fluids and electrolytes

Question 1

intracellular volume is what percent of total body weight?

Answer 1

40% (28L)

Question 2

extracellular volume is what percent of total body weight? (including its makeup and %)

Answer 2

20% (14L)
16% is ISF
4% is plasma volume

Question 3

what is the net filtration pressure equation?

Answer 3

(capillary hydrostatic pressure- interstitial hydrostatic pressure) - (interstitial oncotic pressure - capillary oncotic pressure)

Question 4

osmotic pressure

Answer 4

pressure of a solution across a semi permeable membrane that prevents water from diffusing across that membrane

Question 5

how do you calculate plasma osmolarity and what is normal

Answer 5

normal is 280-290
=2(Na)+(glucose/18)+(BUN/2.8)

Question 6

what can increase plasma osmolarity

Answer 6

hyperglycemia and uremia

Question 7

name two hypotonic solutions

Answer 7

D5W, NaCl .45%

Question 8

name 6 isotonic solutions

Answer 8

NS, LR, plasmalyte A, albumin 5%, voluten 6%, vespan 6%

Question 9

name 5 hypertonic solutions

Answer 9

NaCl 3%
D5 NaCl .9%
D5 NaCl .45%
D5 LR
Dextran 10%

Question 10

how does hypotonic solution affect osmolarity, ECF, and ICF

Answer 10

increases ECF and ICF volumes and decreases osmolarity

Question 11

how does isotonic solution affect osmolarity, ECF, and ICF

Answer 11

increases ECF, but ICF and osmolarity stay the same

Question 12

how does hypertonic solution affect osmolarity, ECF, and ICF

Answer 12

giving hypertonic fluid expands intravascular volume by pulling fluid from ICF to ECF- ECF and plasma osmolarity increase but ICF decreases

Question 13

what does albumin bind to

Answer 13

calcium and it causes hypocalcemia

Question 14

which is the most abundant intracellular cation

Answer 14

potassium

Question 15

hypokalemia presentation

Answer 15

skeletal muscle cramps –> weakness –> paralysis –> worsens digitalis toxicity

Question 16

hyperkalemia presentation

Answer 16

cardiac rhythm disturbances

Question 17

hypokalemia EKG findings

Answer 17

PR interval and QT interval are longer
flat T wave
U wave

Question 18

hyperkalemia EKG findings

Answer 18

(based on serum K concentration)
5.5-6.5 peaked T waves
6.5-7.5 p wave flattening, PR prolongation
7-8 QRS prolongation
8.5 or greater QRS–>sine wave –> VF

Question 19

what is the most abundant extracellular cation

Answer 19

sodium

Question 20

etiologies of hyponatremia (3 categories)

Answer 20

decreased total body Na content (diuretics, salt wasting disease, hypoaldosteronism)
normal total body sodium content (SIADH, hypothyroidism, water intoxication, preoperative stress)
increased total body Na content (cirrhosis, CHF)

Question 21

etiologies of hypernatremia (3 categories)

Answer 21

decreased total body Na content (osmotic diuresis, n/v, adrenal insufficiency)
normal total body Na content (DI, renal failure, diuretics)
increased total body Na content (hyperaldosteronism, increased sodium intake like 3% saline)

Question 22

presentation of hyponatremia
130-135
125-129
115-124
<115

Answer 22

based on serum Na concentration
130-135 no signs to mild signs
125-129 n/v, malaise
115-124 HA, lethargy, altered LOC
115 or less (rapid onset) seizures, coma, cerebral edema, respiratory arrest

Question 23

presentation of hypernatremia

Answer 23

based on serum osmolality
350-375 HA, agitation, confusion
376-400 weakness, tremors, ataxia
401-430 hyperreflexia, muscle twitching
431 or more: seizures, coma, death

Question 24

normal plasma calcium (total) in mg/dL, mEq/L, mmol/dL

Answer 24

8.5-10.5 mg/dL
4.5-5.5 mEq/L
2.12-2.62 mmol/dL

Question 25

normal plasma calcium (ionized) in mg/dL, mEq/L, mmol/dL

Answer 25

4.65-5.28 mg/dL 2.2-2.6 mEq/L 1.16-1/32 mmol/dL

Question 26

how much calcium is ionized

Answer 26

50%

Question 27

which is the most abundant electrolyte in the body

Answer 27

calcium

Question 28

which hormone raises serum calcium and which hormone decreases serum calcium

Answer 28

PTH increases, calcitonin decreases

Question 29

etiologies of hypocalcemia (5)

Answer 29

hypoparathyroidism vitamin D deficiency renal osteodystrophy pancreatitis (same reason as sepsis, increased circulating catecholamines shifts ca into intracellular compartment) sepsis

Question 30

etiologies of hypercalcemia

Answer 30

hyperparathyroidism cancer thyrotoxicosis thiazide diuretics (increases ca reabsorption în exchange for Na) immobilization

