Fluids, Electrolytes, Acids/Bases - Step Up Flashcards Preview

Internal Medicine > Fluids, Electrolytes, Acids/Bases - Step Up > Flashcards

Flashcards in Fluids, Electrolytes, Acids/Bases - Step Up Deck (137):
1

total body water

60% of weight (50% in women)
- decreases with age and obesity

2

ICF is _ % of body weight; ECF is _ % of body weight, _% is interstitial fluid and _% is plasma

40
20
15
5

3

fluid loss due to insensible losses increases with .. (4)

fever, sweating, hyperventilation, tracheostomies (unhumidified air)

4

normal urine output in infants

> 1.0 ml/kg/hr

5

normal urine output in adults

> 0.5-1.0 ml/kg/hr

6

each degree over 37 C, body's water loss increases by..

100 ml/day

7

what patients tend to third-space fluid?

any condition with hypoalbuminemia
- liver failure
- nephrotic syndrome

8

best fluid when pt is dehydrated or has lost blood

normal saline (0.9% NaCl)

9

what is the standard maintenance fluid?

D5 1/2 NS with 20 mEq KCl/L
(5% dextrose and 1/2 normal Saline)

10

which IVF should be avoided in heart failure and renal failure pts due to risk of volume overload?

normal saline

11

which IVF is used to dilute powdered medications?

D5W

12

MC trauma resuscitation fluid

Ringer's Lactated solution
- excellent for replacement of IV fluids
-isotonic solution

13

in which situation should Ringer's Lactate be avoided?

hyperkalemia

14

when should you consider placing a Swan-Ganz catheter in hypovolemic pt?

pt is critically ill
pt w/ cardiac or renal failure

15

what do elevated serum Na, low urine Na and BUN/Cr > 20:1 suggest?

hypoperfusion to the kidneys (sign of hypovolemia)

16

how does hematocrit change with hypovolemia?

3% increase for every liter deficit

17

how does CBC and proteins in serum change with hypovolemia?

increase with an ECF deficit
decrease with an ECF excess

18

how do you correct volume deficit in hypovolemia?

give bolus of either Lactated Ringers or Normal Saline

19

do not give bolus fluids with what? (2)

dextrose - hyperglycemia
potassium - hyperkalemia

20

how do you calculate maintenance fluids?

4-2-1 rule
4 ml for first 10 kg, 2 ml for next 10 kg, 1 ml/kg for every kg over 20
(always give 60 ml for first 20 kg)

21

signs of volume overload (6)

jugular venous distention
elevated CVP or PCWP
pulmonary rales
peripheral edema
weight gain
low hematocrit or albumin conc

22

Tx. of hypervolemia

fluid restriction
diuretics

23

changes in Na+ conc. are a reflection of...

water balance

24

changes in Na+ content are a reflection of...

Na+ balance

25

main osmotically active cation of ECF

sodium

26

increase in Na+ intake results in...

increased ECF volume, increase in GFR and sodium excretion

27

normal plasma hypertonicity

295 mOsm/kg

28

formula for serum osmolarity

(2 Na) + BUN/2.8 + glucose/18
- if BUN and glucose normal, = (2Na) + 10

29

definition of hyponatremia

plasma Na+ conc < 135 mmol/L

30

when do symptoms of hyponatremia occur?

usually around Na+ conc of 120 mmol/L (except in cases of ICP where symptoms are made worse and earlier with low Na)

31

what happens to the deep tendon reflexes in hyponatremia?

hyperactive deep tendon reflexes
(also get muscle twitching and weakness)

32

how do you calculate free water deficit?

TBW (1 - actual Na+/desired Na+)

33

normal serum calcium

8.5-10.5 mg/dl

34

what does calcium balance depend on?

hormonally controlled
albumin level
pH

35

how does albumin affect Ca2+ levels?

most Ca2+ ions are bound to albumin; so if albumin is low, TOTAL Ca2+ is low, but ionized fraction is normal --> pt. does not show sx

36

how can you estimate ionized calcium?

total calcium - (serum albumin x 0.8)

37

how do you assess if person is truly hypocalcemic?

correct Ca2+ = measured total Ca2+ + 0.8 (4-albumin)

38

what effect does pH have on calcium?

increase pH (alkalosis) increases Ca2+ binding to albumin, total Ca2+ is normal but ionized Ca2+ decreases --> pt will manifest w/ signs of hypocalcemia

