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

Fluids, Electrolytes, Acids/Bases - Step Up Flashcards

1
Q

total body water

A

60% of weight (50% in women)

- decreases with age and obesity

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2
Q

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

A

40
20
15
5

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3
Q

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

A

fever, sweating, hyperventilation, tracheostomies (unhumidified air)

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4
Q

normal urine output in infants

A

> 1.0 ml/kg/hr

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5
Q

normal urine output in adults

A

> 0.5-1.0 ml/kg/hr

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6
Q

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

A

100 ml/day

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7
Q

what patients tend to third-space fluid?

A

any condition with hypoalbuminemia

  • liver failure
  • nephrotic syndrome
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8
Q

best fluid when pt is dehydrated or has lost blood

A

normal saline (0.9% NaCl)

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9
Q

what is the standard maintenance fluid?

A

D5 1/2 NS with 20 mEq KCl/L

5% dextrose and 1/2 normal Saline

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10
Q

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

A

normal saline

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11
Q

which IVF is used to dilute powdered medications?

A

D5W

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12
Q

MC trauma resuscitation fluid

A

Ringer’s Lactated solution

  • excellent for replacement of IV fluids
  • isotonic solution
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13
Q

in which situation should Ringer’s Lactate be avoided?

A

hyperkalemia

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14
Q

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

A

pt is critically ill

pt w/ cardiac or renal failure

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15
Q

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

A

hypoperfusion to the kidneys (sign of hypovolemia)

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16
Q

how does hematocrit change with hypovolemia?

A

3% increase for every liter deficit

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17
Q

how does CBC and proteins in serum change with hypovolemia?

A

increase with an ECF deficit

decrease with an ECF excess

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18
Q

how do you correct volume deficit in hypovolemia?

A

give bolus of either Lactated Ringers or Normal Saline

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19
Q

do not give bolus fluids with what? (2)

A

dextrose - hyperglycemia

potassium - hyperkalemia

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20
Q

how do you calculate maintenance fluids?

A

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)

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21
Q

signs of volume overload (6)

A 
jugular venous distention
elevated CVP or PCWP
pulmonary rales
peripheral edema
weight gain
low hematocrit or albumin conc
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22
Q

Tx. of hypervolemia

A

fluid restriction

diuretics

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23
Q

changes in Na+ conc. are a reflection of…

A

water balance

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24
Q

changes in Na+ content are a reflection of…

A

Na+ balance

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25
Q

main osmotically active cation of ECF

A

sodium

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26
Q

increase in Na+ intake results in…

A

increased ECF volume, increase in GFR and sodium excretion

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27
Q

normal plasma hypertonicity

A

295 mOsm/kg

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28
Q

formula for serum osmolarity

A

(2 Na) + BUN/2.8 + glucose/18

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

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29
Q

definition of hyponatremia

A

plasma Na+ conc < 135 mmol/L

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30
Q

when do symptoms of hyponatremia occur?

A

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

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31
Q

what happens to the deep tendon reflexes in hyponatremia?

A

hyperactive deep tendon reflexes

also get muscle twitching and weakness

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32
Q

how do you calculate free water deficit?

A

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

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33
Q

normal serum calcium

A

8.5-10.5 mg/dl

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34
Q

what does calcium balance depend on?

A

hormonally controlled
albumin level
pH

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35
Q

how does albumin affect Ca2+ levels?

A

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

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36
Q

how can you estimate ionized calcium?

A

total calcium - (serum albumin x 0.8)

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37
Q

how do you assess if person is truly hypocalcemic?

A

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

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38
Q

what effect does pH have on calcium?

A

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

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39
Q

effect of PTH on calcium and phosphate

A

increases Ca2+ and decreases PO4-

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40
Q

effect of calcitonin on calcium and phosphate

A

decreases Ca2+ and decreases PO4-

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41
Q

effect of vit. D on calcium and phosphate

A

increases Ca2+ and increases PO4-

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42
Q

MCC of hypocalcemia

A

hypoparathyroidism - usually due to surgery

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43
Q

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

A

pseudohypoparathyroidism - end organ resistance to PTH

vitamin D deficiency

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44
Q

what electrolyte abnormalities cause hyperactive deep tendon reflexes?

A

hyponatremia

hypocalcemia

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45
Q

what are signs of tetany?

A

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

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46
Q

what are signs of increase neuromuscular irritability in hypocalcemia?

A

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

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47
Q

cardiovascular manifestations of hypocalcemia

A

arrhythmias

prolonged QT syndrome

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48
Q

in the setting of hypocalcemia, when is Phosphate high?

A

renal insufficiency

hypoparathyroidism

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49
Q

Tx. of symptomatic hypocalcemia

A

IV calcium gluconate

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50
Q

how do you correct hypocalcemia due to PTH deficiency?