Question 31

presentation of hypocalcemia

Answer 31

skeletal muscle cramps nerve irritability- parasthesia and tetany laryngospasm mental status changes- seizures chovsteks sign (facial nerve/masseter muscle) trusseaus sign (BP inflated above SBP for 3 min, muscle spasms of hand and arm)

Question 32

presentation of hypercalcemia

Answer 32

nausea abdominal pain HTN psychosis mental status changes - seizures

Question 33

EKG finding with hypocalcemia

Answer 33

long QT interval (prolonged plateau phase of AP)

Question 34

EKG finding with hypercalcemia

Answer 34

short QT interval

Question 35

treatment of hypocalcemia

Answer 35

calcium or vitamin D

Question 36

treatment of hypercalemia

Answer 36

NS or loop diuretic (furosemide)

Question 37

normal plasma magnesium (mg/dL and mEq/L)

Answer 37

1.7-2.4mg/dL or 1.5-3mEq/L

Question 38

etiology of hypomagnesemia (5)

Answer 38

poor intake alcohol abuse diuretics critical illness common with hypokalemia (will cause K efflux at renal level) and usually also tells PTH to chill which decreases Ca as well

Question 39

etiology of hypermagenesemia (3)

Answer 39

excessive administration renal failure adrenal insufficiency (addisons aka low cortisol and aldosterone output, which increases tubular magnesium reabsorption)

Question 40

treatment for hypermagnesemia

Answer 40

calcium chloride or gluconate

Question 41

symptoms of a magnesium level <1.2mg/dL

Answer 41

tetany, seizures, dysrhythmias

Question 42

symptoms of a magnesium level between 1.2-1.8mg/dL

Answer 42

neuromuscular irritability hypokalemia hypocalcemia

Question 43

symptoms of a magnesium level between 2.5-5mg/dL

Answer 43

typically none

Question 44

symptoms of a magnesium level between 5-7mg/dL

Answer 44

diminished DTR's lethargy/drowsiness flushing n/v

Question 45

symptoms of a magnesium level between 7-12mg/dL

Answer 45

loss of DTR's hypotension EKG changes somnolence

Question 46

symptoms of a magnesium level >12mg/dL

Answer 46

respiratory depression- apnea complete heart block cardiac arrest coma paralysis

Question 47

cardiac, CNS, pulmonary, other effects of acidosis include

Answer 47

increased p50 (right = release) increased SNS tone increased risk of dysrhythmias decreased contractility increased cerebral BF increased ICP increased PVR hyperkalemia

Question 48

cardiac, CNS, pulmonary, other effects of alkalosis include

Answer 48

decreased p50 (left=love) decreased coronary blood flow increased risk of dysrhythmias decreased CBF decreased ICP decreased PVR hypokalemia decreased ical (promotes binding of calcium to albumin)

Question 49

for acute respiratory acidosis, for every 10mmHg increase in PaCO2, pH decreases by

Answer 49

.08

Question 50

for chronic respiratory acidosis, for every 10mmHg increase in PaCO2, pH decreases by

Answer 50

.03

Question 51

anion gap equation

Answer 51

major cations - major anions OR Na - Cl + HCO3= 8-12mEq/L

Question 52

etiology of anion gap acidosis (>14 gap)

Answer 52

MUDPILES methanol uremia DKA paraldehyde isionazid lactate ethanol, ethylene glycol salicylates (inhibits krebs cycle)

Question 53

etiology of non gap acidosis

Answer 53

HARDUP hypoaldosteronism acetazolamide renal tubular acidosis diarrhea ureterosigmoid fistula pancreatic fistula

Question 54

for every HCO3 decrease of 1mEq/L, PaCO2 decreases by

Answer 54

1-1.5mEq/L

Question 55

metabolic alkalosis etiologies

Answer 55

sodium bicarb administration massive transfusion (liver converts preservatives to HCO3-) loss of gastric fluid (most common) loss of acid in urine diuretics ECF depletion (-->increased Na reabsorption --> H and K excretion (maintains electroneutrality)) cushings syndrome (activation of mineralocorticoid receptors by increased cortisol causes Na reabsorption and K secretion and metabolic alkalosis) hyperaldosteronism (conns disease, increases Na retention and hydrogen ion excretion)

Question 56

treatment of metabolic alkalosis

Answer 56

acetazolamide (carbonic anhydrase inhibitor, increases renal excretion of HCO3) spironolactone (mineralocorticoid antagonist) dialysis

Question 57

fluid replacement per hour for very minimal surgical trauma (orofacial surgery)

Answer 57

1-2mL/kg/h

Question 58

fluid replacement per hour for minimal surgical trauma (inguinal hernia repair)

Answer 58

2-4mL/kg/h

Question 59

fluid replacement per hour for moderate surgical trauma (major nonabdominal surgery)

Answer 59

4-6mL/kg/h

Question 60

fluid replacement per hour for severe surgical trauma (major abdominal surgery)

Answer 60

6-8mL/kg/h

Question 61

4:2:1 rule

Answer 61

4mL/kg/h for first 10kg body weight 2mL/kg/h for second 10kg of body weight 1mL/kg/h for anything over that