Fluids, Electrolytes, Acids/Bases - Step Up Flashcards
(137 cards)
1
Q
total body water
A
60% of weight (50% in women)
- decreases with age and obesity
2
Q
ICF is _ % of body weight; ECF is _ % of body weight, _% is interstitial fluid and _% is plasma
A
40
20
15
5
3
Q
fluid loss due to insensible losses increases with .. (4)
A
fever, sweating, hyperventilation, tracheostomies (unhumidified air)
4
Q
normal urine output in infants
A
> 1.0 ml/kg/hr
5
Q
normal urine output in adults
A
> 0.5-1.0 ml/kg/hr
6
Q
each degree over 37 C, body’s water loss increases by..
A
100 ml/day
7
Q
what patients tend to third-space fluid?
A
any condition with hypoalbuminemia
- liver failure
- nephrotic syndrome
8
Q
best fluid when pt is dehydrated or has lost blood
A
normal saline (0.9% NaCl)
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
10
Q
which IVF should be avoided in heart failure and renal failure pts due to risk of volume overload?
A
normal saline
11
Q
which IVF is used to dilute powdered medications?
A
D5W
12
Q
MC trauma resuscitation fluid
A
Ringer’s Lactated solution
- excellent for replacement of IV fluids
- isotonic solution
13
Q
in which situation should Ringer’s Lactate be avoided?
A
hyperkalemia
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
15
Q
what do elevated serum Na, low urine Na and BUN/Cr > 20:1 suggest?
A
hypoperfusion to the kidneys (sign of hypovolemia)
16
Q
how does hematocrit change with hypovolemia?
A
3% increase for every liter deficit
17
Q
how does CBC and proteins in serum change with hypovolemia?
A
increase with an ECF deficit
decrease with an ECF excess
18
Q
how do you correct volume deficit in hypovolemia?
A
give bolus of either Lactated Ringers or Normal Saline
19
Q
do not give bolus fluids with what? (2)
A
dextrose - hyperglycemia
potassium - hyperkalemia
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)
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
22
Q
Tx. of hypervolemia
A
fluid restriction
diuretics
23
Q
changes in Na+ conc. are a reflection of…
A
water balance
24
Q
changes in Na+ content are a reflection of…
A
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
