Fluids and Electrolytes

Question 1

What percentage of body weight is water?

Answer 1

2/3 (Infants have more body water); women have less body water

Question 2

Among total body water, what percentage is IC vs. EC?

Answer 2

IC: 2/3 (Muscle)
EC: 1/3

Question 3

Among the water that is EC, what percentage is intravascular vs. interstitial

Answer 3

1/4 intravascular

3/4 interstitial

Question 4

Most common cause of volume overload?

Answer 4

Iatrogenic: first sign is weight gain

Question 5

Na and Cl contents of NS

Answer 5

154, 154

Question 6

Ionic composition of LR

Answer 6

Na: 130, K 4, Ca 2.7, Cl 109, lactate/bicarb 28

Question 7

Calculation of plasma osmolarity

Answer 7

2xNa + glucose/18 + bun/2.8

Normal 280-295

Question 8

mIVF calculation rate

Answer 8

4/2/1 (10, 10, 1)

Question 9

IV maintenance fluid after major GI surgery

Answer 9

Intraop, 24 hrs: LR; then switch to D5 1/2 NS with 20 K

Question 10

Why D5 in mIVF?

Answer 10

5% dextrose will stimulate insulin release; resulting in AA uptake and protein synthesis (prevents protein catabolism)

Question 11

D5 1/2 @ 125 provides how much glucose per day?

Answer 11

150 g; 525 kcal/day

Question 12

During open abdominal operations, what is approximate fluid loss?

Answer 12

0.5-1L / hr unless there are measurable blood losses

Question 13

At what point do you have to replace blood loss intraoperatively?

Answer 13

500 cc

Question 14

Best indicator of adequate volume replacement

Answer 14

Urine output (0.5 cc/kg/hr; should not be replaced – a sign of good post-op diruesis)

Question 15

Insensible fluid losses

Answer 15

10 cc/kg/day; 75% skin, 25% respiratory (pure water)

Question 16

Fluid resuscitation for significant dehydration

Answer 16

Sweat: NS
Gastric fluid: NS
HPB: LR
Sm/Lg bowerl: LR
GI losses cc/cc

Question 17

Should GI losses be replaced CC/CC?

Answer 17

Yes

Question 18

GI fluid secretion per day: stomach, biliary, panc, duodenum

Answer 18

Stomach: 1-2 L/day
Biliary: 500cc-1 L/day
Panc: 500 cc-1L/day
Duodenum: 500 cc-1L/day

Question 19

GI Electrolyte Losses: sweat

Answer 19

Hypotonic (Na 35-65)

Question 20

GI Electrolyte Losses: saliva

Answer 20

K+ / highest concentration of K in the body

Question 21

GI Electrolyte Losses: stomach

Answer 21

H+, Cl-

Question 22

GI Electrolyte Losses: pancreas

Answer 22

HCO3

Question 23

GI Electrolyte Losses: bile

Answer 23

HCO3

Question 24

GI Electrolyte Losses: small intestine

Answer 24

HCO3, K

Question 25

GI Electrolyte Losses: large intestine

Answer 25

K

Question 26

What electrolytes can dialysis remove?

Answer 26

K, Ca, Mg, PO4, urea, Scr

Question 27

Normal body K+ requirement per day

Answer 27

0.5-1 mEq/kg/day

Question 28

Normal body Na+ requirement per day

Answer 28

1-2 mEq/kg/day

Question 29

Hypokalemia usually occurs in this setting

Answer 29

Over diuresis; may need to replace the Mg

Question 30

When treating hypokalemia, you may need to replete this electrolyte

Answer 30

Mg

Question 31

Hypernatremia usually results from

Answer 31

Poor PO intake; restlessness, irritability, seizures; correct with D5W slowly to avoid brain swelling

Question 32

Hyponatremia is ususally 2/2

Answer 32

Fluid overload; HA, n/v/seizure * Water restruction, diresus * Correct slowly to avoid CPM (1 meQ/hr)

Question 33

Can hyperglycemia cause pseudohyponatremia?

Answer 33

Yes -- for each 100 increment of glucose over normal, add 2 points to the Na value

Question 34

DI can occur with EtOH or head injury

Answer 34

True: Decreased ADH; increased urine output, decreased spec grav, increase serum Na, increased osmolarity

Question 35

Treatment of DI

Answer 35

Free water; DDAVP

Question 36

SIADH can occur with head injury

Answer 36

True: decreased u/p; concentrated urine; hyponatremia; decreased osmolarity

Question 37

Treatment of SIADH

Answer 37

Fluid restriction; diuresis; conivaptain, tolvaptan

Question 38

Most common malignant cause of hypercalcemia

Answer 38

Breast cancer

Question 39

How high does Ca have to get for symptoms

Answer 39

Lethargy, n/v, hypotension (>13)

Question 40

MCC overall and benign cause of hypercalcemia

Answer 40

Hyperparathyroidism

Question 41

MCC hypercalcemic crissi

Answer 41

Undiagnosed hyperparathyroidism with stressor, i.e. surgery

Question 42

What fluid/diuretic to avoid in hypercalcemia?

Answer 42

LR; thiazide diuretics

Question 43

Treatment of hypercalcemic crisis

Answer 43

NS @ 200-300 cc/hr and Lasix

Question 44

Malignant hypercalcemia treatment

Answer 44

Calcitonin, alendronic acid, bisphosphonates, dialysis

Question 45

Hypocalcemia symptoms at what level

Answer 45

< 8; < 4 ionized; perioral tingling and numbness; hyperreflexia, Chovstek's sign, Trousseau's sign; prolonged QT

Question 46

What electrolyte might you need to replace before treating hypocalcemia?

Answer 46

Mg

Question 47

What is the protein adjustment for calcium?

Answer 47

For every 1 g decrease in protein, add 0.8 to Ca

Question 48

MCC of hypocalcemia

Answer 48

Thyroidectomy

Question 49

HyperMg treatment: Ca

Answer 49

Lethargy; occurs in renal failure; Mg containing laxitives, antacids Treatment: Ca

Question 50

HypoMg

Answer 50

Irritability, confusion, hyperreflexia, seizures | - Occurs with massive diuresis, chronic TPN without Mg replacement, ETOH (similar signs to hypocalcemia)

Question 51

Hyperphosphotemia a/w

Answer 51

renal failure | Tx: Sevelamer hydrochloride (Renagel); low-phosphate diet, dialysis

Question 52

Hypophosphatemia most often a/w

Answer 52

Refeeding syndrome; usually from phosphate shift from EC to IC - Sx: failure to vent wean; muscle weakness

Question 53

Treatment of hypo-phos

Answer 53

K phos

Question 54

Best test for azotemia

Answer 54

Urine Na/Cr / Serum Na/Cr

Question 55

RF for tumor lysis syndromes

Answer 55

Leukemia, lymphoma: Increase BUN/Cr, EKG changes; PO4, K, uric acid; decreased Ca Tx: hydration; rasburicase; allopurinol; diuretics