A

vitamin D and high oral Ca2+ intake

thiazide diuretics - lower urinary calcium

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51
Q

milk alkali syndrome

A

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

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52
Q

drugs that cause hypercalcemia

A

thiazide diuretics

lithium

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53
Q

ECG findings in hypercalcemia

A

shortened QT interval

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54
Q

symptoms of hypercalcemia

A 
nephrolithiasis/nephrocalcinosis
bone aches/pains
muscle pain and weakness
pancreatitis, PUD, gout
constipation
psychiatric symptoms
HTN
weight loss
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55
Q

what additional lab finding is seen in primary hyperparathyroidism?

A

elevated urinary cAMP

56
Q

first steps in management of anyone w/ hypercalcemia?

A
  1. IV fluids - normal saline

2. furosemide

57
Q

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

A

bisphosphonates (pamidronate)

calcitonin

58
Q

when can you use glucocorticoids in tx. of hypercalcemia?

A

vitamin-D related mechanisms

multiple myeloma

59
Q

normal K+ levels

A

3.5-5.0 mmol/L

60
Q

effect of pH on serum k+

A 
alkalosis = hypokalemia
acidosis = hyperkalemia
61
Q

if pt has HTN and hypokalemia…

A

excessive aldosterone activity is likely

62
Q

if pt is normotensive and hypokalemic..

A

either GI or renal loss of K+ is likely

63
Q

Bartter’s syndrome

A

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
Q

GI losses leading to hypokalemia (5)

A 
vomiting, NG suction - alkalosis
diarrhea
laxatives/enemas
intestinal fistulae
decreased K+ absorption
65
Q

renal losses leading to hypokalemia

A 
diuretics
renal tubular or parenchymal disease
hyperaldosteronism
licorice ingestion
excessive steroids
Mg2+ deficiency
Bartter's syndrome
66
Q

other causes of Hypokalemia

A 
Insulin
insufficiency dietary intake
antibiotics - bactrim, amphotericin B
profuse sweating
B2-agonists
67
Q

increased entry of K+ into cells

A

alkalosis
B2 agonists
Insulin
vit. B12 replacement

68
Q

ECG changes in hypokalemia

A

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

69
Q

effect of K+ levels on deep tendon reflexes

A

both hypo and hyperkalemia cause DECREASED deep tendon reflexes

70
Q

CF of hypokalemia

A 
muscle weakness/fatigue/paralysis/cramps
decreased deep tendon reflexes
paralytic ileus
polyuria/polydipsia
NV
exacerbates digitalis toxicity
71
Q

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

A

Calcium

Potassium

72
Q

preferred method of K+ replacement

A

oral K+ - safest

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

73
Q

what kind of fluid should you avoid in hypokalemia?

A

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

74
Q

when can you give IV KCl

A 
hypokalemia severe (<2.5)
pt has arrhythmias
75
Q

infusion rate of IV KCl

A

max 10mEq/hr in peripheral IV line; max 20 in central line

- add 1% lidocaine to decrease burning pain

76
Q

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

A

extra-renal loss

- renal loss has Urinary K+ > 20

77
Q

causes of increased total body K+

A 
renal failure/ type IV RTA
Addison's dz
drugs 
iatrogenic overdose
blood transfusion
78
Q

drugs that cause hyperkalemia

A 
spironolactone
NSAIDs
ACEi
heparin
cyclosporine
digitalis
succinylcholine
Bactrim
B-blockers
79
Q

what can cause a shift of K+ OUT of cells

A 
insulin deficiency
B-blockers
acidosis
tissue/cell breakdown - burns, rhabdo
GI bleeding
80
Q

effect of acidosis on K+ levels

A
  • every 0.1 decrease in pH, K+ increases by 0.7 points
81
Q

what can cause pseudohyperkalemia (spurious elevation)

A

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

82
Q

effect of hyperkalemia on ammonia

A

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

83
Q

ECG changes in hyperkalemia

A

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

84
Q

CF of hyperkalemia

A 
arrhythmias
muscle weakness and flaccid paralysis
decreased deep tendon reflexes
respiratory failure
NVD, intestinal colic
85
Q

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

A

IV calcium gluconate

86
Q

methods to immediately/quickly lower K+ levels

A
  1. insulin + glucose (30-60 min)

2. sodium bicarbonate - emergency measure in severe hyperkalemia

87
Q

methods of removing K+ from the body

A

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

88
Q

who is hemodialysis reserved for in hyperkalemia tx.?

A

intractable hyperkalemia

pts with renal failure

89
Q

normal Mg2+ levels

A

1.8-2.5 mg/dL

90
Q

MCC of hypomagnesemia

A

steatorrheic states

91
Q

causes of hypomagnesemia

A

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

92
Q

drugs causing hypomagnesemia

A

gentamicin
amphotericin B
cisplatin

93
Q

neuromuscular and CNS sx of hypomagnesemia

A

muscle twitching/weakness, tremor
hyperreflexia
mental status changes
seizures

94
Q

ECG changes in hypomagnesemia

A

prolonged QT
T wave flattening
torsades de pointes

95
Q

Tx. of hypomagnesemia

A

mild - oral Mg (Mg2+ oxide)

severe - IV Mg (Mg sulfate)

96
Q

first sign of hypermagnesemia

A

progressive loss of deep tendon reflexes

97
Q

CF of hypermagnesemia

A 
nausea, weakness
facial paresthesias
loss of deep tendon reflexes
ECG changes same as in hyperkalemia
somnolence --> coma and muscular paralysis
98
Q

Tx. of hypermagnesemia

A

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

99
Q

normal plasma phosphate conc.