39

effect of PTH on calcium and phosphate

increases Ca2+ and decreases PO4-

40

effect of calcitonin on calcium and phosphate

decreases Ca2+ and decreases PO4-

41

effect of vit. D on calcium and phosphate

increases Ca2+ and increases PO4-

42

MCC of hypocalcemia

hypoparathyroidism - usually due to surgery

43

what could be the cause of LOW Ca2+ levels, but high PTH levels?

pseudohypoparathyroidism - end organ resistance to PTH
vitamin D deficiency

44

what electrolyte abnormalities cause hyperactive deep tendon reflexes?

hyponatremia
hypocalcemia

45

what are signs of tetany?

hyperactive deep tendon reflexes
Chvostek's sign
Troussaeu's sign

46

what are signs of increase neuromuscular irritability in hypocalcemia?

numbness/tingling - circumoral, fingers, toes
Tetany
Grand Mal seizures

47

cardiovascular manifestations of hypocalcemia

arrhythmias
prolonged QT syndrome

48

in the setting of hypocalcemia, when is Phosphate high?

renal insufficiency
hypoparathyroidism

49

Tx. of symptomatic hypocalcemia

IV calcium gluconate

50

how do you correct hypocalcemia due to PTH deficiency?

vitamin D and high oral Ca2+ intake
thiazide diuretics - lower urinary calcium

51

milk alkali syndrome

hypercalcemia, alkalosis and renal impairment due to excessive intake of calcium and absorbable antacids (calcium carbonate, milk)

52

drugs that cause hypercalcemia

thiazide diuretics
lithium

53

ECG findings in hypercalcemia

shortened QT interval

54

symptoms of hypercalcemia

nephrolithiasis/nephrocalcinosis
bone aches/pains
muscle pain and weakness
pancreatitis, PUD, gout
constipation
psychiatric symptoms
HTN
weight loss

55

what additional lab finding is seen in primary hyperparathyroidism?

elevated urinary cAMP

56

first steps in management of anyone w/ hypercalcemia?

1. IV fluids - normal saline
2. furosemide

57

what tx. inhibits bone resorption in pts with osteoclastic disease?

bisphosphonates (pamidronate)
calcitonin

58

when can you use glucocorticoids in tx. of hypercalcemia?

vitamin-D related mechanisms
multiple myeloma

59

normal K+ levels

3.5-5.0 mmol/L

60

effect of pH on serum k+

alkalosis = hypokalemia
acidosis = hyperkalemia

61

if pt has HTN and hypokalemia...

excessive aldosterone activity is likely

62

if pt is normotensive and hypokalemic..

either GI or renal loss of K+ is likely

63

Bartter's syndrome

chronic volume depletion secondary to AR-defect in salt reabsorption in TAL leading to hyperplasia of JG apparatus and increase renin levels and aldosterone levels; cause of hypokalemia

64

GI losses leading to hypokalemia (5)

vomiting, NG suction - alkalosis
diarrhea
laxatives/enemas
intestinal fistulae
decreased K+ absorption

65

renal losses leading to hypokalemia

diuretics
renal tubular or parenchymal disease
hyperaldosteronism
licorice ingestion
excessive steroids
Mg2+ deficiency
Bartter's syndrome

66

other causes of Hypokalemia

Insulin
insufficiency dietary intake
antibiotics - bactrim, amphotericin B
profuse sweating
B2-agonists

67

increased entry of K+ into cells

alkalosis
B2 agonists
Insulin
vit. B12 replacement

68

ECG changes in hypokalemia

T wave flattens out or inverts if severe
U wave appears
arrhythmias - prolongs normal cardiac conduction

69

effect of K+ levels on deep tendon reflexes

both hypo and hyperkalemia cause DECREASED deep tendon reflexes

70

CF of hypokalemia

muscle weakness/fatigue/paralysis/cramps
decreased deep tendon reflexes
paralytic ileus
polyuria/polydipsia
NV
exacerbates digitalis toxicity

71

what two electrolytes are difficult to correct in case of hypomagnesemia?

