypotonic - 77 mEq/L Na & Cl - 500 mL free water - shifts water intracell

Question 27

3% NaCl

Answer 27

- hypertonic - 513 mEq/L Na & Cl - (-)2133 mL free water - shifts water extracell

Question 28

NS

Answer 28

- isotonic - 154 mEq/L Na & Cl - stays in extracell

Question 29

Lactated ringers

Answer 29

- isotonic - 130 mEq/L Na & 105 mEq/L Cl - stays in extracell

Question 30

5% albumin

Answer 30

- isotonic - no electrolytes - stays in extracell

Question 31

Balanced crystalloids

Answer 31

mimic plasma electrolyte conc - lactated ringers (acidotic) - plasma-lyte A (neutral expensive)

Question 32

N5 D5W

Answer 32

- isotonic - stays in extracell

Question 33

N5 D5W w/ 20mEq KCl

Answer 33

- hypertonic - (-)125 mL free water - shifts water extracell

Question 34

1/2 NS D5W

Answer 34

- hypotonic - 500 mL free water - shifts water intracell

Question 35

1/2 NS D5W w/ 20mEq KCl

Answer 35

- hypotonic - 370 mL free water - shifts water intracell

Question 36

1/2 NS D5W w/ 40mEq KCl

Answer 36

- hypotonic - 240 mL free water - shifts water intracell

Question 37

Hyponatremia labs

Answer 37

Na < 135

Question 38

Drug-induced hyponatremia

Answer 38

syndrome of inappropriate anti diuretic hormone - SSRI - carbemazepine - thiazides - opiates

Question 39

Cause of isotonic hyponatremia

Answer 39

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