A

3.0-4.5 mg/dL

100
Q

decreased intestinal absorption of phosphate due to..

A 
alcohol abuse (MCC)
vit D deficiency
malabsorption
excessive use of antacids
TPN and/or starvation
101
Q

increased renal excretion of phosphate due to…

A 
excess PTH states
hyperglycemia
oncogenic osteomalacia
renal tubular acidosis
hypokalemia/hypomagnesemia
102
Q

other causes of low phosphate levels?

A 
respiratory alkalosis
anabolic steroids
severe hyperthermia
DKA (MCC)
hungry bones syndrome
103
Q

Tx. of hypophosphatemia

A

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

104
Q

CF of hyperphosphatemia

A

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

105
Q

Tx. of hyperphosphatemia

A

phosphate binding antacids contatining AlOH or carbonate

106
Q

anion gap

A

Na - (HCO3 + Cl)

  • normally between 5-15
  • represents ions present in serum but unmeasured
107
Q

effects of acidosis

A 
right shift of O2-Hb dissociation curve
depresses CNS
decreases pulmonary blood flow
arrhythmias
impairs myocardial function
hyperkalemia
108
Q

effects of alkalosis

A 
decreases cerebral blood flow
left shift on O2-Hb curve
arrythmias
tetany
seizures
109
Q

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

A

1 - increase

2 - decrease

110
Q

what causes an increased AG acidosis?

A
  1. ketoacidosis - DKA, starvation, alcohol
  2. lactic acidosis
  3. renal failure - decreased NH4 excretion
  4. intoxication
111
Q

acid-base defect in salicylate overdose

A

primary respiratory alkalosis AND AG metabolic acidosis

112
Q

what causes a normal AG acidosis (hyperchloremic)

A
  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
Q

MCC of non-AG acidosis?

A

diarrhea

114
Q

proximal tubular acidosis

A

causes nonAG acidosis by decreasing reabsoprtion of HCO3-

  • multiple myeloma
  • cytinosis
  • Wilson’s disease
115
Q

distal tubular acidosis

A

inability to make HCO3-

caused by: SLE, Sjogrens and ampho.B

116
Q

CF of metabolic acidosis

A

hyperventilation - Kussmaul breathing
decreased CO
decreased tissue perfusion

117
Q

Winter’s formula

A

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

118
Q

in Winter’s formula, if actual PaCO2 > calculated PaCO2…

A

metabolic acidosis with respiratory acidosis

119
Q

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

A

metabolic acidosis with respiratory alkalosis

120
Q

Tx. of severe metabolic acidosis

A

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

121
Q

saline-sensitive metabolic alkalosis

A

Urinary Cl < 20 = ECF contraction and hypokalemia

122
Q

saline-resistant metabolic alkalosis

A

Urinary Cl > 20 - ECF expansion and HTN

123
Q

causes of saline-sensitive metabolic alkalosis

A 
Vomiting
NG tube suction
diuretics
volume depletion
villous adenoma of colon
124
Q

causes of saline-resistant metabolic alkalosis

A 
primary hyperaldosteronism
Cushing's syndrome
severe hypokalemia
Bartter's syndrome
diuretic abuse
excessive black licorice consumption
125
Q

Tx. of saline-sensitive metabolic alkalosis

A

IVF with normal saline and K+

126
Q

Tx. of saline-resistant metabolic alkalosis

A

IVF will NOT help

  • underlying cause must be addressed
  • spironolactone may help
127
Q

compensation in acute respiratory acidosis

A

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

128
Q

compensation in chronic respiratory acidosis

A

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

129
Q

what is the main cause of respiratory acidosis

A

alveolar HYPOVENTILATION

130
Q

major causes of alveolar hypoventilation (5)

A
  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
Q

signs of acute CO2 retention

A

headache
confusion
papilledema

132
Q

effect of elevated PaCO2 on CNS

A

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

133
Q

which situations in respiratory acidosis require intubation?

A
  1. severe acidosis
  2. PaCO2 > 60 or inability to raise PaO2 w/ O2
  3. deterioration in mental status
  4. respiratory fatigue
134
Q

PaCO2 is primarily determined by…

A
  1. respiratory rate - any disorder that increases RR can lead to alkalosis
  2. tidal volume
135
Q

9 major causes of alveolar hyperventilation:

A
  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
Q

CF of respiratory alkalosis

A
  1. decreased cerebral blood flow - lightheaded/dizzy, anxiety, paresthesias, perioral numbness
  2. tetany
  3. arrhythmias
137
Q

Tx. of respiratory alkalosis

A

inhaled mixture containing CO2

breathing into a paper bag

Internal Medicine (9 decks)

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