Calcium
Potassium

72

preferred method of K+ replacement

oral K+ - safest
- 10 mEq of KCl increases K+ levels by 0.1 mEq/L

73

what kind of fluid should you avoid in hypokalemia?

dextrose containing fluids - increase insulin and cause further K+ shifts into cell

74

when can you give IV KCl

hypokalemia severe (<2.5)
pt has arrhythmias

75

infusion rate of IV KCl

max 10mEq/hr in peripheral IV line; max 20 in central line
- add 1% lidocaine to decrease burning pain

76

in setting of hypokalemia, what does a urine K+ < 20 imply?

extra-renal loss
- renal loss has Urinary K+ > 20

77

causes of increased total body K+

renal failure/ type IV RTA
Addison's dz
drugs
iatrogenic overdose
blood transfusion

78

drugs that cause hyperkalemia

spironolactone
NSAIDs
ACEi
heparin
cyclosporine
digitalis
succinylcholine
Bactrim
B-blockers

79

what can cause a shift of K+ OUT of cells

insulin deficiency
B-blockers
acidosis
tissue/cell breakdown - burns, rhabdo
GI bleeding

80

effect of acidosis on K+ levels

- every 0.1 decrease in pH, K+ increases by 0.7 points

81

what can cause pseudohyperkalemia (spurious elevation)

tight/prolonged tourniquet application
delay in processing - RBC hemolysis
leukocytosis
thrombocytosis

82

effect of hyperkalemia on ammonia

inhibits ammonia synthesis and reabsorption = metabolic acidosis which shifts K+ out of cells and exacerbates it further

83

ECG changes in hyperkalemia

peaked T waves --> widened QRS --> prolonged PR --> loss of P waves --> sine wave pattern --> V.fib

84

CF of hyperkalemia

arrhythmias
muscle weakness and flaccid paralysis
decreased deep tendon reflexes
respiratory failure
NVD, intestinal colic

85

Tx of severe hyperkalemia with ECG changes, muscle paralysis or level > 6.5

IV calcium gluconate

86

methods to immediately/quickly lower K+ levels

1. insulin + glucose (30-60 min)
2. sodium bicarbonate - emergency measure in severe hyperkalemia

87

methods of removing K+ from the body

Kayexalate - sodium polystyrene sulfonate (cation exchange resin)
Hemodialysis
Furosemide

88

who is hemodialysis reserved for in hyperkalemia tx.?

intractable hyperkalemia
pts with renal failure

89

normal Mg2+ levels

1.8-2.5 mg/dL

90

MCC of hypomagnesemia

steatorrheic states

91

causes of hypomagnesemia

GI - steatorrhea, malabsorption, prolonged fasting, TPN, fistulas
alcoholics
renal causes - SIADH, diuretics, Bartter's, drugs, renal transplant

92

drugs causing hypomagnesemia

gentamicin
amphotericin B
cisplatin

93

neuromuscular and CNS sx of hypomagnesemia

muscle twitching/weakness, tremor
hyperreflexia
mental status changes
seizures

94

ECG changes in hypomagnesemia

prolonged QT
T wave flattening
torsades de pointes

95

Tx. of hypomagnesemia

mild - oral Mg (Mg2+ oxide)
severe - IV Mg (Mg sulfate)

96

first sign of hypermagnesemia

progressive loss of deep tendon reflexes

97

CF of hypermagnesemia

nausea, weakness
facial paresthesias
loss of deep tendon reflexes
ECG changes same as in hyperkalemia
somnolence --> coma and muscular paralysis

98

Tx. of hypermagnesemia

IV calcium gluconate for emergent sx
saline + furosemide
dialysis in renal failure pts
intubation

99

normal plasma phosphate conc.

3.0-4.5 mg/dL

100

decreased intestinal absorption of phosphate due to..

alcohol abuse (MCC)
vit D deficiency
malabsorption
excessive use of antacids
TPN and/or starvation

101

increased renal excretion of phosphate due to...

excess PTH states
hyperglycemia
oncogenic osteomalacia
renal tubular acidosis
hypokalemia/hypomagnesemia

102

other causes of low phosphate levels?

respiratory alkalosis
anabolic steroids
severe hyperthermia
DKA (MCC)
hungry bones syndrome

103

Tx. of hypophosphatemia

oral supplementation - neutra-phos capsule, K-phos tablets, milk
severe - parenteral supplementation

104

CF of hyperphosphatemia

metastatic calcifications and soft tissue calcifications - binds calcium (hypocalcemia)

105

Tx. of hyperphosphatemia

phosphate binding antacids contatining AlOH or carbonate

106

anion gap

Na - (HCO3 + Cl)
- normally between 5-15
- represents ions present in serum but unmeasured

107

effects of acidosis

right shift of O2-Hb dissociation curve
depresses CNS
decreases pulmonary blood flow
arrhythmias
impairs myocardial function
hyperkalemia

108

effects of alkalosis

decreases cerebral blood flow
left shift on O2-Hb curve
arrythmias
tetany
seizures

109

an (1) in lactate results in a (2) in HCO3-

1 - increase
2 - decrease

110

what causes an increased AG acidosis?

1. ketoacidosis - DKA, starvation, alcohol
2. lactic acidosis
3. renal failure - decreased NH4 excretion
4. intoxication

111

acid-base defect in salicylate overdose

primary respiratory alkalosis AND AG metabolic acidosis

112

what causes a normal AG acidosis (hyperchloremic)

1. renal tubular acidosis - decreased HCO3 absorption or decreased production of HCO3
2. carbonic anhydrase inhibitors
3. GI loss - diarrhea, pancreatic fistulas, small bowel fistulas, ureterosigmoidostomy
4. adrenal failure

113

MCC of non-AG acidosis?

diarrhea

114

proximal tubular acidosis

causes nonAG acidosis by decreasing reabsoprtion of HCO3-
- multiple myeloma
- cytinosis
- Wilson's disease

115

distal tubular acidosis

inability to make HCO3-
caused by: SLE, Sjogrens and ampho.B

116

CF of metabolic acidosis

hyperventilation - Kussmaul breathing
decreased CO
decreased tissue perfusion

117

Winter's formula

expected PaCO2 = 1.5 (HCO3) + 8 (+/- 2)

118

in Winter's formula, if actual PaCO2 > calculated PaCO2...

metabolic acidosis with respiratory acidosis

119

in Winter's formula, if actual PaCO2 < PaCO2..

metabolic acidosis with respiratory alkalosis

120

Tx. of severe metabolic acidosis

NaHCO3 --> tx. up to a pH of 7.20 (no higher)

121

saline-sensitive metabolic alkalosis

Urinary Cl < 20 = ECF contraction and hypokalemia

122

saline-resistant metabolic alkalosis

Urinary Cl > 20 - ECF expansion and HTN

123

causes of saline-sensitive metabolic alkalosis

Vomiting
NG tube suction
diuretics
volume depletion
villous adenoma of colon

124

causes of saline-resistant metabolic alkalosis

primary hyperaldosteronism
Cushing's syndrome
severe hypokalemia
Bartter's syndrome
diuretic abuse
excessive black licorice consumption

125

Tx. of saline-sensitive metabolic alkalosis

IVF with normal saline and K+

126

Tx. of saline-resistant metabolic alkalosis

IVF will NOT help
- underlying cause must be addressed
- spironolactone may help

127

compensation in acute respiratory acidosis

HCO3- rises acutely -> 1 mmol/L for every 10 mmHg increase in PCO2

128

compensation in chronic respiratory acidosis

renal compensation takes about 5 days to complete --> HCO3- rises 4 mmol/L for every 10 mmHg increase in PaCO2

129

what is the main cause of respiratory acidosis

alveolar HYPOVENTILATION

130

major causes of alveolar hypoventilation (5)

1. primary pulmonary disease - COPD, sleep apnea, CH, Obesity
2. neuromuscular dz - myasthenia, ALS
3. CNS - injury to brainstem, stroke
4. drug-induced - opiods, sedatives
5. respiratory muscle fatigue

131

signs of acute CO2 retention

headache
confusion
papilledema

132

effect of elevated PaCO2 on CNS

elevated PaCO2 = increased cerebral blood flow = increased ICP = generalized CNS depression

133

which situations in respiratory acidosis require intubation?

1. severe acidosis
2. PaCO2 > 60 or inability to raise PaO2 w/ O2
3. deterioration in mental status
4. respiratory fatigue

134

PaCO2 is primarily determined by...

1.respiratory rate - any disorder that increases RR can lead to alkalosis
2.tidal volume

135

9 major causes of alveolar hyperventilation:

1. anxiety
2. PE, pneumonia, pulm edema, atelectasis, effusion
3. sepsis
4. hypoxia - high altitudes
5. mechanical ventilation
6. pregnancy
7. liver disease
8. medications - aspirin
9. hyperventilation syndrome

136

CF of respiratory alkalosis

1. decreased cerebral blood flow - lightheaded/dizzy, anxiety, paresthesias, perioral numbness
2. tetany
3. arrhythmias

137

Tx. of respiratory alkalosis

inhaled mixture containing CO2
breathing into a paper bag